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CONTENTS
Volume 35, Number 3, June20 2010
 

Abstract
The shear contribution of transverse steel in reinforced concrete beams is generally assumed as independent of the concrete strength by most of the building codes. The shear strength of RC beams with web reinforcement is worked out by adding the individual contributions of concrete and stirrups. In this research 70 beams of medium strength concrete in the range of 52-54 MPa, compressive strength were tested in two sets of 35 beams each. In one set of 35 beams no web reinforcement was used, whereas in second set of 35 beams web reinforcement was used to check the contribution of stirrups. The values have also been compared with the provisions of ACI, Eurocode and Japanese Code building codes. The results of two sets of beams, when compared mutually and provisions of the building codes, showed that the shear strength of beams has been increased with the addition of stirrups for all the beams, but the increase is non uniform and irregular. The comparison of observed values with the provisions of selected codes has shown that EC-02 is relatively less conservative for low values of longitudinal steel, whereas ACI-318 overestimates the shear strength of RC beams at higher values of longitudinal steel. The Japanese code of JSCE has given relatively good results for the beams studied.

Key Words
shear; transverse; building codes; stirrups.

Address
Attaullah Shah: Project Directorate, Allama Iqbal Open University Islamabad-Pakistan, Islamabad-44000, Pakistan
Saeed Ahmad: Department of Civil Engineering, University of Engineering and Technology, Taxila, Pakistan
Salimullah Khan: Department of Pharmacy, Hazara University Mansehra, Pakistan

Abstract
This paper addresses the numerical simulation of fatigue crack growth in arbitrary 2D geometries under constant amplitude loading by the using a new finite element software. The purpose of this software is on the determination of 2D crack paths and surfaces as well as on the evaluation of components Lifetimes as a part of the damage tolerant assessment. Throughout the simulation of fatigue crack propagation an automatic adaptive mesh is carried out in the vicinity of the crack front nodes and in the elements which represent the higher stresses distribution. The fatigue crack direction and the corresponding stress-intensity factors are estimated at each small crack increment by employing the displacement extrapolation technique under facilitation of singular crack tip elements. The propagation is modeled by successive linear extensions, which are determined by the stress intensity factors under linear elastic fracture mechanics (LEFM) assumption. The stress intensity factors range history must be recorded along the small crack increments. Upon completion of the stress intensity factors range history recording, fatigue crack propagation life of the examined specimen is predicted. A consistent transfer algorithm and a crack relaxation method are proposed and implemented for this purpose. Verification of the predicted fatigue life is validated with relevant experimental data and numerical results obtained by other researchers. The comparisons show that the program is capable of demonstrating the fatigue life prediction results as well as the fatigue crack path satisfactorily.

Key Words
finite element simulation; stress intensity factors; mixed mode fracture; adaptive mesh; fatigue life prediction.

Address
Abdulnaser M. Alshoaibi: Department of Mechanical Engineering, Jazan University, Jazan, P.O. Box 706, Kingdom of Saudi Arabia

Abstract
The paper presents the results and conclusions of dynamic load tests that were conducted on a road bridge over the Mokrzyca river in Wroclaw (Poland) made of galvanized corrugated steel plates (CSP). The critical speed magnitudes, velocity vibration, vibration frequency were determined in the paper. The dynamic analysis is extremely important, because such studies of soil-steel bridges in the range of dynamic loads are relatively seldom conducted. Conclusions drawn from the tests can be most helpful in the assessment of behaviour of this type of corrugated plate bridge with soil. In consideration of application of this type of structure in the case of small-to-medium span bridges, the conclusions from the research will not be yet generalized to all types of such solutions. The detailed reference to all type of such bridge structures would be requiring additional analysis (field tests and calculations) on the other types of soil-steel bridges.

Key Words
dynamic test; soil-steel bridge; corrugated plate; vibration velocity; vibration frequency; critical speed.

Address
Damian Beben: Faculty of Civil Engineering, Opole University of Technology, Katowicka Street 48, 45-061 Opole, Poland
Zbigniew Manko: Mechanics and Structures Engineering Division, Wroclaw University of Environmental and Life Science, Plac Grunwaldzki No. 24a, 50-365 Wroclaw, Poland

Abstract
The structural behaviors of circular concrete filled steel tube (CFT) structures are investigated by nonlinear finite element method. An efficient three-dimensional (3D) degenerated beam element is adopted. Based on those previous studies, a modified stress-strain relationship for confined concrete which introduces the influence of eccentricity on confining stress is presented. Updated Lagrange formulation is used to consider the geometrical nonlinearity induced by large deformation effect. The nonlinear behaviors of CFT structures are investigated, and the accuracy of the proposed constitutive model for confined concrete is mainly concerned. The results demonstrate that the confining effect in CFT elements subjected to combining action of axial force and bending moment is far sophisticated than that in axial loaded columns, and an appropriate evaluation about this effect may be important for nonlinear numerical simulation of CFT structures.

