Seismic Performance Evaluation of Existing High-Rise Steel Structures

Seismic Performance Evaluation of Existing High-Rise Steel Structures

Steel structures in Taiwan have been developed for nearly 40 years. Due to specification revisions and building material strength and joint performance attenuation by earthquakes, there are doubts about whether existing steel structures have adequate seismic performance. The main objective of this study is to establish a seismic performance evaluation procedure and retrofit method for high-rise steel structures to understand the characteristics of high-rise building responses and common retrofit methods. We considered a 15-floor (15F) steel building model designed according to past specifications, which needs to be retrofitted. We adopted the Taiwan and United States standards for the seismic performance evaluation process to establish a recommended methodology and evaluate design using this case study. The results of this study show that inelastic pushover responses may be similar to dynamic analysis responses due to the absence of highermode effects on the interstory drift of the 15F steel structure. If there are obvious higher mode effects in steel structures with a greater number of floors, dynamic time-history analysis should be carried out. In addition, the 15F building retrofitted with buckling restrained braces has acceptable displacement control efficiency. We recommend performing inelastic timehistory analysis and reviewing the retrofit method. Each building retrofit is case-specific, and the building requirements as well as the advantages and disadvantages of each retrofit strategy must be understood before effectively carrying out the retrofit design.