Direct Displacement-Based Design (DDBD) of PT-SKID Frames: The Linear Equivalent Model

This paper investigates the linear equivalence of the PT-SKID frames based on Jacobsen’s method for estimating peak seismic displacement response. Such linearisation is at the base of the DDBD of such systems. First, a simplified model capturing the hysteretic properties of the PT-SKID frames is proposed. Then, the linear equivalent system of the PT-SKID frame is constructed by its secant stiffness and the equivalent damping ratio. Finally, the accuracy of the linear equivalence to assess the peak seismic displacement response is evaluated by numerically testing 5,880 frames. The results show that the linear equivalence frequently underestimates the peak displacement response.