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ACI Structural Journal     Full-text available via subscription   (Followers: 10)
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: 32)
Advances in Structural Engineering     Full-text available via subscription   (Followers: 19)
Ambiente Construído     Open Access   (Followers: 2)
American Journal of Civil Engineering and Architecture     Open Access   (Followers: 23)
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: 2)
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: 17)
Bulletin of Pridniprovsk State Academy of Civil Engineering and Architecture     Open Access   (Followers: 1)
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: 1)
Case Studies in Structural Engineering     Open Access  
Cement and Concrete Composites     Hybrid Journal   (Followers: 12)
Challenge Journal of Structural Mechanics     Open Access   (Followers: 4)
Change Over Time     Full-text available via subscription   (Followers: 4)
Civil and Environmental Engineering     Open Access   (Followers: 2)
Civil And Environmental Engineering Reports     Open Access   (Followers: 1)
Civil and Environmental Research     Open Access   (Followers: 17)
Civil Engineering     Hybrid Journal   (Followers: 14)
Civil Engineering = Siviele Ingenieurswese     Full-text available via subscription   (Followers: 5)
Civil Engineering and Architecture     Open Access   (Followers: 6)
Civil Engineering and Environmental Systems     Hybrid Journal   (Followers: 5)
Civil Engineering and Technology     Open Access   (Followers: 5)
Civil Engineering Dimension     Open Access   (Followers: 5)
Cohesion and Structure     Full-text available via subscription   (Followers: 2)
Composite Structures     Hybrid Journal   (Followers: 191)
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: 10)
Construction Economics and Building     Open Access  
Construction Engineering     Open Access   (Followers: 4)
Construction Management and Economics     Hybrid Journal   (Followers: 30)
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: 16)
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: 3)
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: 2)
Infrastructure Asset Management     Full-text available via subscription  
Ingenio Magno     Open Access  
Insight - Non-Destructive Testing and Condition Monitoring     Full-text available via subscription   (Followers: 9)
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: 6)
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: 6)
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: 4)
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: 7)
Journal of Bridge Engineering     Full-text available via subscription   (Followers: 18)
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)

        1 2     

Journal Cover   Structural Concrete
  [SJR: 0.739]   [H-I: 9]   [9 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]
  • Modeling Catenary Effect in Progressive Collapse Analysis of Concrete
    • 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
    • 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
    • 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
    • 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
  • Cover Picture: Structural Concrete 3/2015
    • Abstract: “De Oversteek” in Nijmegen is a new 1,400 m long bridge crossing the Waal River. It consists of different sections that were built using different construction techniques and was opened for traffic in November 2013. DSI supplied, installed, stressed and grouted the DYWIDAG Post‐Tensioning Strand Tendons for all its transverse girders. As a rule, 5 Type 27‐0.62″, 1860 N/mm² DYWIDAG Strand Tendons were used per transverse girder. In each construction cycle, the columns and V‐girders were built prior to the construction of the concrete arches. DSI also supplied ∅︁63.5 mm GEWI® Bars that were installed at the highest points of the concrete arch shells. The bar tendons ensure the stability of the arches during erection – particularly after the removal of scaffolding and formwork. (© DSI)
      PubDate: 2015-09-07T02:37:35.394037-05:
      DOI: 10.1002/suco.201590011
  • Contents: Structural Concrete 3/2015
    • PubDate: 2015-09-07T02:37:32.564405-05:
      DOI: 10.1002/suco.201590014
  • 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
  • Modelling uncertainties for the load‐bearing capacity of corroded
           simply supported RC beams
    • Authors: Diego Lorenzo Allaix; Vincenzo Ilario Carbone, Giuseppe Mancini
      Abstract: The probabilistic assessment of corrosion‐damaged structures requires deterministic models of the degradation of the structural performance and probabilistic models accounting for the uncertainties of material properties, geometry and models applied in the reliability analysis. The aim of the present paper is the development of a probabilistic model of the uncertainties which arise from the prediction of the load‐bearing capacity of reinforced concrete structures damaged by corrosion of the reinforcement. The focus of the investigation is on the flexural failure of simply supported beams subjected to chloride‐induced corrosion. The area loss of steel bars, the reduction of strength and ductility of the corroded bars, the reduction of the concrete strength, the loss of bond between reinforcement and concrete, the cracking of the concrete cover are taken into account in the non‐linear finite element analysis. The comparison between experimental results and numerical predictions of the failure load allows the quantification of the model uncertainty according to the framework proposed by the Joint Committee on Structural Safety. A Bayesian updating methodology is proposed to account for prior knowledge and experimental results.
