Seismic behavior of unbonded post-tensioned masonry walls

Abstract

The Masonry Standard Joint Committee (MSJC) defines three types of post-tensioned masonry walls (PT-MWs): plain/ordinary, intermediate, and special with recommendations for R values ranging from 1.5 to 4.5. The American Society of Civil Engineers ASCE/SEI 7, combines the different types of PT-MWs into one type having a response modification coefficient R = 1.5, i.e., similar to that of Unreinforced masonry walls. For intermediate and special walls, the MSJC defines prescriptive bonded mild steel reinforcement; however, the MSJC does not define prescriptive reinforcement for plain/ordinary walls. In addition, there is no explicit maximum spacing between the tendons for ordinary walls. This paper investigates the cyclic behavior of three full-scale post-tensioned masonry walls, namely, ordinary/plain, intermediate, and special. The walls have identical dimensions but different reinforcement details. The walls were subjected to applied lateral cyclic load of increasing intensity. The stresses in the tendons were calculated using different approaches, and then the flexural strength of each wall was calculated and compared with those obtained from the experimental work. The R value of each wall was also calculated and compared with those obtained from the ASCE/SEI 7.