Novel pre-pressure friction spring RC rocking column with enhanced segment: Practical design and numerical investigation

Abstract

A novel pre-pressure friction spring rocking column (PFSRC) with enhanced segment is proposed to improve the seismic resilient of RC frames. The construction of the PFSRC was introduced, and parameters of pre-pressure friction spring device (PFSD), and limit state of PFSRD were analyzed. Based on seismic performance objectives, a practical design method for PFSRC was proposed. Utilizing the developed self-centering constitutive model and rocking interface three-dimensional simulation method, a macroscopic numerical model of PFSRC was established using OpenSEES, and numerical simulations of designed PFSRC under cyclic loading were conducted. Subsequently, further parameter investigations were conducted on the seismic performance of PFSRC. The results indicate that the designed PFSRC demonstrates strength and stiffness equivalent to the fixed-base column under drift limit of 1/550, and, at a drift limit of 1/50, there is no stiffness degradation, and the ultimate resistance is comparable to the fixed-base column. The steel tube effectively avoid the damage of the concrete at the foot of column. Increasing the friction coefficient of friction spring most effectively enhanced the energy dissipation of the PFSRC, and the taper angle has the most significant effect on the post-yield stiffness of the PFSRC, but increasing this parameter leads to decrease the energy dissipation. While increasing the pre-pressure effectively improves the yield strength and resistance of PFSRC. The damage extent of the PFSRC is affected by both axial compression ratio and steel tube diameter-to-thickness ration, and the low damageability of PFSRC can be achieved by adjusting the diameter-to-thickness ratio. For the buildings with unidirectional seismic demands (such as retrofit buildings), it is recommended to placed PFSD at 30° along that direction, for the general building with bidirectional seismic demands, PFSD should be arranged at 45° along that direction.