Behavior of Dry-Stack Interlocking Masonry walls Under Out-of-Plane Loading

Abstract

Masonry is one of the oldest construction materials. However, there are several disadvantages of using conventional masonry system such as time consuming, the need for highly skilled laborers, and the amount of mortar that is required to be mixed on-site. With the use of specially fabricated concrete masonry units known as “dry-stack units”, construction of these mortarless systems is simple, easy and cost effective. Although the worldwide interest for the dry-stack masonry construction technique because of its attractive advantages, the lack of knowledge of loading and deformation behavior of dry-stacked masonry structures exists up till now in contrast to this of mortar layered brickwork. The main objective of this research is to study the behavior of locally produced dry-stack interlocking masonry systems (Azar and spar-lock systems), under out-of-plane loading and comparing their behavior with the conventional masonry system. In addition, assess the efficiency of post-tensioned technique on improving their out-of-plane performance and elimination of grout. To meet these objectives, experimental and analytical studies were conducted and documented in this Thesis. In order to design the test program, a pre-test analysis, based on the investigated material properties, was carried out to predict the initial prestressing force, the failure mechanism, ultimate lateral load, and internal forces at ultimate condition for the proposed test walls. All walls were designed so as to fail in a flexural mode. The test setup was suggested to suppress shear failure mode. The subsequent study involves two main phases. The first phase studies the behavior of locally produced dry stack interlocking masonry systems under out-of-plane loading perpendicular to bed joint in comparison with that of conventional masonry system. Twelve vertical spanning walls were constructed and tested at Properties and Testing of Materials Laboratory of Ain Shams University. The construction systems (conventional and dry-stack), block types (Conventional, Azar and Spar-lock), reinforcement types (ordinary and post-tensioned), grout configuration (fully grouted and ungrouted), Restraining techniques (restrained and unrestrained) are the main parameters considered in this phase. The second phase focuses on the out-of-plane behavior parallel to bed joint of locally produced dry stack interlocking masonry systems in comparison with that of conventional masonry system. Six horizontally spanning walls were constructed and tested at same laboratory. The construction system (conventional and dry-stack), blocks type (Conventional, Azar and Spar-lock), reinforcement type (unreinforced, joint reinforcement, and post-tensioned) are the main parameters considered in this phase.