Experimental Study On Pressure Performance Of GFRP Square Tube Under Axial Load

With the stable development of society,the continuous improvement of the field of civil engineering,the construction technology is becoming more mature,and the materials used tend to be diversified.Therefore,the requirements for building materials are increasingly strict,and the development of new composites and new technologies is imminent.Therefore,Fiber reinforced composites(Fiber reinforced polymer,FRP)began to enter the vision of architectural engineers,it has the advantages of light and high strength,good electric heating performance,high temperature resistance,creep resistance,corrosion resistance,designability and good technology,is an ideal alternative material for new buildings.In this paper,the mechanical properties of pultruded GFRP square tube long column under axial pressure are studied.In this paper,based on the previous tests on the material properties of pultruded GFRP and the mechanical properties of short columns under axial pressure,the reinforcement scheme of the middle column end of pultruded GFRP was studied.Forty-eight groups of specimens with six different width to thickness ratios and eight different slenderness ratios were tested under axial pressure and the overall instability failure was analyzed.By comparing and analyzing the test data,failure forms and curve changes,the mechanical properties of pultruded GFRP square tubes were studied and the following conclusions were drawn:1.The test data of pultrusion type GFRP axis are obtained through the end strengthening scheme test.The results show that there are two basic failure modes of pultrusion type GFRP end failure,and the double-layer closed square ring end strengthening scheme is the best strengthening scheme of square string end.2.The failure mode and ultimate load were obtained through the middle and long axial compression test of 48 square pipe strings.The results show that there are three basic failure modes for pultruded GFRP long columns: end failure of specimen,whole failure caused by local instability of specimen,and whole failure of specimen.The local instability and failure of specimens are greatly affected by the ratio of width to thickness of specimens,while the slenderness ratio of specimens has an effect on the overall instability and failure.There is a linear relationship between the bearing capacity of the specimens with unstable failure and the slenderness ratio of the specimens.The larger the slenderness ratio of the specimens,the lower the bearing capacity of the specimens with unstable failure.3.Through the finite element method,the axial compression test of pultruded GFRP specimens is simulated by progressive damage analysis,and three different failure forms of the specimens are simulated.The results show that the progressive damage analysis method is feasible for the instability simulation of composite materials.Fig50 Tab 17 Ref 70...