Experimental study on the seismic performance of round-ended hollow piers: Fid-Bau Portal

Experimental study on the seismic performance of round-ended hollow piers

Shao, Changjiang / Qi, Qiming / Wang, Meng / Xiao, Zhenghao / Wei, Wang / Hu, Chenxu / Xiao, Laichuan

Highlights • The plastic hinge region moves upwards and lengthens along the height of the pier due to variable hollow section, internal chamfer (transition of the solid-to-hollow section) and solid segment at the bottom being considered in the specimens. • Strain penetration occurs close to the upper edge of the solid segment of the pier instead of the top of cushion cap. • Quantification of the seismic performance objectives was implemented based on damage assessment associated with ductility factors and strength/stiffness degradation factors.

Abstract To investigate the seismic performance of railway bridge piers with round-ended hollow section, five 1/6-scale specimens were tested under low-cyclic loading. The two variable parameters were the volumetric stirrup ratio and axial load level. The damage evolution, strain response, and plastic hinge behavior were meticulously explored. The load-drift relationship, displacement ductility, strength/stiffness degradation, dissipated energy, and viscous damping were analyzed in depth. The quantification of seismic performance objectives was implemented by displacement ductility based on damage assessment. The relationships among the ductility and strength/stiffness degradation and equivalent damping ratio were regressed using the test data. The experiment and analysis results showed that all specimens suffered flexural failure, with flexural cracks covering nearly two-thirds of the pier height. The plastic hinge region lengthened and moved upwards along the column due to the existence of solid segment, internal chamfer and variable section. The displacement ductility capacity enhanced noticeably with increasing stirrup ratio. The increasing axial compression ratio led to higher initial stiffness and seismic capacity to some extent, but excessive axial load would decrease ductility with premature concrete crushing. Furthermore, the seismic safety of the piers were ensured under a ductility factor limitation of 4.8 required by the current seismic code for railway engineering of China.