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CONTENTS
Volume 16, Number 3, September 2003
 

Abstract
The first seismically isolated structure in Taiwan was completed in early 1999. Seven new bridges of the Second National Freeway located at Bai-Ho area, a region which is considered to be of high seismic risk, have been designed and constructed with lead-rubber seismic isolation bearings. Since this is the first application of seismic isolation method to the practical construction in Taiwan, field tests were conducted for one of the seven bridges to evaluate the assumptions and uncertainties in the design and construction. The test program is composed of ambient vibration tests, forced vibration tests, and free vibration tests. For the free vibration tests, a special test setup composed of four 1000 kN hydraulic jacks and a quick-release mechanism was designed to perform the function of push-and-quick release. Valuable results have been obtained based on the correlation between measured and analytical data so that the analytical model can be calibrated. Based on the analytical correlation, it is concluded that the dynamic characteristics and free vibration behavior of the isolated bridge can be well captured when the nonlinear properties of the bearings are properly considered in the modeling.

Key Words
bridge; seismic isolation; lead-rubber bearings; field tests.

Address
Department of Civil Engineering, National Taiwan University, Taipei, Taiwan 10617
Structural Engineering Department II, China Engineering Consultants, Inc., Taipei, Taiwan 10686
Department of Construction Engineering, National Taiwan University of Science and Technology,
Taipei, Taiwan, 10617
Department of Civil Engineering, National Taiwan University, Taipei, Taiwan 10617

Abstract
In this paper, a novel numerical solution technique, the differential cubature method is employed to study the buckling problems of thick plates with arbitrary quadrilateral planforms and non-uniform boundary constraints based on the first order shear deformation theory. By using this method, the governing differential equations at each discrete point are transformed into sets of linear homogeneous algebraic equations. Boundary conditions are implemented through discrete grid points by constraining displacements, bending moments and rotations of the plate. Detailed formulation and implementation of this method are presented. The buckling parameters are calculated through solving a standard eigenvalue problem by subspace iterative method. Convergence and comparison studies are carried out to verify the reliability and accuracy of the numerical solutions. The applicability, efficiency, and simplicity of the present method are demonstrated through solving several sample plate buckling problems with various mixed boundary constraints. It is shown that the differential cubature method yields comparable numerical solutions with 2.77-times less degrees of freedom than the differential quadrature element method and 2-times less degrees of freedom than the energy method. Due to the lack of published solutions for buckling of thick rectangular plates with mixed edge conditions, the present solutions may serve as benchmark values for further studies in the future.

Key Words
differential cubature method; buckling analysis; critical load; thick quadrilateral plates; plates with mixed boundary conditions.

Address
Department of Mechanics and Engineering Science, Shijiazhuang Railway Institute, Shijiazhuang 050043, P.R. China

Abstract
In this study, 24 high-strength concrete dapped-end beams were tested to study the effects of the amount of main dapped-end reinforcement, the nominal shear span-to-depth ratio, and the concrete strength on the shear strength of dapped-end beams. Test results indicate that the shear strength of dapped ends increases with the increase in the amount of main dapped-end reinforcement and the concrete strength. The shear strength of dapped-end beam increases with the decrease of nominal shear span-to-depth ratio. A simplified method for determining the shear strength of reinforced concrete dapped ends is also proposed in this paper. The shear strengths predicted by the proposed method and the approach of PCI Design Handbook are compared with test results. The comparison shows that the proposed method can more accurately predict the shear strength of reinforced concrete dapped-end beams than the approach of PCI Design Handbook.

Key Words
reinforced concrete dapped-end beams; high-strength concrete; softened strut-and-tie model.

Address
Department of Construction Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan 10672, R.O.C.

Abstract
A method is presented to integrate explicitly certain equilibrium problems for no-tension bodies, in absence of body forces and under the assumption that two of the principal stresses are everywhere null. The method is exemplified in the case of rectangular panels, clamped at their bottoms and loaded at their tops.

