Experimental Research On The Flexural Performance Of Ultra-high Performance Concrete Beam

Ultra High Performance Concrete(UHPC)is a new type of composite cement-based material with high strength,high durability,high toughness,corrosion resistance,penetration resistance and frost resistance.Section steel is also a kind of high-strength and high-performance steel.The combination of two materials with outstanding performance and excellent performance is of great research value.,And can give full play to the high strength and good elastoplasticity of the steel,so it has broad development prospects.Looking at the current status of the research,there are few specifications and standards for UHPC steel beams,and they are not targeted;there are not many references to UHPC steel beams.Most of the research is theoretical analysis or All are built on the basis of reduced-size components,so the research depth and width of the entire field need to be strengthened.Therefore,this article is based on the ultra-high performance concrete test beam with a calculated span of 3200 mm and a strength level of 120 MPa ～ 180 MPa.The flexural performance of UHPC steel beams is studied to provide test basis for the compilation of relevant specifications.By setting a single-point loading mechanical test of 6 test beams and 1 contrast beam,and observing the test phenomenon and crack development,the load-deflection curve of the mid-span section of the test piece,the stress distribution curve of the mid-span section steel and UHPC along the section height,Cracking load,yield load,ultimate load of each test piece.By analyzing the test results,the bending failure characteristics and laws of UHPC steel beams are obtained,and the calculation formula of ultimate bearing capacity considering the tensile strength of UHPC is proposed.Finally,the ANASYS finite element analysis software was used to model and analyze the six test beams.The entire test process was simulated,and the simulated stress cloud diagram and the simulated value of the ultimate bearing capacity of the specimen were obtained.The distribution of the cloud map is in line with the actual stress state of the test analysis,which confirms the rationality and accuracy of this test analysis from the side.In this study,the failure process of UHPC steel beams,the distribution of crack development,the development of deflection and stress,and the reference formula for the bearing capacity calculation of the specimens were found.It was found that the UHPC steel beams have ultra-high bending capacity and UHPC tensile strength The strength can affect the ultimate bending capacity of the specimen to a certain extent,not only the strength level of the concrete,but also the increase of the thickness of the web of the steel section can also increase the ultimate bearing capacity of the specimen;the bending failure of the UHPC steel beam is a typical bending Failure,the failure is roughly divided into 4 stages;the initial crack development of the specimen is similar to that of ordinary concrete,but the crack distribution is small and wide in the later stage of failure;finally,the entire failure force characteristics are analyzed,and the UHPC is considered based on the test results Ultimate formula of ultimate bearing capacity of tensile strength.