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CONTENTS
Volume 41, Number 5, March10 2012
 

Abstract
This paper presents a reliability analysis of steel I-beams with rectangular web openings, based on a combination of the common probabilistic reliability methods, such as RSM, FORM and SORM and using data obtained from experimental tests performed at the Istanbul Technical University. A procedure is proposed to obtain the optimum design load that can be applied to this type of structural members, by taking into account specified target values of reliability indices for ultimate and serviceability limit states. The goal of the paper is to present an algorithm to obtain more realistic and economical design of beams and to demonstrate that it can be applied efficiently to steel I-beams with web openings. Finally, a sensitivity analysis is performed allowing to ranking the random variables according to their importance in the reliability analysis.

Key Words
random variable; reliability; target; performance function; failure mechanism; steel I-beams; ultimate; serviceability

Address
Guliz Bayramoglu: Faculty of Civil Engineering, Istanbul Technical University, 34469 Maslak-Istanbul, Turkey

Abstract
This paper provides an iteration approach for the solution of multiple notch problem, which is based on the complex variable boundary integral equation (CVBIE). The contours of notches are applied by some loadings. The source points are assumed on the boundary of individual notch and the displacements along the boundaries become unknowns to be investigated. After discretization of the BIE, many influence matrices are obtained. One does not need to assemble many influence matrices into a larger matrix. This will considerably reduce the work in the program. The displacements along the many boundaries can be obtained from an iteration. There is no limitation for the configuration of notches. Several numerical examples are provided to prove the efficiency of the suggested approach.

Key Words
boundary integral equation; multiple notches; stress concentration factors; iteration

Address
Y. Z. Chen: Division of Engineering Mechanics, Jiangsu University, Zhenjiang, Jiangsu, 212013, P.R. China

Abstract
In this paper, guided circumferential wave propagating in an orthotropic viscoelastic cylindrical curved plate subjected to traction-free conditions is investigated in the frame of the Kelvin-Voight viscoelastic theory. The obtained three wave equations are decoupled into two groups, Lamb-like wave and SH wave. They are separately solved by the Legendre polynomial series approach. The availability of the method is confirmed through the comparison with the published data of the SH wave for a viscoelastic flat plate. The dispersion curves and attenuation curves for the carbon fiber and prepreg cylindrical plates are illustrated and the viscous effect on dispersion curves is shown. The influences of the ratio of radius to thickness are analyzed.

Key Words
viscoelastic materials; guided circumferential wave; Legendre polynomial series; dispersion curves; Attenuation curves

Address
Jiangong Yu and Zhijuan Ma: School of Mechanical and Power Engineering, Henan Polytechnic University, Jiaozuo 454003, P.R. China

Abstract
An isogeometric approach is presented for static analysis of thin plate problems of various geometries. Non-Uniform Rational B-Splines (NURBS) basis function is applied for approximation of the thin plate deflection, as for description of the geometry. The governing equation based on Kirchhoff plate theory, is discretized using the standard Galerkin method. The essential boundary conditions are enforced by the Lagrange multiplier method. Several typical examples of thin plate and thin plate on elastic foundation are solved and compared with the theoretical solutions and other numerical methods. The numerical results show the robustness and efficiency of the proposed approach.

Key Words
isogeometric analysis; NURBS; kirchhoff plate; lagrange multiplier method; elastic foundation

Address
S. Shojaee and N. Valizadeh: Civil Engineering Department, Shahid Bahonar University of Kerman, Kerman, Iran

Abstract
The paper presents the motion editor for the robotic movement in the study. The Motion Editor can edit all motions which we want to need. This method is easy when the beginners edit to motions of robots. And let them have interesting in robot control. This paper proposes two methods to edit movements. First, we edit the robot\'s movement in VB environment, and then we use the Motion Editor to make it. Finally, we compared merit and defect with two methods. Indeed, it is convenient when we use the Motion Editor.

