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  Subjects -> ENGINEERING (Total: 2235 journals)
    - CHEMICAL ENGINEERING (188 journals)
    - CIVIL ENGINEERING (178 journals)
    - ELECTRICAL ENGINEERING (102 journals)
    - ENGINEERING (1194 journals)
    - ENGINEERING MECHANICS AND MATERIALS (374 journals)
    - HYDRAULIC ENGINEERING (54 journals)
    - INDUSTRIAL ENGINEERING (60 journals)
    - MECHANICAL ENGINEERING (85 journals)

CIVIL ENGINEERING (178 journals)                  1 2     

ACI Structural Journal     Full-text available via subscription   (Followers: 11)
Acta Polytechnica : Journal of Advanced Engineering     Open Access  
Acta Structilia : Journal for the Physical and Development Sciences     Open Access   (Followers: 2)
Advances in Civil Engineering     Open Access   (Followers: 34)
Advances in Structural Engineering     Full-text available via subscription   (Followers: 20)
Ambiente Construído     Open Access   (Followers: 2)
American Journal of Civil Engineering and Architecture     Open Access   (Followers: 24)
Architectural Engineering     Open Access   (Followers: 7)
Archives of Civil Engineering     Open Access   (Followers: 8)
Archives of Hydro-Engineering and Environmental Mechanics     Open Access   (Followers: 2)
ATBU Journal of Environmental Technology     Open Access   (Followers: 3)
Australian Journal of Structural Engineering     Full-text available via subscription   (Followers: 5)
Baltic Journal of Road and Bridge Engineering     Full-text available via subscription   (Followers: 3)
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)
Berkeley Planning Journal     Open Access   (Followers: 5)
Bioinspired Materials     Open Access   (Followers: 1)
Bridge Structures : Assessment, Design and Construction     Hybrid Journal   (Followers: 15)
Building and Environment     Hybrid Journal   (Followers: 15)
Building Women     Full-text available via subscription  
Built Environment Project and Asset Management     Hybrid Journal   (Followers: 18)
Bulletin of Pridniprovsk State Academy of Civil Engineering and Architecture     Open Access   (Followers: 2)
Canadian Journal of Civil Engineering     Full-text available via subscription   (Followers: 14)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 4)
Case Studies in Nondestructive Testing and Evaluation     Open Access   (Followers: 2)
Case Studies in Structural Engineering     Open Access   (Followers: 1)
Cement and Concrete Composites     Hybrid Journal   (Followers: 14)
Challenge Journal of Structural Mechanics     Open Access   (Followers: 6)
Change Over Time     Full-text available via subscription   (Followers: 2)
Civil and Environmental Engineering     Open Access   (Followers: 3)
Civil And Environmental Engineering Reports     Open Access   (Followers: 2)
Civil and Environmental Research     Open Access   (Followers: 16)
Civil Engineering = Siviele Ingenieurswese     Full-text available via subscription   (Followers: 5)
Civil Engineering and Architecture     Open Access   (Followers: 8)
Civil Engineering and Environmental Systems     Hybrid Journal   (Followers: 5)
Civil Engineering and Technology     Open Access   (Followers: 4)
Civil Engineering Dimension     Open Access   (Followers: 6)
Cohesion and Structure     Full-text available via subscription   (Followers: 2)
Composite Structures     Hybrid Journal   (Followers: 160)
Computer-aided Civil and Infrastructure Engineering     Hybrid Journal   (Followers: 9)
Computers & Structures     Hybrid Journal   (Followers: 26)
Concrete Research Letters     Open Access   (Followers: 2)
Constructii : Journal of Civil Engineering Research     Open Access   (Followers: 9)
Construction Economics and Building     Open Access  
Construction Engineering     Open Access   (Followers: 4)
Construction Management and Economics     Hybrid Journal   (Followers: 28)
Construction Science     Open Access   (Followers: 1)
Constructive Approximation     Hybrid Journal  
Curved and Layered Structures     Open Access  
DFI Journal : The Journal of the Deep Foundations Institute     Hybrid Journal  
Earthquake Engineering and Structural Dynamics     Hybrid Journal   (Followers: 13)
Enfoque UTE     Open Access   (Followers: 1)
Engineering Project Organization Journal     Hybrid Journal   (Followers: 5)
Engineering Structures     Hybrid Journal   (Followers: 13)
Engineering Structures and Technologies     Hybrid Journal   (Followers: 2)
Engineering, Construction and Architectural Management     Hybrid Journal   (Followers: 15)
Environmental Geotechnics     Open Access   (Followers: 3)
European Journal of Environmental and Civil Engineering     Hybrid Journal   (Followers: 5)
Fatigue & Fracture of Engineering Materials and Structures     Hybrid Journal   (Followers: 14)
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: 2)
Geosystem Engineering     Hybrid Journal   (Followers: 2)
Geotechnik     Hybrid Journal   (Followers: 1)
Géotechnique Letters     Hybrid Journal   (Followers: 4)
HBRC Journal     Open Access   (Followers: 2)
Hormigón y Acero     Full-text available via subscription  
HVAC&R Research     Hybrid Journal   (Followers: 1)
Indoor and Built Environment     Hybrid Journal   (Followers: 1)
Infrastructure Asset Management     Hybrid Journal   (Followers: 1)
Ingenio Magno     Open Access  
Insight - Non-Destructive Testing and Condition Monitoring     Full-text available via subscription   (Followers: 14)
International Journal for Service Learning in Engineering     Open Access  
International Journal of 3-D Information Modeling     Full-text available via subscription   (Followers: 2)
International Journal of Advanced Structural Engineering     Open Access   (Followers: 7)
International Journal of Concrete Structures and Materials     Open Access   (Followers: 8)
International Journal of Condition Monitoring     Full-text available via subscription   (Followers: 1)
International Journal of Construction Engineering and Management     Open Access   (Followers: 6)
International Journal of Geosynthetics and Ground Engineering     Full-text available via subscription   (Followers: 1)
International Journal of Protective Structures     Full-text available via subscription   (Followers: 5)
International Journal of Steel Structures     Hybrid Journal   (Followers: 4)
International Journal of Structural Engineering     Hybrid Journal   (Followers: 7)
International Journal of Structural Integrity     Hybrid Journal  
International Journal of Structural Stability and Dynamics     Hybrid Journal   (Followers: 6)
International Journal of Sustainable Built Environment     Open Access   (Followers: 3)
International Journal of Sustainable Construction Engineering and Technology     Open Access   (Followers: 11)
International Journal on Pavement Engineering & Asphalt Technology     Open Access   (Followers: 3)
Journal of Accessibility and Design for All     Open Access   (Followers: 6)
Journal of Bridge Engineering     Full-text available via subscription   (Followers: 17)
Journal of Building Engineering     Hybrid Journal  
Journal of Building Materials and Structures     Open Access  
Journal of Building Performance Simulation     Hybrid Journal   (Followers: 5)
Journal of Civil Engineering and Construction Technology     Open Access   (Followers: 3)
Journal of Civil Engineering and Management     Hybrid Journal   (Followers: 7)
Journal of Civil Engineering and Science     Open Access   (Followers: 13)
Journal of Civil Engineering Research     Open Access   (Followers: 12)
Journal of Civil Society     Hybrid Journal   (Followers: 3)

