Study On Mechanical Properties Of GFRP-ECC-Steel Double Skin Tubular Columns

Fiber cement matrix composite(ECC)is composed of fibers added to cement matrix composites,which are widely used in marine engineering,and in recent years,with its excellent ductility,compressive strength and construction convenience,it has attracted wide attention in civil engineering circles.GFRP-concrete-steel pipe combined column(DSTC)is a new type of hollow column,and the combination of the two can give full play to the structural properties of the material,so this paper proposes GFRP-ECC-steel pipe column is proposed,in which GFRP pipe and steel pipe are used as molds,and ECC is cast directly between GFRP and steel pipe.This combined column has high load capacity,good corrosion resistance,strong resistance to deformation,and good seismic performance and low cost.To explore the axial compression performance of GFRP-ECC-tubular steel composite columns(DSTC),a total of 29 full-scale GFRP-ECC-tubular steel columns were designed in this paper with hollow ratio(e),number of GFRP layers(ng),ECC strength,and steel tube thickness as the main parameters.Based on the existing theories,four similar structural members were successfully verified and analyzed by finite elements,and the errors were found to be within 8%,so the finite element modeling method was verified to be reasonable.On this basis,this paper adopts ABAQUS finite element software to establish and analyze finite element simulation for 29 GFRP-ECC-tubular steel composite columns(DSTC),by studying the load-displacement curve of the members,analyzing the axial compression performance of different parameters on the members and the change law of the ultimate bearing capacity of the members under different parameters,the results found that: the number of GFRP layers is controlled at 6-18 layers,which can effectively improve the member bearing capacity,but with economy when the number of GFRP layers is 12;the hollow ratio is between 0.5-0.7,the bearing capacity is unfavorable to the combined column force when the hollow ratio increases,and the bearing capacity decreases when the hollow ratio becomes larger;with the increase of ECC strength,the ultimate bearing capacity of the member is significantly improved;when the steel tube thickness is influenced by the DSTC column,the thickness increases at 6-12 mm can effectively improve the bearing capacity of DSTC column.Based on the axial pressure performance analysis of GFRP-ECC-pipe composite columns,this paper analyzes the influence law of different parameters on the hysteresis performance,skeleton curve,energy dissipation capacity,ductility performance and stiffness degradation of the members when 12 GFRP-ECC-pipe composite columns are subjected to low circumferential repeated loading with three factors as the main parameters: axial pressure ratio(n),hollow ratio(e),and thickness of mixed steel pipe(ts),and provides seismic design suggestions for the application of such composite columns in practical engineering within the parameters analyzed in this paper.