Advances in Civil Engineering The latest articles from Hindawi © 2017 , Hindawi Limited . All rights reserved. Seismic Fragility Assessment of an Isolated Multipylon Cable-Stayed Bridge Using Shaking Table Tests Thu, 12 Oct 2017 00:00:00 +0000 In recent decades, cable-stayed bridges have been widely built around the world due to the appealing aesthetics and efficient and fast mode of construction. Numerous studies have concluded that the cable-stayed bridges are sensitive to earthquakes because they possess low damping characteristics and high flexibility. Moreover, cable-stayed bridges need to warrant operability especially in the moderate-to-severe earthquakes. The provisions implemented in the seismic codes allow obtaining adequate seismic performance for the cable-stayed bridge components; nevertheless, they do not provide definite yet reliable rules to protect the bridge. To date, very few experimental tests have been carried out on the seismic fragility analysis of cable-stayed bridges which is the basis of performance-based analyses. The present paper is aimed at proposing a method to derive the seismic fragility curves of multipylon cable-stayed bridge through shake table tests. Toward this aim, a 1/20 scale three-dimensional model of a 22.5 m cable-stayed bridge in China is constructed and tested dynamically by using the shaking table facility of Tongji University. The cable-stayed bridge contains three pylons and one side pier. The outcomes of the comprehensive shaking table tests carried out on cable-stayed bridge have been utilized to derive fragility curves based on a systemic approach. Yutao Pang Copyright © 2017 Yutao Pang. All rights reserved. Static and Dynamic Mechanical Properties of Long-Span Cable-Stayed Bridges Using CFRP Cables Thu, 07 Sep 2017 00:00:00 +0000 The elastic modulus and deadweight of carbon fiber-reinforced polymer (CFRP) cables are different from those of steel cables. Thus, the static and dynamic behaviors of cable-stayed bridges using CFRP cables are different from those of cable-stayed bridges using steel cables. The static and dynamic performances of the two kinds of bridges with a span of 1000 m were studied using the numerical method. The effects of geometric nonlinear factors on static performance of the two kinds of cable-stayed bridges were analyzed. The live load effects and temperature effects of the two cable-stayed bridges were also analyzed. The influences of design parameters, including different structural systems, the numbers of auxiliary piers, and the space arrangement types of cable, on the dynamic performance of the cable-stayed bridge using CFRP cables were also studied. Results demonstrate that sag effect of the CFRP cable is much smaller than that of steel cable. The temperature effects of CFRP cable-stayed bridge are less than those of steel cable-stayed bridge. The vertical bending natural vibration frequency of the CFRP cable-stayed bridge is generally lower than that of steel cable-stayed bridge, whereas the torsional natural vibration frequency of the former is higher than that of the latter. Mei Kuihua, Sun Shengjiang, Jin Guoqing, and Sun Yamin Copyright © 2017 Mei Kuihua et al. All rights reserved. A Comparative Study of First-Order Reliability Method-Based Steepest Descent Search Directions for Reliability Analysis of Steel Structures Thu, 07 Sep 2017 00:00:00 +0000 Three algorithms of first-order reliability method (FORM) using steepest descent search direction are compared to evaluate the reliability index of structural steel problems which are designed by the Iranian National Building code. The FORM formula is modified based on a dynamic step size which is computed based on the merit functions named modified Hasofer-Lind and Rackwitz-Fiessler (MHL-RF) method. The efficiency of the gradient, HL-RF, and MHL-RF method was compared for a bar structure under tensile capacity, a multispan beam under bending capacity, a connection under tension load, and a column under axial force. The results illustrated that the MHL-RF method is more efficient than the HL-RF and gradient method. The designed steel components by the Iranian National Building code showed good confidence levels with the reliability index in the range from 2.5 to 3.0. Hamed Makhduomi, Behrooz Keshtegar, and Mehdi Shahraki Copyright © 2017 Hamed Makhduomi et al. All rights reserved. Construction Marketing: Developing a Reference Framework Wed, 23 Aug 2017 08:26:29 +0000 Successful companies are strongly committed to marketing management. However, marketing is either misunderstood or completely neglected in many construction companies, mainly due to the difficulty of applying conventional marketing in the industry, accompanied by the lack of sufficient research on the nature of marketing and tailored marketing theories and strategies for the construction. This study attempts to fill a part of this gap by examining the nature of the construction industry from the marketing viewpoint and developing a comprehensive framework. A systematic investigation into the nature via a combination of Kotler’s product classification system and Lovelock’s classification criteria reveals that construction is an “industrial, project-based, and primarily service-oriented” (IPS) product with specific characteristics from the marketing perspective. Based on this nature, a reference framework for strategic marketing planning is developed through a literature review based on grounded theory and using the focus group discussion as a refinement tool. The framework indicates that construction companies are involved in and should plan for three working fields—project-based activities, relationship marketing, and marketing mix-related functions. The findings provide a fundamental basis that helps researchers and practitioners gain a true understanding of the concepts and scope of construction marketing and draw a clear and practical roadmap for future work. Mahmood Mokhtariani, Mohammad Hassan Sebt, and Hamid Davoudpour Copyright © 2017 Mahmood Mokhtariani et al. All rights reserved. The Effect of Aging on the Cracking Resistance of Recycled Asphalt Mon, 21 Aug 2017 00:00:00 +0000 Fatigue cracking is an important concern when a high percentage of Reclaimed Asphalt Pavement (RAP) is used in an asphalt mixture. The aging of the asphalt binder reduces its ductility and makes the pavement more susceptible to cracking. Rejuvenators are often added to high-RAP mixtures to enhance their performance. The aging of a rejuvenated binder is different from virgin asphalt. Therefore, the effect of aging on a recycled asphalt mixture can be different from its effect on a new one. This study evaluated the cracking resistance of 100% recycled asphalt binders and mixtures and investigated the effect of aging on this performance parameter. The cracking resistance of the binder samples was tested by a Bending Beam Rheometer. An accelerated pavement weathering system was used to age the asphalt mixtures and their cracking resistance was evaluated by the Texas Overlay Test. The results from binder and mixture tests mutually indicated that rejuvenated asphalt has a significantly better cracking resistance than virgin asphalt. Rejuvenated mixtures generally aged more rapidly, and the rate of aging was different for different rejuvenators. Mojtaba Mohammadafzali, Hesham Ali, James A. Musselman, Gregory A. Sholar, and Aidin Massahi Copyright © 2017 Mojtaba Mohammadafzali et al. All rights reserved. Inversion Calculation Analysis of Operational Tunnel Structure Based on the Distributed Optical-Fiber Sensing System Thu, 17 Aug 2017 00:00:00 +0000 In combination of the actual project in Dalian Baiyun Mountain Tunnel, this paper introduces the principle of fiber optic sensor monitoring system based on optical time domain reflectometer. Then, based on the orthogonal design and even design scheme, this paper carries out a numerical experiment on the tunnel surrounding rock and establishes a regression model of the mapping relation between surrounding rock parameters of operation tunnel and the monitored displacement in order to set the difference between the monitored displacement and the calculated displacement as the fitness function. In the end, this paper carries out parameter identification based on the differential evolution algorithm. Achievements of the study proved that real-time safety warning could be realized inside the tunnel by monitoring the deformation parameters of tunnel vault at real time relying on the optical-fiber sensing system of the optical time domain reflectometer (OTDR). Parameters identification was carried out on the structure with differential evolution according to measured data and selected parameters, and great coincidence was obtained between the measured displacement and the identified parameters displacement, which proved the strong adaptability of the method. Jie Zhao, Jiang Feng, and Liang Ren Copyright © 2017 Jie Zhao et al. All rights reserved. Permeability and Tensile Strength of Concrete with Arabic Gum Biopolymer Tue, 15 Aug 2017 07:52:01 +0000 The use of materials of vegetal origin is increasingly being promoted in many industries due to their cost effectiveness and the rising sensitivity to environmental protection and sustainability. Arabic Gum Biopolymer (AGB) is a wild plant byproduct that is abundantly found in Sudan and is also produced in other African countries. It has long been used in various industries. However, its utilization is very limited in the construction sector although there appears to be a significant potential for use of AGB in the building industry. As an example, there is evidence that AGB may be an effective additive to concrete mixes that would improve fresh and hardened concrete properties. The aim of the present work is to provide further experimental evidence on the improvement that can be achieved in the physical and mechanical properties of hardened concrete when AGB is added to the mixture. The experimental results show a significant reduction in permeability for an optimum percentage of AGB and an increase in flexural and tensile strength and in the elastic modulus. Abdeliazim Mustafa Mohamed, Mohd Hanim Osman, Hichem Smaoui, and Mohd Azreen Mohd Ariffin Copyright © 2017 Abdeliazim Mustafa Mohamed et al. All rights reserved. Measurement of Pozzolanic Activity Index of Scoria, Pumice, and Rice Husk Ash as Potential