        1 2     

Journal Cover Structural Concrete
  [SJR: 0.739]   [H-I: 9]   [10 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1464-4177 - ISSN (Online) 1751-7648
   Published by John Wiley and Sons Homepage  [1597 journals]
  • Structural Performance of Continuous R.C. Slabs Strengthened in Negative
           Moment Region using Mineral Based Composite
    • Authors: Ahmad Atta; Fahmy Zaher, Emad Etman
      Abstract: An experimental program was proposed and carried out to assess the effectiveness of the Mineral Based Composite (MBC) technique for the flexural strengthening of a negative moment in continuous reinforced concrete slabs. In addition to the testing of the two control specimens, the experimental program included the testing of nine continuous RC slab specimens with different details of the strengthening techniques, namely, using ordinary steel bars, and Mineral Base Composite (MBC) material. This experimental program was conducted to study the modes of failure, the load‐deflection behavior, and the failure loads. Furthermore, we present and describe a comparative study between the two strengthening techniques, namely, reinforced steel bars with Mineral Based Composite (MBC) or steel bars with epoxy mortar. Based on the presented experimental results, both strengthening techniques of the continuous slabs are evidently efficient. In this study, the measured results for the average cracks spacing were compared with the limits stipulated in CEB‐FIP code 1990 and the failure load calculations were extended with an analytical approach based on the ultimate theory for the failure load calculation. In conclusion, the results obtained from the analytical model are in agreement with the experimental results.
      PubDate: 2016-02-01T05:40:10.001804-05:
      DOI: 10.1002/suco.201500026
       
  • Numerical limit analysis of keyed shear joints in concrete structures
    • Authors: Morten A. Herfelt; Peter N. Poulsen, Linh C. Hoang, Jesper F. Jensen
      Abstract: This paper concerns the shear capacity of keyed joints, which are transversely reinforced with overlapping U‐bar loops. It is known from experimental studies that the discontinuity of the transverse reinforcement affects the capacity as well as the failure mode; however, to the best knowledge of the authors, previous theoretical works and present design equations in standards do not account for this important effect. In this paper, a detailed model based on finite element limit analysis is introduced to assess the effect of the discontinuous reinforcement. The model is based on the lower bound theorem and uses the modified Mohr‐Coulomb yield criterion, which is formulated for second‐order cone programming. The model provides a statically admissible stress field as well as the failure mode. Twenty‐four different test specimens are modelled and the calculations are compared to the experimental results. The results of the model show satisfactory agreement with the experimental observations. The model produces significantly better estimates of the shear capacity than the design equations of Eurocode 2.
      PubDate: 2016-02-01T05:39:54.825221-05:
      DOI: 10.1002/suco.201500161
       
  • Accuracy of design‐oriented formulations for the evaluation of
           flexural and shear capacities of FRP strengthened RC beams
    • Abstract: Fiber reinforced polymer (FRP) composites have been largely employed in the last few decades for strengthening and retrofitting existing reinforced concrete (RC) structures. Several studies are available in the literature and different analytical models were proposed for the evaluation of the FRP contribution in strengthened RC elements. This paper analyzes the accuracy of widely used analytical models, some of which are included in design guidelines, for the evaluation of flexural and shear contributions provided by the FRP. In particular, the analytical models for the evaluation of the FRP strain at intermediate crack‐induced debonding failure are analyzed. The accuracy of each formulation is assessed comparing the analytical provisions with the experimental results collected from two databases, one for bending and one for shear. The results obtained showed that most of the analytical flexural models attained a good level of accuracy and only few models provide inadequate results. A new formulation proposed for the evaluation of the FRP shear contribution is shown to be generally conservative, which comes at the expense of accuracy.
      PubDate: 2016-02-01T05:39:42.934696-05:
      DOI: 10.1002/suco.201500066
       
  • Punching shear strength of flat slabs: Critical review of Eurocode 2 and
           fib Model Code 2010 design provisions
    • Authors: Marcus Ricker; Carsten Siburg
      Abstract: fib Model Code 2010 introduces a new design concept for punching shear, which is based on the Critical Shear Crack Theory. In this paper, the design provisions for punching shear according to fib Model Code 2010, Eurocode 2 and the corresponding German National Annex to Eurocode 2 are presented and background information is given. By means of parameter studies and a comparison of the calculated resistances and test results, the different punching shear design provisions are critically reviewed. The safety levels of the code provisions are verified and the influence of the different punching parameters on the calculated resistances is examined in detail.
      PubDate: 2016-02-01T05:39:28.80501-05:0
      DOI: 10.1002/suco.201500106
       
  • Mechanics closed form solutions for moment redistribution of RC beams
    • Authors: Phillip Visintin; Deric J. Oehlers
      Abstract: For the efficient design of reinforced concrete beams and frames, moment redistribution is used to: reduce the absolute maximum magnitude of the moment in the critical region; equalise the critical moments at either side of interior columns and fully utilise the capacity of the non‐critical regions of a member. Although important, moment redistribution has historically proved to be difficult to quantify due to the complexity of quantifying hinge rotations. Although numerous empirical expressions exist for plastic hinge lengths, that is, the length over which the ultimate curvature can be integrated in order to give hinge rotations, a comparison with a global data set yields poor results. Using a recently developed mechancis based moment rotation approach it is possible to quantify the moment rotation characteristics of reinforced concrete hinges. In the tension region, the approach directly applies partial interaction theory to simulate the mechanisms associated with slip of the reinforcement relative to the surrounding concrete as cracks widen. While in the compression region, partial interaction shear friction theory is used to describe the formation and failure of concrete softening wedges. It is shown how the moment rotation approach explicitly allows for the size dependency. Furthermore, mechanics based solutions for moment redistribution are then derived and it is shown how these can be simplified at the ultimate limit state for use in the design office.
      PubDate: 2016-02-01T05:39:16.314284-05:
      DOI: 10.1002/suco.201500085
       
  • Investigation of the buckling behavior of thin‐walled concrete
           hollow piers
    • Abstract: Hollow tall concrete piers with high width‐to‐thickness ratios are commonly used in long‐span box girder bridges. Such thin‐walled structures present the possibility of failure due to local buckling. So, in common practice, diaphragms are usually set in hollow piers to improve the local stability, however, is it necessary? Although experimental research on the buckling behavior of hollow piers had been conducted extensively, only little analytical attempts have been made to reveal the effects of width‐to‐thickness ratio on local buckling behavior. To this end, an analytical model has been proposed to investigate the local buckling behavior of hollow piers. Following the Ritz‐Timoshenko methods, an analytical formula for critical local buckling stress is developed and verified to have good accuracy compared with finite element analyses. Based on the buckling failure mode of the hollow pier with the slenderness ratio over 6, it can be reasonably postulated that the strength of the hollow pier will be unaffected by local compression flange buckling when the wall width‐to‐thickness ratio is less than 24, and it is entirely unnecessary to set diaphragms in hollow piers in the view of stability. Additionally, it is equally interesting that the critical width‐to‐thickness ratio of the hollow pier with the slenderness ratio over 4 derived by the proposed model is the same as the value given by the current AASHTO‐LRFD Bridge Design Specifications.
      PubDate: 2016-01-22T03:10:07.982898-05:
      DOI: 10.1002/suco.201500043
       
  • Estimating loads on shores during the construction of RC building
           structures
    • Abstract: When constructing reinforced concrete (RC) building structures, knowing the loads to which the shoring system will be subjected during the entire process is one of the key aspects to ensure safety during the work. Although various simplified methods of estimating the load transmission between shores and slabs during construction have been proposed to date, none of these methods can estimate the loads on individual shores during the different construction phases. This paper proposes a calculation method that allows the loads on individual shores to be calculated for each construction phase, without having to resort to the use of advanced software. The proposal was validated by comparison with the results obtained from two actual buildings under construction and represents a step forward in the construction of RC building structures, as it is the first method that offers the possibility of estimating the loads acting on each shore during all the construction phases.
      PubDate: 2015-12-14T03:50:37.79987-05:0
      DOI: 10.1002/suco.201500130
       
