Research On Seismic Damage Of Steel Reinforced High Strength And High Performance Concrete Members And Frame Structures

Steel reinforced high strength and high performance concrete (SRHSHPC) structures possess excellent seismic behaviour and good endurance, so they were applied to high-rise, super high-rise buildings as well as towering, long-span and heavy-load structures in the high intensity earthquake zone widely. This paper was devoted to studying on seismic damage of SRHSHPC members and frame structures, especially seismic damage of frame columns by the way of combining physical model experiment, theoretical analysis and numerical simulation.Firstly, the damage evolution of SRHSHPC frame columns was investigated through low cycle reversed loading experiment of 12 frame column specimens with various axial compression rations, stirrups ratios, steel rations and loading histories. The change law of the ultimate bearing capacity, ultimate deformation and ultimate hysteretic energy dissipation of specimens subjected to different numbers cycle loading were obtained. The influence of design parameters and loading history change on loading-displacement curve, skeleton curve, strength and stiffness degradation, deformability and energy dissipation capacity were analyzed from the damage viewpoint. The results show that the damage process of specimens can be divided into three stages:undamaged, damage developed stably and damage developed rapidly. With the increase of cycle number and displacement amplitude, the damage of specimens is accumulated gradually, which causes strength and stiffness degradation and decrease of energy dissipation capacity and ultimate deformability. Compared with variation displacement amplitude cycle loading, the process of damage evolution of specimens is slower under constant displacement amplitude cycle loading, and the amount of the energy dissipation of specimens is comparably larger. The research can supply experimental data for establishing seismic damage model and revealing the effect of damage on mechanical property of SRHSHPC frame columns further.The deficiency of existing seismic damage models was concluded and analyzed. In the light of the test results, the seismic damage characteristic of SRHSHPC frame columns was analyzed. Based on the nonlinear double parameters combination of deformation and energy, the damage model, which can well reflect the mechanical characters change of members subjected to horizontal earthquake action, was established by reasonably considering the effect of cycle number on ultimate resistance capacity (ultimate deformation and ultimate energy dissipation capacity) of members, and the effect of loading history on damage etc.. According to the test results, the related parameters were defined and fixed in the damage model proposed inhere. Finally, the validity of damage model was verified by comparison with the test results. The result shows that the damage model proposed can well describe the seismic damage evolution process and degree of SRHSHPC frame columns, and is more reasonable in theory. The study results will supply the theory support for the seismic damage assessment and the establishment of damage-based earthquake-resistant design method of SRHSHPC members.According to the experimental hysteretic curves, the hysteretic model for SRHSHPC frame columns was proposed by considering the effect of damage. Based on seismic damage model obtained inhere, the cycle deterioration index was introduced to describe the performance degradation of SRHSHPC frame columns at different stages theoretically. Then, the damage-based restoring force model of SRHSHPC frame columns was established. By comparing the test results with calculation results for hysteretic curve, the applicability and accuracy of the proposed model was verified. The results show the given restoring force model can well describe the hysteretic behaviour of SRHSHPC frame columns under low cycle reversed loading.The test of SRHSHPC frame structure carried out by companion previously was intorduced to study the multi-scale effect of migration and transformation from member damage to structure damage. The relationship of member, local structure and global structure failure was studied. Based on the damage evolution process of SRHSHPC frame structure, the global damage model, which could reflect migration and evolution law from member damage to local damage and global damage, was established through the reasonable assumption. Finally, the damage states and corresponding damage index range of SRHSHPC frame structure were defined by combining the damage indexes and the test failure process of frame structure.