Supplementary Cementitious Materials for Portland Cement Sun, 06 Aug 2017 00:00:00 +0000 This work investigated the properties of scoria and pumice as supplementary cementitious materials (SCMs) for Portland cement and compared to those of rice husk ash (RHA). X-ray fluorescence, X-ray diffraction, and pozzolanic activity index (PAI) tests confirmed the suitability of these two materials as potential SCMs. Scoria and RHA samples achieved over 75% PAI at 7 days whereas pumice did this after 28 days. Initial and final mean setting times observed for the composite cement blended with these materials were 166 and 285 min, respectively. These setting times are longer than that of ordinary Portland cement but shorter compared to that of common Portland pozzolana cement. The ultimate mean compressive strengths achieved at 28 days of curing were 42.5, 44.8, and 43.0 MPa for scoria, pumice, and RHA, respectively, signifying that these materials are good SCMs. Higher fineness yielded higher ultimate mean strength. For instance, a scoria sample with a fineness of 575 m2/kg achieved the strength of 52.2 MPa after 28 days. Hieronimi A. Mboya, Cecil K. King’ondu, Karoli N. Njau, and Alex L. Mrema Copyright © 2017 Hieronimi A. Mboya et al. All rights reserved. Using Expert Opinion to Quantify Uncertainty in and Cost of Using Nondestructive Evaluation on Bridges Wed, 19 Jul 2017 09:53:33 +0000 A previous literature review indicated that there is little published experimental data that can be used to determine quantities such as bias, accuracy, reliability, and cost of common Nondestructive Evaluation (NDE) methods as far as their use on bridges is concerned. This study attempts to quantify these parameters for common bridge NDE methods through a four-round Delphi method survey with experts in the NDE bridge field. The survey results indicate that most commonly used bridge NDE methods tend to be underbiased and relatively reliable. Furthermore, the accuracy of commonly used bridge NDE methods tends to be relatively variable with the average test measuring a true response between 80% and 85% of the time. In general, it was shown by the participant responses that the more expensive the method was, the better the bias, accuracy, and reliability the method had, and vice versa. The information presented in this paper can serve as a starting point for characterizing different NDE methods for use in bridge management and inspection planning and identifies the type of information that is still needed. As such, this research has the potential to promote further research on this subject. Alex A. Hesse, Rebecca A. Atadero, and Mehmet E. Ozbek Copyright © 2017 Alex A. Hesse et al. All rights reserved. Cumulative Ductility and Hysteretic Behavior of Small Buckling-Restrained Braces Sun, 16 Jul 2017 06:59:24 +0000 Cumulative ductility is defined as a ratio of total energy to elastic energy which is dissipated by an element of the structural system during cyclic loading. An element of the structural system is categorized hysteretic if the cumulative ductility factor fulfills certain criteria. This study investigated both analytically and experimentally Small Buckling-Restrained Braces (SBRBs). The core of bracings was modeled using Menegotto-Pinto and bilinear functions. The restrained bracing members were in the shape of square hollow steel section. They were made of the assembly of two L-shaped steel sections. From the experimental study on four SBRB specimens, it was proven that the proposed SBRBs have performed relatively stable hysteretic curves up to two percent of strain and the cumulative ductility factor of 199–450. This value is sufficient for the Buckling-Restrained Brace (BRB) elements as elastoplastic structural components. The comparisons of the hysteretic behaviors resulted by SBRB specimens using the Menegotto-Pinto functions and experiments exhibited good agreements, while the amount of energy dissipated by the SBRB specimens using the bilinear model agreed well with the experimental results. Based on the behavior of the experimental hysteretic, implementing the proposed SBRBs as components in ductile truss system is recommended. Hidajat Sugihardjo and Tavio Copyright © 2017 Hidajat Sugihardjo and Tavio. All rights reserved. Research on Fatigue Strain and Fatigue Modulus of Concrete Wed, 12 Jul 2017 07:22:06 +0000 Concrete fatigue strain and fatigue modulus evolution play a vital role in the evaluation of the material properties. In this paper, by analyzing the advantages and disadvantages of existing concrete strain analysis methods, the level-S nonlinear fatigue strain model was proposed. The parameters’ physical meaning, the ranges, and the impact on the shape of the curve were all discussed. Then, the evolution model of fatigue modulus was established based on the fatigue strain evolution model and the hypothesis of fatigue modulus inversely related fatigue strain amplitude. The results indicate that the level-S model covered all types of fatigue strain evolution. It is very suitable for the description of strain evolution of concrete for its strong adaptability and high accuracy. It was found that the fitting curves coincided with the experimental