Seismic resiliency using confined masonry :

Abstract

Earthquakes throughout the world can be devastating catastrophes, especially in developing nations. Confined masonry (CM) structures have proven to be a viable solution for seismic resiliency in the unique restraints and conditions of developing nations. CM provides benefits of increased shear capacity with smaller concrete frame members that provides economic benefit as well. However, the behavior of CM is highly non-linear during a seismic event and requires expertise to correctly model and analyze structures. A need for simplified guidelines are required for successful implementation of CM as a low cost solution for developing nations. The study parameterizes a simplified procedure for the design of CM buildings that takes into account irregularities and torsional effects in order to provide a tool to aid in the development of simplified design guidelines for CM. Different building configurations are sampled in geometric and material studies to provide recommendations for the design guidelines. The design guidelines are developed for the context of the Kathmandu Valley in Nepal to aid in their reconstruction efforts following the 2015 Gorkha earthquake. The parameters can be easily changed according to the country location to develop similar guidelines. Then a prototypic study on school buildings will show the structural and economic benefit of CM structures. Building shape typologies (L-, T-, and C-shaped plans) are explored in the geometric study. In the context of Nepal, only 3 story buildings have significant torsional effects. Design guidelines are recommended based on the building plan parameters. The material study aids in the understanding of the influence of wall thickness and brick strength. In the study, the increase in wall thickness and masonry compressive strength does decrease the utilization of the structure. However, there is a diminishing return and a limit on amount of improvement with the increase of both parameters. In an effort to contribute to the school sector as well, a prototypic study of approved school designs from Nepal is performed. While the approved school designs are for other material types (RC frame with brick infill, stone and mud, earthbag, etc.), the proposed architectural layout is maintained and analyzed as CM. Then the designs are compared with the same layout but a more economical design in CM. Saving in material quantities for the school building, the study shows that CM provides superior economic and structural benefits.