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CONTENTS
Volume 7, Number 4, April 1999
 

Abstract
A general framework for the nonlinear geometric analysis of elastic space trusses is presented. Both total Lagrangian and finite incremental formulations are derived from the three key ingredients of statics, kinematics and constitutive law. Particular features of the general methodology include the preservation of static-kinematic duality through the concept of fictitious forces and deformations, and an exact description for arbitrarily large displacements, albeit small strain, that can be specialized to any order of geometrical nonlinearity. As for the numerical algorithm, we consider specifically the finite incremental case and suggest the use of a conventional, simple and flexible arc-length based method. Numerical examples are presented to illustrate and validate the accuracy of the approach.

Key Words
large displacement, nonlinear analysis, space trusses

Address
Tin-Loi F, Univ New S Wales, Sch Civil & Environm Engn, Sydney, NSW 2052, Australia
Univ New S Wales, Sch Civil & Environm Engn, Sydney, NSW 2052, Australia

Abstract
This paper presents an analytic method of examining the out-of-plane vibration of continuous curved beam on periodical supports. The orthogonality of two distinct sets of mode shape functions is derived. The forced vibration of beam due to moving loads is examined. Two types of moving loads, which are concentrated load and uniformly distributed load, are considered. The response characteristics of beam induced by these loads are investigated as well.

Key Words
out-of-plane, curved beam, orthogonality, moving loads

Address
Wang RT, Natl Cheng Kung Univ, Dept Engn Sci, Tainan 70101, Taiwan
Natl Cheng Kung Univ, Dept Engn Sci, Tainan 70101, Taiwan

Abstract
The stress distribution in a symmetrically laminated composite plate subjected to in-plane compression are evaluated using finite element analysis. Six different finite element models are created for the study of stresses in the plate after buckling. Two finite element modelling approaches are adopted to obtain the stress distribution. The first approach starts with a full model of shell elements from which sub-models of solid elements are spin-off The second approach adopts a full model of solid elements at the beginning from which sub-models of solid elements are created. All sub-models have either 1-element thickness or 14-element thickness. Both techniques show high interlaminar direct and shear stresses at the free edges. The study also provides vital information of the distribution of all components of stresses along the unloaded edges in length direction and also in the thickness direction of the plate.

Key Words
laminate, composite plate, buckling, stability, stress analysis, interlaminar shear

Address
Chai GB, Nanyang Technol Univ, Sch Mech & Prod Engn, Nanyang Ave, Singapore 639798, Singapore
Nanyang Technol Univ, Sch Mech & Prod Engn, Singapore 639798, Singapore
Minist Def, Singapore, Singapore

Abstract
Damage detection in civil engineering structures using the change in dynamic system parameters has gained a lot of scientific interest during the last decade. By repeating a dynamic test on a structure after a certain time of use, the change in modal parameters can be used to quantify and qualify damages. To be able to use the modal parameters confidentially for damage evaluation, the effect of other parameters such as excitation type, ambient conditions,... should be considered. In this paper, the influence of excitation type on the dynamic system parameters of a highway prestressed concrete bridge is investigated. The bridge, B13, lies between the villages Vilvoorde and Melsbroek and crosses the highway E19 between Brussels and Antwerpen in Belgium. A drop weight and ambient vibration are used to excite the bridge and the response at selected points is recorded. A finite element model is constructed to support and verify the dynamic measurements. It is found that the difference between the natural frequencies measured using impact weight and ambient vibration is in general less than 1%.

Key Words
dynamic measurement on bridges, system identification, ambient/forced vibration

Address
Wahab MMA, Univ Surrey, Dept Mech & Mat Engn, Guildford GU2 5XH, Surrey, England
Univ Surrey, Dept Mech & Mat Engn, Guildford GU2 5XH, Surrey, England
Katholieke Univ Leuven, Dept Civil Engn, B-3001 Heverlee, Belgium

Abstract
The purpose of this paper is to show how the Evolutionary Structural Optimization (ESO) algorithm developed by Xie and Steven can be extended to optimal design problems of thin shells subjected to thermal loading. This extension simply incorporates an evolutionary iterative process of thermoelastic thin shell finite element analysis. During the evolution process, lowly stressed material is gradually eliminated from the structure. This paper presents a number of examples to demonstrate the capabilities of the ESO algorithm for solving topology optimization and thickness distribution problems of thermoelastic thin shells.

Key Words
topology and thickness design, thin shell, thermoelasticity, finite element analysis, evolutionary structural optimization

Address
Li Q, Univ Sydney, Fac Engn, Dept Aeronaut Engn, Bldg J07, Sydney, NSW 2006, Australia
Univ Sydney, Fac Engn, Dept Aeronaut Engn, Sydney, NSW 2006, Australia
Victoria Univ Technol, Fac Sci & Engn, Melbourne, Vic 8001, Australia

Abstract
A macro-element model is developed to account for shear deformation and bond slip of reinforcement bars in the beam-column joint region of reinforced concrete structures. The joint region is idealized by two springs in series, one representing shear deformation and the other representing bond slip. The softened truss model theory is adopted to establish the shear force-shear deformation relationship and to determine the shear capacity of the joint. A detailed model for the bond slip of the reinforcing bars at the beam-column interface is presented. The proposed macro-element model of the joint is validated using available experimental data on beam-column connections representing exterior joints in ductile and nonductile frames.

Key Words
reinforced concrete, connections, sheer strength, bond slip, modelling, shear deformation, joints

Address
Biddah A, McMaster Univ, Dept Civil Engn, Hamilton, ON L8S 4L7, Canada
McMaster Univ, Dept Civil Engn, Hamilton, ON L8S 4L7, Canada


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