Multi-Level Response Modification Factors for Performance-Based Seismic Design of Tunnel-Form Building Structures

Abstract

ABSTRACT The code-based response modification factors are mainly developed based on engineering judgments and experiences from past earthquakes, and hence, they may not lead to reliable solutions considering different performance targets and hazard levels. On the other hand, the uncertainties associated with these proposed values are more significant for new lateral load-carrying systems, such as tunnel-form buildings, due to insufficient information about their performance against seismic events. To address these challenges, this study aims to propose a multi-level approach for the estimation of response modification factors for tunnel-form building structures by taking into account the site seismicity and the damage level defined as the target performance. Using the proposed approach, the modification factors corresponding to different ranges of earthquake intensity and damage levels are obtained for 2-, 5-, 7-, and 10-storey tunnel-form buildings. The results are then used to verify the efficiency of the response modification factors proposed by design codes for the preliminary design (code-based factors) of such systems. It is shown that, in general, by adopting a response modification factor between 4 and 6, the tunnel-form structural systems exhibit excellent seismic performance and can satisfy the requirements of the Immediate Occupancy (IO) performance level even under the Maximum Considered Earthquake (MCE). The outcomes of this study could be useful for performance-based design of tunnel-form building structures aligned with the new generation of seismic design codes.