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CONTENTS
Volume 35, Number 1, May10 2010
 

Abstract
Bonding of carbon fiber reinforced polymer (CFRP) composites has become a popular technique for strengthening concrete structures in recent years. The bond stress between concrete and CFRP is the main factor determining the strength, rigidity, failure mode and behavior of a reinforced concrete member strengthened with CFRP. The accurate evaluation of the strain is required for analytical calculations and design processes. In this study, the strain between concrete and bonded CFRP sheets across the notch is tested. In this paper, indirect axial tension is applied to CFRP bonded test specimen by a four point bending tests. The variables studied in this research are CFRP sheet width, bond length and the concrete compression strength. Furthermore, the effect of a crack- modeled as a notch- on the strain distribution is studied. It is observed that the strain in the CFRP to concrete interface reaches its maximum values near the crack tips. It is also observed that extending the CFRP sheet more than to a certain length does not affect the strength and the strain distribution of the bonding. The stress distribution obtained from experiments are compared to Chen and Teng

Key Words
CFRP; bonding strain; bonded joints; debonding.

Address
Ozgur Anil: Civil Engineering Department, Gazi University, Maltepe, Ankara 06570, Turkey
Cagatay M. Belgin: Civil Engineering Department, Gazi University, Maltepe, Ankara 06570, Turkey
M. Emin Kara: Civil Engineering Department, Aksaray University, Aksaray, Turkey

Abstract
This paper proposes a hybrid heuristic and criteria-based method of optimum design which combines the advantages of both the iterated simulated annealing (SA) algorithm and the rigorously derived optimality criteria (OC) for structural optimum design of reinforced concrete (RC) buildings under multi-load cases based on the current Chinese design codes. The entire optimum design procedure is divided into two parts: strength optimum design and stiffness optimum design. A modified SA with the strategy of adaptive feasible region is proposed to perform the discrete optimization of RC frame structures under the strength constraints. The optimum stiffness design is conducted using OC method with the optimum results of strength optimum design as the lower bounds of member size. The proposed method is integrated into the commercial software packages for building structural design, SATWE, and for finite element analysis, ANSYS, for practical applications. Finally, two practical frame-shear-wall structures (15-story and 30-story) are optimized to illustrate the effectiveness and practicality of the proposed optimum design method.

Key Words
reinforced concrete structure; strength; stiffness; simulated annealing; optimality criteria.

Address
Gang Li: Department of Engineering Mechanics, State Key Laboratory of Structural Analysis of Industrial Equipment, Dalian University of Technology, Dalian, 116024, China
Haiyan Lu: School of Architecture & Civil Engineering, Shenyang University of Technology, Shenyang, 110023, China
Xiang Liu: Department of Engineering Mechanics, State Key Laboratory of Structural Analysis of Industrial Equipment, Dalian University of Technology, Dalian, 116024, China

Abstract
Special-shape arch bridge for self-balance (SBSSAB) in Zhongshan City is a kind of new fashioned spatial combined arch bridge composed of inclined steel arch ribs, curved steel box girder and inclined suspenders, and the mechanical behavior of the SBSSAB is particularly complicated. The SBSSAB is aesthetic in appearance, and design of the SBSSAB is artful and particular. In order to roundly investigate the mechanical behavior of the SBSSAB, 3-D finite element models for spatial member and shell were established to analyze the mechanical properties of the SBSSAB using ANSYS. Finite element analyses were conducted under several main loading cases, moreover deformation and strain values for control section of the SBSSAB under several main loading cases were proposed. To ensure the safety and rationality for optimal design of the SBSSAB and also to verify the reliability of its design and calculation theories, the 1/10 scale model tests were carried out. The measured results include the load checking calculation, lane loading and crowd load, and dead load. A good agreement is achieved between the experimental and analytical results. Both experimental and analytical results have shown that the SBSSAB is in the elastic state under the planned test loads, which indicates that the SBSSAB has an adequate load-capacity. The calibrated finite-element model that reflects the as-built conditions can be used as a baseline for health monitoring and future maintenance of the SBSSAB.

Key Words
special-shape arch bridge; self-balance; model tests; finite element method; structural safety.

Address
Pengzhen Lu: School of Civil Engineering, Southwest Jiaotong University, Chengdu, 610031, PR China
Renda Zhao: School of Civil Engineering, Southwest Jiaotong University, Chengdu, 610031, PR China
Junping Zhang: School of Civil Engineering, Guangzhou University, Guangzhou, 510006, PR China

Abstract
The rigid body inertia properties of a structure including the mass, the center of gravity location, the mass moments and principal axes of inertia are required for structural dynamic analysis, modeling of mechanical systems, design of mechanisms and optimization. The analytical approaches such as solid or finite element modeling can not be used efficiently for estimating the rigid body inertia properties of complex structures. Several experimental approaches have been developed to determine the rigid body inertia properties of a structure via Frequency Response Functions (FRFs). In the present work two experimental methods are used to estimate the rigid body inertia properties of a frame. The first approach consists of using the amount of mass as input to estimate the other inertia properties of frame. In the second approach, the property of orthogonality of modes is used to derive the inertia properties of a frame. The accuracy of the estimated parameters is evaluated through the comparison of the experimental results with those of the theoretical Solid Work model of frame. Moreover, a thorough discussion about the effect of accuracy of measured FRFs on the estimation of inertia properties is presented.

Key Words
rigid body; inertia properties; frequency response functions; mode shapes; transformation matrix.

