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  Subjects -> ENGINEERING (Total: 2298 journals)
    - CHEMICAL ENGINEERING (192 journals)
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    - ENGINEERING (1209 journals)
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CIVIL ENGINEERING (192 journals)                     

Showing 1 - 192 of 192 Journals sorted alphabetically
ACI Structural Journal     Full-text available via subscription   (Followers: 17)
Acta Polytechnica : Journal of Advanced Engineering     Open Access   (Followers: 2)
Acta Structilia : Journal for the Physical and Development Sciences     Open Access   (Followers: 2)
Advances in Civil Engineering     Open Access   (Followers: 36)
Advances in Structural Engineering     Full-text available via subscription   (Followers: 28)
Agregat     Open Access  
Ambiente Construído     Open Access   (Followers: 1)
American Journal of Civil Engineering and Architecture     Open Access   (Followers: 31)
Architectural Engineering     Open Access   (Followers: 4)
Archives of Civil and Mechanical Engineering     Full-text available via subscription   (Followers: 1)
Archives of Civil Engineering     Open Access   (Followers: 10)
Archives of Hydro-Engineering and Environmental Mechanics     Open Access   (Followers: 2)
ATBU Journal of Environmental Technology     Open Access   (Followers: 4)
Australian Journal of Structural Engineering     Full-text available via subscription   (Followers: 6)
Baltic Journal of Road and Bridge Engineering     Full-text available via subscription   (Followers: 1)
BER : Building and Construction : Full Survey     Full-text available via subscription   (Followers: 10)
BER : Building Contractors' Survey     Full-text available via subscription   (Followers: 4)
BER : Building Sub-Contractors' Survey     Full-text available via subscription   (Followers: 3)
BER : Survey of Business Conditions in Building and Construction : An Executive Summary     Full-text available via subscription   (Followers: 4)
Bioinspired Materials     Open Access   (Followers: 5)
Bridge Structures : Assessment, Design and Construction     Hybrid Journal   (Followers: 16)
Building & Management     Open Access  
Building and Environment     Hybrid Journal   (Followers: 15)
Building Women     Full-text available via subscription  
Built Environment Project and Asset Management     Hybrid Journal   (Followers: 15)
Bulletin of Pridniprovsk State Academy of Civil Engineering and Architecture     Open Access   (Followers: 6)
Canadian Journal of Civil Engineering     Hybrid Journal   (Followers: 12)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 8)
Case Studies in Nondestructive Testing and Evaluation     Open Access   (Followers: 11)
Case Studies in Structural Engineering     Open Access   (Followers: 9)
Cement and Concrete Composites     Hybrid Journal   (Followers: 17)
Challenge Journal of Concrete Research Letters     Open Access   (Followers: 2)
Challenge Journal of Structural Mechanics     Open Access   (Followers: 5)
Change Over Time     Full-text available via subscription   (Followers: 2)
Civil and Environmental Engineering     Open Access   (Followers: 7)
Civil And Environmental Engineering Reports     Open Access   (Followers: 6)
Civil and Environmental Research     Open Access   (Followers: 19)
Civil Engineering = Siviele Ingenieurswese     Full-text available via subscription   (Followers: 4)
Civil Engineering and Architecture     Open Access   (Followers: 18)
Civil Engineering and Environmental Systems     Hybrid Journal   (Followers: 3)
Civil Engineering and Technology     Open Access   (Followers: 10)
Civil Engineering Dimension     Open Access   (Followers: 8)
Civil Engineering Infrastructures Journal     Open Access  
Cohesion and Structure     Full-text available via subscription   (Followers: 2)
Composite Structures     Hybrid Journal   (Followers: 269)
Computer-aided Civil and Infrastructure Engineering     Hybrid Journal   (Followers: 11)
Computers & Structures     Hybrid Journal   (Followers: 36)
Concrete Research Letters     Open Access   (Followers: 6)
Construction Economics and Building     Open Access   (Followers: 2)
Construction Engineering     Open Access   (Followers: 9)
Construction Management and Economics     Hybrid Journal   (Followers: 22)
Construction Science     Open Access   (Followers: 4)
Constructive Approximation     Hybrid Journal  
Curved and Layered Structures     Open Access   (Followers: 2)
DFI Journal : The Journal of the Deep Foundations Institute     Hybrid Journal   (Followers: 1)
Earthquake Engineering and Structural Dynamics     Hybrid Journal   (Followers: 17)
Enfoque UTE     Open Access   (Followers: 4)
Engineering Project Organization Journal     Hybrid Journal   (Followers: 7)
Engineering Structures     Hybrid Journal   (Followers: 13)
Engineering Structures and Technologies     Hybrid Journal   (Followers: 2)
Engineering, Construction and Architectural Management     Hybrid Journal   (Followers: 14)
Environmental Geotechnics     Hybrid Journal   (Followers: 5)
European Journal of Environmental and Civil Engineering     Hybrid Journal   (Followers: 9)
Fatigue & Fracture of Engineering Materials and Structures     Hybrid Journal   (Followers: 16)
Frattura ed Integrità Strutturale : Fracture and Structural Integrity     Open Access  
Frontiers in Built Environment     Open Access  
Frontiers of Structural and Civil Engineering     Hybrid Journal   (Followers: 6)
Geomaterials     Open Access   (Followers: 4)
Geosystem Engineering     Hybrid Journal   (Followers: 1)
Geotechnik     Hybrid Journal   (Followers: 3)
Géotechnique Letters     Hybrid Journal   (Followers: 7)
GISAP : Technical Sciences, Construction and Architecture     Open Access  
HBRC Journal     Open Access   (Followers: 2)
Hormigón y Acero     Full-text available via subscription  
HVAC&R Research     Hybrid Journal  
Indonesian Journal of Urban and Environmental Technology     Open Access  
Indoor and Built Environment     Hybrid Journal   (Followers: 2)
Infrastructure Asset Management     Hybrid Journal   (Followers: 2)
Infrastructures     Open Access  
Ingenio Magno     Open Access   (Followers: 1)
Insight - Non-Destructive Testing and Condition Monitoring     Full-text available via subscription   (Followers: 22)
International Journal for Service Learning in Engineering     Open Access  
International Journal of 3-D Information Modeling     Full-text available via subscription   (Followers: 3)
International Journal of Advanced Structural Engineering     Open Access   (Followers: 16)
International Journal of Civil, Mechanical and Energy Science     Open Access   (Followers: 1)
International Journal of Concrete Structures and Materials     Open Access   (Followers: 14)
International Journal of Condition Monitoring     Full-text available via subscription   (Followers: 2)
International Journal of Construction Engineering and Management     Open Access   (Followers: 9)
International Journal of Geo-Engineering     Open Access   (Followers: 3)
International Journal of Geosynthetics and Ground Engineering     Full-text available via subscription   (Followers: 4)
International Journal of Masonry Research and Innovation     Hybrid Journal   (Followers: 1)
International Journal of Pavement Research and Technology     Open Access   (Followers: 6)
International Journal of Protective Structures     Hybrid Journal   (Followers: 6)
International Journal of Steel Structures     Hybrid Journal   (Followers: 2)
International Journal of Structural Engineering     Hybrid Journal   (Followers: 10)
International Journal of Structural Integrity     Hybrid Journal   (Followers: 2)
International Journal of Structural Stability and Dynamics     Hybrid Journal   (Followers: 7)
International Journal of Sustainable Built Environment     Open Access   (Followers: 4)
International Journal of Sustainable Construction Engineering and Technology     Open Access   (Followers: 8)
International Journal on Pavement Engineering & Asphalt Technology     Open Access   (Followers: 7)
International Journal Sustainable Construction & Design     Open Access  
Journal of Bridge Engineering     Full-text available via subscription   (Followers: 15)
Journal of Building Engineering     Hybrid Journal   (Followers: 1)
Journal of Building Materials and Structures     Open Access   (Followers: 2)
Journal of Building Performance Simulation     Hybrid Journal   (Followers: 6)
Journal of Civil Engineering and Construction Technology     Open Access   (Followers: 12)
Journal of Civil Engineering and Management     Hybrid Journal   (Followers: 7)
Journal of Civil Engineering and Science     Open Access   (Followers: 8)
Journal of Civil Engineering Research     Open Access   (Followers: 6)
Journal of Civil Engineering, Science and Technology     Open Access  
Journal of Civil Society     Hybrid Journal   (Followers: 4)
Journal of Civil Structural Health Monitoring     Hybrid Journal   (Followers: 4)
Journal of Composites for Construction     Full-text available via subscription   (Followers: 13)
Journal of Computing in Civil Engineering     Full-text available via subscription   (Followers: 24)
Journal of Construction Engineering     Open Access   (Followers: 7)
Journal of Construction Engineering and Management     Full-text available via subscription   (Followers: 19)
Journal of Constructional Steel Research     Hybrid Journal   (Followers: 8)
Journal of Earth Sciences and Geotechnical Engineering     Open Access   (Followers: 4)
Journal of Fluids and Structures     Hybrid Journal   (Followers: 6)
Journal of Frontiers in Construction Engineering     Open Access   (Followers: 2)
Journal of Green Building     Full-text available via subscription   (Followers: 11)
Journal of Highway and Transportation Research and Development (English Edition)     Full-text available via subscription   (Followers: 14)
Journal of Infrastructure Systems     Full-text available via subscription   (Followers: 21)
Journal of Legal Affairs and Dispute Resolution in Engineering and Construction     Full-text available via subscription   (Followers: 5)
Journal of Marine Science and Engineering     Open Access   (Followers: 1)
Journal of Materials and Engineering Structures     Open Access   (Followers: 5)
Journal of Materials in Civil Engineering     Full-text available via subscription   (Followers: 10)
Journal of Nondestructive Evaluation     Hybrid Journal   (Followers: 11)
Journal of Performance of Constructed Facilities     Full-text available via subscription   (Followers: 4)
Journal of Pipeline Systems Engineering and Practice     Full-text available via subscription   (Followers: 7)
Journal of Rehabilitation in Civil Engineering     Open Access   (Followers: 3)
Journal of Solid Waste Technology and Management     Full-text available via subscription   (Followers: 1)
Journal of Structural Engineering     Full-text available via subscription   (Followers: 40)
Journal of Structural Fire Engineering     Full-text available via subscription   (Followers: 6)
Journal of Sustainable Architecture and Civil Engineering     Open Access   (Followers: 3)
Journal of Sustainable Design and Applied Research in Innovative Engineering of the Built Environment     Open Access   (Followers: 1)
Journal of the Civil Engineering Forum     Open Access  
Journal of the South African Institution of Civil Engineering     Open Access   (Followers: 4)
Journal of Water and Environmental Nanotechnology     Open Access  
Jurnal Spektran     Open Access   (Followers: 1)
Jurnal Teknik Sipil dan Perencanaan     Open Access   (Followers: 1)
Konstruksia     Open Access  
KSCE Journal of Civil Engineering     Hybrid Journal   (Followers: 2)
Latin American Journal of Solids and Structures     Open Access   (Followers: 4)
Materiales de Construcción     Open Access  
Mathematical Modelling in Civil Engineering     Open Access   (Followers: 3)
Nondestructive Testing And Evaluation     Hybrid Journal   (Followers: 17)
npj Materials Degradation     Open Access  
Obras y Proyectos     Open Access   (Followers: 1)
Open Journal of Civil Engineering     Open Access   (Followers: 7)
Photonics and Nanostructures - Fundamentals and Applications     Hybrid Journal   (Followers: 2)
Practice Periodical on Structural Design and Construction     Full-text available via subscription   (Followers: 4)
Proceedings of the Institution of Civil Engineers - Bridge Engineering     Hybrid Journal   (Followers: 8)
Proceedings of the Institution of Civil Engineers - Civil Engineering     Hybrid Journal   (Followers: 12)
Proceedings of the Institution of Civil Engineers - Management, Procurement and Law     Hybrid Journal   (Followers: 8)
Proceedings of the Institution of Civil Engineers - Municipal Engineer     Hybrid Journal   (Followers: 3)
Proceedings of the Institution of Civil Engineers - Structures and Buildings     Hybrid Journal   (Followers: 4)
Random Structures and Algorithms     Hybrid Journal   (Followers: 5)
Research in Nondestructive Evaluation     Hybrid Journal   (Followers: 7)
Revista IBRACON de Estruturas e Materiais     Open Access   (Followers: 1)
Road Materials and Pavement Design     Hybrid Journal   (Followers: 11)
Russian Journal of Nondestructive Testing     Hybrid Journal   (Followers: 6)
Science and Engineering of Composite Materials     Hybrid Journal   (Followers: 61)
Selected Scientific Papers - Journal of Civil Engineering     Open Access   (Followers: 3)
Slovak Journal of Civil Engineering     Open Access   (Followers: 2)
Soils and foundations     Full-text available via subscription   (Followers: 5)
Steel Construction - Design and Research     Hybrid Journal   (Followers: 3)
Structural and Multidisciplinary Optimization     Hybrid Journal   (Followers: 10)
Structural Concrete     Hybrid Journal   (Followers: 11)
Structural Control and Health Monitoring     Hybrid Journal   (Followers: 9)
Structural Engineering International     Full-text available via subscription   (Followers: 12)
Structural Mechanics of Engineering Constructions and Buildings     Open Access  
Structural Safety     Hybrid Journal   (Followers: 7)
Structural Survey     Hybrid Journal  
Structure     Full-text available via subscription   (Followers: 23)
Structure and Infrastructure Engineering: Maintenance, Management, Life-Cycle Design and Performance     Hybrid Journal   (Followers: 13)
Structures     Hybrid Journal   (Followers: 1)
Study of Civil Engineering and Architecture     Open Access   (Followers: 9)
Superlattices and Microstructures     Hybrid Journal   (Followers: 2)
Surface Innovations     Hybrid Journal  
Technical Report Civil and Architectural Engineering     Open Access  
Teknik     Open Access  
The IES Journal Part A: Civil & Structural Engineering     Hybrid Journal   (Followers: 6)
The Structural Design of Tall and Special Buildings     Hybrid Journal   (Followers: 6)
Thin Films and Nanostructures     Full-text available via subscription   (Followers: 2)
Thin-Walled Structures     Hybrid Journal   (Followers: 4)
Transactions of the VŠB - Technical University of Ostrava. Construction Series     Open Access   (Followers: 1)
Transportation Geotechnics     Full-text available via subscription   (Followers: 1)
Transportation Infrastructure Geotechnology     Hybrid Journal   (Followers: 8)
Underground Space     Open Access  
Water Science & Technology     Partially Free   (Followers: 25)
Water Science and Technology : Water Supply     Partially Free   (Followers: 22)


