| At present,as a major construction country,my country has a large number of buildings have been unable to be directly used because of longer service life,functional degradation,poor construction quality and unpredictable damage..In order to meet the requirements of sustainable development in today’s society,it is necessary to reinforce these building structures.The reinforced concrete column is one of the commonly used load-bearing members of structures such as houses,bridges and hydraulic engineering.Its damage is directly related to the safety of the entire structure.Therefore,the damaged column needs to be reinforced.This paper adopts the reinforcement method of self-compacting concrete filled steel tube to strengthen the column.The seismic performance of reinforced columns with this reinforcement method is mainly studied.The specific work and main conclusions are as follows:(1)According to the axial compression ratio,the new and old concrete interface treatment,different original column defects and steel tube section forms,the defects of original column and the section form of steel tube,one reinforced concrete cylinder specimen,three reinforced columns with round steel tube and seven reinforced columns with square steel tube were designed and fabricated,and the low-cycle reciprocating tests were carried out on them.The entire stress process of unreinforced and reinforced columns was observed,and their respective destruction form were obtained.According to the results,the hysteresis curve and skeleton curve of the reinforced column,the degradation of strength and stiffness,ductility performance and energy dissipation capacity of the column are analyzed.Then,the effect of reinforcement and the influence of various parameters are analyzed.The results show: Compared with the original column,the horizontal bearing capacity,ductility,stiffness and energy dissipation capacity of the self-compacting concrete column reinforced with steel tube are significantly improved.When the axial compression ratio is small,the horizontal bearing capacity,stiffness and energy dissipation capacity increase with the increase of axial compression ratio,decrease gradually with the increase of fault rate,and slightly increase with the increase of planting reinforcement ratio.The reinforcement effect of square steel tube reinforced column is greater than that of round steel tube reinforced column because of the larger hoop coefficient.(2)The finite element analysis of the seismic performance of the square steel tube reinforced column was carried out by ABAQUS software.The hysteresis curve,skeleton curve and deformation shape are basically consistent with the experimental results.The reasonable and effective settings in unit selection,contact setting,meshing and material constitutive are verified.At the same time,the stress changes of square steel tube reinforced concrete and original column concrete during loading are analyzed.On this basis,the parametric analysis of square steel tube reinforced columns with different axial compression ratio,steel tube thickness and concrete strength is carried out by using the established finite element model.The hysteresis curves and skeleton curves of each specimen were obtained.The hysteresis loops of the the specimens were presented as full bows with good horizontal bearing capacity and energy dissipation capacity.The influence of axial compression ratio of specimen is bounded by 0.6.When the value is lower than this range,the increase of its value will improve the horizontal bearing capacity,and when the value exceeds the range,the change trend is just the opposite.The increase of steel tube thickness and reinforced concrete strength has an increasing effect on horizontal bearing capacity.The increase of steel tube thickness has an increase effect on ductility and the increase of concrete strength has a decrease effect on ductility. |
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