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CONTENTS
Volume 63, Number 5, September10 2017
 

Abstract
The study covers the behavior of reinforced concrete deep beams loaded under 4-point bending, failed by shear and repaired using bonding glass fiber reinforced plastics fabrics (GFRP) patches. Two rehabilitation methods have been used to highlight the influence of the composite on the ultimate strength of the beams and their failure modes. In the first series of trials the work has been focused on the reinforcement/rehabilitation of the beam by following the continuous configuration of the FRP fabric. The patch with a U-shape did not provide satisfactory results because this reinforcement strategy does not allow to increase the ultimate strength or to avoid the abrupt shear failure mode. A second methodology of rehabilitation/reinforcement has been developed in the form of SCR (Strips of Critical Region), in which the composite materials reinforcements are positioned to band the inclined cracks (shear) caused by the shear force. The results obtained by using this method lead a superior out come in terms of ultimate strength and change of the failure mode from abrupt shearing to ductile bending.

Key Words
glass fiber; shear reinforcement; reinforced concrete; beams; repair; failure modes; cracking

Address
M. Boumaaza, N. Benzennache : Department of Civil Engineering, Laboratory of Civil Engineering & Hydraulics, University of Guelma, BP 401, Guelma 24000, Algeria
A. Bezazi : Department of Mechanical Engineering, Laboratory of Applied Mechanics of New Materials, University of Guelma,
BP 401, Guelma 24000, Algeria
H. Bouchelaghem : Department of Mechanical Engineering, Laboratory of Applied Mechanics of New Materials, University of Guelma,
BP 401, Guelma 24000, Algeria
/Department of Mechanical Engineering, University of Constantine Mentouri brothers, Road Ain El Bey, Constantine 25000, Algeria
S. Amziane : Department of Civil Engineering, Polytech Clermont Ferrand, Blaise Pascal University, UMR 6602 BP 206, 63174 Aubière, France
F. Scarpa : Bristol Composites Institute (ACCIS), University of Bristol, BS8 1TR Bristol, UK

Abstract
This study aimed to presents a simple analytical approach to investigate the thermal buckling behavior of thick functionally graded sandwich by employing both the sinusoidal shear deformation theory and stress function. The material properties of the sandwich plate faces are continuously varied within the plate thickness according to a simple power-law distribution in terms of the volume fractions of the constituents. The core layer is still homogeneous and made of an isotropic material. The thermal loads are considered as uniform, linear and non-linear temperature rises across the thickness direction. Numerical examples are presented to prove the effect of power law index, loading type and functionally graded layers thickness on the thermal buckling response of thick functionally graded sandwich.

Key Words
functionally graded materials; thermal buckling; sandwich plate; sinusoidal shear deformation theory; stress function

Address
Fouzia El-Haina and Ahmed Bakora : Material and Hydrology Laboratory, Faculty of Technology, Civil Engineering Department, University of Sidi Bel Abbes, Algeria
Abdelmoumen Anis Bousahla : Material and Hydrology Laboratory, Faculty of Technology, Civil Engineering Department, University of Sidi Bel Abbes, Algeria
/Laboratoire de Modélisation et Simulation Multi-échelle, Université de Sidi Bel Abbés, Algeria
/Centre Universitaire de Relizane, Algérie
Abdelouahed Tounsi : Material and Hydrology Laboratory, Faculty of Technology, Civil Engineering Department, University of Sidi Bel Abbes, Algeria
/Laboratoire de Modélisation et Simulation Multi-échelle, Université de Sidi Bel Abbés, Algeria
S.R. Mahmoud : Department of Mathematics, Faculty of Science, King Abdulaziz University, Saudi Arabia
/Mathematics Department, Faculty of Science, University of Sohag, Egypt

Abstract
Our work aims to analyze using the finite element method the evolution of the stress intensity factor (SIF) parameter K of three laminated folded plates stacks [+a,-a], made of the same epoxy matrix and different reinforcement fibers (boron, graphite and glass). Our results show that the angle of orientation of the boron/epoxy composite has no great influence on the variation of the parameter KI. Compared to composite graphite/epoxy and glass/epoxy, the laminated composite boron/epoxy reduces more the SIF KI in the middle of the plate for angles 0 <= a <= 30.