Journal Cover Engineering Structures
  [SJR: 1.813]   [H-I: 83]   [13 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0141-0296
   Published by Elsevier Homepage  [3118 journals]
  • Quasi-static cyclic tests of precast bridge columns with different
           connection details for high seismic zones
    • Abstract: Publication date: 1 March 2018
      Source:Engineering Structures, Volume 158
      Author(s): Zhiqiang Wang, Hongya Qu, Tiantian Li, Hongyi Wei, Hao Wang, Hongliang Duan, Haixi Jiang
      In this study, seven 1/3-scale bridge column specimens are investigated under the same quasi-static cyclic loading protocol both experimentally and numerically. The specimens consist of one cast-in-place (CIP) reference column and six precast columns. The precast columns are designed with different connection details, and they are tested for the feasibility study of the urban viaducts of highway S6 in Shanghai, China. The seismic performance of the precast columns needs to be investigated and verified prior to the practical application of these connection designs. Based on the experimental results, the precast specimens solely using mild reinforcement exhibit similar hysteretic behavior to the CIP reference column, though various grouted connection approaches are employed. The differences between these precast specimens and the CIP reference column are less than 15% for all indices. The precast specimens with bonded tendons (prestressing strands or prestressing bars) retain higher strength, but no less than 30% decrease of energy dissipation capacity is found. The bonded prestressing strands give at least 10% increase in strength compared with the CIP reference column, while the bonded prestressing bars provide approximately 50% improvement. The precast specimen utilizing unbonded tendon (prestressing strands) shows unique self-centering capability with equivalent energy dissipation capacity of the CIP reference column, but it has 33% lower ductility. Finite element modeling is performed and calibrated with the test data. Bond-slip behavior near column-to-footing interface is modeled by using a ZeroLength element at the interface. Buckling, fatigue and strength reduction of reinforcement are also considered in the model. Hysteretic behaviors of the specimens can be effectively simulated, and differences of ultimate strengths between the experimental and numerical results are less than 9%.

      PubDate: 2017-12-27T03:13:42Z
  • Finite element modelling of composite cold-formed steel flooring systems
    • Abstract: Publication date: 1 March 2018
      Source:Engineering Structures, Volume 158
      Author(s): Pinelopi Kyvelou, Leroy Gardner, David A. Nethercot
      The findings from a numerical investigation into the degree of composite action that may be mobilised within floor systems comprising cold-formed steel joists and wood-based particle boards are presented herein. Finite element models have been developed, simulating all the components of the examined systems, as well as the interaction between them. The models include initial geometric imperfections, the load-slip response of the fasteners employed to achieve the shear connection as well as both geometric and material nonlinearities. The developed models were first validated against 12 physical tests reported in the literature, which showed them to be capable of accurately capturing the load-deformation curves and failure modes exhibited by the tested specimens. Parametric studies were then performed to examine the influence of key parameters on the structural behaviour of these systems, including the depth and thickness of the cold-formed steel section, as well as the spacing of the employed fasteners; in total, about 100 systems have been examined. Significant benefits in terms of structural response have been identified from the presented numerical study as a result of the mobilisation of composite action; for the systems investigated, which were of typical, practical proportions, up to 140% increases in moment capacity and 40% increases in stiffness were found. The presented research reveals the substantial gains in structural performance and the influence of the key governing parameters for this novel form of composite construction.

      PubDate: 2017-12-27T03:13:42Z
  • Numerical analysis of framed building response to tunnelling induced
           ground movements
    • Abstract: Publication date: 1 March 2018
      Source:Engineering Structures, Volume 158
      Author(s): Jinyang Fu, Zhiwu Yu, Shuying Wang, Junsheng Yang
      Tunnelling in congested urban area may inevitably induce ground movement causing damage to adjacent surface buildings. Past research usually oversimplified surface structure as an equivalent elastic beam, which is unable to represent behaviour of a framed building realistically due to frame action. In this study, a series of numerical analyses were conducted to investigate the behaviour and damage mechanism of a framed building with individual footing due to tunnelling induced ground movements. Nonlinear behaviour of the infilled wall and the interfaces between soil-structure and between frame-wall were explored to interpret the complex interaction effects in the system. A non-uniform deformation around the tunnel was applied to simulate the realistic tunnelling induced ground movements while the distribution of initial ground stiffness affected by building weight was reproduced by a user defined nonlinear constitutive model. The different responses in terms of angular distortion, horizontal strain and smeared crack pattern of the framed building subject to scenarios with different ground stiffness, interface parameters and different frame infill configurations were evaluated. The results can be practically used to assess the performance of framed building subject to different ground deformation conditions resulting from tunnelling. The presented analysis provided a useful background for properly understanding and prioritizing those factors having a significant effect on the response of framed building to tunnelling induced ground movements.

      PubDate: 2017-12-27T03:13:42Z
  • Vulnerability analysis of industrial RC precast buildings designed
           according to modern seismic codes
    • Abstract: Publication date: 1 March 2018
      Source:Engineering Structures, Volume 158
      Author(s): Marianna Ercolino, Davide Bellotti, Gennaro Magliulo, Roberto Nascimbene
      Seismic performance-based design approach is currently implemented in modern building codes. Design requirements and provisions ensure an adequate structural performance under different intensity levels of seismic action. However, the probability of attainment of a performance level is implicitly considered in the code design approach (provisions and requirements); for instance, the minimum requirements in concrete structures cannot be simply correlated to the probability of collapse of the building as well as to its overall structural response. The aim of this work is to assess the vulnerability with respect to the collapse limit state of industrial single-story RC precast buildings designed according to the current Italian seismic code. The comparison between the Italian code and the Eurocodes is provided throughout the paper. A parametric study is performed by investigating the safety against the collapse of 40 RC single-story precast structures. Multi-stripe analyses are performed by non-linear dynamic analyses at 10 intensity levels. The fragility of the structures is defined by means of the incremental N2 method, which has been demonstrated to be a suitable method for evaluating the collapse capacity of single-story precast buildings. The results demonstrate that the buildings are safe against the collapse mainly because of the structural overstrength with respect to seismic actions. The modelling assumptions are also validated in order to demonstrate the negligible influence of the cracking on the collapse as well as the importance of the geometrical nonlinearities for precast buildings.

