Super elastic system using parallel spine frames with steel braces

Abstract

To reduce the seismic response and residual deformation of structures, this study proposes a super elastic bracing system comprising parallel spine frames with steel rods acting as the braces connecting adjacent spine frames. The brace‐end connections are located on the outer side of the pin supports of spine frames to ensure that the axial deformation of the braces is lower than that of a regular bracing system with identical brace angles. To verify the feasibility and elastic range of the proposed system, cyclic loading tests were conducted using scaled specimens consisting of two spine frames with four different brace configurations. Numerical models created in OpenSees were used to simulate the loading tests appropriately. Four evaluation methods were developed for predicting the force and deformation relation considering the geometrical nonlinearity of the proposed system. Through parametric analyses, the influence of key parameters on structural behaviors is clarified, and the applicability of the evaluation methods is investigated.

Seismic performance of rocking‐delayed spine frame system with base initial gaps

“…in s w 0 (11) Equation ( 9) can be split into Equations (12) and (13). Equation (12) represents the forces from the dampers and vertical load F w and Equation (13) the forces from the strands as expressed below:…”

“…Contrarily, the nonuplifting spine frames are not necessarily equipped with PT elements and do not possess restoring abilities for the first‐mode vibration. Hence, nonuplifting spine frames are generally used with essentially elastic moment frames or other elastic structural components that provide sufficient restoring force against strong earthquakes 2,4,11–13 . The nonuplifting spine frame system bears the risk of unexpectedly large deformation if plasticity in the moment frames develops beyond a specific level, particularly in the structures mainly composed of spine frames and in the case of earthquakes that exceed the maximum intensity level considered in the design.…”