      PubDate: 2015-07-20T06:20:19.920241-05:
      DOI: 10.1002/suco.201500016
  • 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
  • Safety assessment of punching shear failure according to level of
           approximation approach
    • Abstract: The ModelCode 2010 introduced the concept of levels‐of‐approximation (LoA) as a strategy for simplifying the procedures involved in preliminary design stages, or in the design of non‐critical structural elements, while still providing the tools for engineers to use state‐of‐the‐art techniques in the assessment of existing structures or in advanced stages of design of critical structural elements. In this paper, this concept is applied to the determination of the punching shear resistance of reinforced concrete slabs. A procedure is validated for the highest LoA involving nonlinear finite element analysis (NLFEA) with multi‐layered shell elements and the Critical Shear Crack Theory. The safety format proposed to be used in the safety verification assisted by NLFEA is based on the definition of a global resistance safety factor. A semi‐probabilistic approach is followed, based on the assumption of a log‐normal distribution for the resistance and on an estimate of its coefficient of variation. This approach is validated by means of comparison with the results from a probabilistic analysis. The LoA approach is initially applied to the study of statically determined slabs supported on one column to verify the effectiveness of the presented procedure compared with other validated methods, available in literature. The paper concludes with a case study illustrating the applicability of the proposed procedure to a bridge deck slab and highlighting the benefits of using higher LoA.
      PubDate: 2015-06-19T05:50:54.248455-05:
      DOI: 10.1002/suco.201500015
  • Assessing and updating the reliability of concrete bridges subjected to
           spatial deterioration ‐ principles and software implementation
    • Abstract: Inspection and maintenance of concrete bridges is a major cost factor in transportation infrastructure, and there is a significant potential in using information gained during inspection to update predictive models of the performance and reliability of these structures. In this context, we present an approach for assessing and updating the reliability of pre‐stressed concrete bridges subjected to chloride‐induced reinforcement corrosion. The system deterioration state is determined based on a Dynamic Bayesian Network (DBN) model that considers the spatial variability of the corrosion process. The overall system reliability is computed by means of a probabilistic structural model coupled with the deterioration model. Inspection data are included in the system reliability calculation through Bayesian updating on the basis of the DBN model. As a proof of concept, a software prototype is developed implementing the presented method. The software prototype is applied to a typical highway bridge and the influence of inspection information on the system deterioration and the structural reliability is quantified under consideration of the spatial correlation of the corrosion process. This work is a step towards developing a software tool that can be used by engineering practitioners to perform reliability assessments of aging concrete bridges and update their reliability with inspection and monitoring data.
      PubDate: 2015-06-19T05:50:52.916009-05:
      DOI: 10.1002/suco.201500014
  • Acceptable risks to persons associated with building structures
    • Authors: Peter Tanner; Ramon Hingorani
      Abstract: In routine engineering practice, the risks associated with safety considerations addressed when designing new or assessing existing structures are not quantified and the corresponding acceptance criteria may diverge widely. While the use of explicit risk analysis methods to quantify structural safety would therefore deliver significant benefits, the implementation of such methods is hindered by a series of technical and administrative obstacles. The present study explores methods and tools for the practical application of explicit risk analysis methods. Structure‐related risks to persons are established on the grounds of the probability of structural failure and its consequences in terms of loss of human life. The procedure adopted is applied to a representative set of building structures. Acceptance criteria for risks to persons associated with such structures are deduced from the findings. These criteria provide a rational basis for decision‐making in structural engineering. They may be used in explicit risk analysis or as a basis for the consistent calibration of simplified models for determining partial factors in the design of new or the assessment of existing structures.
      PubDate: 2015-06-19T05:50:51.331695-05:
      DOI: 10.1002/suco.201500012
  • Target reliability levels for assessment of existing structures based on
           economic optimisation and human safety criteria
    • Authors: R.D.J.M. Steenbergen; M. Sykora, D. Diamantidis, M. Holicky, A.C.W.M. Vrouwenvelder
      Abstract: Specification of the target reliability levels is one of the key issues in assessment of existing structures. For a majority of existing buildings and infrastructures the design life has been reached or will be reached in the near future. These structures need to be reassessed in order to verify their safety. Eurocodes provide a general basis primarily intended for design of new structures, but basic principles can be used also for assessment of existing buildings. Reliability levels are generally based on both the economic optimization and the criteria for human safety. In this study, both methods are elaborated for existing structures. It appears that the requirement for the same target reliability for existing and new structures is uneconomical. Further, the cost optimisation seems to yield rather low reliability levels and human safety criteria become commonly decisive. The study concludes with practical guidelines for establishing reliability indices for existing structures linked to Eurocode principles.
