The centre of earthquake loading on tall buildings

H M Irvine

doi:10.5459/bnzsee.9.4.195-198

Abstract

A response spectrum technique is applied to two well known linear elastic continuous models of slender high rise buildings in order to obtain likely positions for the centres of earthquake loading. The models chosen are the uniform cantilever shear beam and the uniform cantilever shear wall, which represent the two extremes of pure shear deformation and pure flexural deformation, respectively. The results obtained are at variance with the static provisions of the current New Zealand code; this is especially so in the case of the shear wall. On the basis of these findings a tentative suggestion is made for a change to the familiar equivalent static lateral load distribution at present specified by the code.

Highlights

In a recent investigation of slender shear wall structures, Blakeley, Cooney and Meggetd) have shown that the base shear existing with a given base moment may be substantially in excess of that specified by the equivalent static provisions of the code of practice NZS 4203 : 1976
198 that the centres of earthquake loading frequently lie at positions which are substantially below that given by the code, and the present elastic study is in complete agreement with this
The base shear existing with a given overturning moment may be greatly in excess of that indicated by the code

Summary

INTRODUCTION

In a recent investigation of slender shear wall structures, Blakeley, Cooney and Meggetd) have shown that the base shear existing with a given base moment (say that at flexural capacity) may be substantially in excess of that specified by the equivalent static provisions of the code of practice NZS 4203 : 1976. This indicates that the lever arm of the dynamic forces may be considerably smaller than was originally thought possible. The present paper involves the linear elastic analysis of a closely related problem, namely, the evaluation of likely positions for the centre of earthquake loading on slender high rise buildings

FORMULATION

RESULT

Findings

DISCUSSION AND CONCLUSION