curves very well, and the correlation coefficients were all above 0.98. The evolution curves of fatigue strain modulus both have three stages, namely, variation phase, linear change stage, and convergence stage. The difference is that the fatigue strain evolution curve is from the lower left corner to the upper right corner, but the fatigue modulus evolution curve is from the upper left corner to the right lower corner. Fangping Liu and Jianting Zhou Copyright © 2017 Fangping Liu and Jianting Zhou. All rights reserved. Advanced Cementitious Building Materials with Applications in Civil Engineering Tue, 11 Jul 2017 00:00:00 +0000 Peng Zhang, Song Han, Serina Ng, and Xu-Hao Wang Copyright © 2017 Peng Zhang et al. All rights reserved. An Analytical Method for Determining the Load Distribution of Single-Column Multibolt Connection Thu, 06 Jul 2017 10:16:58 +0000 The purpose of this research was to investigate the effect of geometric variables on the bolt load distributions of a cold-formed steel bolt connection. The study was conducted using an experimental test, finite element analysis, and an analytical method. The experimental study was performed using single-lap shear testing of a concentrically loaded bolt connection fabricated from G550 cold-formed steel. Finite element analysis with shell elements was used to model the cold-formed steel plate while solid elements were used to model the bolt fastener for the purpose of studying the structural behavior of the bolt connections. Material nonlinearities, contact problems, and a geometric nonlinearity procedure were used to predict the failure behavior of the bolt connections. The analytical method was generated using the spring model. The bolt-plate interaction stiffness was newly proposed which was verified by the experiment and finite element model. It was applied to examine the effect of geometric variables on the single-column multibolt connection. The effects were studied of varying bolt diameter, plate thickness, and the plate thickness ratio () on the bolt load distribution. The results of the parametric study showed that the ratio controlled the efficiency of the bolt load distribution more than the other parameters studied. Nirut Konkong and Kitjapat Phuvoravan Copyright © 2017 Nirut Konkong and Kitjapat Phuvoravan. All rights reserved. Experimental Study on Structural Performance of RC Exterior Beam-Column Joints Retrofitted by Steel Jacketing and Haunch Element under Cyclic Loading Simulating Earthquake Excitation Wed, 07 Jun 2017 00:00:00 +0000 Several retrofitting methods for reinforced concrete (RC) beam-column joints in old buildings without seismic details were developed. Four half-scale RC exterior beam-column joints were fabricated and tested under cyclic loading simulating earthquake excitation. The control specimen was designed to fail in joint shear. Two practical retrofitting strategies were applied to the control specimen which consider the architectural characteristic in real buildings, including steel jacketing and haunch retrofit solution. The structural performance of the test specimens was investigated in terms of various factors including damage and failure, load-drift relationship, ductility, dissipated energy, and strain profiles of longitudinal reinforcement. Experimental results confirmed that the proposed retrofit methods were shown to enhance the seismic capacity of the joints in terms of the strength, deformation capacity, and energy dissipation capacity while the shear deformation in the panel zone significantly reduced in comparison with the control specimen. Cong-Thuat Dang and Ngoc-Hieu Dinh Copyright © 2017 Cong-Thuat Dang and Ngoc-Hieu Dinh. All rights reserved. Optimization of Rigidly Supported Guyed Masts Mon, 29 May 2017 06:20:08 +0000 A technique for simultaneous topology, shape, and sizing optimization of tall guyed masts is presented in this paper. The typical scheme of telecommunication masts that are triangular in plan and supported by a certain number of guys’ levels is examined. The objective function is the total mass of the mast, including the mass of the guys. The mast structure is optimized for self-weight and wind loading that is evaluated according to Eurocodes. The nonlinear behaviour of the guyed mast is simplified idealizing the nonlinear guys as approximate boundary conditions for the mast. A comparison of the simplified solution with the results of nonlinear analysis with Ansys shows small discrepancies that are on the safe side. The constraints involve all strength, local and global stability, and slenderness requirements. The optimization problem is solved using evolutionary algorithm with original genome repair procedure. As an example, a typical 96 m guyed broadcasting antenna for mobile-phone networks was designed employing the proposed optimization technique and taking up to 10 guys’ levels. It is shown that the optimal mast is supported by 3–5 guys’ levels. The optimal ranges of all remaining design variables were also obtained. R. Belevičius, D. Jatulis, D. Rusakevičius, and D. Mačiūnas Copyright © 2017 R. Belevičius et al. All rights reserved. 