| This dissertation aims to advance the understanding of unbonded post-tensioned masonry wall systems. Previous research has shown that unbonded post-tensioned masonry walls can adequately resist in-plane loading but their possible use in regions of high seismic activity has not been widely accepted. The research described in this dissertation focuses primarily on clay brick masonry. The first study is on the in-plane cyclic behavior of unbonded post-tensioned masonry walls with openings. Openings can interrupt the standard path of the compression strut. The compression strut is how unbonded post-tensioned masonry walls distribute the lateral load to the foundation, and without it the wall can become unstable. The results show that the size and location of the opening has a major effect of the overall response of the wall. As the opening size increases the compression strut becomes more unstable. Experimental studies involved the construction and testing of three walls. A parametric study was conducted to determine the effect of opening size and aspect ratio on the behavior of unbonded post-tensioned masonry walls with openings. Several tables are proposed for the initial design of these walls depending on the opening size and aspect ratio of the wall.;The latter part of the dissertation focuses on the Direct Displacement-Based Design (DDBD) of unbonded post-tensioned clay brick masonry walls. A unique problem of the use of clay brick masonry walls arose and was studied. Because clay brick masonry and the concrete foundation's Young moduli are different, the interaction between the two surfaces was analyzed. It is shown that the foundation locally confines the clay brick masonry, thereby increasing its compressive strength. Without including this confinement, effect the lateral resisting strength is greatly underestimated. Previous methods are modified to predict the compressive strength of clay brick masonry at the wall/foundation interface. The method is verified against previous unbonded post-tensioned clay brick masonry walls and established methods of calculating the compressive strength of masonry prisms. Then using the proposed method of calculating the compressive strength of clay brick masonry at the interface, a design methodology is proposed for unbonded post-tensioned clay brick masonry walls. |
