Improving the Seismic Performance of Structures Based on Minimizing the Total Damage Index and the Uniform Distribution of Damage at the Height of Structures

Abstract

Usually, the damage to structural members is not the same during earthquakes. As a result, the collapse times of members would be different from each other. So, one or a couple of stories would collapse sooner than others. Therefore, other members’ potential and resisting ability would not be used completely. As a result, it needs to use all the potential of the structural members during the earthquake. There are several ways to quantify the damage value of buildings and structural elements. Many researchers use the Park–Ang index, one of the most common and accurate quantitative damage indices. This index can calculate the damage index for members, stories, and the whole structure separately by considering dissipated energy and displacement of members. Since control systems can cause a reduction in structural responses and, consequently, reduce damages by absorbing and dissipating energy, they have been used in many modern structures. The nonlinear viscous damper is one type of control system. This study aims to reduce the Park–Ang damage index of a 10-story steel moment frame modeled in OpenSees software and distribute the damage index uniformly in the structure’s height. We will achieve this aim by optimizing nonlinear viscous dampers using a metaheuristic algorithm. This research chose six earthquakes that caused the most damage to the structure. The result shows that equipping the structure with an optimized damper has reduced the structural damage from all earthquakes. The reductions in structure damage index after the Gazli, Imperial Valley, Kocaeli, Loma Prieta, Northridge, and Duzce earthquakes are 82%, 68%, 62%, 49%, 53%, and 67%, respectively. Also, story damage indices are between 0 and 0.3 after controlling the structure. During earthquakes, structural members’ collapse times vary, leading to underutilization of other members’ potential and resistance abilities due to differences in damage and collapse times. Damage to the first story of the structure exacerbates the situation, leading to the collapse of the entire structure. Therefore, it is crucial to fully utilize the potential of all structural members during an earthquake. The study aims to optimize the parameters of the nonlinear viscous dampers to reduce the Park–Ang damage index of a controlled steel moment frame. The dampers are designed to distribute the damage index uniformly throughout the structure’s height, thereby reducing structural and story damage during earthquakes. Also, it helps to utilize the full potential of all structural members. The results show that equipping the structure with the optimized dampers reduces structural damage.