  • Unified cyclic stress‐strain model for FRP‐confined concrete
           circular, square and rectangular prisms
    • Authors: Hadi Ziaadiny; Reza Abbasnia
      Abstract: Behavior and modeling of concrete columns confined with FRP composites under monotonic compression has been extensively studied, but cyclic behavior of FRP‐confined circular and rectangular columns has much less been investigated. A reliable model indicating the cyclic stress‐strain behavior of FRP‐confined columns is of great importance especially for seismic retrofit and design of these columns. In this paper, based on the results from a series of cyclic compressive loading tests of FRP‐confined specimens, a unified cyclic stress‐strain model is proposed for circular, square and rectangular columns confined with FRP composites. The model contains different parts of cyclic stress‐strain curve, including plastic strain, maximum strain of unloading path and corresponding stress, stress deterioration, effect of loading history, partial unloading and partial reloading. New expressions are also proposed for predicting unloading and reloading paths. The proposed model provides good agreement with the test results.
      PubDate: 2015-12-11T06:40:09.127092-05:
      DOI: 10.1002/suco.201500128
       
  • Background to European seismic design provisions for the retrofit of R.C.
           elements using FRP materials
    • Authors: S.J. Pantazopoulou; S.P. Tastani, G.E. Thermou, T. Triantafillou, G. Monti, D. Bournas, M. Guadagnini
      Abstract: This paper is a comprehensive state of the art background document on European seismic design provisions which was assembled in support of the development of design guidelines by the fib Committee 5.1 regarding the use of externally applied Fiber Reinforced Polymers (FRP) materials in the seismic retrofitting of reinforced concrete structures. In the context of developing design guidelines, the underlying mechanistic models that support the derivation of provisions were assembled after critical evaluation of the existing proposals and with careful reference to the available experimental evidence, the comparative assessment of past models in the literature, and requirements established from first principles.
      PubDate: 2015-12-11T06:40:08.17766-05:0
      DOI: 10.1002/suco.201500102
       
  • Cover Picture: Structural Concrete 4/2015
    • Abstract: The 2,815 m long, four‐lane Laguna Bridge, also known as the Anita Garibaldi Bridge, will be Brazil's third longest bridge and will significantly improve the transport connection from north to south to other South American countries. In October 2012, work started on this 52 span bridge that includes a 400 m long main span stay cable bridge. Protendidos DYWIDAG supplied the following products for this project 30,600 m of ∅︁ 32 mm DYWIDAG Bar Tendons and 860 m of ∅︁ 36 mm DYWIDAG Bar Tendons with Accessories. Diameter 32 mm DYWIDAG Bar Tendons were used both for the production of the precast segments and for widening the bridge deck using laterally mounted precast cantilever elements. (© DSI)
      PubDate: 2015-12-03T09:06:08.45423-05:0
      DOI: 10.1002/suco.201590016
       
  • Contents: Structural Concrete 4/2015
    • PubDate: 2015-12-03T09:06:08.287331-05:
      DOI: 10.1002/suco.201590020
       
  • Modeling Catenary Effect in Progressive Collapse Analysis of Concrete
           Structures
    • Authors: Arash Naji
      Abstract: Progressive collapse is a phenomenon in which local failure of a structural component due to gas explosion or blast may leads to failure of the entire structure or significant part of it. RC structures can resist progressive collapse through various mechanisms like frame action and catenary action. In this paper, using Limit Analysis, the effect of catenary action on resistance of concrete frame structures against progressive collapse is modeled. In this regard, nonlinear optimization is performed. It is observed that although frame action is known as the main mechanism that resist progressive collapse, but at the end of this action, after rupture of bottom bars, catenary effects may have noticeable increase on resistance of the structure. The results have good agreement with experimental results done by other researchers.
      PubDate: 2015-11-13T02:20:15.073582-05:
      DOI: 10.1002/suco.201500065
       
  • Time‐variant reliability analysis of RC bridge girders subjected to
           corrosion – shear limit state
    • Authors: P.V. Ahsana; K. Balaji Rao, M.B. Anoop
      Abstract: Chloride induced corrosion of reinforced concrete (RC) bridge girders has led to huge loss of national resources. One of the important concerns of RC bridge girders is corrosion of stirrups, because of which, failure mechanism can even change from a ductile flexural mode to a brittle shear mode. Hence, analysis of reduction of shear capacity with time is essential in their reliability assessment, which is the topic of the paper. This paper proposes a stochastic modeling approach for estimation of time‐variant shear capacity and reliability within the framework of Monte Carlo simulation, which assists in sustainability‐based service‐life design of bridge girders. Such modern concepts of design require methodologies for estimating whole life cost at the design stage itself. Development of such methodologies would provide the designer various options to arrive at optimum design having desired performance level during the service life. The proposed approach takes into account:1) randomness in basic variables, 2) effect of micro‐environment and spatial variation of corrosion, 3) number of stirrups resisting web shear failure, and 4) ductile to brittle transition of stirrup steel with corrosion propagation. Incorporation of this transition is found to have significant influence in the time‐variant reliability of the girder. Though PFA concrete is known to have better durability characteristics than OPC concrete, this paper gives a framework for its quantification in terms of time variant reliability.
      PubDate: 2015-11-13T02:20:13.896505-05:
      DOI: 10.1002/suco.201500081
       
  • Investigation of optimal layout of ties in STM developed by topology
           optimization
    • Abstract: Strut‐and‐tie models (STMs) have been wildly used for the design of disturbed regions in structural concrete members. The STM developed based load path method or with the aid of stress trajectories is not unique and varies with the designer's intuition and past experience. As a result, topology optimization methods have been adopted to generate STMs in reinforced concrete structures. However, such models are just a preliminary configuration, and the detailed layout of ties in STM can not be determined by the optimal topology. This is because the reinforced concrete is assumed to be a uniform elastic continuum. Therefore, the effect of the steel reinforcement on the load transmission can not be considered in the optimization process. Recently, the criterion of minimum strain energy has been proposed to determine the optimal layout of STM obtained by the modified optimization method. However, such strain energy criterion does not work when the minimum strain energy in ties is zero evaluated by mathematical equations. To address this issue, the maximum stiffness criterion is proposed to find out the optimal layout of ties in STM by evaluating the stiffness of strut ties.
      PubDate: 2015-11-13T02:20:12.865972-05:
      DOI: 10.1002/suco.201500093
       
  • A New Approach for the Calculation of Internal Forces, Moments and
           Deflections of Sandwich Panels with Reinforced Concrete Facings
    • Abstract: As part of a research project at the Technische Universität Kaiserslautern, software for the calculation of internal forces, moments and deflections of sandwich elements with reinforced concrete facings has been developed. Sandwich elements with stiff concrete facings are internally statically indeterminate. The cracking of the concrete facings leads to a redistribution of internal forces and moments over the length and across the cross‐section of the element. This redistribution must be considered in the structural design of these elements. An existing program for the calculation of metal‐faced sandwich elements was considerably extended by an iterative approach, which allows the calculation of the internal forces and moments with the accurate stiffness of the cracked facings. In the following paper, this iterative approach as well as the calculation algorithm behind the new software, called swe2+, are explained. Furthermore, a verification of the calculation results and a parametric study on a two‐span sandwich element are presented.
      PubDate: 2015-11-13T02:20:11.78297-05:0
      DOI: 10.1002/suco.201500104
       