      PubDate: 2015-06-19T05:50:50.093558-05:
      DOI: 10.1002/suco.201500022
  • Monitoring based performance assessment of rail‐bridge interaction
           based on structural reliability
    • Authors: Alfred Strauss; Saeed Karimi, Fritz Kopf, Catalin Capraru, Konrad Bergmeister
      Abstract: In today's railway construction, the continuous welded rail, which enhances driving dynamics and comfort for passengers, is often the construction method of choice. Bridges and viaducts, which can be seen as singularities in the railway substructure, still pose a few unsolved problems. Under the impacts of thermal variation, creep, shrinkage, train passage and braking, the bridge structure deforms. The track‐bridge interaction is an important parameter in railway bridge design. Measurement campaigns and research projects were performed to investigate the interaction process and learn to predict longitudinal forces in the rail and the concrete slab track. For the construction of long bridges on high speed railway lines, new computation tools, monitoring systems and enhanced verification methods for tolerable rail stresses on bridges had to be developed. In order to take the modified stiffness conditions and recent findings on rail resistance into account, the verification schemes and safety concepts based on monitored information have to be revised and performance based methods need to be developed. The target of this contribution is to present monitoring and reliability based assessment methods for the concrete structure‐rail interaction using monitoring and nonlinear analyses techniques.
      PubDate: 2015-06-19T05:50:48.803484-05:
      DOI: 10.1002/suco.201500019
  • 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
  • Solution strategy for non‐linear Finite Element Analyses of large
           reinforced concrete structures
    • Abstract: When performing non‐linear Finite Element Analyses during design of large reinforced concrete structures, there is need for a general, robust and stable solution strategy with a low modelling uncertainty that comprises choices regarding force equilibrium, kinematic compatibility and constitutive relations. In this paper, analyses of experiments with a range of structural forms, loading conditions, failure modes and concrete strengths showed that an engineering solution strategy was able to produce results with good accuracy and low modelling uncertainty. It was advised to shift the attention from a detailed description of the post‐cracking behaviour of concrete to a rational description of the pre‐cracking compressive behaviour for cases where large elements are used and the ultimate limit capacity is sought.
      PubDate: 2015-03-26T05:24:10.090639-05:
      DOI: 10.1002/suco.201400088
  • 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
    • 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
  • Defects in epoxy coated reinforcement and their impact on service life of
           concrete structures
    • Abstract: Epoxy coated reinforcement (ECR) as a protection against chloride‐induced corrosion of steel in concrete is used only in a few countries due to doubts concerning its effectiveness. A common misconception is that possible defects in the coating are particularly weak points as these may favor high local corrosion rates and thus loss of steel cross section. This work discusses why a certain number of small defects can be tolerated. It is argued that prolongation of the initiation phase is caused by a higher critical chloride content as compared to uncoated steel due to the “size effect”. Additionally, the propagation phase is with ECR likely to be extended due to the strongly limited cathodic area that limits the corrosion rate. This paper presents experimental and numerical tests to verify these assumptions.
      PubDate: 2015-03-20T04:40:21.902071-05:
      DOI: 10.1002/suco.201400085
  • 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
  • Analysis of Cracking in Steel Fibre Reinforced Concrete (SFRC) Structures
           in Bending using Probabilistic Modelling
    • Abstract: In this paper, an improvement of the probabilistic discrete cracking model of fibre reinforced concretes, originally developed by Rossi, is proposed. In this new model: – Crack creation and propagation in the concrete is taken into account by using special interface elements. These interface elements open once the normal tensile stress at their centre of gravity reaches the tensile strength of the element. The probabilistic aspect of the cracking process is taken into account by the fact that the tensile strength is randomly distributed through the mesh elements. – Immediately after the creation of cracks, the fiber bridging effect is considered by a damage model approach. The probabilistic aspect consists of randomly distributing the post‐cracking energy. The improved numerical model is used to analyze the bending behaviour of three SFRC beam sizes that consist of the same material. The numerical simulations are compared with experimental results in terms of the beams' global behaviour and the cracking process.