      PubDate: 2017-12-27T03:13:42Z
  • Performance assessment of metallic sandwich panels under quasi-static
    • Abstract: Publication date: 1 March 2018
      Source:Engineering Structures, Volume 158
      Author(s): Yasser A. Khalifa, Wael W. El-Dakhakhni, Manuel Campidelli, Michael J. Tait
      The current study forms a part of a larger experimental program investigating the performance of novel, lightweight, cost-effective, cold-formed, steel sandwich panels with different core configurations under blast induced out-of-plane loading. In the body of literature on sandwich panels, no general methodology is provided to assess their post-elastic behavior under either static or dynamic loading. This study represents a first step in determining the resistance of novel sandwich panels under blast pressure: it focuses on evaluating the quasi-static resistance function of the panels, which is instrumental to the determination of their dynamic response to blast, in accordance with recent American (ASCE/SEI 59-11) and Canadian (CSA S850-12) design standards. The tests carried out by the authors involve twenty-one panels categorized in several configurations, each characterized by a different core topology and deck profile, including uni-directional corrugated, bi-directional corrugated, and X-core panels. These configurations are investigated as plausible solutions to the problem of improving the strength, ductility, and energy absorption capabilities of panels tested in a previous stage of the experimental program. The modes of failure experienced by the test panels are identified and discussed. The load and deflection measurements recorded during the tests are used for the characterization of each panel resistance function in terms of yield load, ultimate load, and the corresponding displacements. The influence of core configuration and sheet thickness on the panels’ ductility and energy absorption capacity is also examined. The results presented in this study will be instrumental in the future development of lightweight, cost–effective sandwich panels, to be used as sacrificial cladding in blast resistant buildings.

      PubDate: 2017-12-27T03:13:42Z
  • Non-linear bending analysis of nanocomposites reinforced by
           graphene-nanotubes with finite shell element and membrane enhancement
    • Abstract: Publication date: 1 March 2018
      Source:Engineering Structures, Volume 158
      Author(s): S. Zghal, A. Frikha, F. Dammak
      The purpose of this paper is to investigate the non-linear bending behavior of functionally graded shell structures reinforced by carbon nanotubes (FG-CNTRC) using non-linear double directors shell model and membrane enhancement. This model induces a high order variation of the displacement field along the thickness direction and imposes a zero transverse shear stresses condition in the top and bottom surfaces. The effective material properties of FG-CNTRC are estimated by the modified rule of mixtures using some efficiency parameters. Uniformly (UD) and three graded distributions, known as FG-V, FG-O and FG-X, are considered to show the effects of carbon nanotubes (CNTs) profiles and their volume fractions on non-linear deflections of various shapes of shell structures. To illustrate these effects, a set of numerical examples including beams, plates, cylindrical panels and hemispherical shells are presented. The effects of some geometrical parameters are also examined. A convergence studies are carried out to validate the proposed non-linear model, then non-linear results for FG-CNTRC shell structures are provided leading hence to outline the applicability and the efficiency of the present model.

      PubDate: 2017-12-27T03:13:42Z
  • Comparison of the seismic performance of a partial mass isolation
           technique with conventional TMD and base-isolation systems under
           broad-band and narrow-band excitations
    • Abstract: Publication date: 1 March 2018
      Source:Engineering Structures, Volume 158
      Author(s): Hamidreza Anajafi, Ricardo A. Medina
      In the present study a partial mass isolation (PMI) technique is proposed. This approach, through isolating different portions of masses at different stories, can provide a building with multiple inherent vibration suppressors without the need to add extra masses. Optimization of the PMI system’s parameters is conducted for reference structural models with 6, 12, and 20 stories to minimize root-mean-square inter-story drift responses under Kanai-Tajimi filtered Gaussian white noise excitations, while parameter constraints are specified to control isolated components’ (ICs) responses. The seismic performance of the PMI technique under excitations with different frequency contents (representing different soil profiles) is compared to that of conventional tuned mass damper (TMD) and base-isolation (BI) systems as baseline configurations. Simulation results indicate that the PMI system with extreme isolated mass ratios of 5% or 90% exhibits dynamic behaviors equivalent to those of an equivalent TMD or an ideal BI systems, respectively. Meanwhile, this technique can resolve some of the inherent difficulties associated with the implementation of TMD (e.g., weight restriction) and BI (e.g., problems due to the superstructure flexibility, overturning moments, and heavy loads) in high-rise buildings.

      PubDate: 2017-12-27T03:13:42Z
  • Evaluation of the seismic retrofitting of an unreinforced masonry building
           using numerical modeling and ambient vibration measurements
    • Abstract: Publication date: 1 March 2018
      Source:Engineering Structures, Volume 158
      Author(s): Clotaire Michel, Amin Karbassi, Pierino Lestuzzi
      Ambient vibration measurements and 3-D nonlinear time-history numerical modeling are used to assess the retrofitting measures conducted in a 6-story unreinforced masonry building (URM) built in the end of the 19th century in Switzerland. Retrofitting measures were taken in order to improve the soundproofing and possibly the seismic performance of the building. Reinforced concrete (RC) footings were added under the walls and horizontal steel beams were added to link the walls together with a RC slab at each floor, though the wooden beams were left in place. Several ambient vibration recordings were performed before, during and after the retrofitting work in order to monitor the evolution of the dynamic behavior of the structure. Moreover, numerical models representing the state of the building before and after the retrofit work have been developed to perform nonlinear dynamic analyses using various ground motion records. The change in the modal vibration frequencies, mode shapes, and failure mechanism are presented and discussed in further details. According to ambient vibration measurements, the performed retrofitting resulted in an increase of about 25% of the fundamental frequency. From the results of both the numerical modeling and the ambient vibration measurements, it is confirmed that the in-plane behavior of the slabs evolved from non-rigid floors with in-plane deformation to rigid floors with diaphragm effects. The ambient vibration measurements show that the new stiff slabs could lead to torsion behavior in the building as the result of the diaphragm effect and to higher seismic demand. However, the numerical models show that the displacement capacity of the building increases as a result of those new stiff slabs. Consequently, higher deformation capacity, indicated by the inter-story drift values, on average, are observed for all the damage grades in the post-retrofit state of the building. Finally, the overall seismic safety was only slightly improved.

      PubDate: 2017-12-27T03:13:42Z
  • Upheaval buckling of pipelines due to internal pressure: A geometrically
           nonlinear finite element analysis
    • Abstract: Publication date: 1 March 2018
      Source:Engineering Structures, Volume 158
      Author(s): Marina Vendl Craveiro, Alfredo Gay Neto
      This work presents an analysis of upheaval buckling of pipelines triggered by internal pressure. It discusses the existing relationship between internal pressure and equivalent compressive axial force in the buckling context. The main focus is on the relative influence of prop imperfections and soil friction coefficients in critical load prediction and post-buckling configuration. To perform the analyses, numerical models are developed using geometrically-exact finite element of beams, undergoing large displacements and finite rotations. Contact between the pipeline and the soil is also included in the models. As a result, the work shows the equivalence of applying the internal pressure as a distributed load dependent on pipe curvature and as a follower compressive axial force, both in terms of critical load and post-buckling configuration. Varying prop imperfections and soil friction coefficients, it is concluded that the first parameter has more influence in critical load prediction than the last one. The same occurs in terms of post-buckling configuration: for the same increase of internal pressure from critical load, the imperfections have more influence in the post-buckling displacements than the friction between the pipeline and the soil.

      PubDate: 2017-12-27T03:13:42Z
  • Engine to wing structural design under critical loads caused by a
           propeller blade loss
    • Abstract: Publication date: 1 March 2018
      Source:Engineering Structures, Volume 158
      Author(s): I. Armendáriz, J. Olarrea, J. García-Martínez
      To support the propeller blade loss loads in a turboprop aircraft the engine mounting system has to be carefully designed. The joints have to withstand the flight loads, however, during the blade loss event they have to fail before the wing gets damaged. Using a FEM model and Monte Carlo simulation techniques the possible failure sequences for a broad spectrum of flight conditions have been obtained, including different propeller frequencies, blade loss sizes, angular positions where the blade is lost and also material properties. The structural model includes non-linear behavior, damages, and several types of failure together with stochastic variables which can incorporate parameter uncertainties. Finally, the pylon to wing support is designed to guarantee, with high level of confidence, no major hazard on the aircraft due to this dynamical phenomenon.

      PubDate: 2017-12-27T03:13:42Z
  • Active vibration control design using the Coral Reefs Optimization with
           Substrate Layer algorithm
    • Abstract: Publication date: 15 February 2018
      Source:Engineering Structures, Volume 157
      Author(s): C. Camacho-Gómez, X. Wang, E. Pereira, I.M. Díaz, S. Salcedo-Sanz
      Active vibration control (AVC) via inertial-mass actuators is a viable technique to mitigate human-induced vibrations in civil structures. A multi-input multi-output (MIMO) AVC has been previously proposed in the literature to simultaneously find the sensor/actuator pairs’ optimal placements and tune the control gains. However, the method involved local gradient-based methods, which is not affordable when the number of possible locations of actuators is large. In this case, the computation time to obtain a local solution may be huge and unaffordable, which limits the number of test points and/or actuators/sensors considered. This paper proposes an alternative approach based on a recently proposed meta-heuristic, the Coral Reefs Optimization (CRO) algorithm. More concretely, an enhanced version of the CRO is considered, the Coral Reefs Optimization with Substrate Layer (CRO-SL). The CRO-SL is a competitive co-evolution algorithm in which different exploration procedures are jointly evolved within a single population of potential solutions to the problem. The proposed algorithm is thus able to promote competition among different search methods to solve hard optimization problems. In terms of structural design, this work provides an important step to improve the applicability of AVC systems to real complex structures (with a large number of vibration modes and/or with a large number of test points) by achieving global optimum designs with affordable computation time. A finite element model of a real complex floor structure is used to illustrate the contributions of this paper.