  • Properties of stabilized recycled plastic concretes made with three types
           of cements
    • Authors: Faiz Uddin Ahmed Shaikh; Sarvesh Mali
      Abstract: The growing concern for ready mix concrete industry is the disposal of returned unused concrete. In a plastic state, the concrete is a perishable product and the disposal of any unused concrete provides a set of challenges. An increase in environmental regulations requires the industry to implement the best practices that effectively reduces the quantity of by‐product materials require disposal. This paper reports a preliminary experimental study on the effect of commercial stabilizer on the plastic and harden properties of concretes made with three different types of cements commonly used in Australia, namely general purpose Portland cement (GP) (100% ordinary Portland cement (OPC)), general purpose blended (GB) cement (75% OPC + 25% Class F fly ash (FA)) and low heat (LH) cement (35% OPC + 65% blast furnace slag). In the initial phase, the effect of various stabilizer dosages on the efflux time (flow time) of GP, GB and LH cements grouts is studied. The results showed that for a constant efflux time the holding duration of the grouts increases with increasing stabilizer dosages (or amounts) and in the case of GB and LH cements grouts the holding duration is longer than the GP cement grout for the same stabilizer dosage. In the next phase, the predicted stabilizer dosage was added in concretes made with above three cements to evaluate the plastic and harden properties of fresh concretes, stabilized concretes and blend of fresh concretes with 10%, 25% and 50% stabilized concretes. Results show that, the initial slump values are within the tolerance except it is higher when stabilizer dosage is added after an hour, but the final slump is within the tolerance of control concrete. After stabilization of the concretes, the initial and final setting time of stabilized concretes is increased to more than 24 hours. The initial and final setting time of the blended concrete containing fresh concrete and 10%, 25% and 50% stabilized concretes are similar to those of fresh concrete for all cements types. The stabilized concretes do not have any significant effect on compressive strength and shrinkage compared to the control concrete.
      PubDate: 2015-11-13T02:20:10.44568-05:0
      DOI: 10.1002/suco.201500111
       
  • Influence of reinforcement bar layout on fibre orientation and
           distribution in slabs cast from fibre‐reinforced
           self‐compacting concrete (FRSCC)
    • Abstract: Fibre orientation and volume distribution affect the post‐cracking tensile strength, which is one of the main design parameters of fibre‐reinforced concrete (FRC). This paper discusses the influence of unidirectional and grid reinforcement on fibre orientation and distribution in FRC slabs. Slabs without conventional reinforcement bars were used as reference. The slab size was 1200x1200x150mm3. Numerical simulations were used to predict the fibre orientation. To determine the actual fibre orientation and distribution, X‐ray Computed Tomography (CT) was used. Beams were sawn from each slab, CT‐scanned, and tested in three‐point bending tests in accordance with EN 14651. Both the numerical simulations and the CT results show that the rebars caused a more isotropic fibre orientation in the lower halves of the slabs. This was confirmed in the bending tests, where the lowest variation and highest residual tensile strengths were documented for beams sawn from grid‐reinforced slabs. Fibre migration from the upper layer to middle and lower layers of the slabs due to gravity was observed in all slabs, and in the reinforced slabs migration also depended on the distance from the casting point. The reinforcement led to an accumulation of fibres above the rebars in the middle layer of the reinforced slabs. A set of mechanisms is proposed to explain the experimental results.
      PubDate: 2015-11-13T02:10:08.905309-05:
      DOI: 10.1002/suco.201500064
       
  • Experimental Study on Fatigue Behavior of CFRP Plates Externally Bonded to
           Concrete Substrate
    • Authors: Wei Zhang
      Abstract: The behavior of the bond between fiber‐reinforced polymer (FRP) and concrete greatly influences the behavior of concrete structures strengthened with FRP composites. Although numerous experimental studies have investigated this bond, experimental data concerning fatigue tests on carbon FRP plates applied to concrete blocks are still lacking. Thus, a series of double‐lap shear tests under monotonic and fatigue loadings were performed on concrete prismatic specimens reinforced with CFRP plates. First, a series of experimental investigations are summarized. Thereafter, the fatigue behavior of CFRP plate debonding is characterized using S–N diagrams, which represent the relationship of the upper‐limit fatigue load with the monotonic load strength and the number of cycles to debonding on a semi‐logarithmic scale.
      PubDate: 2015-11-13T02:10:07.746729-05:
      DOI: 10.1002/suco.201500044
       
  • Probabilistic Degradation Modeling of Segmental Linings Assembled Circular
           Tunnels
    • Authors: Qing Ai; Yong Yuan, Sankaran Mahadevan, Xiaomo Jiang
      Abstract: Cross‐section deformation is considered an important indicator for assessing the structural safety in inspection and maintenance of tunnels. Its increase during lifetime is an indication of the gradual degradation of structural performance. In order to take timely and appropriate maintenance measures before the tunnel reaches the ultimate limit state, a predictive degradation model of cross‐section deformation should be established. In this paper, a probabilistic degradation model is developed based on an average uniform rigidity ring model for segmental linings assembled circular tunnels. By considering the uncertainties and relevant time‐varying performances of parameters the model is able to give probabilistic and time‐dependent predictions. Critical parameters are identified and the model is simplified after sensitivity analysis. Based on the measuring data, a Bayesian updating method is proposed to improve the input assumptions and predictions of the model. This research provides a perspective on the degradation modelling of the cross‐section deformation of segmental linings assembled circular tunnels and methods for improving the proposed predictive model.
      PubDate: 2015-11-13T02:10:07.541513-05:
      DOI: 10.1002/suco.201400122
       
  • European Design Rules for Point Load Near Support evaluated with Data from
           Shear Tests on Non‐Slender Beams with Vertical Stirrups
    • Abstract: This paper includes a presentation of a shear test database that contains 278 tests conducted on reinforced concrete beams with vertical stirrups and without horizontal skin reinforcement. These beams are commonly referred to as non‐slender beams since they were tested by using loading arrangements that created shear span‐to‐depth ratios (a/d) less than 2.4. In an effort to arrive at a database that can be used for the purposes of evaluating the accuracy and conservativeness of design provisions, several control and filtering criteria were applied. After this process 178 beams remained in the evaluation database. The analyses conducted by using this database indicated that the application of strut‐and‐tie models (STM) of Eurocode 2 (EC2) to non‐slender beams with stirrups was unconservative, i.e. the database analyses yielded results that were above the desired 5%‐fractile. Almost all unconservative strength estimations were obtained for test specimens containing large quantities of stirrups. Conversely, statistical evaluations showed that FIP Recommendations model for beams with point loads near the support were conservative.
      PubDate: 2015-10-12T04:21:16.797618-05:
      DOI: 10.1002/suco.201500089
       
  • Evaluation of safety formats for non‐linear Finite Element Analyses
           of statically indeterminate concrete structures subjected to different
           load paths
    • Authors: Mattias Blomfors; Morten Engen, Mario Plos
      Abstract: To increase the efficiency of new structures and to perform safety evaluations of existing structures the nonlinear behavior of reinforced concrete should be modelled and analyzed. The applicability of the safety formats in present design codes to indeterminate structures subjected to loading in several directions is unclear. The safety formats in Model Code 2010 have been evaluated for a reinforced concrete frame subjected to vertical and horizontal loading and the influence of load history was studied. Basic reliability methods were used together with response surfaces to assess the failure probabilities and all safety formats did not meet the intended safety level. The results indicate the importance of load history and it is concluded that more research regarding how it influences the safety level of complex structures is required.
      PubDate: 2015-09-23T03:30:09.452015-05:
      DOI: 10.1002/suco.201500059
       
  • Bella Sky Hotel – Exploring the potentials in precast concrete
           design
    • Abstract: The Bella Sky Hotel comprises two towers both leaning with 15 degrees angles. The inclination introduces enormous forces throughout the building which entails large challenges in the design. Moreover the building is made of precast concrete elements which further leads to large design challenges. A full 3D linear elastic FE (Finite Element) model modified to approximate non‐linear support conditions is used for the design of the hotel. A detailed design is carried out using specific post design programs. These programs are developed for handling the design of lintels, in‐plane forces, stability, horizontal joints, vertical joints and joint reinforcement. The large forces in the building require a large amount of reinforcement and thereby several complex geometric design solutions. For Rambøll the design has been the start of a new era in concrete in‐situ cast and precast building design.
      PubDate: 2015-09-14T04:30:24.744207-05:
      DOI: 10.1002/suco.201500100
       
