Estimating the accuracy of single-mode pushover analysis for unreinforced masonry buildings with flexible diaphragms

Abstract

Nonlinear static analyses of unreinforced masonry buildings are typically carried out assuming a single-mode response of the structure. While this assumption is appropriate when the floor and the roof diaphragms are rigid in their own planes, many existing unreinforced masonry buildings have flexible timber diaphragms, for which the applicability of a single-mode pushover analysis becomes questionable. This paper explores whether the accuracy of a single-mode pushover analysis can be estimated from the results of the pushover analysis itself. From the theoretical consideration, a key parameter that reflects the validity of the single-mode pushover analysis is shown to be the sensitivity of the analysis to the control node location, and a measure of the control node sensitivity is proposed. Preliminary parametric studies conducted on idealised single-storey systems and a two-storey building show that the proposed measure can provide an indicative error of the single-mode pushover analysis.