Rehabılıtatıon Of Buıldıng Structures Wıth Soft Story Irregularıty Vıa Optımal Vıscous Damper Dıstrıbutıon

Abstract

Application of viscous dampers in structural and earthquake engineering as passive energy damping devices has become popular in last couple of decades. Research on application of viscous dampers in building structures to reduce seismic response started at 1990s. Nowadays application of viscous dampers is still an important topic in the field of structural and earthquake engineering. Viscous damper applications in building structures has two major objectives. These are designing more resilient structures and rehabilitating existing structures. Design of viscous dampers are similar to the design of the structural components of the building structures. Distribution of the viscous dampers has a great influence on seismic behavior of the structure. Viscous dampers are expensive passive energy damping devices; therefore, optimal damper distribution in building structure is an important subject. Extensive research on optimum viscous damper distribution via meta-heuristic search algorithms started at late 1990s. Application of meta-heuristic search algorithms on optimal damper distribution problems has important advantages. These are they do not require a preliminary design, they do not require gradient information, and they require significantly low computational time when they are compared with exhaustive search methods. In this thesis work a methodology based on peak inter story drift ratios is proposed to rehabilitate building structures with soft story irregularity via optimal viscous damper distribution. Soft story structural irregularity is a type of vertical structural irregularity that is caused by abrupt stiffness changes between adjacent stories. These structures suffer from severe structural damages after earthquakes due to abnormal peak inter story drift ratios. This study proposes a methodology to keep peak inter story drift ratios in an allowable limit by optimal viscous damper distribution. Two different meta-heuristic search algorithms are utilized to find optimal viscous damper distributions. These are Differential Evolution and Particle Swarm Optimization algorithms. The suggested methodology is numerically tested on different shear buildings under different earthquake ground motion records, and results are compared with no viscous damper case and optimum damper distribution case.