  • Anchorage of composite dowels in UHPC under fatigue loading
    • Authors: Joerg Gallwoszus; Alexander Stark, Martin Classen
      Abstract: In steel‐concrete composite structures, innovative composite dowels can be used for the connection of ultra‐high performance concrete (UHPC) slabs and high‐strength steel members. In addition to sufficient shear capacity, composite dowels have to ensure the transmission of tensile forces in the composite connection in order to prevent lifting of the concrete slab. This may lead to structural problems, particularly in the very slender concrete slabs of high‐strength composite beams, where composite dowels have very small embedment depths. Although there already exist findings concerning the structural anchorage behavior of composite dowels under static loads, studies on the fatigue of composite dowels under cyclic pull out loading are still lacking, so far. As the fatigue behavior in crucial for applications in bridge construction, the present paper introduces cyclic pull out tests of composite dowels in UHPC slabs. Here, the influence of different load‐dependent parameters (upper load level and load range) as well as the use of a transverse reinforcement has been investigated. Furthermore, an approach to assess the lifetime of composite dowels in UHPC under cyclic pull out loading is proposed.
      PubDate: 2015-09-03T03:41:58.79363-05:0
      DOI: 10.1002/suco.201500034
       
  • Mechanical, durability and hygrothermal properties of concrete produced
           using Portland cement‐ceramic powder blends
    • Abstract: Blended Portland cement‐ceramic powder binder containing up to 60% of fine‐ground waste ceramics from a brick factory is used in concrete mix design, as an environmental‐friendly alternative to the commonly used Portland cement. The experimental analysis of basic physical characteristics, mechanical and fracture‐mechanical properties, durability properties and hygrothermal characteristics shows that the optimal amount of ceramic powder in the mix is 20% of the mass of blended cement. The decisive parameters in that respect are the compressive strength, liquid water transport parameters and resistance against deicing salts which are not satisfactory for higher ceramics dosage in the blends. In the case of other studied parameters, the limits for the effective use of ceramic powder are higher, 40% for the effective fracture toughness and specific fracture energy, 60% for the frost resistance and chemical resistance to MgCl2, NH4Cl, Na2SO4, HCl and CO2. The water vapor diffusion coefficient is found to increase with the increasing content of ceramics which for wet envelopes can be considered as a positive feature but for dry envelopes it may have a negative effect. The thermal conductivity of all mixes increases fast with growing moisture content; up to 50% differences between the dry‐ and water saturated state values are observed. This has to be taken into account in energy‐related calculations.
      PubDate: 2015-08-07T02:10:07.454623-05:
      DOI: 10.1002/suco.201500029
       
  • A New Method for Proportioning Recycled Concrete
    • Authors: Pramod K. Gupta; Ziyad A. Khaudhair , Ashok K. Ahuja
      Abstract: In this paper, a new modified mix proportioning method named as Equivalent Coarse Aggregate Mass (ECAM) to produce normal strength concrete using recycled concrete aggregate is proposed. Basic concepts of the proposed method with calculations for mix design are presented through designing fourteen mixes and testing of 99 concrete samples including 57 cubes and 42 cylinders. Experimental work was carried out in two phases. In the first phase, an experimental program was carried out to verify the proposed mix design method by studying a single parameter uniaxial compressive strength. Five different mixes with initial 0%, 25%, 50%, 75% and 100% replacements by mass were designed, casted and tested in this phase. It was concluded from the first phase that the proposed method can be adopted for designing the recycled concrete up to a nominal replacement ratio of 50%. Accordingly, the second phase of experimental study was conducted to design three different grades of concrete strength using the proposed method to investigate the mechanical properties of the recycled concrete. Seven different mechanical properties which include compressive strength, splitting tensile strength, modulus of elasticity, Schmidt Hammer test, ultrasonic pulse velocity test, fresh density and hardened density were investigated, presented and discussed.
      PubDate: 2015-08-07T02:10:06.388782-05:
      DOI: 10.1002/suco.201400076
       
  • The Effects of Alkali‐Silica Reaction on Mechanical Properties of
           Concretes with Three Different Types of Reactive Aggregates
    • Authors: Okpin Na; Yunping Xi, Edward Ou, Victor E. Saouma
      Abstract: This paper investigated the degradation of mechanical properties of concretes made of three types of aggregates affected by alkali‐silica reaction (ASR). To identify the reactivity of ASR of the three selected aggregates, three standard testing methods were used: ASTM C289, JASS 5N T‐603, and ASTM C1260. The test results showed that all three aggregates were potentially deleterious. A new acceleration method was proposed based on JASS 5N T‐603 and ASTM C1260 for concrete specimens. In the acceleration method, cylindrical concrete specimens were used, additional alkali material was added into the concrete mixture, and the specimens were stored under the condition similar to ASTM C1260. The preconditioned concrete specimens were then used for the evaluation of mechanical properties of the ASR affected concrete in terms of strength and stiffness. Test results showed that special attention must be made to the effects of two opposing mechanisms on strength and stiffness of concrete: hydration reactions and ASR. Hydration reactions enhance the mechanical properties, while ASR does the opposite. Length change of concrete specimens were also measured which showed that the basic trends for the length change and for the mechanical properties may be different. It is better to examine the effect of ASR on both length change and the mechanical properties. The size and reactivity of aggregate are very important factors for the mechanical properties of the ASR affected concretes. Within the two month testing period, the reactive fine aggregate may cause ASR expansion and the reactive coarse aggregates may not.
      PubDate: 2015-08-07T02:10:05.270837-05:
      DOI: 10.1002/suco.201400062
       
  • Life Cycle Analysis for Concrete Beams Designed with Cross Sections of
           Equal Durability
    • Authors: Lin Chen; Wenjun Qu, Peng Zhu
      Abstract: The durability at the corners of the cross section is relatively weak in the concrete beam of bridges; therefore, the reinforcements at the corners would corrode first. In order to delay the durability failure at the corners, measures such as application of corner concrete coating or adjustments of reinforcements at the corners should be taken. In this way, the durability resistance would be adjusted to be equal in the section, which is called equal durability design method. In this paper, the life cycle analysis of a component designed with equal durability and one designed in traditional way both in carbonation environment was conducted and compared. A probabilistic model of service life was established based on empirical degradation models. Service life distribution was calculated with Monte Carlo simulation method. Costs associated with durability failure were estimated based on the service life distribution. Related influencing factors were analyzed as well. Finally, life cycle cost analysis of the component designed with equal durability and the one designed in traditional way was conducted and compared. Results showed that the component designed with equal durability is more economic in the life cycle if the construction cost was controlled within about 1.1 times that of component designed traditionally.
      PubDate: 2015-07-20T06:20:18.816856-05:
      DOI: 10.1002/suco.201400117
       
  • Estimation of Transfer Lengths in Precast Pretensioned Concrete Members
           Based on a Modified Thick‐Walled Cylinder Model
    • Abstract: In pretensioned concrete members, prestress is introduced by the bond mechanism between prestressing tendon and surrounding concrete. Therefore, to secure the intended level of effective prestress in the tendon, sufficient bond stresses between the prestressing tendon and the concrete should be developed at release, for which a certain length from end of the pretensioned concrete member is required, and this required distance is defined as the transfer length of the prestressing tendon. In this study, the prestress introduction mechanism between the concrete and the prestressing tendon was mathematically formulated based on the thick‐walled cylinder theory (TWCT). On this basis, an analytical model for estimation of the transfer length was presented. The proposed model was also verified by comparing with test results collected from the literatures, and it was confirmed that the proposed model can accurately evaluate the effects of influential factors, such as diameter of prestressing tendon, compressive strength of concrete, concrete cover thickness, and magnitude of initial prestress, on the transfer lengths of prestressing tendons in various types of pretensioned concrete members.
      PubDate: 2015-07-15T05:20:18.517507-05:
      DOI: 10.1002/suco.201500049
       