4D Applications of GIS in Construction Management Mon, 22 May 2017 00:00:00 +0000 Construction industries broadly involve different set of construction activities which are to be executed as per schedule and the major software used for scheduling is PRIMAVERA and Microsoft Project (MSP). But the software still lacks a feature of providing spatial aspects of information in construction schedule. Recently, advanced technology like 4D GIS plays a major role in overcoming the limitation of the software. 4D GIS technology includes integration of 2D drawings from AutoCAD and schedules prepared in PRIMAVERA software. In the present study, a multistair residential building has been selected. ARCMAP 10.2 is used for interlinking of schedules as well as drawings and ARCSCENE has been used for developing 4D view. This linkage between scheduled activities and respective drawings in GIS helps in identifying construction sequences and also in detecting logical errors that occur in project schedules. The developed 4D view provides better visualization of construction progress of a project. A. Chaitanya Kumar and T. Reshma Copyright © 2017 A. Chaitanya Kumar and T. Reshma. All rights reserved. Experimental Research and Finite Element Analysis on Mechanical Property of SFRC T-Beam Thu, 04 May 2017 09:26:39 +0000 Research on mechanical property of SFRC was done through experiments of two SFRC T-beams and one concrete T-beam, while the influences of different volume fractions of steel fibers on integral rigidity, ultimate shear capacity, and the crack distribution characteristics were analyzed. ANSYS finite element software was used to simulate the tests and it was found that there was good conformation between the results of ANSYS simulation and tests. The test results and finite element software simulation both showed that the incorporation of steel fibers in the concrete can increase the integral rigidity and ultimate shear capacity, while partially reducing the propagation of cracks effectively. It was also proved that it is reliable to simulate SFRC T-beam by ANSYS software. Min Sun, Jiapeng Zhu, Ning Li, and C. C. Fu Copyright © 2017 Min Sun et al. All rights reserved. Numerical Simulations of Restrained Shrinkage Cracking in Glass Fibre Reinforced Shotcrete Slabs Wed, 03 May 2017 06:56:55 +0000 Modern tunnels in hard rock are usually constructed by drill and blast with the rock reinforced by shotcrete (sprayed concrete) in combination with rock bolts. The irregular rock surface and the projection method of shotcrete lead to a tunnel lining of varying thickness with unevenly distributed stresses that affect the risk of cracking during shrinkage of the young and hardening material. Depending on water conditions, shotcrete is sprayed directly either onto the rock surface or over a drainage system, creating a fully restrained or an end-restrained structural system. In this paper, a method for nonlinear numerical simulations has been demonstrated, for the study of differences in stress build-up and cracking behaviour of restrained shotcrete slabs subjected to shrinkage. Special focus was given to the effects of the irregular shape and varying thickness of the shotcrete. The effects of glass fibre reinforcement and bond were implemented in the study by changing the fracture energy in bending and in the interaction between shotcrete and the substrate. The study verifies that an end-restrained shotcrete slab is prone to shrinkage induced cracking and shows the importance of a continuous bond to avoid wide shrinkage cracks when shotcrete is sprayed directly onto the rock. Andreas Sjölander and Anders Ansell Copyright © 2017 Andreas Sjölander and Anders Ansell. All rights reserved. Influence of Crumb-Rubber in the Mechanical Response of Modified Portland Cement Concrete Tue, 02 May 2017 09:51:27 +0000 The influence of crumb-rubber on the mechanical properties of Portland cement concrete (PCC) is studied by experimental tests and numerical simulations. The main hypothesis of the study is that replacing part of the stone aggregate with crumb-rubber in the mix modifies the energy dissipation during the cracking process and affects the concrete behaviour under monotonically increasing loads. The experimental research program characterizes the mechanical properties of PCC for three different types of concrete with a variable content of crumb-rubber. The experimental results showed that fracture energy and other properties are directly related to the rubber fineness used in the mixture. The material properties derived for these laboratory tests are used to study, by numerical models, its response through its damage evolution. The numerical model used to simulate the damage evolution of the concrete is the Embedded Discontinuity Method (EDM). One characteristic of the EDM is that it does not need to modify the mesh topology to propagate the damage through the continuum solid. For this study, the Disk-Shaped Compact Tension specimen geometry, normed by the D7313-13 of the ASTM, is used. Results showed that the numerical methods provide good approximation of the experimental curve in the elastic and softening branches. J. Retama and A. G. Ayala Copyright © 2017 J. Retama and A. G. Ayala. All rights reserved. Design Diagrams for the Analysis