Pedram Poshtiban

Topic

Seismic Performance of CLT Structures with Base Isolation

Department of Civil Engineering

Date & location

• Thursday, April 14, 2022

• 10:00 A.M.

• Virtual Defence

Reviewers

Supervisory Committee

• Dr. Lina Zhou, Department of Civil Engineering, University of Victoria (Supervisor)

• Dr. Chun Li, Department of Civil Engineering, UVic (Member)

External Examiner

• Dr. Keivan Ahmadi, Department of Mechanical Engineering, University of Washington 

Chair of Oral Examination

• Dr. Takahiro Endo, Peter B. Gustavson School of Business, UVic 

Abstract

Although there has been significant rise in the use of seismic isolation in reinforced concrete and steel structures built to withstand major earthquakes with little or no damage, the use of seismic isolation in wood structures is practically stationary around the world. To prepare for a shift in seismic design philosophy toward low or no damage structural systems, performance of cross-laminated timber (CLT) structure with seismic isolation was studied. This will explore new opportunities for applications of wood structures in high importance or post-disaster buildings, such as hospitals, schools, and elderly care facilities, etc. where an "operational" or "fully operational" state after a major earthquake is expected or required. The effect of three base isolation technologies on the seismic performance of CLT structures was studied through comparisons of the structural performance (base-shear, acceleration of the top story, inter-story drift) of base-isolated buildings to that of a reference CLT structure without base isolation. The SAP2000 software was used to conduct the nonlinear time history analysis of 3-, 6-, and 12-story CLT structures under three types of ground motions that may occur in the Cascadia Subduction Zone. Results show that, although all of the three isolation systems showed an acceptable performance in terms of reducing the base shear, acceleration, and also inter-storey drifts, the friction pendulums showed higher reduction than rubber isolators generally. The effect of aspect ratio on seismic behavior of non-isolated and isolated CLT structures is also investigated. A comparison is made between different aspect ratios (1:1 and 2:1) before and after base isolation. It indicates that for the non-isolated cases, the aspect ratio plays an important role in seismic performance of CLT structures including energy dissipation and deformation capacity, while it is not a controlling key for isolated CLT structures.