  • Effect of ultrafine fly ash on properties of concretes containing
           construction and demolition wastes as coarse aggregates
    • Authors: Faiz U.A. Shaikh
      Abstract: This paper presents preliminary results on the effect of ultrafine fly ash (UFFA) on the properties of concretes containing recycled coarse aggregates (RCA) originated from construction and demolition (C&D) wastes. The effect of 10% UFFA on compressive strength, tensile strength, sorptivity and chloride ion permeability of concretes containing 25% and 50% RCA is evaluated at 7, 28 and 56 days. The addition of UFFA increased the compressive strength of recycled aggregates concretes at all ages up to 56 days. However, a slight reduction in the tensile strength of recycled aggregate concretes is observed. Concrete containing 25% RCA and 10% UFFA achieved 94% of the control concrete's compressive strength at 56 days. In both recycled aggregate concretes the sorptivity and chloride ion permeability are much lower at all ages due to the addition of 10% UFFA given the fact that it acts to promote the hydration and block the large capillary pores within the concrete.
      PubDate: 2015-07-14T09:55:12.735578-05:
      DOI: 10.1002/suco.201500030
       
  • Sulfate Attack Induced Damage and Micro‐Mechanical Properties of
           Concrete Characterized by Nano‐indentation Coupled with X‐Ray
           Computed Tomography
    • Authors: Chunxiang Qian; Yanfeng Nie, Tianji Cao
      Abstract: Sulfate attack is a serious problem for concrete served in marine environment. Sulfate attack can change the composition and microstructure of concrete and influence the mechanical and durable performances eventually. In this paper, the heterogeneity and mechanical properties of concrete exposed to sulfate was investigated from microscopic to mesoscopic scale. X‐ray computed tomography (XCT) and Nano‐indentation was adopted to define the defect zone and establish the relationship between interfacial transition zone (ITZ) and matrix of concrete (mortar). The experiments were based on concrete and mortar specimens in different strength. The results of XCT and Nano‐indentation indicated that the specimens had similar damaged degree regionally and a good correlation existed between the elastic modulus of the ITZ and mortar. The concrete could partition into three parts: the cracked zone with heavy damage, damaged zone and the undamaged zone. The elastic modulus of mortar phase and ITZ had a linear relation.
      PubDate: 2015-07-14T09:55:11.809917-05:
      DOI: 10.1002/suco.201400123
       
  • Scatter in the Shear Capacity of RC Slender Members without Web
           Reinforcement: Overview Study
    • Authors: Filippo Sangiorgio; Johan Silfwerbrand, Giuseppe Mancini
      Abstract: All researchers that have tested the shear capacity of RC members without stirrups have observed a large scatter in the results. The objective of this paper is to conduct an overview study of the causes to the great shear failure scatter of RC beams without stirrups. Thirteen groups of shear tests on comparable experiments, extracted from the ACI‐DAfStb evaluation database, are considered. The amount of data available is increased numerically. To this end, based on Eurocode 2 equations for shear resistance and shrinkage strain, a full probabilistic model according to JCSS Probabilistic Model Code is defined. A multivariate statistical evaluation of outcomes is then performed. The investigation highlights that both tensile strength of concrete and high values of shrinkage may be useful to be considered for more in‐depth studies of the phenomenon, whereas geometrical properties and concrete compressive strength seem to be less important or can even be neglected.
      PubDate: 2015-07-14T09:55:10.85857-05:0
      DOI: 10.1002/suco.201400107
       
  • A Theoretical Method for Calculating Compressive Arch Capacity of RC Beams
           against Progressive Collapse
    • Authors: Reza Abbasnia; Foad Mohajeri Nav
      Abstract: Compressive arch action is one of the main resistance mechanisms against progressive collapse in reinforced concrete (RC) buildings. Hence, many studies investigated the development of arching action in RC beams and frames but less attention has been paid to calculate the corresponding enhancement in structural capacity. In the present study, a theoretical method is introduced in order to calculate the arching capacity of RC beams and also to obtain a quantitative assessment about structural robustness against progressive collapse. The proposed method is validated using the experiments in the literature. The evaluation indicates that the introduced procedure could establish a reliable foundation for estimating the arching capacity of beams and also structural robustness.
      PubDate: 2015-07-14T09:55:09.84253-05:0
      DOI: 10.1002/suco.201400119
       
  • A reliability‐based investigation into ductility measures of RC
           beams designed based on fib Model Code 2010
    • Authors: Hassan Baji; Hamid Reza Ronagh
      Abstract: A reliability‐based investigation into the ductility measures of reinforced concrete (RC) beams designed based on the current fib Model Code 2010 (MC 2010) is presented in this paper. Based on ductility ratio (strain at tensile rebar to yield stress of steel), a limit state to ensure adequate ductility in RC beams is proposed. Results show that the ductility ratio generally follows a right‐skewed distribution, and due to variability in the material properties and model error, there is high variability in the strain ductility. This high variability in the ductility ratio leads to a high probability of non‐ductile behaviour for RC beams designed based on the code. This is more pronounced for normal‐strength concrete and grade S500 steel. Based on a target probability taken from the literature, a modification to the allowable neutral axis depth advised by the code is proposed. Results presented in this paper indicate that more reliability‐based studies into the safety factors provided by the MC 2010 for ensuring adequate ductility in RC beams are needed.
      PubDate: 2015-07-14T09:55:08.836358-05:
      DOI: 10.1002/suco.201400116
       
  • Behaviour of RC Beams with Openings Strengthened by Externally Bonded
           Carbon Fiber Reinforced Polymer (CFRP)
    • Authors: Siew Choo Chin; Nasir Shafiq, Muhd Fadhil Nuruddin
      Abstract: A detailed investigation was conducted to study the behaviour of reinforced concrete (RC) beams with large openings strengthened by externally bonded carbon fiber reinforced polymer (CFRP) laminates. A total of six simply‐supported beams consisting of two solid beams and four beams with openings were constructed and tested under four‐point bending. Each beam had a cross‐section of 120 × 300 mm and length of 2000 mm. A large opening was placed symmetrically in the mid‐span of the beams. Test parameters included the opening shape and size as well as the strengthening configuration of CFRP laminates. The study was conducted in both experimental testing and finite element analysis. Experimental results show that provision of a large opening at mid‐span reduces the beam capacity to about 50%. Strength gain due to strengthening using CFRP laminate in the experimental results obtained was in the range of 80–90%. Comparison between the finite element and experimental results were performed.
      PubDate: 2015-07-14T09:55:07.775283-05:
      DOI: 10.1002/suco.201400111
       
  • Estimating fixed‐end rotations of reinforced concrete members at
           yielding and ultimate
    • Authors: Panagiotis E. Mergos; Andreas J. Kappos
      Abstract: Strain‐penetration of the longitudinal reinforcement of reinforced concrete (RC) members in the joints and/or footings results in fixed‐end rotations at the member ends. Several experimental studies have shown that fixed‐end rotations caused by strain‐penetration contribute significantly (up to 50%) to the total displacement capacity of RC members. Hence, accurate determination of these fixed‐end rotations at yielding and ultimate limit states becomes of primary importance when defining the structural response of RC members. The purpose of this study is to present the theoretical background and the assumptions behind the most common relationships found in the literature for determining strain‐penetration induced fixed‐end rotations at yielding and ultimate. Furthermore, new simple relationships are proposed on the basis of realistic and mechanically‐based assumptions. Comparisons between the existing and proposed relationships demonstrate the limitations of the former. Finally, the proposed relationships are calibrated against experimental measurements of RC column specimens subjected to cyclic loading with recorded fixed‐end rotations due to strain‐penetration in the adjacent joints and/or footings.
      PubDate: 2015-07-14T09:55:06.804186-05:
      DOI: 10.1002/suco.201400067
       
