Evaluation of damage index and seismic vulnerability of an existing high-rise building

Seismic analysis of a structure assisted with damage index is vital for an efficient and reliable assessment of any impact of the earthquake on structures. The seismic vulnerability of a structure gives us the quantity associated with its weakness which allows us to estimate the amount of damage caused by future earthquakes. Indian region has been struck with earthquakes of various magnitudes since 1978, and many researchers have given an insight into the seismic vulnerability assessment of the structure after the earthquake has occurred by field investigation. Damage indices quantitatively estimate the degree of seismic damage a structure may suffer from an earthquake. Hence, damage indices can be used for earthquake damage assessment, evaluating the structure's performance, and assisting retrofitting decisions that can be taken based on the damage incurred. Various damage indices have been proposed by a lot of authors in the past, considering various theories and assumptions based on the topographical data of research. However, their reliability under IS code provisions is still ambiguous and questionable. This paper has attempted to investigate the damage index and check the variation for various output characteristics by altering the input parameter using ETABS. The work presented in the paper aims to estimate the seismic vulnerability of an existing building in the city of Coimbatore (India) by adopting the Maximum inter-storey drift ratio (MIDR) as the damage index. Further, the building's seismic response has been investigated by varying the inputs such as soil type and seismic zones using the response spectrum method to understand the various impacts of the input parameters of seismic analysis on the damage index adopted. Among all the cases analyzed, the configuration where the structure was investigated in soft soil under zone 5 has displayed the maximum degree of damage and the maximum displacement response.