      PubDate: 2017-12-27T03:13:42Z
  • Approximate two-component incremental dynamic analysis using a
           bidirectional energy-based pushover procedure
    • Abstract: Publication date: 15 February 2018
      Source:Engineering Structures, Volume 157
      Author(s): Sahman Soleimani, Armin Aziminejad, A.S. Moghadam
      Incremental dynamic analysis (IDA) is recognized as a valuable method for assessing the performance of structures under earthquake excitation. Since IDA is computationally intensive, a number of previous studies have attempted to approximate IDA curves using pushover analysis. As a requirement for assessments of asymmetric buildings, IDA under two-component ground motions has received minimal attention throughout these studies. To bridge this gap, the current research puts forth an approximate two-component IDA procedure on the basis of a bidirectional energy-based pushover (BEP) analysis. BEP uses the work done by lateral loads and torques through pushover analysis as an index to determine the characteristics of the modal single-degree-of-freedom systems. The suggested formula pertaining to this procedure allows for the simultaneous effect of both components of a ground motion on each mode. To combine the modal responses of this method, a modified complete quadratic combination (CQC) rule is also presented, which is specialized for two-component excitations. The accuracy of the proposed procedure was examined on a two-way asymmetric 3-story building. The findings suggest that BEP is capable of estimating two-component IDA results with a sufficient degree of accuracy.

      PubDate: 2017-12-27T03:13:42Z
  • Progressive instability in circular masonry columns
    • Abstract: Publication date: 15 February 2018
      Source:Engineering Structures, Volume 157
      Author(s): M. Broseghini, P. Zanetti, A.D. Jefferson, M. Gei
      The instability behaviour of eccentrically loaded circular masonry columns is investigated. Two approaches are considered for the analysis. One is based on a semi-analytical formulation of the relevant boundary-value problem for a no-tension material response; the other employs a plastic-damage-contact constitutive model, the CraftS model, to capture the complex microstructural behaviour of the material. The latter has been implemented in the finite element program LUSAS and has been already successfully employed to describe progressive instability in eccentrically loaded brickwork wallettes of rectangular cross section. Equilibrium paths and limit load estimates are computed for both analysis approaches for a range of column aspect ratios and load eccentricities. It is shown that the type of material response becomes less important for specimens with height-to-diameter aspect ratios greater than 7.5 and for loads applied to points in the kernel of the cross section, while for higher eccentricities the presence of a tensile strength increases considerably the limit load. The damage evolution predicted by the models is also investigated for selected cases, showing that the formulation based on the no-tension material is able to capture with good agreement the damaged zone of the column for loads with low eccentricities. For the same type of loading, a useful design formula is provided.
      Graphical abstract image

      PubDate: 2017-12-27T03:13:42Z
  • Method for evaluating the displacement response of RC beams subjected to
           close-in explosion using modified SDOF model
    • Abstract: Publication date: 15 February 2018
      Source:Engineering Structures, Volume 157
      Author(s): M. Nagata, M. Beppu, H. Ichino, J. Takahashi
      This study proposes a method for evaluating the displacement response of RC beams using the equivalent single-degree-of-freedom (SDOF) model considering a close-in blast load distribution. First, to examine the spatial distributions of the peak overpressure and impulse in a close-in explosion, explosion tests were conducted with C-4 explosives at scaled distances of 3.0–0.15 m/kg1/3. Approximation formulae for the spatial distributions of peak overpressure and impulse were proposed as functions of explosive mass, stand-off distance, and target member length. The peak overpressure and impulse estimated by the approximation formulae reproduced the test data adequately. Secondly, close-in explosion tests on RC beams using 110, 160, and 250 g C-4 explosives at a scaled distance of 0.20 m/kg1/3 were conducted to examine the failure states of the RC beams. The modified SDOF model considering blast load distribution owing to close-in explosion was proposed. The proposed SDOF model effectively evaluated the displacement response of the RC beam subjected to the close-in explosive load, while the experimental results were marginally overestimated.

      PubDate: 2017-12-27T03:13:42Z
  • Hierarchical life-cycle design of reinforced concrete structures
           incorporating durability, economic efficiency and green objectives
    • Abstract: Publication date: 15 February 2018
      Source:Engineering Structures, Volume 157
      Author(s): Zhujun Wang, Weiliang Jin, You Dong, Dan M. Frangopol
      Current structural design methods mostly emphasize the short-term structural behavior while neglect the long-term performance, social effects and environmental impacts. To address these problems, the Life-Cycle Design (LCD) method considering environmental impacts and structural deterioration could be adopted within the design process to ensure that the structural performance satisfies various objectives. Due to the complexity and the long lifespan of engineering structures, as well as the lack of standardized design approach, studies and application of LCD that cover all the design objectives are limited. This paper proposes a hierarchical LCD method for concrete structures by combining traditional design with green design and other engineering aspects. The design process is divided into six levels that cover the aspects of structural safety and reliability, durability, economic efficiency, local environment, social impacts, and global environment. The proposed design method is then applied to a reinforced concrete highway bridge in marine environment for the purpose of illustration, and a comprehensive comparison between traditional design and the hierarchical LCD approach is made within six design levels. A brief discussion on the hierarchical LCD framework and the future works is presented before conclusions are made.

      PubDate: 2017-12-27T03:13:42Z
  • Torsional behavior of a hybrid FRP-aluminum space truss bridge:
           Experimental and numerical study
    • Abstract: Publication date: 15 February 2018
      Source:Engineering Structures, Volume 157
      Author(s): Dongdong Zhang, Qilin Zhao, Feng Li, Jie Tao, Yifeng Gao
      A novel lightweight hybrid fiber-reinforced polymer (FRP) – aluminum space truss structure that consists of two triangular deck-truss beams has been designed for rapid emergency bridging system. This paper reports a large-scale pure torsion test on a cantilever full-scale specimen to evaluate the detailed linear-elastic torsional behavior and the load-carrying mechanism of the hybrid twin-trackway spatial structure. Additionally, a structural computational finite element model (FEM) was constructed and validated against the experiments. To fully understand the load-carrying mechanism obtained from the experiments, numerical analyses were performed by equivalently converting the torsion reaction of the hybrid twin-trackway structure to the bending and torsion of its twin triangular deck-truss beams. The results indicate that the experimental structure exhibits a good and specific torsional response, which can be well described by FEM. The unidirectional pultruded FRP profiles are mainly subjected to axial forces and are thus appropriate for application to this unique twin-trackway space truss, unlike in the case of the alone single-trackway triangular beam under torsion. The vertical bending of the twin triangular deck-truss beams play a key role in the behavior of load-carrying of the entire bridge, unlike in the case of the conventional torsional calculation method for the separated box beam. In the initial design, the torsional calculation of such a novel bridge can be carried out using the flexural analytical and numerical models of the triangular deck-truss beam.

      PubDate: 2017-12-27T03:13:42Z
  • Evaluating the seismic behaviour of rammed earth buildings from Portugal:
           From simple tools to advanced approaches
    • Abstract: Publication date: 15 February 2018
      Source:Engineering Structures, Volume 157
      Author(s): Rui A. Silva, Nuno Mendes, Daniel V. Oliveira, Antonio Romanazzi, Oriol Domínguez-Martínez, Tiago Miranda
      Despite the use of rammed earth became marginal in the second half of the past century, Portugal still holds an important built heritage. Recently, a growing use of rammed earth has been observed in modern constructions, but it is putting aside the roots of traditional rammed earth construction. The seismic behaviour of rammed earth buildings is still insufficiently comprehended, constituting a matter of great concern, since most of the traditional dwellings are built on regions with important seismic hazard. Moreover, the complex architecture of modern rammed earth buildings is expected to make their seismic behaviour even more fragile. This paper intends to provide a better comprehension on the seismic behaviour of rammed earth constructions from Portugal. For this purpose, twenty traditional dwellings were evaluated on the basis of a simplified approach, while a modern construction was investigated by means of destructive and non-destructive testing approaches. The main findings of these approaches are discussed in detail, but it can be highlighted that the architectural features of traditional rammed earth buildings benefit their seismic behaviour, while the complex architecture of modern rammed earth buildings demands using advanced engineering tools for their seismic assessment.

      PubDate: 2017-12-27T03:13:42Z
  • R-Funicularity of form found shell structures
    • Abstract: Publication date: 15 February 2018
      Source:Engineering Structures, Volume 157
      Author(s): Stefano Gabriele, Valerio Varano, Giulia Tomasello, Davide Alfonsi
      The study of new design methods targeted to minimize the use of materials is a theme of great relevance nowadays; structural designers pursue structural solutions characterized by efficiency, sustainability and optimization. Funicular systems adopt the “right” shape in accordance with the applied load and are ideally able to act without introducing bending. In this work an effective and easy-to-read method to study and quantify the funicularity is presented and applied to structural shells obtained using form finding, and analyzed under different static loads. In order to formulate the new method, the classical funicularity concept has been extended and the definition of Relaxed Funicularity (R-Funicularity) introduced. The parameter used to define the funicularity is the eccentricity and a structural shell is called R-Funicular when the eccentricity is included into an admissibility interval.

      PubDate: 2017-12-27T03:13:42Z
  • A hysteresis model for timber joints with dowel-type fasteners
    • Abstract: Publication date: 15 February 2018
      Source:Engineering Structures, Volume 157
      Author(s): Matteo Izzi, Giovanni Rinaldin, Andrea Polastri, Massimo Fragiacomo
      Predicting the mechanical behaviour and the failure mechanism of timber joints with dowel-type fasteners requires consideration of several factors, including the geometrical and mechanical properties of the metal fastener, the physical properties of timber and the interaction between such elements. This paper proposes a numerical model where a joint is schematized as an elasto-plastic beam in a non-linear medium with a compression-only behaviour. Unlike the differential approach adopted by most of the hysteresis models published in literature, this model predicts the load-displacement response using simple mechanical relationships and basic input parameters. Furthermore, the model is capable of reproducing the effect of the cavity formed around the fastener by timber crushing, and simulates the hysteretic behaviour and the energy dissipation under cyclic conditions. Shear tests are reproduced on nailed steel-to-timber joints in Cross-Laminated Timber and results are compared to the experimental test data obtained on similar single fastener joints. Simulations lead to accurate predictions of both the mechanical behaviour (initial stiffness, maximum load-carrying capacity, global shape of the loading curve and of the hysteresis cycles) and the total energy dissipation observed in the tests.