  • Experimental investigation of soil‐structure interaction for
           transition slabs of integral bridges
    • Abstract: This paper presents the results of an experimental test series on the soil‐structure‐pavement interaction in the vicinity of the transition slab at the end of an integral bridge. The main function of transition slabs is to ease the transition between the bridge deck and the embankment in case of differential settlements. Additionally, in the case of integral bridges, they can solve the problem of moderate imposed longitudinal deformations at the bridge ends. In this case, the displacements imposed to the transition slab can lead to vertical and longitudinal surface displacements and to cracking of the pavement. Based on the observed behaviour, some recommendations are proposed for the geometry and surface conditions to optimise the behaviour of the transition slabs.
      PubDate: 2015-06-12T04:40:29.679194-05:
      DOI: 10.1002/suco.201500018
       
  • Towards the early‐age performance control in precast concrete
           immersed tunnels
    • Authors: Wei Jiang; Xian Liu, Yong Yuan, Shengnian Wang, Quanke Su, Luc R. Taerwe
      Abstract: In engineering practice, the prevention of early‐age cracking in massive concrete structures is of great importance to their serviceability during the whole‐life cycle. From the scientific aspect, this engineering concern requires the control of the early‐age performance of concrete structures. Following earlier research projects with the background project of the Hong Kong‐Zhuhai‐Macao Link, the focus of this work is to obtain insight into the evolution of the early‐age behavior of precast concrete in an immersed tunnel. To this end, a full‐scale test is performed, from which the behavior of early‐age concrete is observed directly. After validation of the developed constitutive model with the test results, the early‐age performance during the entire fabrication process of the precast concrete immersed tunnel is evaluated numerically. It is also found that stress relaxation is playing a major role for the stress development in the immersed tunnel, although the thermal strain is the main origin of the early‐age stresses. Through this in‐depth investigation, a comprehensive understanding is obtained of the early‐age behaviour of an actual precast concrete immersed tunnel. What is more important, the early‐age performance of concrete structures can be accurately evaluated and further adjusted or controlled with the merit of the validated numerical modeling, which is no doubt beneficial to the control of early‐age cracking in massive concrete structures in engineering.
      PubDate: 2015-04-23T04:13:41.472227-05:
      DOI: 10.1002/suco.201400125
       
  • Experimental analyses of an optimised shear load transfer in
           circumferential joints of concrete segmental linings
    • Authors: Thomas Putke; Roksana Bohun, Peter Mark
      Abstract: Coupling of subsequent rings in circumferential joints of tunnel lining systems is of particular interest in mechanised tunnelling and discussed as a controversial issue. On the one hand interlocking systems like “cam & pot” can be of use to limit the lining's deformation. But on the other hand unfavourable conditions lead to often repeated and significant damages decreasing the tunnel's lifetime. This paper provides experimental results of a three‐part optimisation concept (structural analysis, topological optimisation and experimental verification), tested for concrete linings at the example of the shear coupling mechanism. At first, geometrical dependencies are analysed that reveal predominantly stronger cams than corresponding pots. Hence, bearing capacities of pots are increased transferring topological optimisation results into reinforcement concepts featuring micro‐mesh reinforcement, steel fibre cocktails and rebars welded to anchor plates. Especially the latter resulted in comparatively stronger pots along with a considerably increased ductility. Nevertheless, pots still represent the weaker part and are crucial for the design. Therefore, a concept with steel dowels and predefined static boundary conditions is tested. Its results are characterised by a significantly lower scatter of bearing capacities accompanied by a strongly increased ductility.
      PubDate: 2015-04-20T05:10:31.541881-05:
      DOI: 10.1002/suco.201500013
       
  • Shear strength of self‐compacting concrete beams with small amounts
           of stirrups
    • Abstract: In comparison with a vibrated concrete (VC) of the same strength class, the self‐compacting concrete (SCC) typically has lower coarse aggregate content and, eventually, smaller maximum aggregate size. This may result in reduction of aggregate interlock between fracture surfaces of SCC. Since the aggregate interlock plays an important role in the shear strength of slender beams, SCC beams may have a shear strength lower than similar VC beams, but studies on that subject are still limited. This article summarizes an experimental program that includes beams of high strength SCC and transverse reinforcement ratios around the minimum given by different codes, case that has not been investigated. The shear strengths of those beams are compared with the ones of VC beams with similar concrete compressive strength and small amounts of transverse reinforcement and also to the calculated ones according to different code procedures.
      PubDate: 2015-04-20T05:10:30.055478-05:
      DOI: 10.1002/suco.201400084
       
  • Concrete fatigue in composite dowels
    • Abstract: In modern bridge construction, steel‐concrete composite structures with composite dowels are being applied more than ever, especially for small and medium spans. In contrast to headed studs, in which initial steel cracks occur after only a few load cycles [1], [2], the lifetime of composite dowels is characterized by the compression of the multiaxially stressed concrete in front of the composite dowel. Here, plastic compression strains occur in the concrete, which accumulate over load cycles, leading to a cyclical increase of relative displacements in the connection. Certain proportions of these relative displacements, called inelastic slip, remain in the connection, even after the loading is released. The inelastic slip changes the characteristics of the static dowel curve. The initially rigid connection degrades over the lifetime, leading to redistributions of internal forces, which may be decisive for fatigue design. In order to consider the degradation of the composite connection a cyclic dowel curve can be used, which may be developed from the static dowel curve by introducing the inelastic slip. In this paper, the results of cyclic shear tests on different composite dowel geometries are presented. Here, the effect of load‐dependent parameters (upper load level and load range) was investigated. Furthermore, an engineering model for determining the cyclic dowel curve is presented, which was developed based on the results of experimental and numerical investigations.
      PubDate: 2015-04-02T05:40:05.295233-05:
      DOI: 10.1002/suco.201400120
       
  • Behaviour of Eccentrically Loaded High Strength Concrete Columns
           Intersected by Lower Strength Concrete Slabs
    • Abstract: This paper presents the results of experimental investigations of the edge and corner high strength concrete columns intersected by concrete slabs. It was considered effect of intersection by weaker slab concrete on load carrying capacities of reinforced concrete columns. The only considered parameter was location of column with respect to the edge of the slab. It was stated that providing a small slab overhang beyond the column edge makes it possible to increase the actual strength of the joint concrete significantly. The results of the author's research have clearly demonstrated, that providing a sufficiently large slab overhang allows to treat the edge and corner column – slab connection joints as the internal joints. Existing code provisions concerning strength of concrete of edge and corner column – slab connection joints are in some cases too conservative and require clarification.
      PubDate: 2015-03-26T05:24:12.391819-05:
      DOI: 10.1002/suco.201400114
       
  • Nonlinear analysis of shear‐critical reinforced concrete beams using
           the softened membrane model
    • Authors: Wael Kassem
      Abstract: An analysis method for predicting the shear strength and behaviour of shear‐dominated reinforced concrete beams is presented in this paper. The proposed model is based on the softened membrane model that accounts for the Poisson's effect on the behaviour of reinforced concrete beams subjected to the combined effect of shear and flexure. The softened membrane model is appealing for modelling the shear behaviour of concrete elements as it is based on solid mechanics of materials fundamentals. The accuracy of the proposed mathematical model was validated against the experimental results of 66 reinforced concrete elements tested under pure shear as well as 167 shear‐dominated RC beams available in the literature. Analysis results showed that the proposed model could satisfactorily predict the shear strength as well as the entire shear stress‐shear strain behaviour of shear‐dominated beams.
      PubDate: 2015-03-26T05:24:12.254262-05:
      DOI: 10.1002/suco.201400093
       