of Active Pressure on Retaining Walls with the Effect of Line Surcharge Tue, 02 May 2017 08:42:42 +0000 In this study, a formulation has been proposed to calculate the pressure on wall and determine the angle of failure wedge based on limit equilibrium method. The mentioned formulation is capable of calculating active pressure coefficient, culmination of forces in failure surface, and pressure distribution on wall with the effect of line surcharge. In addition, based on the proposed method, a simple formula has been proposed to calculate the angle of failure wedge by the effect of surcharge. Moreover, the proposed approach has the advantage of taking into account the effect of surcharge on elastoplastic environment by considering the parameters of soil and determining the extent to which the surcharge is effective in pressure distribution on the wall. However, in most previous methods and specifications, resultant lateral pressure from surcharge in elastic environment had been considered. Finally, based on the obtained results, the design diagrams for different soils and different surcharges have been proposed. According to these diagrams, pressure on wall, pressure distribution on wall, and angle of failure wedge will easily be achieved. Also, a computer program has been written in MATLAB software environment. Using the results of these codes, the pressure on wall with the effect of surcharge, the angle of failure wedge, and pressure distribution on wall will be determined. Mojtaba Ahmadabadi and Mohammad Karim Faghirizadeh Copyright © 2017 Mojtaba Ahmadabadi and Mohammad Karim Faghirizadeh. All rights reserved. Bond Effects between Concrete and Steel Bar Using Different Diameter Bars and Different Initial Crack Width Sun, 02 Apr 2017 08:08:37 +0000 The importance of an accurate simulation of service conditions in the bond performance of reinforced concrete structures in coastal regions is highlighted. Four widths of initial crack of 0, 80, 150, and 210 microns were artificially made by inserting slice into bond specimens during concrete casting. Three bar diameters of 10 mm, 14 mm, and 18 mm were selected. At 28 days, the bond specimens were exposed to the environment of wet-dry cycles of seawater and atmosphere for another 90 days. The pull-out test was then conducted and chloride contents were tested at crack area along 40 mm depth. Results show that, for the specimen with 10 mm bar diameter, cracks width of less than 80 microns vanished rapidly during wet-dry cycles; for other specimens, cracks width of 100–150 microns decreased slightly. However the cracks of width more than 200 microns increased gradually; the chloride content decreased along the depth of concrete, and the chloride content increased as the widths of initial cracks increased or as the bar diameters increased. The ductility of bond specimens decreased as the diameter increased. Papa Niane Faye, Yinghua Ye, and Bo Diao Copyright © 2017 Papa Niane Faye et al. All rights reserved. Experimental Studies on Punching Shear and Impact Resistance of Steel Fibre Reinforced Slag Based Geopolymer Concrete Wed, 22 Mar 2017 08:29:28 +0000 The study was focused on slag based geopolymer concrete with the addition of steel fibre. The slag based geopolymer concrete was under shear load and sudden impact load to determine its response. The punching shear represents the load dissipation of the material and the energy absorption capacity of the geopolymer concrete to impact load. The various percentage of steel fibre in the slag based geopolymer concrete was 0.5%, 1.0%, and 1.5%. Overall the dosage 0.5% of steel fibre reinforced slag based geopolymer shows better results with a punching shear of 224 kN and 1.0% of steel fibre incorporated geopolymer concrete had the better energy absorption capacity with 3774.40 N·m for first crack toughness and 4123.88 N·m for ultimate failure toughness. Srinivasan Karunanithi Copyright © 2017 Srinivasan Karunanithi. All rights reserved. Tests and Analyses of Slotted-In Steel-Plate Connections in Composite Timber Shear Wall Panels Mon, 20 Mar 2017 00:00:00 +0000 The authors present an experimental and analytical study of slotted-in connections for joining walls in the Masonite flexible building (MFB) system. These connections are used for splicing wall elements and for tying down uplifting forces and resisting horizontal shear forces in stabilizing walls. The connection plates are inserted in a perimeter slot in the PlyBoard™ panel (a composite laminated wood panel) and fixed mechanically with screw fasteners. The load-bearing capacity of the slotted-in connection is determined experimentally and derived analytically for different failure modes. The test results show ductile postpeak load-slip characteristics, indicating that a plastic design method can be applied to calculate the horizontal load-bearing capacity of this type of shear walls. Ulf Arne Girhammar and Bo Källsner Copyright © 2017 Ulf Arne Girhammar and Bo Källsner. All rights reserved. Behavior of Low Grade Steel Fiber Reinforced Concrete Made with Fresh and Recycled Brick Aggregates Thu, 16 Mar 2017 07:47:18 +0000 In recent years, recycled aggregates from construction and demolition