V. Thevendran

Design formula for axially compressed perforated plates

This paper is concerned with post-buckling behaviour and the ultimate load capacity of perforated plates with different boundary conditions and subjected to uniaxial or biaxial compression. Plates were analysed using the finite element method (FEM), and extensive studies were carried out covering parameters such as plate slenderness, opening size, boundary conditions and the nature of loading. A design formula to determine the ultimate load carrying capacity was established based on a best-fit regression analysis using the results from the finite element analyses. The accuracy of the proposed formula was established by comparison with experimental values of ultimate capacity and similar finite element values. Ultimate load values are also presented in the form of charts for various values of plate slenderness and opening size.

Finite element modelling of plate girders with web openings

Abstract This paper is concerned with a finite element model to predict the behaviour and ultimate load of plate girders with web openings. The finite element package ABAQUS is used to model the plate girders with web openings. Accuracy of the model is assessed by applying it to plate girders tested earlier by other researchers. Comparison of analytical results with the available experimental results for yielding patterns, ultimate load values and load–deflection relationships show good agreement between the finite element and experimental results thus validating the accuracy of the proposed model. The proposed finite element method was extended to carry out a parametric study. The study covered parameters such as web slenderness and flange stiffness.

Experimental study on steel-concrete composite beams curved in plan

Abstract This paper is concerned with experimental study on the ultimate load behaviour of steel-concrete composite beams curved in plan. Five beams of realistic dimensions built from rolled steel beam and concrete slab were tested to failure. Extensive measurements of strain in both concrete and steel, and of displacements were made in order to obtain a complete picture of elastic and ultimate load behaviour. Each of the beams was simply supported at the ends and was subjected to a concentrated load applied at mid-span. All the beams tested were analyzed by using the finite element method and the results were compared with those obtained experimentally. The test results indicate that the load-carrying capacity decreases with the increase in the “span/radius of curvature” ratio. The experimental results for deformations, for stress distributions and for ultimate strengths were found to be in good agreement with the corresponding values predicted by finite element analysis.

Buckling of annular plates elastically restrained against rotation along edges

The problem of elastic buckling of thin annular plates under in-plane radial loads along either free or simply supported with elastic rotational restraints at inner and outer edges has been analysed. A variant of the classical energy methods has been used to obtain a comprehensive set of new buckling results for several combinations of boundary conditions with partial rotational fixity. Results for the special case of simply supported full circular plates with elastic rotational restraint are also obtained by making the inner edge free and permitting the inner radius to become very small.

Lateral buckling of narrow rectangular beams containing openings

Abstract The paper deals with the critical lateral buckling load of deep slender rectangular beams containing openings along the centre-lines of the beams. The numerical method proposed to predict the critical load is outlined in detail; cantilever beams and simply supported beams are considered. The critical loads evaluated numerically using the energy approach are compared with those values obtained experimentally. The study shows good agreement between the values obtained numerically and experimentally.

Optimum vibrating shapes of beams and circular plates

Optimum vibrating shapes of beams and circular plates, having piecewise linear variation in thickness, are treated herein. The study is concerned with two problems pertaining to (i) the fundamental mode of lateral vibration of beams and (ii) the fundamental mode of axisymmetric vibration of circular plates. These are (a) to find the best shape of the structure which would provide the highest elevation of this fundamental frequency, keeping the volume constant, and (b) to find the minimum volume and shape of the structure for a given minimum allowable fundamental frequency. A numerical procedure incorporating the finite element method and an iterative optimization technique has been used. This has enabled various boundary conditions to be conveniently treated in the analysis. Results indicate that often a very large elevation (>100%%) in the fundamental frequency for volume constraint, and a considerable saving (>50%) in material for frequency constraint, are possible by merely altering the shape. Moreover, the number of slopes and the allowable minimum thickness influence the results.

Design of reinforced concrete cylindrical water tanks for minimum material cost

Abstract The minimum material cost design of reinforced concrete cylindrical water tanks according to BS8007 is considered. The material cost takes into account the amount of reinforcement and concrete required. The analysis is simplified by using the beam on elastic foundation (BEF) analogy. The tank wall is modelled as consisting of linear piecewise slopes. The non-linear constrained minimization problems have been solved numerically by direct search methods using a microcomputer. The results are presented and discussed.

Minimum weight design of conical concrete water tanks

Abstract The minimum weight design of circular conical concrete water tanks is studied in this paper. The internal base radius, the depth and the semi-vertical angle of the cone are fixed while the thickness of the wall along the length is varied so that the bending (tensile) and hoop stresses attain values as close as possible to their respective allowable values. Only piecewise linear variations of wall thickness are considered. For the analysis the finite element method is used. This procedure is embedded into a minimization routine to deal with design problems. Results of some examples are presented and discussed.

Minimum weight design of multi-bay multi-storey steel frames

Abstract The present paper considers the minimum weight (volume) design of multi-bay multi-storey steel frames according to BS5950. The problems are formulated as nonlinear constrained minimization problems and then solved using numerical optimization techniques. The study illustrates different possible configurations of sections based on minimum weight designs. The problems have been solved using a 80386-25 microcomputer equipped with a math co-processor.

Simplified analysis of asymmetric buildings subjected to lateral loads

Abstract A simple procedure is presented for lateral load analysis of asymmetric buildings, taking into account the coupling between the lateral and torsional components of response. Bending rotations of the vertical members are taken into consideration and these are made proportional to the stiffnesses of the members resulting in an analysis with 5n degrees of freedom for a building with n storeys. The entire analysis is conveniently programmed and gives quick results on a microcomputer. Numerical examples pertaining to both static and free vibration analyses are presented and the results are in good agreement with those from a comprehensive package program.