Performance based out-of-plane posttensioning seismic retrofit design of unreinforced masonry walls

Abstract

A performance based design procedure was developed based on the out-of-plane flexural testing of seismically retrofitted unreinforced masonry (URM) walls using posttensioning. A macro level single degree of freedom (SDOF) dynamic model for the retrofit design of URM walls was developed. The test walls were dynamically tested by exciting the walls with a hammer and the developed model was updated to match the actual dynamic response of the tested walls. The developed SDOF model was used to find the pushover capacity curve for the posttensioned walls. The New Zealand Loading Standard's (NZS 1170) defined elastic site spectrum was used to develop the demand spectra. Consequently, a simplified demand-capacity phase diagram was developed to study the seismic behaviour of posttensioned walls and was used to analyse the tested posttensioned URM wall. Using the graphically aided analysis, seismic performance of the wall was investigated and it was inferred that the simplified analysis procedure can be used for performance based posttensioning seismic retrofit design of New Zealand URM buildings.