Seismic performance of CLT structures with base isolation




Poshtiban, Pedram

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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) structures with base isolation was studied. This will explore new opportunities for application 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 comparison 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 with fixed base. 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, all three isolation systems showed significant reduction on the base shear, acceleration, and inter-storey drift. In general, the friction pendulum isolators showed higher reduction than rubber isolators. The effect of aspect ratio on seismic behavior of non-isolated and isolated CLT structures was also investigated. A comparison is made between different aspect ratios (1:1 and 2:1) before and after base isolation. Results show that for the non-isolated cases, the aspect ratio plays an important role on seismic performance of CLT structures, while it is not a controlling key for isolated CLT structures.



CLT structures, seismic isolation, base isolation, cross laminated timber, hold-down, angle bracket, SAP2000