  • Toughness Behaviour of High Performance Lightweight Foamed Concrete
           Reinforced with Hybrid Fibres
    • Authors: Eethar Thanon Dawood; Ali Jihad Hamad
      Abstract: Lightweight foamed concrete (LWFC) is a high performance concrete having structural strength with lightweight density and high flowability. High performance lightweight foamed concrete (HPLWFC) is used in modern concrete technology and intensely in the construction applications of high‐rise buildings, long‐span concrete structures and road sub‐bases among others. The present work deals with the fresh and hardened properties of LWFC. The fresh properties of LWFC are measured by using the flow test and fresh density test. Whereas, the hardened properties include compressive strength, flexural strength, flexural toughness, static modulus of elasticity, ultrasonic pulse velocity, water absorption and oven dry density tests. Besides, the study focuses mainly on the effect of the added fibres to LWFC mixes. Two types of fibres have been used which are glass fibres and polypropylene fibres, the combination of the glass fibres (GF) and polypropylene fibres (PPF) to obtain the hybrid fibres (GF+PPF). Additionally, this study focuses mainly on the effect of hybrid fibres on flexural toughness of high performance lightweight foamed concrete. Trial mixes have been used to choose the optimum mix, the definition to choose the best mix depended on three parameters: oven dry density, flowability and compressive strength. The volume fraction of glass and polypropylene fibres are 0.06%, 0.2%, 0.4%, 0.6% and 0.2%, 0.6%, 1%, 1.4%, respectively. The percentages of hybrid fibres “GF+PPF” are “0.2+0.6”%, “0.4+0.6”%, “0.2+1”% and “0.4+1”%. The results show that adding fibres to the LWFC reduces the flowability and improve the hardened properties of such concrete. The greatest increment in compressive and flexural strength of LWFC is 51% and 21% due to the use of 0.6% glass fibres. On the other hand, the LWFC reinforced with polypropylene fibres exhibits a slight increase in compressive, splitting tensile and flexural strength. The best percentage of hybrid fibres which yields the highest increment in LWFC is “0.4% GF+ 0.6 PPF%”. Such increments are 21.4% and 16.7% for the compressive, flexural strength of LWFC. The results of flexural toughness indicate that the polypropylene fibres denote a higher efficiency in the flexural toughness than that of glass fibres. The flexural toughness results increase with volume fraction of fibres increases. The hybridization shows the best flexural toughness values due to the cooperative work of the glass and polypropylene fibres to boost the performance of flexural toughness at pre‐crack and post‐crack zones. Therefore, the use of 0.4 glass fibres + 1% polypropylene fibres gives the best results in this regards.
      PubDate: 2015-03-26T05:24:09.777434-05:
      DOI: 10.1002/suco.201400087
       
  • Blast resistance characteristics of concrete with different fibre
           reinforcement
    • Abstract: The paper summarizes the results of the development of advanced fibre reinforced concrete intended for explosion resistant applications. Experimental research aimed at contributing to understanding the effect of different type of reinforcement on the behaviour of high performance fibre reinforced concrete subjected to the blast load was carried out. The fine grained concrete matrix was reinforced by various types of dispersed fibres – metallic, carbon, mineral and polymer ‐ with different lengths (6 – 55 mm) (0.24 – 2.16 in.) and combinations, while the volume content (3%) of fibres was kept constant. Physico‐mechanical and explosion tests were performed on prismatic and slab shaped specimens and the effect of different kinds of reinforcement on blast resistance and mechanical performance of the concrete samples was evaluated. The accelerations of the specimens within the blast load were captured. The material characteristics and explosion test data obtained were used for creation of finite element model in LS‐DYNA. The numerical and experimental investigation resulted in the design of concrete elements for population protection, which are able to resist the explosion defined by weight and placement of the charge. The resistance of the newly designed concrete element was confirmed by a field blast test.
      PubDate: 2015-03-20T07:10:47.381813-05:
      DOI: 10.1002/suco.201400080
       
  • Birmingham Gateway: Structural Assessment and Strengthening
    • Authors: John Orr; D. Pask, K. Weise, M. Otlet
      Abstract: Birmingham New Street is the busiest UK rail station outside of London. Growing demand following upgrade works to the West Coast Main Line has seen passenger numbers exceed the design capacity of the current station, which was constructed in 1967. To meet projected increases in passenger numbers, a redevelopment of the historic station is currently underway. Retaining all major structural features, the redevelopment is being undertaken over a live railway in the heart of Birmingham while maintaining existing passenger capacity. This paper details the structural assessment and strengthening design work undertaken to facilitate the regeneration of Birmingham New Street. The assessment methodologies used in examining this historic concrete structure are discussed before the design of subsequent strengthening works is presented.
      PubDate: 2015-03-20T04:40:20.714211-05:
      DOI: 10.1002/suco.201400068
       
  • ASR and sulphate performance of mortar containing industrial waste
    • Abstract: Greener concrete using adequate industrial waste is a preferred option for sustainable construction. Alkali‐silica reaction (ASR) and sulfate attack (SA) on concrete can be minimized by the use of mineral additions being particularly interesting if waste derived. Grits from a paper industry, waste glass and two types of biomass ash were used as 10% cement replacement in mortar and tested for ASR and SA. Results and Scanning Electron Mycroscopy observations were compared to plain mortar and to mortar containing commercial silica fume. All waste materials mitigated ASR compared to control mortar. Resistance to sulphates was increased for one of the biomass ashes used and especially for glass powder which surpassed silica fume. Therefore two of these waste materials seem to be promising to use as partial replacement material for cement leading to enhanced durability and thus contributing to sustainable construction.
      PubDate: 2015-03-20T04:40:16.421192-05:
      DOI: 10.1002/suco.201400095
       
  • On shear verification according to the fib Model Code 2010 in FRC elements
           without traditional reinforcement
    • Authors: Simona Coccia; Alberto Meda, Zila Rinaldi
      Abstract: Fiber Reinforced Concrete (FRC) without any traditional reinforcement is extensively used in particular structures such as pavements or tunnels. Model Code 2010 introduced the possibility of using FRC for structural design and it is becoming a reference document for this kind of structures. The application of Model Code 2010 suggestions for flexural and axial forces, once the constitutive relationships of the material are defined, allows for safe design. However, the shear verification is often a cause of discussion in the design community. The aim of this paper is to clarify this aspect and to provide a procedure that can be followed in the design process. A case study is also presented.
      PubDate: 2015-03-16T07:10:15.278386-05:
      DOI: 10.1002/suco.201400026
       
  • Working together, we can reach further...
    • Authors: Johan Vyncke
      Pages: 447 - 448
      PubDate: 2015-12-03T09:06:09.694726-05:
      DOI: 10.1002/suco.201590021
       
  • 2015 reviewers
    • Pages: 583 - 583
      PubDate: 2015-12-03T09:06:08.357147-05:
      DOI: 10.1002/suco.201590017
       
  • fib‐news: Structural Concrete 4/2015
    • Pages: 585 - 591
      Abstract: RILEM‐fib MoC A continuing evolution fib on LinkedIn™ ICCRRR 2015 Departure of fib Secretary General Petra Schumacher fib Bulletin 76 fib MC2020 Short notes A.G.S. Bruggeling 1923–2015 George Somerville OBE FREng 1934–2015 Congresses and symposia Acknowledgement
      PubDate: 2015-12-03T09:06:03.84907-05:0
      DOI: 10.1002/suco.201590018
       
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    • Pages: 592 - 592
      PubDate: 2015-12-03T09:06:06.151076-05:
      DOI: 10.1002/suco.201590019
       
 
 
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