Key Words
no-tension materials; pressureless gasses; explicit solutions.

Address
Dipartimento di Costruzioni, Universit?di Firenze, Piazza Brunelleschi 6, Firenze, Italy

Abstract
The tension leg platform (TLP) is a moored floating offshore structure whose buoyancy is more than its weight. The mooring system, known as tethers, is vulnerable to failure due to extreme (maximum and minimum) tensions. In the present study the reliability of these tethers under maximum and minimum tension (ultimate limit state) has been studied. Von-Mises failure criteria has been adopted to define the failure of a tether against maximum tension. The minimum tension failure criteria has been assumed to meet when the tethers slack due to loss of tension. First Order Reliability method (FORM) has been adopted for reliability assessment. The reliability, in terms of reliability index, and probability of failure has been obtained for twelve sea states. The probabilities of failure so obtained for different sea states have been adopted for the calculation of annual and life time probabilities of failure.

Key Words
structural reliability; TLP; offshore; ultimate limit state; tethers.

Address
Department of Civil Engineering, Aligarh Muslim University, Aligarh - 202 002, India
Department of Applied Mechanics, Indian Institute of Technology, Delhi, New Delhi 110 016, India

Abstract
Variations in system parameters due to uncertainties of parameters may result in system performance deterioration and create system internal stability problems. Uncertainties in structural modeling of structures are often considered to ensure that the control system is robust with respect to response errors. So the uncertain concept plays an important role in the analysis and design of the engineering structures. In this paper, the active control of the intelligent structures with the uncertainties is studied and a new method for analyzing the robustness of systems with the uncertainties is presented. Firstly, the system with uncertain parameters is considered as the perturbation of the system with deterministic parameters. Secondly, the feedback control law is designed on the basis of deterministic system. Thirdly, perturbation analysis and robustness analysis of intelligent structures with uncertainties are discussed when the feedback control law is applied to the original system and perturbed system. Combining the convex model of uncertainties with the finite element method, the analysis theory of the robustness of intelligent structures with the uncertainties can be developed. The description and computation of the robustness of intelligent structures with uncertain parameters is obtained. Finally, a numerical example of the application of the present method is given to show the validity of the method.

Key Words
robust; uncertainty; feedback control; perturbation; intelligent structure.

Address
Department of Engineering Mechanics, Shanghai Jiaotong University, Shanghai, 200240, P.R. China
School of Mechanical Engineering and Automation, Northeastern University, Shenyang, 110004, P.R. China
Department of Engineering Mechanics, Shanghai Jiaotong University, Shanghai, 200240, P.R. China

Abstract
The goal of this paper is to determine the eigenvalues of a uniform rectangular plate carrying any number of spring-damper-mass systems using an analytical-and-numerical-combined method (ANCM). To this end, a technique was presented to replace each

Key Words
analytical-and-numerical-combined method (ANCM); eigenvalues; equivalent \"spring-damper\"system; finite element method (FEM).

Address
Department of Naval Architecture and Marine Engineering, Chung Cheng Institute of Technology, National Defense University, Yuansulin, Dashi, Taoyuan, Taiwan 335, Republic of China

Abstract
In this paper, the structural behavior of R/C cylindrical panel is analyzed by experimental results. To avoid the geometric imperfection, R/C shell specimens are made by use of a stiff steel mold. From experimental results, the load carrying behavior of R/C cylindrical panel is presented under an external lateral pressure. Even if R/C shell does not posses geometric imperfections, the inaccuracy of the reinforcement position strongly affects to the ultimate strength and the failure patterns of such shells. To explain these effects, FEM nonlinear analyses are done under the same conditions as those of experiments. The behavior of R/C cylindrical shells are well simulated under the consideration of both the geometric imperfection and several inaccuracies.

Key Words
R/C shell; imperfection; experiment; FE Analysis.

Address
Tokuyama College of Technology, Shunan 745-8585, Japan


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