      PubDate: 2017-12-27T03:13:42Z
  • The continuous strength method for the design of hot-rolled steel
    • Abstract: Publication date: 15 February 2018
      Source:Engineering Structures, Volume 157
      Author(s): X. Yun, L. Gardner, N. Boissonnade
      The continuous strength method (CSM) is a deformation-based structural design approach that enables material strain hardening properties to be exploited, thus resulting in more accurate and consistent capacity predictions. To date, the CSM has featured an elastic, linear hardening material model and has been applied to cold-formed steel, stainless steel and aluminium. However, owing to the existence of a yield plateau in its stress-strain response, this model is not well suited to hot-rolled carbon steel. Thus, a tri-linear material model, which can closely represent the stress-strain response of hot-rolled carbon steel, is introduced and incorporated into the CSM design framework. Maintaining the basic design philosophy of the existing CSM, new cross-section resistance expressions are derived for a range of hot-rolled steel structural section types subjected to compression and bending. The design provisions of EN 1993-1-1 and the proposed CSM are compared with experimental results collected from the literature and numerical simulations performed in this paper. Overall, the CSM is found to offer more accurate and consistent predictions than the current design provisions of EN 1993-1-1. Finally, statistical analyses are carried out to assess the reliability level of the two different design methods according to EN 1990 (2002).

      PubDate: 2017-12-27T03:13:42Z
  • Strength and ductility of simple supported R/C beams retrofitted with
           steel plates of different width-to-thickness ratios
    • Abstract: Publication date: 15 February 2018
      Source:Engineering Structures, Volume 157
      Author(s): S.M. Rakgate, M. Dundu
      The concept of strengthening reinforced concrete beams using epoxy-bonded steel plates (EBSP) is a well-known solution in structural engineering, however, there is little information about the effect of the width-to-thickness ratio of steel plates on the behaviour of steel–concrete composite beams. This paper presents an experimental study of the flexural behaviour of under-reinforced concrete beams, strengthened in flexure by externally-bonded steel plates (EBSP) of varying width-to-thickness ratios. A total of 23 reinforced concrete beams were tested; 6 beams in Series 1 tests and 17 beams in Series 2 tests. One beam in Series 1 tests and two beams in Series 2 tests were regarded as control specimens, whilst the remaining beams were strengthened with steel plates of different width-to-thickness ratios. In each group, the width of the bonded steel plate varied from 75 mm to 175 mm, in increments of 25 mm. The beams were tested as simply supported, under two-point static loadings until failure. From the experimental results, it was observed that the externally bonded steel plates led to substantial increase in flexural stiffness, which resulted in an increase in the capacity and cracking load of the strengthened beams and a decrease in vertical deflections and crack-widths, compared to the control beams. It was also found that the width-to-thickness ratio of steel plates as low as 12.5 can promote flexural yielding and extensive ductility in strengthened beams.

      PubDate: 2017-12-27T03:13:42Z
  • Experimental study of shear strength and failure mechanisms in RC beams
           scaled along height or length
    • Abstract: Publication date: 15 February 2018
      Source:Engineering Structures, Volume 157
      Author(s): J. Suchorzewski, E. Korol, J. Tejchman, Z. Mróz
      The paper presents results of laboratory experiments carried out on longitudinally reinforced concrete beams subjected to four-point bending. Beams of separately varying height and length were analyzed to investigate the size effect on nominal strength and post-critical brittleness. Beams were scaled in the height direction in the first test series and in the length direction in the second series. Due to lack of geometrical similarity, different failure mechanisms were exhibited. Load-deflection diagrams and crack paths were registered during experiments. The digital image correlation technique was applied to visualize strain localization on the concrete surface. The crack opening and crack slip displacements were also measured. The beam response was characterized by two non-dimensional parameters ηa  = a/D and ηb  = b/D defined as the ratios of shear and bending spans to the beam depth D assumed as the size parameter and the reinforcement position parameter ηc  = c′/D. Two major failure mechanisms were observed: flexural failure in the central beam zone combined with plastic yielding of the reinforcement and the diagonal shear crack failure in external shear zones. Two distinct modes of shear failure can be specified depending on the dominance of crack opening or crack closure contact zones. Two different effective stresses associated with failure mechanisms were defined to specify the beam strength’s dependence on ηa , ηb , ηc and D. Some analytical formulae specifying the critical shear stress dependence on ηa , ηc and strengths ratio of reinforcement and concrete were presented at the end of paper and compared with experimental data.
      Graphical abstract image

      PubDate: 2017-12-27T03:13:42Z
  • Time-dependent and long-term mechanical properties of concretes
           incorporating different grades of coarse recycled concrete aggregates
    • Abstract: Publication date: 15 February 2018
      Source:Engineering Structures, Volume 157
      Author(s): Aliakbar Gholampour, Togay Ozbakkaloglu
      It is now accepted that replacement of natural aggregates in concrete with recycled concrete aggregates obtained from construction and demolition waste is a promising technology to conserve natural resources and reduce the environmental impact of concrete. This paper presents a study on long-term properties of concretes manufactured with recycled aggregates of different parent concrete strengths. A total of six batches of recycled aggregate concretes (RACs) were manufactured. Tests were undertaken to establish the long-term compressive strength, elastic modulus, splitting tensile strength, workability, drying shrinkage, and creep of each batch. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) characterizations were performed to explain the mechanisms behind the observed time-dependent and mechanical properties of RACs. Test parameters comprised the replacement ratio and parent concrete strength of the recycled aggregates used in the preparation of the new concrete mixes. The results indicate that the parent concrete strength of the recycled aggregates significantly affects the time-dependent and long-term mechanical properties of RACs. It is shown that concrete mixes containing lower strength recycled concrete aggregates develop lower mechanical properties and higher shrinkage strain and creep deformation compared to mixes prepared with higher strength recycled concrete aggregates. Normal-strength RAC mixes containing higher strength recycled concrete aggregates develop slightly lower splitting tensile strength at all curing ages but similar compressive strength and elastic modulus in longer term (i.e. over 90 days) compared to those of the control mix. It is also shown that high-strength RACs, prepared with full replacement of natural aggregates with recycled concrete aggregates having a higher parent concrete strength, exhibit time-dependent and long-term mechanical properties that are similar to or better than those of companion natural aggregate concretes.

      PubDate: 2017-12-27T03:13:42Z
  • A new approach to determine strength of Perfobond rib shear connector in
           steel-concrete composite structures by employing neural network
    • Abstract: Publication date: 15 February 2018
      Source:Engineering Structures, Volume 157
      Author(s): Hamed Allahyari, Iman M. Nikbin, Saman Rahimi R., Amin Heidarpour
      The main objective of this study is to introduce a novel numerical approach, based on Artificial Neural Network (ANN), to predict the shear strength of Perfobond rib shear connector (PRSC). For this purpose, 90 records were extracted from the literature and were used to develop a number of Bayesian neural network models for predicting the shear strength of PRSC. An accurate ANN model was attained with a high value of correlation coefficient for the train and test subsets. Having a reliable ANN, a parametric study on the shear strength of PRSC was carried out to establish the trend of main contributing factors. The majority of assumptions, considered by empirical equations, were predicted by the developed ANN. Moreover, a sensitivity analysis of input variables was conducted; the outcomes revealed that the area of concrete dowels had the strongest influence on the shear strength of PRSC. Eventually, using the validated ANN, an abundant number of curves (Master Curves) were generated to introduce a user-friendly equation. According to the results, both the ANN model and the proposed equation reflect a higher accuracy than other existing empirical equations.

      PubDate: 2017-12-27T03:13:42Z
  • Experimental study on the cyclic behavior of steel fiber reinforced high
           strength concrete columns and evaluation of shear strength
    • Abstract: Publication date: 15 February 2018
      Source:Engineering Structures, Volume 157
      Author(s): Baek-Il Bae, Joo-Hong Chung, Hyun-Ki Choi, Hyung-Suk Jung, Chang-Sik Choi
      In this paper, the effectiveness of steel fiber inclusion on the structural performance of steel fiber reinforced high strength concrete columns was investigated with test of 7-high strength concrete specimens with and without steel fiber. All test specimens were subjected to axial load and reversed cyclic lateral loads. It was shown that test steel fiber inclusion significantly increase the structural performance. Steel fiber inclusion was remarkably effective than the transverse reinforcement about structural performance such as strength and energy dissipation capacity. Steel fiber reinforcement was more effective with high volumetric ratio of transverse reinforcement. Compressive strength of matrix affect to the strength and ductility. High strength matrix column specimens showed better performance than normal strength matrix column specimens. In order to verify the safety of existing strength estimation equations, test results were compared with estimated values. Most of the estimation equations were over estimated the shear strength of concrete. Therefore, in this study, for the safe design of steel fiber reinforced high strength concrete columns, newly developed estimation equation was suggested.

      PubDate: 2017-12-27T03:13:42Z
  • Effect of reinforcement anchorage end detail and spacing on seismic
           performance of masonry shear walls
    • Abstract: Publication date: 15 February 2018
      Source:Engineering Structures, Volume 157
      Author(s): Hany M. Seif ElDin, Khaled Galal
      The most recent design codes for masonry structures necessitate the use of reinforced masonry (RM) shear walls in medium and high seismic areas. In addition, they provide requirements for the seismic reinforcement for walls. This paper investigates the in-plane seismic performance of fully grouted RM shear walls dominated by shear-flexural failure. The experimental work involved assessing the response of five single-story RM shear walls when subjected to in-plane axial compressive stress and cyclic lateral excitations. The studied parameters were the horizontal reinforcement anchorage end detail and the spacing of the horizontal and vertical reinforcement. Three anchorage end detail were evaluated in this study; 180° standard hook, 90° hook, and straight. Two vertical spacing of the horizontal reinforcement, 400 mm and 800 mm, and two horizontal spacing of the vertical reinforcement, 200 mm and 800 mm, were considered in the test matrix. Based on the test results, the 180° standard hook was the most efficient in terms of strength and ductility with a slight difference in the strength and 15% higher ductility than using the straight end detail. On the contrary, the spacing of the reinforcement had a significant effect on the behavior of tested walls. Walls that were constructed with closely spaced reinforcement were able to reach 15% and 80% higher strength and ductility than similar walls with large spacing when using the same reinforcement ratio. Hence, the current values for the maximum spacing of reinforcement in the Canadian Standards Association CSA S304-14 for the design of masonry structures need to be modified by specifying lower spacing limits.

