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CONTENTS
Volume 7, Number 3, March 1999
 

Abstract
This paper presents a procedure to minimize the cost of materials of cable-stayed bridges with composite box girder and concrete tower. Two sets of iterations are included in the proposed procedure. The first set of iteration performs the structural analysis for a cable-stayed bridge. The second set of iteration performs the optimization process. The design is formulated as a general mathematical problem with the cost of the bridge as the objective function and bending forces, shear forces, fatigue stresses, buckling and deflection as constraints. The constraints are developed based on the Canadian National Standard CAN/CSA-S6-88. The finite element method is employed to perform the complicated nonlinear structural analysis of the cable-stayed bridges. The internal penalty function method is used in the optimization process. The limit states design method is used to determine the load capacity of the bridge. A computer program written in FORTRAN 77 is developed and its validity is verified by several practical-sized designs.

Key Words
bridges, cables, structures, structural analysis, nonlinearity, optimization, optimum design, box girder, composite structures

Address
Long WY, Dept Transportat, Transportat Syst Informat Program, Off Highway Syst Engn, 1120 N St,MS 38,POB 942873, Sacramento, CA 94273 USA
Dept Transportat, Transportat Syst Informat Program, Off Highway Syst Engn, Sacramento, CA 94273 USA
Concordia Univ, Dept Civil Engn, Montreal, PQ H3G 1M8, Canada

Abstract
An analytical solution for the shape functions of a beam segment supported on a generalized two-parameter elastic foundation is derived. The solution is general, and is not restricted to a particular range of magnitudes of the foundation parameters. The exact shape functions can be utilized to derive exact analytic expressions for the coefficients of the element stiffness matrix, work equivalent nodal forces for arbitrary transverse loads and coefficients of the consistent mass and geometrical stiffness matrices. As illustration, each distinct coefficient of the element stiffness matrix is compared with its conventional counterpart for a beam segment supported by no foundation at all for the entire range of foundation parameters.

Key Words
two-parameter elastic foundation, Winkler model, Pasternak model, element stiffness matrix, work equivalent nodal force, consistent mass matrix, consistent geometrical stiffness matrix

Address
Gulkan P, Middle E Tech Univ, Dept Civil Engn, TR-06531 Ankara, Turkey
Middle E Tech Univ, Dept Civil Engn, TR-06531 Ankara, Turkey

Abstract
This paper presents a fuzzy optimum design of axisymmetrically loaded thin shells of revolution. This paper consists of two parts, namely: an elastic analysis using the new curved element for finite element analysis developed in this study for axisymmetrically loaded thin shells of revolution, and the volume optimization on the basis of results evaluated from the elastic analysis. The curved element to meridian direction is used to develop the computer program. The results obtained from the computer program are compared by exact solution of each analytic example. The fuzzy optimizations of thin shells of revolution are done using [Model 2] which is in the form of a conventional crisp objective function and constraints with non-membership function, and nonlinear optimum GINO (General Interactive Optimizer) programming. In this paper, design examples show that the fuzzy optimum designs of the steel water tank and the steel dome roof could provide significant cost savings.

Key Words
fuzzy optimum design, thin shells of revolution, curved shell element, flat shell element, shape function, objective function, fuzzy constraints, membership function, non-membership function

Address
Kang MM, Kyungpook Natl Univ, Dept Architectural Engn, Taegu 702701, South Korea
Kyungpook Natl Univ, Dept Architectural Engn, Taegu 702701, South Korea
Semyung Univ, Sch Ind Architectural & Environm Engn, Jaecheon 390230, South Korea
Sung Kyun Kwan Univ, Dept Architectural Engn, Suwon 440746, South Korea

Abstract
An approximate method for analyzing the bending problems of irregular-shaped plates is proposed. In this paper irregular-shaped plates are such plates as plate with opening, circular plate, semi-circular plate, elliptic plate, triangular plate, skew plate, rhombic plate, trapezoidal plate or the other polygonal plates which are not uniform rectangular plates. It is shown that these irregular-shaped plates can be considered finally as a kind of rectangular plates with non-uniform thickness. An opening in a plate can be considered as an extremely thin part of the plate, and a non-rectangular plate can be translated into a circumscribed rectangular plate whose additional parts are extremely thin or thick according to the boundary conditions of the original plate. Therefore any irregular-shaped plate can be replaced by the equivalent rectangular plate with non-uniform thickness. For various types of irregular-shaped plates the convergency and accuracy of numerical solution by proposed method are investigated.

Key Words
irregular-shaped plate, bending problem, equivalent rectangular plate, discrete solution

Address
Sakiyama T, Nagasaki Univ, Grad Sch Marine Sci & Engn, Nagasaki 852, Japan
Nagasaki Univ, Grad Sch Marine Sci & Engn, Nagasaki 852, Japan

Abstract
Cracking of reinforced concrete flexural members is a highly random phenomenon. In this paper reliability models are presented to determine the probabilities of failure of flexural members against the limit states of first crack and maximum crackwidth. The models proposed take into account the mechanism of cracking. Based on the reliability models discussed, Eqs. (8) and (9) useful in the reliability-based design of flexural members are presented.

Key Words
beam, flexural member, cracking, limit state, probability, reliability-based design

Address
Rao KB, Struct Engn Res Ctr, CSIR Campus, Madras 600113, Tamil Nadu, India
Struct Engn Res Ctr, Madras 600113, Tamil Nadu, India

Abstract
The design of composite space trusses is a demanding task that involves taking several decisions on the truss depth, number of panels, member configuration, number of chord layers and concrete slab thickness and grade. The focus in this paper is on the design of top concrete slabs of composite space trusses, and in particular their thickness. Several effects must be considered in the process of designing the slab before an optimum thickness can be chosen. These effects include the inplane forces arising from shear interaction with the steel sub-truss and the flexural. and sheer effects of direct lateral slab loading. They also include a constructional consideration that the thickness must allow for sufficient cover and adequate space for placing the reinforcement. The work presented in this paper shows that the structural requirements on the concrete slab thickness are in many cases insignificant compared with the constructional requirements.

Key Words
space trusses, composite action, design

Address
El-Sheikh A, Univ Dundee, Dept Civil Engn, Dundee DD1 4HN, Scotland
Univ Dundee, Dept Civil Engn, Dundee DD1 4HN, Scotland

Abstract
This paper provides an analysis of the transient behaviour of a right-angled bent cantilever beam subjected to a suddenly applied force at its tip perpendicular to its plane. Based on a rigid, perfectly plastic material model, a double-hinge mechanism is required to complete the possible deformation under a rectangular force pulse (constant force applied for a finite duration) with a four-phase response mode. The kinematics of the various response phases are described and the partitioning of the input energy at the plastic hinges during the motion is evaluated.

Key Words
impulsive load, dynamic plasticity, inertia effect, plastic hinge

Address
Wang B, Deakin Univ, Sch Engn & Technol, Geelong, Vic 3217, Australia
Deakin Univ, Sch Engn & Technol, Geelong, Vic 3217, Australia
Swinburne Univ Technol, Sch Mech & Mfg Engn, Hawthorn, Vic 3122, Australia


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