Study on seismic damage assessment and performance level #br#
quantification of hollow pier
Qi Qiming1 Shao Changjiang1，2 Hu Chenxu3 Wei Wang1 Xiao Zhenghao1
1. Civil Engineering School, Southwest Jiaotong University Chengdu 610031, China；2. National Engineering Laboratory for Disaster Prevention Technology in
Land Transportation, Southwest Jiaotong University, Chengdu 610031, China; 3. West Investment Co., Ltd., of CCTEB, Chengdu 610041, China
Abstract：Accurate quantification on the damage state of a hollow pier is the basis of determining its seismic performance level, and also an important content in the performance-based seismic framework. Therefore, based on the quasi-static test results of 19 hollow piers, the damage characteristics and evolution mechanism of hollow columns are analyzed in depth. The classification of performance levels for hollow specimens is conducted and the quantified relationship between the performance levels and indexes are established. Based on the evolution curves of damage indices, the applicability of some existing damage models to the seismic damage assessment of hollow piers is discussed. The results show that compared with solid-section pier, the shear-flexural coupling action of hollow pier is more remarkable. Moreover, the plastic damage scope is larger and the phenomena of longitudinal rebar yielding and crushing of core concrete is more severe. Due to the varying sectional stiffness along pier, the vulnerable part of round-ended hollow pier moves from the pier bottom to the upper edge of internal chamfer. The five performance levels of hollow pier, namely, intact, minor damage, moderate damage, major damage and collapse control, can be well quantified by using the crack width, reinforcement/concrete strain and damage components (strength/stiffness degradation and residual displacement). The damage curves of these models differ remarkably, and the scatter of the damage indices under the same state is evident. The Park-Ang model can reasonably describe the process from initial loading to moderate damage, but it overestimates the severe damage state of the hollow pier. It is observed that Zengs model agrees well with the test results with less scatter, indicating that the proposed formula can be used for seismic damage assessment on concrete hollow pier.