Key Words
concrete-filled steel tube; nonlinear finite element analysis; degenerated beam element; updated lagrange formulation.

Address
Tengfei Xu: Department of Bridge Engineering, Southwest Jiaotong University, Chengdu 610031, P.R. China
Tianyu Xiang: Department of Bridge Engineering, Southwest Jiaotong University, Chengdu 610031, P.R. China
Renda Zhao: Department of Bridge Engineering, Southwest Jiaotong University, Chengdu 610031, P.R. China
Yulin Zhan: Department of Bridge Engineering, Southwest Jiaotong University, Chengdu 610031, P.R. China

Abstract
Cutouts are often provided in structural and aircraft components for ventilation, for access, inspection, electric lines and fuel lines or sometimes to lighten the structure. This paper addresses the effects of cutout shape (i.e., circular, square, diamond, elliptical-vertical and elliptical-horizontal) and size on buckling and postbuckling response of quasi-isotropic (i.e., (+45/−45/0/90)2s) composite laminate under uni-axial compression. The finite element method is used to carry out the investigation. The formulation is based on first order shear deformation theory and von Karman

Key Words
buckling; composite laminates; cutouts; failure; postbuckling; strength.

Address
S.B. Singh: Department of Civil Engineering, Birla Institute of Technology and Science, Pilani 333031, India
Dinesh Kumar: Department of Mechanical Engineering, Birla Institute of Technology and Science, Pilani 333031, India

Abstract
The impact behaviour and the impact-induced damage in laminated composite cylindrical shell subjected to transverse impact by a foreign object are studied using three-dimensional non-linear transient dynamic finite element formulation. A layered version of 20 noded hexahedral element incorporating geometrical non-linearity is developed based on total Langragian approach. Non-linear system of equations resulting from non-linear strain displacement relation and non-linear contact loading are solved using Newton-Raphson incremental-iterative method. Some example problems of graphite/epoxy cylindrical shell panels are considered with variation of impactor and laminate parameters and influence of geometrical non-linear effect on the impact response and the resulting damage is investigated.

Key Words
finite element analysis; large deformation; 20 noded layered hexahedral element; polymer matrix composites; laminated shell; impact.

Address
Surendra Kumar: CSIR Centre for Mathematical Modelling and Computer Simulation, NAL Belur Campus, Bangalore-560037, India

Abstract
In the present article, effect of non-uniform excitation due to spatially variation of seismic input on nonlinear response of concrete gravity dams is considered. The reservoir is assumed compressible. Isotropic damage mechanics approach is used to model static and dynamic nonlinear behavior of mass concrete in 2D space. The validity of utilized nonlinear model is considered using available theoretical results under static and dynamic conditions. The tallest monolith of Pine Flat dam is selected as a case study. Two cases are analyzed for considering the effect of limited wave propagation velocity on seismic behavior of the dam-reservoir system in which travelling velocities are chosen as 2000 m/s and infinity. It is found that tensile damage in neck and toe regions and also, in the vicinity of the base increase when the system is excited non-uniformly.

Key Words
concrete gravity dam; damage mechanics; fluid-structure interaction; spatial variation; seismic nonlinear response.

Address
H. Mirzabozorg: Civil Engineering Department, KN-Toosi University of Technology, Tehran, Iran
R. Kianoush: Civil Engineering Department, Ryerson University, Toronto, Canada
M. Varmazyari: Civil Engineering Department, KN-Toosi University of Technology, Tehran, Iran

Abstract


Key Words


Address
Ioannis G. Raftoyiannis: Laboratory of Steel Structures, Department of Civil Engineering, National Technical University of Athens, 9 Iroon Polytechneiou St., Zografou Campus, Athens 15780, Greece
Tassos P. Avraam: Laboratory of Steel Structures, Department of Civil Engineering, National Technical University of Athens, 9 Iroon Polytechneiou St., Zografou Campus, Athens 15780, Greece
George T. Michaltsos: Laboratory of Steel Structures, Department of Civil Engineering, National Technical University of Athens, 9 Iroon Polytechneiou St., Zografou Campus, Athens 15780, Greece

Abstract


Key Words


Address
Lizhong Xu: Mechanical Engineering Institute, Yanshan University, Qinhuangdao 066004, China
Jin Huang: Mechanical Engineering Institute, Yanshan University, Qinhuangdao 066004, China


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