      PubDate: 2017-12-27T03:13:42Z
  • A modal approach to determine direct shear of beams subjected to impulse
    • Abstract: Publication date: 1 February 2018
      Source:Engineering Structures, Volume 156
      Author(s): Alireza Kermani, Ali Ashrafi, Arghavan Louhghalam
      Protecting important structures against blast loading is vital. Most engineering practitioners use either a Single Degree of Freedom (SDOF) approximation of the dynamic response to blast loading or a computationally expensive numerical model. In this paper, a modal approach is proposed that provides a more accurate and less conservative estimate of direct shear, the transient dynamic shear response developed within a few milliseconds of pressure wave arrival, than the estimate based on SDOF. By way of example and via the proposed approach, simple analytical expressions to estimate the direct shear are developed for simply-supported beams. The estimates are compared with the results of a series of dynamic analyses of a refined finite element model of the beam, performed using LS-DYNA. Very close agreement between the results of numerical modeling and analytical estimates are observed. In addition, the estimated direct shear is significantly lower than the value obtained from the SDOF method. The proposed approach, thus provides an efficient and accurate estimate of the direct shear to be used in structural design.

      PubDate: 2017-12-27T03:13:42Z
  • Multi-level damage identification of a bridge structure: a combined
           numerical and experimental investigation
    • Abstract: Publication date: 1 February 2018
      Source:Engineering Structures, Volume 156
      Author(s): You-Lin Xu, Chao-Dong Zhang, Sheng Zhan, Billie F. Spencer
      Damage identification of a large and complex bridge structure often requires an enormous computational effort to solve an ill-posed inverse problem with a large number of unknowns. Moreover, the predefined sensors usually cannot sufficiently cover all the potential damage regions for a large bridge structure, which will introduce additional difficulties in damage identification. To deal with these challenges, a multi-level damage identification method with response reconstruction that uses a divide-and-conquer approach is proposed. An entire bridge structure is firstly decomposed into several manageable substructures and condensed as super elements using component mode synthesis (CMS); damage identification is then carried out at the substructure level to locate potentially damaged (target) substructures. The second level is at the element (member) level to further localize and quantify damage for the target substructures. To this end, a Kalman filter-based response reconstruction is performed on the target substructure for more accurate damage quantification. To examine the feasibility and effectiveness of the proposed method, a combined numerical and experimental investigation is performed on a laboratory testbed model of the Tsing Ma suspension bridge (TMB). Numerical studies are firstly conducted to inform optimal sensor placement for response reconstruction and multi-level damage identification. The sensor system is then installed on the TMB testbed model, and the proposed multi-level damage identification method is validated through comparison with experimental results. The numerical and experimental results demonstrate that the proposed multi-level damage identification method is capable of identifying damage in a large bridge structure.

      PubDate: 2017-12-27T03:13:42Z
  • Experimental study of a novel precast prestressed reinforced concrete
           beam-to-column joint
    • Abstract: Publication date: 1 February 2018
      Source:Engineering Structures, Volume 156
      Author(s): Haishen Wang, Edoardo M. Marino, Peng Pan, Hang Liu, Xin Nie
      Precast reinforced concrete (r.c.) structures can provide important advantages over their cast-in-place counterpart. However, lessons learned by past earthquakes evidence that beam-to-column joints may be a critical point of these structure and can undermine the seismic performance if not properly conceived. This paper presents a novel prestressed precast r.c. beam-to-column joint. The beam ends adjacent to the column are reinforced by steel jacket to prevent concrete from spalling. Steel strands are used to provide the joint with self-centering capacity. Replaceable mild steel bars provide the joint with energy dissipation capacity. The effectiveness of the proposed joint is investigated by experimental tests. The obtained results demonstrate the good properties of the joint in terms of strength and deformation capacity, control of story drift, easy reparability, and preventing beams and columns from damage. Finally, the comparison with a conventional cast-in-place beam-to-column joint points out the superior resilience against earthquake of the proposed precast prestressed joint.

      PubDate: 2017-12-27T03:13:42Z
  • Meshfree analysis of structures modeled as extensible slender rods
    • Abstract: Publication date: 1 February 2018
      Source:Engineering Structures, Volume 156
      Author(s): Yanbin Bai, John M. Niedzwecki
      The analysis of members that can be modeled as extensible elastic slender rods is investigated. A meshfree formulation using a Local Radial Point Interpolation Method (LRPIM) is developed that utilizes radial basis functions in curvilinear coordinates. This approach bypasses the need to utilize more conventional element meshes and significantly reduces the number of equations needed for the numerical solution. The slender rod formulation presented allows for tension variation, axial stretch, incremental loading and distributed load variation along the rod. It is well suited for nonlinear problems that involve large deflections and rigid rotations. The position and tangent vectors are expressed using Hermite-type approximations, and radial basis functions, while the interpolation of tension variation and distributed loads are described using polynomials. The solution procedure of weighted residuals Galerkin weak formulation combined with an incremental iterative numerical scheme is introduced to address the incremental loading and large deflection issues for static and quasi-static problems. The implementation of the analytical formulation and the numerical procedure are illustrated using three nonlinear problems. The first two examples provide insight into the validity, accuracy, and efficiency of the methodology. The third example presents the case of a moving boundary condition problem which models a cable entangled by fishing boat-trawling equipment.

      PubDate: 2017-12-27T03:13:42Z
  • Hysteretic behaviour of steel fibre RC coupled shear walls under cyclic
           loads: Experimental study and modelling
    • Abstract: Publication date: 1 February 2018
      Source:Engineering Structures, Volume 156
      Author(s): Jun Zhao, Gaochuang Cai, Amir Si Larbi, Yang Zhang, Huahua Dun, Hervé Degée, Bram Vandoren
      This paper presents the hysteretic behaviour of three 1/3-scale three-storey steel fibre reinforced concrete (SFRC) coupled shear walls (CSWs) under cyclic loads. The deformation, ductility, energy dissipation, stiffness and crack propagation of the specimens are also discussed and analysed. The results show steel fibre improves the ductility and energy dissipation capacity, and restrains the crack propagation of the CSWs, and delays the degradation of their lateral stiffness and force. Based on the experiments, a simple trilinear model is developed to simulate the skeleton curve of lateral force–displacement of the SFRC CSWs. Through analysing several typical cycles of the hysteretic of these CSWs, the feature points of the proposed hysteretic model are defined which subsequently is used to evaluate the complete hysteretic behaviour of the CSWs. Using existing experimental data and this study, several representative experimental hysteretic cycles are compared with the proposed model. The result indicates a good agreement is reached between the model and experimental results.

      PubDate: 2017-12-27T03:13:42Z
  • Computer vision for SHM of civil infrastructure: From dynamic response
           measurement to damage detection – A review
    • Abstract: Publication date: 1 February 2018
      Source:Engineering Structures, Volume 156
      Author(s): Dongming Feng, Maria Q. Feng
      To address the limitations of current sensor systems for field applications, the research community has been actively exploring new technologies that can advance the state-of-the-practice in structural health monitoring (SHM). Thanks to the rapid advances in computer vision, the camera-based noncontact vision sensor has emerged as a promising alternative to conventional contact sensors for structural dynamic response measurement and health monitoring. Significant advantages of the vision sensor include its low cost, ease of setup and operation, and flexibility to extract displacements of any points on the structure from a single video measurement. This review paper is intended to summarize the collective experience that the research community has gained from the recent development and validation of the vision-based sensors for structural dynamic response measurement and SHM. General principles of the vision sensor systems are firstly presented by reviewing different template matching techniques for tracking targets, coordinate conversion methods for determining calibration factors to convert image pixel displacements to physical displacements, measurements by tracking artificial targets vs. natural targets, measurements in real time vs. by post-processing, etc. Then the paper reviews laboratory and filed experimentations carried out to evaluate the performance of the vision sensors, followed by a discussion on measurement error sources and mitigation methods. Finally, applications of the measured displacement data for SHM are reviewed, including examples of structural modal property identification, structural model updating, damage detection, and cable force estimation.

      PubDate: 2017-12-27T03:13:42Z
  • Concrete-filled steel tube (CFT) truss girders: Experimental tests,
           analysis, and design
    • Abstract: Publication date: 1 February 2018
      Source:Engineering Structures, Volume 156
      Author(s): Wenjin Huang, Zhichao Lai, Baochun Chen, Zhitao Xie, Amit H. Varma
      This paper investigates the behavior of Warren-vertical CFT truss girders by conducting both experimental tests and finite element analyses. Experimental tests on three CFT truss girders are first conducted. The test parameter is the compressive strength of the concrete infill. Finite element models, which were developed and benchmarked previously by the authors, are then used to further investigate the behavior of CFT truss girders and the influence of parameters such as the brace-to-chord strength ratio, shear span-to-depth ratio, and concrete compressive strength. Results from the parametric studies indicate that CFT truss girders are flexure dominated if (i) the brace-to-chord strength ratio ≥0.8 and (ii) the shear span-to-depth ratio ≥4.8. Both the experimental tests and FEM analyses indicate that the concrete compressive strength has negligible effects on the failure mode of CFT truss girders. Based on results from the experimental tests and FEM analyses, design equations are also proposed for estimating the flexural strength of Warren-vertical CFT truss girders.

      PubDate: 2017-12-27T03:13:42Z
  • Effects of the shear lag on longitudinal strain and flexural stiffness of
           flanged RC structural walls
    • Abstract: Publication date: 1 February 2018
      Source:Engineering Structures, Volume 156
      Author(s): Zhongwen Zhang, Bing Li
      The shear lag effect is a commonly reported observation in tests on flanged reinforced concrete (RC) structural walls. This effect is conventionally ignored but more evidence has shown that calculation and analyses ignoring this effect could significantly overestimate flexure strength and stiffness. Existing research indicates that well distributed diagonal cracks exist in the flange of the flanged RC walls with the shear lag effect and the effect should be calculated based on shear stiffness of the cracked concrete. A truss model was proposed but the model can only consider the effect at the bottom sections of cantilever flanged walls loaded at the top which therefore precludes its application in the design of flanged RC structural walls. This paper presents an improved truss analogy for calculating the shear lag effect for flanged section at any height of RC walls with any lateral load distributions. Predictions of the proposed method are compared with available experimental data and finite element (FE) results. The method is then applied to improve the fibre beam-column element models to generate a new prediction model which was found to predict to be able to accurately predict the flexure stiffness of RC walls.