Key Words
cracks; delamination; stress intensity factor; fibers orientations; finite element method and laminates

Address
Habib Achache : Department of Materials Engineering, University Dr Yahia Fares of Medea, Urban Pole - 26000 Medea, Algeria
Abdelouahab Benzerdjeb : Department of Mechanical Engineering University of Science and Technology Oran Mohammed Boudiaf (USTO), BP1505 El Menaouar, 31036 Oran, Algeria
Abdelkader Mehidi and Benali Boutabout : Laboratory of Mechanical and Physical of Materials (LMPM), University Djillali Liabes of Sidi Bel Abbes,
BP 89, Street Ben M\'Hidi, Sidi Bel Abbes, Algeria
Djamel Ouinas : Laboratory of Numerical and Experimental Modeling of Mechanical Phenomena, University of Mostaganem,
Route Belahcel 27000 Mostaganem, Algeria

Abstract
This study presents optimum design of plane steel bridges considering corrosion effect by using teaching-learning based optimization (TLBO) method. Optimum solutions of three different bridge problems are linearly carried out including and excluding corrosion effect. The member cross sections are selected from a pre-specified list of 128 W profiles taken from American Institute of Steel Construction (AISC). A computer program is coded in MATLAB to carry out optimum design interacting with SAP2000 using OAPI (Open Application Programming Interface). The stress constraints are incorporated as indicated in AISC Allowable Stress Design (ASD) specifications and also displacement constraints are applied in optimum design. The results obtained from analysis show that the corrosion effect on steel profile surfaces causes a crucial increase on the minimum steel weight of bridges. Moreover, the results show that the method proposed is applicable and robust to reach the destination even for complex problems.

Key Words
optimum design; steel bridge; teaching-learning based optimization; MATLAB-SAP2000 OAPI

Address
Musa Artar : Department of Civil Engineering, Bayburt University, Bayburt 69000, Turkey
Recep Catar : Department of Mechanical Engineering, Bayburt University, Bayburt 69000, Turkey
Ayse T. Daloglu : Department of Civil Engineering, Karadeniz Technical University, Trabzon 61000,Turkey

Abstract
In order to study the failure mode and seismic behavior of the interior-joint in steel traditional-style buildings, a single beam-column joint and a double beam-column joint were produced according to the relevant building criterion of ancient architectural buildings and the engineering instances, and the dynamic horizontal loading test was conducted by controlling the displacement of the column top and the peak acceleration of the actuator. The failure process of the specimens was observed, the bearing capacity, ductility, energy dissipation capacity, strength and stiffness degradation of the specimens were analyzed by the load-displacement hysteresis curve and backbone curve. The results show that the beam end plastic hinge area deformed obviously during the loading process, and tearing fracture of the base metal at top and bottom flange of beam occurred. The hysteresis curves of the specimens are both spindle-shaped and plump. The ultimate loads of the single beam-column joint and double beam-column joint are 48.65 kN and 70.60 kN respectively, and the equivalent viscous damping coefficients are more than 0.2 when destroyed, which shows the two specimens have great energy dissipation capacity. In addition, the stiffness, bearing capacity and energy dissipation capacity of the double beam-column joint are significantly better than that of the single beam-column joint. The ductility coefficients of the single beam-column joint and double beam-column joint are 1.81 and 1.92, respectively. The cracks grow fast when subjected to dynamic loading, and the strength and stiffness degradation is also degenerated quickly.

Key Words
traditional-style buildings; dynamic test; double beam-column joints; peak acceleration; tearing fracture

Address
Jianyang Xue, Kun Yang and Zhanjing Wu : Department of Civil Engineering, Xi\'an University of Architecture and Technology, Xi\'an 710055, China
Liangjie Qi : Department of Civil Engineering, Xi\'an University of Architecture and Technology, Xi\'an 710055, China
/Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, 24060, USA

Abstract
Continuous concrete beams are commonly used as structural members in the reinforced concrete constructions. The use of fiber reinforced polymer (FRP) bars provide attractive solutions for these structures particularly for gaining corrosion resistance. This paper presents experimental results of eight two-span continuous concrete beams; two of them reinforced with pure glass fiber reinforced polymer (GFRP) bars and six of them reinforced with combinations of GFRP and steel bars. The continuous beams were tested under monotonically applied loading condition. The experimental load-deflection behavior and failure mode of the continuous beams were examined. In addition, the continuous beams were analyzed with a numerical method to predict the load-deflection curves and to compare them with the experimental results. Results show that there is a good agreement between the experimental and the theoretical load-deflection curves of continuous beams reinforced with pure GFRP bars and combinations of GFRP and steel bars.