Address
M.R. Ashory: Department of Mechanical Engineering, Semnan University, Semnan, Iran
A. Malekjafarian: Department of Mechanical Engineering, Semnan University, Semnan, Iran
P. Harandi: Department of Mechanical Engineering, Semnan University, Semnan, Iran

Abstract
The beam string structure (BSS) has been widely applied in large span roof structures, while no analytical solutions of BSS were derived for it in the existing literature. In the first part of this paper, calculation formulas of displacement and internal forces were obtained by the Ritz-method for the most commonly used arc-shaped BSS under the vertical uniformly distributed load and the prestressing force. Then, the failure mode of BSS was proposed based on the static equilibrium. On condition the structural stability was reliable, BSS under the uniformly distributed load would fail by tensile strength failure of the string, and the beam remained in the elastic or semi-plastic range. On this basis, the limit load of BSS was given in virtue of the elastic solutions. In order to verify the linear elastic and limit state solutions proposed in this paper, three BSS modal were tested and the corresponding elastoplastic large deformation analysis was performed by the ANSYS program. The proposed failure mode of BSS was proved to be correct, and the analytical results for the linear elastic and limit state were in good agreement with the experimental and FEM results.

Key Words
beam string structure; Ritz method; limit state; failure mode; ANSYS; modal test; elastoplastic large deformation analysis.

Address
Weichen Xue: Department of Building Engineering, Tongji University, Shanghai 200092, China
Sheng Liu: Department of Building Engineering, Tongji University, Shanghai 200092, China

Abstract
In this paper, the mass optimization of four bar linkages is carried out using genetic algorithms (GA) with single and dual constraints. The single constraint of bending stress and the dual constraints of bending and buckling stresses are imposed. From the movement response of the bar linkage mechanism, the analysis of the mechanism is developed using the combination of kinematics, kinetics, and finite element analysis (FEA). A penalty-based transformation technique is used to convert the constrained problem into an unconstrained one. Lastly, a detailed comparison on the effect of single constraint and of dual constraints is presented.

Key Words
mass optimization; bar linkage; finite element analysis; genetic algorithms; buckling constraints.

Address
M.R.A. Hassan: Faculty of Mechanical Engineering, Penang Campus, Universiti Teknologi MARA, 13500 Permatang Pauh, Pulau Pinang, Malaysia
I.A. Azid: School of Mechanical Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang, Malaysia
M. Ramasamy: School of Mechanical Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang, Malaysia
J. Kadesan: School of Mechanical Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang, Malaysia
K.N. Seetharamu: M.S. Ramaiah School of Advanced Studies, New B E L Road, Bangalore-560054, India
A.S.K. Kwan: Division of Structural Engineering, Cardiff School of Engineering, PO Box 686 The Parade,
Cardiff CF24 3TB, U.K.
P. Arunasalam: Department of Mechanical Engineering, T.J. Watson School of Mechanical Engineering, State University of New York at Binghamton, NY 13902, USA

Abstract
Beam-column joints are the key structural elements, which dictate the behavior of structures subjected to earthquake loading. Though large experimental work has been conducted in the past, still various issues regarding the post-yield behavior, ductility and failure modes of the joints make it a highly important research topic. This paper presents experimental results obtained for eight beam-column joints of different sizes and configuration under cyclic loads along with the analytical evaluation of their response using a simple and effective analytical procedure based on nonlinear static pushover analysis. It is shown that even the simplified analysis can predict, to a good extent, the behavior of the joints by giving the important information on both strength and ductility of the joints and can even be used for prediction of failure modes. The results for four interior and four exterior joints are presented. One confined and one unconfined joint for each configuration were tested and analyzed. The experimental and analytical results are presented in the form of load-deflection. Analytical plots are compared with envelope of experimentally obtained hysteretic loops for the joints. The behavior of various joints under cyclic loads is carefully examined and presented. It is also shown that the procedure described can be effectively utilized to analytically gather the information on behavior of joints.

Key Words
beam-column joints; cyclic loading; nonlinear static pushover analysis; strength; ductility.

Address
Akanshu Sharma: Reactor Safety Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085, India
G.R. Reddy: Reactor Safety Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085, India
Rolf Eligehausen: Institut fur Werkstoffe im Bauwesen, Universitat Stuttgart, Pfaffenwaldring 4, 70569 Stuttgart, Germany
K.K. Vaze: Reactor Safety Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085, India
A.K. Ghosh: Reactor Safety Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085, India
H.S. Kushwaha: Health Safety & Environment Group, Bhabha Atomic Research Centre, Trombay, Mumbai-400085, India

Abstract


Key Words


Address
Dora Foti: Dipartimento di Ingegneria Civile e Ambientale, Politecnico di Bari, Via Orabona n. 4, 70125 Bari, Italy
Mariella Diaferio: Dipartimento di Ingegneria Civile e Ambientale, Politecnico di Bari, Via Orabona n. 4, 70125 Bari, Italy
Riccardo Nobile: Dipartimento di Ingegneria dell\'Innovazione, Universita del Salento, via per Arnesano, 73100 Lecce, Italy

Abstract


Key Words


Address
F. Alemdar: Paul C. Rizzo Associates, Inc., 105 Mall Boulevard, Suite 270-E, Monroeville, Pennsylvania 15146, USA
H. Sezen: Department of Civil and Environmental Engineering and Geodetic Science, The Ohio State University, 470 Hitchcock Hall, 2070 Neil Ave., Columbus, Ohio 43210-1275, USA


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