      PubDate: 2017-12-27T03:13:42Z
  • In-plane behavior of cavity masonry infills and strengthening with textile
           reinforced mortar
    • Abstract: Publication date: 1 February 2018
      Source:Engineering Structures, Volume 156
      Author(s): Farhad Akhoundi, Graça Vasconcelos, Paulo Lourenço, Luis M. Silva, Fernando Cunha, Raúl Fangueiro
      The seismic vulnerability of masonry infilled reinforced concrete (rc) frames observed during past earthquakes in some south European countries resulted in losses of human lives and huge repair or reconstruction costs, justifies the need of deeper study of the seismic behavior of masonry infills enclosed in rc frames. Therefore, the main goals of this study are related to: (1) better understanding of the cyclic in-plane behavior of traditional brick infills built in the past decades as enclosures in rc buildings in Portugal; (2) analysis of a strengthening technique based on textile reinforced mortar (TRM) aiming at enhancing the in-plane behavior. To accomplish the objectives, an extensive experimental campaign based on in-plane static cyclic tests on seven reduced scale rc frames with masonry infill walls was carried out. The performance of strengthening of masonry infill based on textile reinforced mortar was also evaluated experimentally. Among the conclusions of this research, it should be stressed that: (1) the presence of infill inside the bare frame could significantly enhance the in-plane stiffness and resistance of bare frame; (2) TRM technique could enhance the in-plane behavior of infilled frames by improving the lateral strength and by reducing significantly the damage of the brick infill walls.

      PubDate: 2017-12-27T03:13:42Z
  • Impacts of soil-structure interaction on the structural control of
           nonlinear systems using adaptive control approach
    • Abstract: Publication date: 15 February 2018
      Source:Engineering Structures, Volume 157
      Author(s): Fereidoun Amini, Maryam Bitaraf, Mohammad Seddiq Eskandari Nasab, Mohammad Mahdi Javidan
      Though there is no doubt that soil-structure interaction (SSI) effects could significantly impact on the response of structures under seismic loads, this phenomenon is often neglected in control of structures. In the present research, the simple adaptive control (SAC) algorithm is utilized in conjunction with the magnetorheological (MR) damper to control the responses of a nonlinear structure based on soft soil analytically and the results are compared with passive-on and passive-off states. As the prototype structure is from an experimental test, a reliable framework is established by validating the accuracy of the structural model. The SSI effects are investigated from several aspects such as effects on control forces and performance of SAC in control of soil-structure systems. In addition to using conventional evaluation criteria in control problems, fragility analysis is carried out to study the structural behavior and SSI effects in-depth. It is observed that the SAC algorithm is capable of controlling the responses of structures and the outcomes are satisfying comparing to the passive approaches. The results show that neglecting SSI could completely underestimate damage to controlled structures especially structures based on soft soil and it will lead to error in the first estimation of control forces during design.

      PubDate: 2017-12-12T12:41:55Z
  • A multi-level model correlation approach for low-frequency vibration
           transmission in wood structures
    • Abstract: Publication date: 15 February 2018
      Source:Engineering Structures, Volume 157
      Author(s): O. Flodén, K. Persson, G. Sandberg
      The main challenge in predicting structure-borne sound in wood buildings is to accurately model the vibration transmission between the source and the receiving room. Large variations in model parameters make it difficult to predict absolute vibration levels and to make conclusions regarding the relative effects of different designs. A step towards establishing reliable models is to investigate the possibilities and limitations of using deterministic methods, which requires correlations between simulations and measurements. In this paper, we present a multi-level model correlation approach for low-frequency vibration transmission in wood buildings. We apply the proposed approach to a scaled-size experimental structure representing a part of a two-storey wood building, and we evaluate the results for frequencies up to 100 Hz. We perform correlations between simulations and measurements four different levels: structural components (viz. beams and boards), planar structures (viz. floor, ceiling and walls), room structures and the complete structure. The results indicate that the dynamic behaviour of the experimental structure was to a great extent captured by the developed model. Based on the observations made in the multi-level correlations, we discuss important model parameters and propose modelling guidelines. We conclude that it is possible to employ deterministic methods in order to simulate the low-frequency vibration transmission in wood buildings provided that measurement data for calibration purposes are available. The developed numerical model can be used as a reference model for investigations on the effects of variations and uncertainties in the modelling.

      PubDate: 2017-12-12T12:41:55Z
  • Dynamic analyses of operating offshore wind turbines including
           soil-structure interaction
    • Abstract: Publication date: 15 February 2018
      Source:Engineering Structures, Volume 157
      Author(s): Haoran Zuo, Kaiming Bi, Hong Hao
      In the dynamic analyses of offshore wind turbines subjected to the external vibration sources, the wind turbines are normally assumed in the parked condition and the blades are considered by a lumped mass located at the top of the tower. In reality, the geometrical characteristics and rotational velocity of the blades can directly influence the wind loads acting on the blades. Moreover, the centrifugal stiffness generated by the rotating blades can increase the stiffness and natural frequencies of the blades, which in turn can further affect the structural responses. The lumped mass model, therefore, may lead to inaccurate structural response estimations. On the other hand, monopile, a long hollow steel member inserting into the water and sea bed, is generally designed as the foundation of an offshore wind turbine. The soil-monopile interaction can further alter the vibration characteristics and dynamic responses of offshore wind turbines. In the present study, the dynamic responses of the modern NREL 5 MW wind turbine subjected to the combined wind and sea wave loadings are numerically investigated by using the finite element code ABAQUS. The blades are explicitly modelled and soil-structure interaction (SSI) is considered. The influences of operational condition and rotor velocity on the dynamic behaviours are systematically investigated. It is found that the responses of the wind turbine in the operating condition are much larger than those in the parked condition; SSI can affect the tower vibrations substantially, while it has a negligible effect on the in-plane vibrations of the blades.

      PubDate: 2017-12-12T12:41:55Z
  • Buckling capacity of radially compressed thin-walled reinforced
           cementitious spheres
    • Abstract: Publication date: 15 February 2018
      Source:Engineering Structures, Volume 157
      Author(s): Apostolos Koukouselis, Apostolos Grammatopoulos, Euripidis Mistakidis
      High performance cementitious materials have made possible the construction of slender thin cementitious shells. For their design, the most relevant recommendations are those provided by the International Association of Spatial Structures (IASS), which, however, are inconsistent with the modern European design framework. In the case of steel shells, Eurocode 3 provides a simplified design approach based on the well-known buckling capacity curves. The aim of this paper is the determination of the capacity curve of a radially compressed spherical cementitious shell, for different fabrication quality classes and the determination of the four buckling parameters that describe the curve.

      PubDate: 2017-12-12T12:41:55Z
  • Structural behaviour of slender columns of high strength S690 steel welded
           H-sections under compression
    • Abstract: Publication date: 15 February 2018
      Source:Engineering Structures, Volume 157
      Author(s): Tian-Yu Ma, Xiao Liu, Yi-Fei Hu, Kwok-Fai Chung, Guo-Qiang Li
      This paper presents an experimental investigation into structural behaviour of slender columns of high strength S690 steel welded H-sections under axial compression. A total of seven slender columns with four sections of different cross-sectional dimensions and two different effective lengths were tested successfully. As expected, all of these columns failed in overall buckling about minor axes of their cross-sections, similar to those of conventional steel welded H-sections. Hence, these tests may be regarded to be confirmatory tests to structural behaviour of slender columns of high strength S690 steel welded H-sections under axial compression. No welding failure was observed after close inspection to all the columns after tests. It should be noted that the measured failure loads of these slender columns were directly compared with predicted resistances of corresponding sections based on their measured geometrical and materials properties according to current design rules given in European, Chinese, and American Steel Codes, namely, EN 1993-1-1, GB 50017-2003, and ANSI/AISC 360-16 respectively. As effects of residual stresses in S690 steel welded H-sections were considered to be proportionally less pronounced when compared with those in S355 steel welded H-sections, their buckling resistances should be significantly increased when compared with those S355 welded H-sections. It was found that the current design rules given in both EN 1993-1-1 and GB 50017-2003 underestimated buckling resistances of slender columns of S690 steel welded H-sections significantly, and use of a different buckling curve with an increased structural efficiency was suggested. However, the predicted resistances of these slender columns to the current design rules given in ANSI/AISC 360-16 were found to be close to the measured failure loads. Hence, they were considered to be applicable to design slender columns of S690 steel welded H-sections.

      PubDate: 2017-12-12T12:41:55Z
  • Active vibration control for seismic excited building structures under
           actuator saturation, measurement stochastic noise and quantisation
    • Abstract: Publication date: 1 February 2018
      Source:Engineering Structures, Volume 156
      Author(s): Lanlan Xu, Yunyan Yu, Yanliang Cui
      This paper investigates the active vibration control for seismic excited building structures in presenting of actuator saturation, stochastic measurement noise and quantisation. The active vibration controllers are placed in some storeys, meanwhile, some active tuned mass dampers (ATMDs) are also installed at the top floor and oscillating under their control forces. All of the control forces are generated by actuators which are only capable of providing limited outputs. Since the system states are difficult or barely impossible to be accurately measured, an observer based control law is proposed to guarantee system stability, meanwhile, an H 2 / H ∞ index is employed for further improving the control performance. By the proposed control strategy, the mean square exponentially stability of close-looped system can be guaranteed almost surely while the desired H 2 / H ∞ performance can be achieved simultaneously. In addition, the convergence rate of system state can be pre-scheduled. By regulating the different locations of sensors and controllers, the vibration response can be mitigated in different level. Numerical examples are provided to demonstrate the effectiveness of the proposed method.

      PubDate: 2017-12-12T12:41:55Z
  • Elastic buckling of steel arches with discrete lateral braces
    • Abstract: Publication date: 1 February 2018
      Source:Engineering Structures, Volume 156
      Author(s): Chao Dou, Zi-Qin Jiang, Yong-Lin Pi, Wei Gao
      Lateral brace is an effective way to increase the out-of-plane stability of steel arches, and the certain bracing stiffness achieving full restraining effect is concerned. Unlike braced columns and beams, the buckling of steel arches with discrete lateral braces and the effect of bracing stiffness are not well explored. This paper deals with the bracing stiffness effect of equally-spaced lateral translational braces and rotational braces in steel circular arches pertaining to elastic out-of-plane flexural-torsional buckling. Firstly, for arches with discrete lateral translational braces in uniform compression, an analytical solution for the threshold bracing stiffness is derived by the Rayleigh–Ritz method, ensuring full restraint of the displacement at the bracing points. Then for arches with discrete rotational braces in uniform compression, the flexural-torsional buckling modes are explored using the finite element analysis (FEA), then improved predictions to the buckling load related to the bracing stiffness are obtained theoretically by assuming proper buckling shapes. Compared with the FEA results, it is found that the analytical solutions of threshold stiffness proposed for arches in uniform compression are reasonably accurate and can be used in other loading cases for arches under combined compression and bending moment conservatively.