waste (CDW) have been widely accepted in construction sectors as the replacement of coarse aggregate in order to minimize the excessive use of natural resources. In this paper, an experimental investigation is carried out to observe the influence of low grade steel fiber reinforcements on the stress-strain behavior of concrete made with recycled and fresh brick aggregates. In addition, compressive strength by destructive and nondestructive tests, splitting tensile strength, and Young’s modulus are determined. Hooked end steel wires with 50 mm of length and an aspect ratio of 55.6 are used as fiber reinforcements in a volume fraction of 0% (control case), 0.50%, and 1.00% in concrete mixes. The same gradation of aggregates and water-cement ratio () were used to assess the effect of steel fiber in all these concrete mixes. All tests were conducted at 7, 14, and 28 days to perceive the effect of age on different mechanical properties. The experimental results show that around 10%~15% and 40%~60% increase in 28 days compressive strength and tensile strength of steel fiber reinforced concrete, respectively, compared to those of the control case. It is observed that the effect of addition of 1% fiber on the concrete compressive strength is little compared to that of 0.5% steel fiber addition. On the other hand, strain of concrete at failure of steel fiber reinforced concrete has increased almost twice compared to the control case. A simple analytical model is also proposed to generate the ascending portions of the stress-strain curve of concrete. There exists a good correlation between the experimental results and the analytical model. A relatively ductile failure is observed for the concrete made with low grade steel fibers. Md. Shariful Islam and Mohammad Al Amin Siddique Copyright © 2017 Md. Shariful Islam and Mohammad Al Amin Siddique. All rights reserved. A Simplified Parametric Study on Occupant Comfort Conditions in Base Isolated Buildings under Wind Loading Sun, 19 Feb 2017 00:00:00 +0000 Vibrations in buildings can cause occupant discomfort in the form of annoyance, headache, or sickness. While occupant comfort is considered in international standards regarding the design of high rise buildings against wind loading, it is neglected in the design of buildings with seismic protective base isolation systems. Nevertheless, due to their low flexibility, base isolated buildings can be prone to wind-induced vibrations, which makes occupant discomfort a potentially significant serviceability limit state. This paper presents a study on occupant comfort conditions in wind-excited base isolated buildings. A numerical simplified parametric procedure is proposed in order to evaluate the return period of wind events causing human discomfort. A parametric investigation is then presented to evaluate the effects of salient parameters on comfort conditions. The procedure is based on (i) the nonlinear dynamic analysis of the structure modeled as a single-degree-of-freedom oscillator with hysteretic base isolators, (ii) the digital generation of time histories of turbulent wind velocity, and (iii) comfort evaluations based on international standards. Results demonstrate that discomfort conditions can occur a few times in a year, depending upon the wind-exposure of the site, what suggests considering this serviceability limit state in the design of base isolated buildings. F. Ubertini, F. Comodini, A. Fulco, and M. Mezzi Copyright © 2017 F. Ubertini et al. All rights reserved. Parameter Analysis on Wind-Induced Vibration of UHV Cross-Rope Suspension Tower-Line Thu, 16 Feb 2017 07:15:31 +0000 This paper analyzes the influences of important structural design parameters on the wind-induced response of cross-rope suspension tower-line. A finite element model of cross-rope suspension tower-line system is established, and the dynamic time-history analysis with harmonic wave superposition method is conducted. The two important structural design parameters such as initial guy pretension and sag-span ratio of suspension-rope are studied, as well as their influences on the three wind-induced vibration responses such as tensile force on guys, the reaction force on mast supports, and the along-wind displacement of the mast top; the results show that the value of sag-span ratio of suspension-rope should not be less than 1/9 and the value of guy pretension should be less than 30% of its design bearing capacity. On this occasion, the tension in guys and compression in masts would be maintained in smaller values, which can lead to a much more reasonable structure. Xilai Li, Dengke Yu, and Zhengliang Li Copyright © 2017 Xilai Li et al. All rights reserved. Moment-Curvature Behaviors of Concrete Beams Singly Reinforced by Steel-FRP Composite Bars Wed, 15 Feb 2017 07:56:42 +0000 A steel-fiber-reinforced polymer (FRP) composite bar (SFCB) is a kind of rebar with inner steel bar wrapped by FRP, which can achieve a better anticorrosion performance than that of ordinary steel bar. The high ultimate strength of FRP can also provide a significant increase in load bearing capacity. Based on the adequate simulation of the load-displacement behaviors of concrete beams reinforced by