Key Words
biped robot; displacement; dynamics; intelligent robot; artificial intelligence

Address
Chen-Yuan Chen: Department and Graduate School of Computer Science, National Pingtung University of Education, No. 4-18, Ming Shen Rd., Pingtung 90003, Taiwan; Global Earth Observation and Data Analysis Center (GEODAC), National Cheng Kung University, No 1, Ta-Hsueh Road, Tainan 701, Taiwan; Department of Information Management, National Kaohsiung First University of Science and Technology,
2 Jhuoyue Rd. Nanzih, Kaohsiung 811, Taiwan
Ling-Huei Wang: Department and Graduate School of Computer Science, National Pingtung University of Education, No. 4-18, Ming Shen Rd., Pingtung 90003, Taiwan

Abstract
Deteriorative effects of steel corrosion on the structural response of reinforced concrete are simulated for varying degrees of corrosion. The simulation approach is based on a three-dimensional irregular lattice model of the bulk concrete, in which fracture is modeled using a crack band approach that conserves fracture energy. Frame elements and bond link elements represent the reinforcing steel and its interface with the concrete, respectively. Polylinear stress-slip properties of the link elements are determined, for several degrees of corrosion, through comparisons with direct pullout tests reported in the literature. The link properties are then used for the lattice modeling of reinforced concrete beams with similar degrees of corrosion of the main reinforcing steel. The model is successful in simulating several important effects of steel corrosion, including increased deflections, changes in flexural cracking behavior, and reduced yield load of the beam specimens.

Key Words
steel corrosion; reinforced concrete; irregular lattice model; concrete-reinforcement interface; fracture

Address
Kunhwi Kim: Department of Civil & Environmental Engineering, Yonsei University, Seoul, Korea
John E. Bolander: Department of Civil & Environmental Engineering, University of California, Davis, USA
Yun Mook Lim: Department of Civil & Environmental Engineering, Yonsei University, Seoul, Korea

Abstract
A number of mode shape-based structure damage identification methods have been verified by numerical simulations or experiments for on-line structure health monitoring (SHM). However, many of them need a baseline mode shape generated by the healthy structure serving as a reference to identify damages. Otherwise these methods can hardly perform well when multiple cracks conditions occur. So it is important to solve the problems above. By aid of the fractal dimension method (FD), Qiao and Wang proposed a generalized fractal dimension (GFD) to detect the delamination damage. As a modification of GFD, Qiao and Cao proposed the approximate waveform capacity dimension (AWCD) technique to simplify the calculation of fractal and overcome the false peak appearing in the high mode shapes. Based on their valued work, this paper combined and applied the AWCD method and curvature mode shape data to detect multiple damages in beam. In the end, the identification properties of the AWCD for multiple damages have been verified by groups of Monte Carlo simulations and experiments.

Key Words
curvature mode shape; fractal dimension; waveform dimension; multiple damages; damage detection

Address
Zhibo Yang, Xuefeng Chen, Shaohua Tian and Zhengjia He: The State Key Laboratory for Manufacturing Systems Engineering, School of Mechanical Engineering, Xi\'an Jiaotong University, Xi\'an 710049, PR China

Abstract
Most connections of steel structures exhibit flexible behaviour under cyclic loading. The flexible connections can be assumed as nonlinear rotational springs attached to the ends of each beam. The nonlinear behaviour of the connections can be considered by suitable moment-rotation relationship. Time-history analysis by direct integration method can be used as a powerful technique to determine the nonlinear dynamic response of the structure. In conventional numerical integration, the response is evaluated for a series of short time increments. The limitations on the size of time intervals can be removed by using Chen and Robinson improved time history analysis method, in which the integrated displacements are used as the new variables in integrated equation of motion. The proposed method permits longer time intervals and reduces the computational works. In this paper the nonlinearity behaviour of the structure is summarized on the connections, and the step by step improved time-history analysis is used to calculate the dynamic response of the structure. Several numerical calculations which indicate the applicability and advantages of the proposed methodology are presented. These calculations illustrate the importance of the effect of the nonlinear behaviour of the flexible connections in the calculation of the dynamic response of steel frames.

Key Words
steel frames; nonlinear analysis; time-history analysis; flexible connection; semi-rigid connection; integrated displacement method

Address
M.A. Hadianfard: Department of Civil and Environmental Engineering, Shiraz University of Technology, Shiraz, Iran


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