      PubDate: 2017-12-12T12:41:55Z
  • Loading paths of confined concrete in circular concrete loaded CFT stub
           columns subjected to axial compression
    • Abstract: Publication date: 1 February 2018
      Source:Engineering Structures, Volume 156
      Author(s): Yan-Gang Zhao, Siqi Lin, Zhao-Hui Lu, Takasuke Saito, Liusheng He
      So far, the loading path effect on the compressive strength of confined concrete has been poorly investigated. To clarify the compressive strength of confined concrete in concrete-filled steel tube (CFT) columns, experimental tests with a total of 18 specimens are conducted to investigate the loading paths of confined concrete in concrete loaded CFT stub columns. The parameters that are varied in the experiment include the steel strength, the unconfined concrete strength and the D/t ratio. Two evaluation indices, namely the laterally dominant index and the effect index, are proposed to characterize the loading path and its effect on the compressive strength of confined concrete, respectively. A detailed parametric study is conducted on the loading paths and the corresponding effects on compressive strength. The results suggest that the loading paths of confined concrete in CFT column are affected by the column parameters. Depending on the loading paths by which the concretes are confined, the loading path effects on the compressive strength of the confined concrete in CFT columns could be totally different. Based on the test results, a compressive strength model incorporating the loading path effect is developed and good performance was found in comparison with the experimental results.

      PubDate: 2017-12-12T12:41:55Z
  • Flexural performance of reinforced concrete beams made with recycled
           concrete coarse aggregate
    • Abstract: Publication date: 1 February 2018
      Source:Engineering Structures, Volume 156
      Author(s): Sindy Seara-Paz, Belén González-Fonteboa, Fernando Martínez-Abella, Javier Eiras-López
      This work deals with the flexural performance of recycled concrete subjected to increasing loads up to failure. For this purpose, eight reinforced concrete beams were made with recycled coarse aggregates using two different water to cement ratios (0.50 and 0.65) and four replacement percentages (0%, 20%, 50% and 100%). Firstly, the basic concrete properties were determined (mechanical strengths and modulus of elasticity) and then, beam specimens were loaded up to failure using a four-point bending test at 28 days. As a result, bending moments, deflections, strains and curvatures were obtained at different load levels (cracking, service, yielding and ultimate state conditions), and also, the crack pattern. On the basis of these results, it can be noted that service, yielding and ultimate state of recycled concrete exhibits, in general, a similar trend to that of conventional concrete. However, the cracking behaviour shows differences between recycled and conventional concrete. Finally, code-based expressions were used to calculate bending moments and deflections under flexural load, taking into account the different content of recycled coarse aggregate.

      PubDate: 2017-12-12T12:41:55Z
  • Effect of yield penetration on column plastic hinge length
    • Abstract: Publication date: 1 February 2018
      Source:Engineering Structures, Volume 156
      Author(s): K.G. Megalooikonomou, S.P. Tastani, S.J. Pantazopoulou
      The required confined zone in critical regions of columns and piers undergoing lateral sway during earthquakes is related to the plastic hinge length where inelastic deformation and damage develops. The exact definition of the plastic hinge length stumbles upon several uncertainties, the most critical being that the extent of the inelastic region evolves and spreads with the intensity of lateral displacements. Design codes quantify a reference value for the plastic hinge length, through calibrated empirical relationships that account primarily for the length of the shear span and the diameter of primary reinforcing bars. The latter term reflects the effects of bar yielding penetration in the support of columns. Here a consistent definition of plastic hinge length is pursued analytically with reference to the actual strain state of the reinforcement. Strain penetration extending bilaterally on the reinforcing bars from the critical section towards the column shear span and towards the bar anchorage is evaluated. Considering that bar yielding is synonymous to degradation of interfacial bond between bar and concrete over the yielded area, the field equations of bond are solved explicitly along the column primary reinforcement over the shear span, following the process of gradual crack formation along the member. Boundary effects and important design variables are considered, such as the shear span aspect ratio and the stress-resultants (axial load and flexural moment) carried by the column. Using this solution, the parametric sensitivities of the plastic hinge length are illustrated and compared with other alternatives that have been obtained through experimental calibration. Analytical estimations are also compared with experimental evidence from a number of column specimens tested under axial load and reversed cyclic lateral drift histories reported in the literature.

      PubDate: 2017-12-12T12:41:55Z
  • The influence of environmental parameters on the dynamic behaviour of the
           San Frediano bell tower in Lucca
    • Abstract: Publication date: 1 February 2018
      Source:Engineering Structures, Volume 156
      Author(s): Riccardo Mario Azzara, Guido De Roeck, Maria Girardi, Cristina Padovani, Daniele Pellegrini, Edwin Reynders
      This paper aims at assessing the influence of environmental parameters on the modal characteristics of age–old masonry constructions. The results of a long–term ambient vibration monitoring of the San Frediano bell tower in Lucca (Italy) are reported. The tower, dating back to the 11th century, has been fitted along its height with four triaxial seismometric stations, which were left active for about one year. Data from the monitoring system have been processed via the Stochastic Subspace Identification Method in order to identify the tower’s modal characteristics and their variations over the year. The dependence of the tower’s frequencies on the ambient temperature was first studied and simulated via simple auto–regressive models. Then, some output–only models based on the principal component analysis (PCA) were applied, under the hypotheses of both linear and nonlinear (Kernel PCA) dependence of the natural frequencies on the unknown environmental parameters. The results indicate PCA to be an effective tool for detecting changes in the dynamic characteristics of masonry constructions.

      PubDate: 2017-12-12T12:41:55Z
  • Wind loads of moving vehicle on bridge with solid wind barrier
    • Abstract: Publication date: 1 February 2018
      Source:Engineering Structures, Volume 156
      Author(s): Huoyue Xiang, Yongle Li, Suren Chen, Guangyang Hou
      A wind tunnel experimental study is conducted to study the wind loads acting on a moving vehicle model on a bridge installed with a solid wind barrier. The repeatability of the tests is verified by the cases with different wind and vehicle speeds. For comparison purposes, the difference of the results between the static and moving vehicle models are discussed. The effects of different heights of wind barriers and wind directions on the wind loads acting on the vehicles are analyzed. Finally, the wind loads acting on the vehicles are further evaluated to assess the potential impact of wind barriers on traffic safety. The results show that the relative movement between the vehicle, bridge and solid wind barriers affects the aerodynamic characteristics of the vehicle. The variation patterns of aerodynamic characteristics with different yaw angles are altered by the solid wind barriers with different heights, and there is a most unfavorable yaw angle for the protective effect of solid wind barriers in terms of side force. The wind direction has some impact on the five-component coefficients of vehicles after installing a solid wind barrier. However, the solid wind barrier has similar protective efficiency in terms of the side force acting on the vehicle under different wind directions.

      PubDate: 2017-12-12T12:41:55Z
  • Nonlinear harmonically excited vibration of third-order shear deformable
           functionally graded graphene platelet-reinforced composite rectangular
    • Abstract: Publication date: 1 February 2018
      Source:Engineering Structures, Volume 156
      Author(s): Raheb Gholami, Reza Ansari
      The geometrically nonlinear harmonically excited vibration of third-order shear deformable functionally graded graphene platelet-reinforced composite (FG-GPLRC) rectangular plates with different edge conditions is examined. The considered plate with N L -layers is made from a mixture of an isotropic polymer matrix and graphene platelets (GPLs) in each layer. The weight fraction of GPLs changes in a layer-wise manner. The modified Halpin-Tsai model and rule of mixture are utilized to compute the effective material properties of FG-GPLRCs. To mathematically model the vibrations of FG-GPLRC plates, the displacement field, strain tensor and constitutive relations as well as the energy functional of system including strain and kinetic energies and external work are represented in matrix forms as a function of the displacement components. Then, by simultaneous use of Hamilton’s principle and an efficient numerical scheme namely, the variational differential quadrature (VDQ) technique, the weak form of discretized nonlinear equations of motion is obtained. The present model includes the influences of geometric nonlinearity, rotary inertia and transverse shear deformation. Furthermore, a multistep numerical approach based on the Galerkin method, time periodic discretization method and pseudo arc-length continuation technique in conjunction with the modified Newton-Raphson method is employed to solve the problem of nonlinear harmonically excited vibration of FG-GPLRC rectangular plates. Results are plotted in the form of frequency-response and force-response curves to indicate the effect of various parameters such as GPL distribution pattern, weight fraction, geometry of GPL nanofillers and boundary constraints of FG-GPLRC plates.

      PubDate: 2017-12-12T12:41:55Z
  • Detailing of concrete-to-concrete interfaces for improved ductility
    • Abstract: Publication date: 1 February 2018
      Source:Engineering Structures, Volume 156
      Author(s): Eduardo Cavaco, Ilton Pacheco, José Camara
      Recent research has shown that reinforced concrete (RC) beams with concrete-to-concrete casting interfaces where plastic hinges are likely to develop, may experience reduced ductility in comparison to similar structural elements casted at once, due to a potential shear slippage along the casting interfaces. Although of relevant importance for both precast and cast in situ RC structures, this problem is still not addressed in current codes and standards, which limit the safety check of casting interfaces to the verification of their strength based on improved expressions of the “shear friction theory”, the latter proposed in the 60’s. However, recent research has shown that friction strength of casting interfaces depends on interface width opening, and it is significantly reduced after the yield of the bending reinforcement. During the formation of plastic hinges, shear stresses run preferentially across the compressed zones of the interfaces, reducing their strength, and ultimately the specimens’ ductility. In this paper, different and alternative details for interfaces are proposed to improve global behaviour, and in particular, ductility of RC beams with casting interfaces located on plastic hinges regions. An experimental campaign was carried out to study the effect of: (i) epoxy and latex based adhesion promoters’ usage between castings; (ii) web reinforcement; (iii) geometry of interfaces; (iv) and shear level. Results show that both epoxy and latex based adhesion promoters, currently used in construction, hardly improve the tensile strength of casting interfaces, to a point that the interface presence has negligible impact on the cracking pattern. A much better result was observed from the use of a web reinforcement crossing the interface perpendicularly. Although this solution revealed itself also incapable to avoid preferential cracking along the interfaces, it proved to be efficient in limiting shear slippages. The adoption of inclined interfaces either perpendicular or parallel to the expected direction of shear cracks proved also to be an efficient solution. Finally, the likelihood of experiencing a shear slippage along the interface is strongly dependent on the existing shear level after the formation of a plastic hinge.

      PubDate: 2017-12-12T12:41:55Z
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