Experimental Testing of a Low-Damage Post-Tensioned C-shaped CLT Core-Wall

Abstract

The development of strong and stiff lateral load resisting systems (LLRS) is essential for mid-rise and high-rise timber buildings. On the other hand, within a seismic design philosophy strength/stiffness and ductility/drift capacity typically appear as opposite target parameters, depending on the acceptable level of damage. For improved stiffness and strength, core-wall tubular structural forms are commonly used for taller reinforced concrete buildings. This paper presents an experimental study on a new type of LLRS in cross-laminated timber (CLT). A post-tensioned C-shaped CLT core-wall mainly using screwed connections was designed and tested under uni-directional and bi-directional cyclic loading. It was found that the mixed angle screwed connection solution was the most effective. The highest partial composite action of 60-70% was reached and the core-wall system stiffness at serviceability limit state increased more than four times when compared to a decoupled test with only friction between the CLT panels. The (unbonded) post-tensioning technology provided strong and stiff core-wall base connections with re-centering capability and small residual displacements. The experimental test results confirmed that significant system strength/ stiffness and ductility/drift capacity can be achieved in a post-tensioned C-shaped CLT core-wall system with minimal damage through careful connection detailing.