Seismic performance quantification and direct displacement-based design of CLT-glulam hybrid structures

Abstract

By incorporating cross-laminated timber (CLT) shear walls for glulam frames, CLT-glulam hybrid structures provide a prospective solution for multi-story timber construction. This paper aims to develop a direct displacement-based design (DDBD) approach for CLT-glulam hybrid structures, with the maximum inter-story drift ratio (MaxISDR) and the maximum inter-story CLT shear wall damage index (MaxISWDI) as engineering demand parameters (EDPs). To address the knowledge gaps in developing the DDBD approach, a series of incremental dynamic analyses (IDAs) was conducted on 12 prototype CLT-glulam hybrid structures. The IDA results served as a database for quantifying performance levels and base shear distributions of CLT-glulam hybrid structures. The results showed that the MaxISWDI limits governed by connection damage were respectively 0.18, 0.48, and 0.72 for immediate occupancy (IO), life safety (LS), and collapse prevention (CP) performance levels. The connection-damage-associated MaxISDR limits were 1.5 %, 3.9 %, and 5.4 % for IO, LS, and CP performance levels, with the MaxISDR limit governed by global stability being 2.7 % for CP performance level. Analytical models were then developed to establish the displacement profile for CLT-glulam hybrid structures, differentiating between platform-type and balloon-type CLT shear wall subsystems. With the acquired knowledge and results, the DDBD approach was extended for the seismic design of CLT-glulam hybrid structures, with a case study provided to demonstrate the design procedure.