      PubDate: 2015-03-20T04:40:19.024096-05:
      DOI: 10.1002/suco.201400081
  • Shear Tests on Continuous Prestressed Concrete Beams with External
    • Authors: Martin Herbrand; Martin Classen
      Abstract: Many of the existing road bridges exhibit calculative shear capacity deficits according to current design codes. This is partly because of increased traffic loads and changes in the code provisions. In order to extend the service life of these bridges, either refined design approaches may be used or strengthening measures may be performed. This paper describes the results of experimental investigations on the influence of additional external prestressing on the shear capacity of continuous prestressed concrete beams. Within the research project, six shear tests on three test beams with parabolic internal post‐tensioning and additional variable external prestressing were performed. The aim of the project was to determine the effect of external prestressing on the shear capacity of existing bridges, and whether current design approaches lead to conservative results when used for the recalculation of existing bridge structures.
      PubDate: 2015-03-20T04:40:17.877338-05:
      DOI: 10.1002/suco.201400082
  • 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
  • Does EN 1992‐1‐1 and the European Concrete Platform comply
           with Tests? Commentary to the Rules for Strut and Tie Models with
           Corbels as Example
    • Authors: Thore Hagberg
      Abstract: EN 1992 [1] is presently under revision. In that context it is justified to set a critical eye on the standard, and in particular if the models and the resistance functions for the Ultimate Limit State complies with results from tests. The present contribution is limited to S&T models. The results of the analysis will primarily have relevance to corbels, however, some conclusions are general and should be considered when choosing the mathematical model for any S&T model. [1] is not sufficiently detailed to give basis for a complete dimensioning of e.g. corbels. The European Concrete Platform [2], which contains worked examples, has been prepared in accordance with and to support [1]. The two topics dealt with are 1) Selection of main model, and 2) Details and use of the S&T model in [1] + [2] and particularly its ability to predict results from tests. The tests for the analysis are taken from a thorough study described in [3]. To evaluate results from using [1] + [2] a concept for design of corbels suggested earlier has been used to calculate the same tests [4]. It will be claimed that the models in [1] + [2] and their ability to predict the outcome of tests has some flaws compared with calculations according to [4]. The detailed calculations are given in Annexes, i.e. Part 1 for dimensioning according to [1] + [2], and Part 2 for dimensioning according to [4]. The Annexes as well as reference [4] can be obtained by the publisher or the author.
      PubDate: 2015-03-16T07:20:13.53891-05:0
      DOI: 10.1002/suco.201400066
  • Displacement based simulation of time dependent behaviour of RC beams with
           prestressed FRP or steel tendons
    • Authors: Daniel Knight; Phillip Visintin, Deric J. Oehlers
      Abstract: Predicting the time dependent behaviour of prestressed concrete (PC) beams is crucial as time effects under serviceability loading can result in a critical loss of prestress. The conventional technique of moment‐curvature (M/χ) to simulate the behaviour of PC beams is based on the Euler‐Bernoulli corollary of a linear strain profile, in which all deformations are accommodated through changes in the material strain that is it is strain based. Consequently, the M/χ approach cannot directly accommodate discrete deformations associated with tension‐stiffening such as the formation of individual cracks and reinforcement slip. Hence the M/χ approach can simulate the behaviour prior to cracking purely through mechanics. However post‐cracking, it requires empirically derived correction factors, such as empirically derived flexural rigidities, to allow for the deformations associated with tension‐stiffening. This paper presents a displacement based moment‐rotation (M/Θ) approach for determining the behaviour of PC beams by applying the Euler‐Bernoulli theorem of plane sections, as opposed to the conventional M/χ approach of a linear strain profile. Being based on plane sections, the M/Θ approach deals directly with displacements and consequently can simulate the mechanics of tension‐stiffening directly. The approach is shown to accommodate time effects of concrete creep, shrinkage and reinforcement relaxation and can develop equivalent flexural rigidities directly from mechanics.
      PubDate: 2015-03-16T07:10:16.427876-05:
      DOI: 10.1002/suco.201400039
  • 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
  • Special issue of “Structural Concrete” with articles from the
           JCSS workshop on “Risk‐ and reliability‐based assessment
           of existing structures”
    • Pages: 313 - 313
      PubDate: 2015-09-07T02:37:33.209984-05:
      DOI: 10.1002/suco.201590015
  • fib‐news: Structural Concrete 3/2015
    • Pages: 438 - 445
      Abstract: Copenhagen 2015 Brazil and the fib: a close alliance MC2010 talks on YouTube JCI turns 50 SC impact factor Porto ideal for MSLB 2015 fib Bulletin 75 Short notes C. R. Alimchandani 1935–2015 Congresses and symposia Acknowledgement
      PubDate: 2015-09-07T02:37:36.097611-05:
      DOI: 10.1002/suco.201590012
  • Structural Concrete 4/2015
    • Pages: 446 - 446
      PubDate: 2015-09-07T02:37:37.1705-05:00
      DOI: 10.1002/suco.201590013
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