Research On Dynamic Splitting Mechanical Properties Of GFRP-mortar Composite Structure

Bridges,waterway collision columns and other structures that have been built or under construction are faced with impact loads such as cars and ships,which will cause major safety accidents in serious cases.Nowadays,there are many researches on static mechanics of FRP confined concrete structures,but there were few studies on high-speed rate dynamic loads.Lack of relevant theoretical support under the action of high-speed dynamic loads such as explosive load and impact load,it was bound to limit the popularization and use of FRP constrained structures in various fields.Therefore,the dynamic mechanical characteristics of hollow GFRP-mortar tube structure under high-speed rate dynamic load were studied in this paper,so as to provide theoretical reference for the further popularization of FRP material in engineering.In order to investigate the dynamic tensile failure characteristics of glass fiber reinforced plastic(GFRP)-mortar tube under the dynamic loading,the dynamic tensile tests on the cement mortar and GFRP-mortar tube with two kinds of hollow ratio were conducted by using the split SHPB test device.The results showed that the smaller the hollow ratio and the larger the impact pressure and wall thickness,the greater the peak tensile strength of the specimen.The peak tensile strength of GFRP-mortar tube increased continuously with the increase of the wall thickness of GFRP tube.When the hollow ratio was 0.292,the peak tensile strength decreased as a logarithmic function as the wall thickness of GFRP tube increased,while when the hollow ratio was 0.187,the peak tensile strength increased as a logarithmic function as the wall thickness of GFRP tube increased.The tensile strength of cement mortar specimen was low,the stress-strain curve was unimodal,the tensile strength of GFRP-mortar specimen was significantly higher than that of cement mortar specimen,and the stress-strain curve was double-peak type,the peak strain of GFRP-mortar specimen was obviously higher than that of cement mortar specimen,and the peak strain has obvious loading rate effect.The dynamic elastic modulus of the two specimens varies greatly with the impact pressure and hollow rate,and the dynamic elastic modulus of cement mortar specimen was generally higher than that of GFRP-mortar tube specimen.The dynamic failure process of GFRP-mortar tube specimen was recorded by high-speed video camera,and the failure mode of cement mortar specimen was quite different from that of GFRP-mortar tube specimen.Without GFRP pipe,the cement mortar specimen was symmetrically four pieces broken.Under different hollow rates and wall thicknesses,under different hollow rates and wall thicknesses,the damage degree of the cement mortar filled inside the GFRP-mortar pipe continues to increase under the impact air pressure of 0.5MPa-0.8MPa,the part in contact with the incident rod produces "wedge-shaped" damage,but the specimen was still relatively complete and the damage was still lower than that of the cement mortar pipe,As the wall thickness of the GFRP-mortar pipe increases,the degree of damage decreases,indicating that the GFRP pipe has a better protective effect on the cement mortar and can better improve the dynamic tensile strength of the cement mortar.Figure 34 Table 7 Reference 69...