| At present,the seismic resistance of structures in engineering structures and the durability of structures in complex environments are a major research hotspot.In bridge engineering and housing construction,traditional reinforced concrete structures not only face the test of earthquake action,but also face increasingly severe environmental problems.In view of the shortcomings of traditional reinforced concrete structures,this paper proposes a composite column of glass fiber reinforced composite(GFRP)and ultra-high performance concrete(UHPC).The composite column has the advantages of high strength,free formwork and simple fabrication,and the external corrosion-resistant GFRP material can effectively isolate the internal concrete from the external environment.In this paper,the seismic performance of the proposed composite column is mainly studied by the test method,which provides a reference and theoretical basis for practical engineering and subsequent research.The main results obtained in this paper are as follows:(1)In this paper,two parameters of axial compression ratio(0.2,0.3,0.4)and GFRP tube filament winding angle(45°,80°)are considered,and six GFRP-UHPC composite column specimens and one UHPC of the same size are compared.The horizontal low-cycle reciprocating load test was carried out on the column specimen,and the mechanical properties of GFRP pipe and UHPC were measured.In the test,it is found that GFRP pipe can not only prevent the crushing and peeling phenomenon of concrete during the loading process to a certain extent,improve the failure form of the specimen,but also effectively improve the seismic performance of the specimen.Through the analysis and processing of the test data,a series of seismic performance characteristics of the composite column specimen are obtained,including the hysteresis curve,ductility coefficient,strength and stiffness degradation coefficient,strain change and energy dissipation capacity of the specimen.(2)When the axial compression ratio of the GFRP-UHPC composite column is constant,the ultimate horizontal bearing capacity and equivalent stiffness of the 45-degree filament wound tube composite column are lower than those of the 80-degree filament wound tube composite column,but its ductility coefficient is higher and the energy dissipation capacity is higher.Better,the strength degradation is slower,and the GFRP pipe has a stronger confinement effect on the concrete,and the synergistic deformation ability is better.Therefore,the characteristics of the 45-degree winding pipe are more conducive to its application in engineering practice.(3)When the winding angle of the composite column specimen is constant,the law of the 45-degree filament wound tube composite column and the 80-degree filament winding tube composite column is basically the same.In the range of the test axial compression ratio of 0.2-0.4,with the increase of the axial compression ratio,the ultimate horizontal bearing capacity of the specimen decreases continuously,the ductility gradually decreases,and the energy dissipation capacity decreases.Therefore,in practical engineering,under the premise of meeting the needs of use,the appearance of high axial pressure ratio columns should be avoided.(4)On the basis of the experiment,the obtained skeleton curve data is processed dimensionless,and then the regression analysis is carried out.The dimensionless skeleton curves of each specimen have good regularity and coincidence,so the three-fold skeleton model of the composite column specimen is obtained.The key points of the three-fold skeleton curve model are yield point,peak point and limit point,which can be used as the basis for elastic-plastic analysis of GFRP-UHPC composite columns. |
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