Key Words
concrete; glass fiber reinforced polymer (GFRP); continuous beam; load-deflection; stress-strain

Address
Ismail Unsal, Ismail H. Cagatay and Cengiz Dundar : Department of Civil Engineering, Cukurova University, 01330 Adana, Turkey
Serkan Tokgoz : Department of Civil Engineering, Adana Science and Technology University, 01180 Adana, Turkey

Abstract
According to the multi-index system of dam safety assessment and the standard of safety, a comprehensive evaluation model for dam safety based on a cloud model is established to determine the basic probability assignment of the Dempster-Shafer theory. The Dempster-Shafer theory is improved to solve the high conflict problems via fusion calculation. Compared with the traditional Dempster-Shafer theory, the application is more extensive and the result is more reasonable. The uncertainty model of dam safety multi-index comprehensive evaluation is applied according to the two theories above. The rationality and feasibility of the model are verified through application to the safety evaluation of a practical arch dam.

Key Words
dam safety; comprehensive evaluation; cloud model; Dempster-Shafer theory

Address
Fan Jia, Meng Yang, Huaizhi Su and Erfeng Zhao : State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University, Nanjing 210098, China
/College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing 210098, China
/National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety, Nanjing 210098, China
Jianlei Wang : State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University, Nanjing 210098, China
/College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing 210098, China
Bingrui Liu : College of Harbour, Coastal and Offshore Engineering, Hohai University, Nanjing 210098, China
Jiaorong Gao : Engineering Training Center, Hohai University, Nanjing 210098, China


Abstract
To achieve this goal, two four-span concrete box-girder bridges with typical configurations of California highway bridges are selected as representative bridges: an integral abutment bridge and a seat-type abutment bridge. A detailed numerical model of the representative bridges is created in OpenSees to perform dynamic analyses. To examine the effect of earthquake incidence angle on the fragility of skewed bridges, the representative bridge models are modified with different skew angles. Dynamic analyses for all bridge models are performed for all earthquake incidence angles examined. Simulated results are used to develop demand models and component and system fragility curves for the skewed bridges. The fragility characteristics are compared with regard to earthquake incidence angle. The results suggest that the earthquake incidence angle more significantly affects the seismic demand and fragilities of the integral abutment bridge than the skewed abutment bridge. Finally, a recommendation to account for the randomness due to the ground motion directionality in the fragility assessment is made in the absence of the predetermined earthquake incidence angle.

Key Words
ground motion directionality; skewed bridge; integral and seat abutments; fragility curves

Address
Jong-Su Jeon : Department of Civil Engineering, Andong National University, 1375 Gyeongdong-ro, Andong-si, Gyeongsangbuk-do 36729, Republic of Korea
Eunsoo Choi : Department of Civil Engineering, Hongik University, 94 Wausan-ro, Mapo-gu, Seoul 04066, Republic of Korea
Myung-Hyun Noh : Structure Research Group, Steel Solution Marketing Division, POSCO, 100 Songdogwahak-ro, Yeonsu-gu, Incheon 21985, Republic of Korea

Abstract
Rail support failure is inevitably subjected to track geometric deformations. Due to the randomness and evolvements of track irregularities, it is naturally a hard work to grasp the trajectories of dynamic responses of railway systems. This work studies the influence of rail fastener failure on dynamic behaviours of wheel/rail interactions and the railway tracks by jointly considering the effects of track random irregularities. The failure of rail fastener is simulated by setting the stiffness and damping of rail fasteners to be zeroes in the compiled vehicle-track coupled model. While track random irregularities will be transformed from the PSD functions using a developed probabilistic method. The novelty of this work lays on providing a method to completely reveal the possible responses of railway systems under jointly excitation of track random irregularities and rail support failure. The numerical results show that rail fastener failure has a great influence on both the wheel/rail interactions and the track vibrations if the number of rail fastener failure is over three. Besides, the full views of time-dependent amplitudes and probabilities of dynamic indices can be clearly presented against different failing status.

