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CONTENTS
Volume 4, Number 1, February 2004
 

Abstract
Tests on steel tubular columns of square, rectangular and circular section filled with normal and lightweight aggregate concrete were conducted to investigate the failure modes of such composite columns. Thirty-six full scale columns filled with lightweight and normal weight aggregate concrete, eighteen specimens for each, were tested under axial loads. Nine hollow steel sections of similar specimens were also tested and results were compared to those of filled sections. The test results were illustrated by a number of load-deflection and axial deformation curves. The results showed that both types of filled columns failed due to overall buckling, while hollow steel columns failed due to bulging at their ends (local buckling). According to the above-mentioned results, and due to low specific gravity and thermal conductivity of the lightweight concrete the further interest should be concentrated in replacing the normal concrete by the lightweight aggregate concrete.

Key Words
deformation; deflection; composite columns; steel columns; tubular columns; lightweight concrete; normal concrete; local buckling; overall buckling.

Address
Shehdeh GhannamrnWadi Seer Engineering College, Balqa

Abstract
The present study aims at the reliability analysis of steel towers against the limit state of deflection. For this purpose tip deflection of the tower has been obtained after carrying out the dynamic analysis of the tower using modal method. This tip deflection is employed for subsequent reliability analysis. A limit state function based on serviceability criterion of deflection is derived in terms of random variables. A complete procedure of reliability computation is then presented. To study the influence of various random variables on tower reliability, sensitivity analysis has been carried out. Design points, important for probabilistic design of towers, are also located on the failure surface. Some parametric studies have also been included to obtain the results of academic and field interest.

Key Words
latticed tower; structural reliability; first order reliability method.

Address
Department of Civil Engineering, Aligarh Muslim University, Aligarh 202002, India

Abstract
The inelastic lateral-distortional buckling of doubly-symmetric hot-rolled I-section beamcolumns subjected to a concentric axial force and uniform bending with elastic restraint which produce single curvature is investigated in this paper. The numerical model adopted in this paper is an energy-based method which leads to the incremental and iterative solution of a fourth-order eigenproblem, with very rapid solutions being obtained. The elastic restraint considered in this paper is full restraint against translation, but torsional restraint is permitted at the tension flange. Hitherto, a numerical method to analyse the elastic and inelastic lateral-distortional buckling of restrained or unrestrained beam-columns is unavailable. The prediction of the inelastic lateral-distortional buckling load obtained in this study is compared with the inelastic lateraldistortional buckling of restrained beams and the inelastic lateral-torsional buckling solution, by suppressing the out-of-plane web distortion, is published elsewhere and they agree reasonable well. The method is then extended to the lateral-distortional buckling of continuously restrained doubly symmetric I-sections to illustrate the effect of web distortion.

Key Words
beam-column; continuous restraint; distortion; residual stress; yielding.

Address
4-6 Tangarra Street Croydon Park, NSW 2133, Australia

Abstract
This paper deals with the strength and deformation of both short and slender concrete filled steel tubular columns under the combined actions of axial compression and bending moment. Sixteen specimens were tested to investigate the effect of fiber reinforced concrete on the ultimate strength and behavior of therncomposite column. The primary test parameters were load eccentricity and column slenderness. Companion tests were also undertaken on eight numbers of similar empty steel tubes to highlight the synergistic effects of composite column. The test results demonstrate the influence of fiber reinforced concrete on the strength andrnbehavior of concrete filled steel tubular columns.

Key Words
composite column; hollow steel tube; fiber reinforced concrete; slenderness ratio; eccentricity; ultimate load; ductility.

Address
S. Ramana GopalrnSri Venkateswara College of Engineering, Sriperumbudur, IndiarnP. Devadas ManoharanrnAnna University, Chennai, India

Abstract
The paper derives, validates and illustrates the application of GBT-based formulae to estimate distortional critical lengths and bifurcation stress resultants in cold-formed steel rack-section columns, beam and beam-columns with arbitrarily inclined mid-stiffeners and four support conditions. After a brief review ofrnthe Generalised Beam Theory (GBT) basics, the main concepts and procedures employed to obtain the formulae are addressed. Then, the GBT-based estimates are compared with exact results and, when possible, also with values yielded by formulae due to Lau and Hancock, Hancock and Teng et al. A few remarks onrnnovel aspects of the rack-section beam-column distortional buckling behaviour, unveiled by the GBT-based approach, are also included.

Key Words
distortional buckling; distortional buckling formulae; generalised beam theory (GBT); racksection members; flexural end support conditions; warping end support conditions.

Address
Department of Civil Engineering, IST, Technical University of Lisbon,rnAv. Rovisco Pais, 1049-001 Lisboa, Portugalrn


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