- مبلغ: ۸۶,۰۰۰ تومان
- مبلغ: ۹۱,۰۰۰ تومان
In order to study the seismic behavior of earthquake-damaged composite steel-concrete columns strengthened by enveloped steel, based on current design codes, four composite steel-concrete column models were designed and manufactured. Destructive tests on the models under low-cyclic loading were then carried out. The feasibility and effectiveness of earthquake-damaged columns strengthened by enveloped steel and the reinforcement effect on different levels of seismic damage were studied. The results show that enveloped-steel-strengthened earthquake-damaged composite steel-concrete columns meet the strong column-weak beam requirement of seismic design, and the failure mode of all the columns was in bending. The performance of the rehabilitated columns can reach or even exceed the level of their original seismic performance before seismic damage. Composite steel-concrete frame columns strengthened by enveloped steel were also simulated using the finite element (FE) analysis software ABAQUS. The analytical study was conducted and compared with the experimental results, and it was basically consistent with the experimental data.
In this test, the four test specimens were subjected to transverse cyclic loading test. The damage model, the force-displacement relation, the deformation ability, the strength and stiffness degradation and strain response of the test specimens were compared and analyzed. The finite element analysis was carried out and compared with the experimental results for verification. Numerical simulation was conducted to verify and evaluate mechanical properties of test specimens with different axial compression ratios and different reinforcement heights. The following conclusions can be drawn: (1) It was observed that the damage development sequences of the four groups were similar. However, there were more cracks in the steel reinforced concrete comparative column (without damage and reinforcement). At the same time, steel reinforced concrete comparative column showed shear bending failure. Due to restraint effect of encased steel jacket, encased steel jacket-strengthened test specimen showed no shear yield. (2) The cracks of encased steel jacket-strengthened steel reinforced concrete columns increased with the increase of seismic damage degree, which indicates that encased steel jacket-strengthened test specimen suppressed lateral burst of the concrete at the column foot and cannot fundamentally prevent increase of concrete cracks. (3) Compared with the steel reinforced concrete comparative column, damage of encased steel jacket-strengthened test specimen was zero damage, moderate damage, severe damage, respectively, with ultimate load increased by 23.0%, 12.9% and 7.4%, respectively, and ultimate displacement increased by 23.7%, 12.4%, 8.0%, respectively. Due to the restraint effect of encased steel,the ultimate load and ultimate displacement of severely damaged test specimen strengthened with encased steel jacket exceeded that of original contrast test specimen, which is beneficial to improvement of seismic performance of the structure. However, the deformation capacities of core steel reinforced concrete parts of the four types were similar.