Key Words
vehicle/track interaction; rail fastener failure; track random irregularity; probabilistic method; power spectral density

Address
Lei Xu, Jianmin Gao and Wanming Zhai : Train and Track Research Institute, State Key Laboratory of Traction Power, Southwest Jiaotong University,
No. 111, North Section 1, Erhuan Road, Chengdu 610031, China

Abstract
The design of reinforced concrete buildings must satisfy the serviceability stiffness criteria in terms of maximum lateral deflections and inter story drift in order to prevent both structural and non-structural damages. Consideration of plastic hinge formation is also important to obtain accurate failure mechanism and ultimate strength of reinforced concrete frames. In the present study, an iterative procedure has been developed for the analysis of reinforced concrete frames with cracked elements and consideration of plastic hinge formation. The ACI and probability-based effective stiffness models are used for the effective moment of inertia of cracked members. Shear deformation effect is also considered, and the variation of shear stiffness due to cracking is evaluated by reduced shear stiffness models available in the literature. The analytical procedure has been demonstrated through the application to three reinforced concrete frame examples available in the literature. It has been shown that the iterative analytical procedure can provide accurate and efficient predictions of deflections and ultimate strength of the frames studied under lateral and vertical loads. The proposed procedure is also efficient from the viewpoint of computational time and convergence rate. The developed technique was able to accurately predict the locations and sequential development of plastic hinges in frames. The results also show that shear deformation can contribute significantly to frame deflections.

Key Words
reinforced concrete (R/C) structure, nonlinear analysis, analytical method, static analysis, iteration method

Address
Ilker Fatih Kara : Civil Engineering Department, Bursa Technical University, 16330, Bursa, Turkey
Ashraf F. Ashour : School of Engineering, Faculty of Engineering and Informatics, University of Bradford, BD7 1DP, Bradford, United Kingdom
Cengiz Dundar : Civil Engineering Department, Cukurova University, 01330, Adana, Turkey

Abstract
In this paper, a hyperbolic shear deformation theory is presented for bending analysis of functionally graded beams. This theory used in displacement field in terms of thickness co-ordinate to represent the shear deformation effects and does not require shear correction factor, and gives rise to transverse shear stress variation such that the transverse shear stresses vary parabolically across the thickness satisfying shear stress free surface conditions. The governing equations are derived by employing the virtual work principle and the physical neutral surface concept. A simply supported functionally graded beam subjected to uniformly distributed loads and sinusoidal loads are consider for detail numerical study. The accuracy of the present solutions is verified by comparing the obtained results with available published ones.

Key Words
functionally graded; Navier\'s solution; physical neutral surface; virtual work; sinusoidal loads

Address
Nafissa Zouatnia and Amar Kassoul : Department of Civil Engineering, Laboratory of Structures, Geotechnics and Risks (LSGR), Hassiba Benbouali University of Chlef, Algeria, BP 151, Hay Essalam, UHB Chlef, Chlef (02000), Algeria
Lazreg Hadji : Department of Civil Engineering, Ibn Khaldoun University, BP 78 Zaaroura, 14000 Tiaret, Algeria

Abstract
Clearances are essential for the assemblage of mechanisms to allow the relative motion between the joined bodies. This clearance exists due to machining tolerances, wear, material deformations, and imperfections, and it can worsen the mechanism performance when the precision and smoothly-working are intended. Energy is a subject which is less paid attention in the area of clearance. The effect of the clearance on the energy of a flexible slider-crank mechanism is investigated in this paper. A clearance exists in the joint between the slider and the coupler. The contact force model is based on the Lankarani and Nikravesh model and the friction force is calculated using the modified Coulomb\'s friction law. The hysteresis damping which has been included in the contact force model dissipates energy in clearance joints. The other source for the energy loss is the friction between the journal and the bearing. Initial configuration and crank angular velocity are changed to see their effects on the energy of the system. Energy diagrams are plotted for different coefficients of friction to see its influence. Finally, considering the coupler as a flexible body, the effect of flexibility on the energy of the system is investigated.

Key Words
clearance; energy loss; flexibility; floating frame of reference

Address
Saeed Ebrahimi, Esmaeil Salahshoor : Department of Mechanical Engineering, Yazd University, Yazd, Iran
Shapour Moradi : Department of Mechanical Engineering, Shahid Chamran University of Ahvaz, Ahwaz, Iran


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