SFCBs, a parametric analysis of the moment-curvature behaviors of concrete beams that are singly reinforced by SFCB was conducted. The critical reinforcement ratio for differentiating the beam’s failure mode was presented, and the concept of the maximum possible peak curvature (MPPC) was proposed. After the ultimate curvature reached MPPC, it decreased with an increase in the postyield stiffness ratio (), and the theoretical calculation method about the curvatures before and after the MPPC was derived. The influence of the reinforcement ratio, effective depth, and FRP ultimate strain on the ultimate point was studied by the dimensionless moment and curvature. By calculating the envelope area under the moment-curvature curve, the energy ductility index can obtain a balance between the bearing capacity and the deformation ability. This paper can provide a reference for the design of concrete beams that are reinforced by SFCB or hybrid steel bar/FRP bar. Zeyang Sun, Yang Yang, Wenlong Yan, Gang Wu, and Xiaoyuan He Copyright © 2017 Zeyang Sun et al. All rights reserved. Effect of Modified Rubber Particles Mixing Amount on Properties of Cement Mortar Sun, 29 Jan 2017 06:25:51 +0000 The crumb rubber cement mortar is prepared by the crumb rubber aggregates in 60 mesh which are modified by 1% polyvinyl alcohol (PVA) solution. Some mechanical properties of cement mortar with different crumb rubber aggregate amounts are researched including compressive strength, flexural strength, the ratio of compressive strength to flexural strength, impact resistance, and dry contraction percentage. In our tests, we consider six kinds of the rubber contents, 0%, 7.5%, 15%, 19%, 22.5%, and 30%, respectively. The optimal mixing amount of crumb rubber is determined by measuring three indices, the ratio of compressive strength to flexural strength, impact resistance, and dry contraction percentage. It is shown by test that the ratio of compressive strength to flexural strength is the smallest when the mixing amount of rubber is 19%; meanwhile high impact resistance and rational drying shrinkage are observed. The optimal mixing amount of the rubber particles is 19% determined by this test. Gang Xue and Mei-ling Cao Copyright © 2017 Gang Xue and Mei-ling Cao. All rights reserved. Bond Strength between Hybrid Fiber-Reinforced Lightweight Aggregate Concrete Substrate and Self-Compacting Concrete as Topping Layer Mon, 23 Jan 2017 00:00:00 +0000 Structural performance evaluation of composite concrete slabs that were constructed using partially precast concreting system which utilized Hybrid Fiber-Reinforced Lightweight Aggregate Concrete (HyFRLWAC) as stay in-place formwork and self-compacting concrete (SCC) as topping layer was conducted in this research. This paper focused on determining the appropriate strength limit criteria of interface between two different concrete layers. The tensile strength was tested using pull-off test, while concrete cohesion was investigated based on modified bisurface shear test, and dual L-shaped shear test was used to determine the effect of normal force on the shear strength of concrete interface. Sample variants were designed based on the substrate surface conditions, compressive strength of the topping layer, and magnitude of perpendicular normal force acting on interface area. The substrate surfaces were prepared in as-placed and grooved conditions for tensile test, cohesion, and shear strength test. Test results indicate that tensile strength, cohesion, and shear strength of the concrete interface are affected by surface condition of the substrate, compressive strength of the topping layer, and the normal force acting perpendicularly on the concrete interface area. Proposed formulation for bond strength prediction between HyFRLWAC as substrate and SCC as topping layer is also presented in this paper. Slamet Widodo Copyright © 2017 Slamet Widodo. All rights reserved. Proposal of Design Formulae for Equivalent Elasticity of Masonry Structures Made with Bricks of Low Modulus Tue, 17 Jan 2017 00:00:00 +0000 Bricks of low elastic modulus are occasionally used in some developing countries, such as Indonesia and India. Most of the previous research efforts focused on masonry structures built with bricks of considerably high elastic modulus. The objective of this study is to quantify the equivalent elastic modulus of lower-stiffness masonry structures, when the mortar has a higher modulus of elasticity than the bricks, by employing finite element (FE) simulations and adopting the homogenization technique. The reported numerical simulations adopted the two-dimensional representative volume elements (RVEs) using quadrilateral elements with four nodes. The equivalent elastic moduli of composite elements with various bricks and mortar were quantified. The numerically estimated equivalent elastic moduli from the FE simulations were verified using previously established test data. Hence, a new simplified formula for the calculation of the equivalent modulus of elasticity of such masonry structures is proposed in the present study. Muhammad Ridwan, Isamu Yoshitake, and Ayman Y. Nassif Copyright © 2017 Muhammad Ridwan et al. All rights reserved.