Study On Ultimate Bearing Capacity And Optimal Design Of GFRP Truss Pedestrian Bridge

FRP truss bridge is a new material truss bridge developed in recent 20 years.It is light and high-strength.It has the characteristics of fast erection speed,strong corrosion resistance,good fatigue resistance and seismic performance,and meets the higher requirements of modern bridge structure.With the increasing application and research of FRP truss bridge at home and abroad,the safety reserve of FRP truss bridge is also concerned,and the ultimate bearing capacity has become one of the research focuses.Based on the research background of the pedestrian bridge of a city museum,The ultimate bearing capacity of GFRP truss pedestrian bridge is studied by nonlinear analysis method,and the bridge is optimized according to the material and size parameters of the structure.The main contents are as follows:(1)This paper studies the constitutive relationship of materials used in GFRP truss arch bridge,introduces some basic mechanical theories of FRP pultrusion profiles,studies the stress-strain relationship of FRP single-layer plate and laminated plate from the perspective of material mechanics,and the criteria of material failure,so as to provide material parameters for the following chapters.(2)The structural design of truss arch bridge is carried out,including arch rib design,main beam design and transverse brace design;the finite element model is established with ANSYS in combination with the actual engineering,and the detailed process of establishing the finite element model is given;the modal analysis,deformation analysis and stress analysis are carried out for GFRP truss arch bridge,and the results of finite element analysis show that the maximum stress appears in the arch rib span under the action of crowd load At the node of the section.(3)Firstly,the geometric nonlinear factors that affect the ultimate bearing capacity of the arch bridge structure are studied.Secondly,the stability safety factor of GFRP truss arch bridge under the linear elastic analysis method is studied,and the solution process of the live load factor is given.Then,the ultimate bearing capacity of GFRP truss arch bridge under the two methods of online elastic analysis and geometric nonlinear analysis under the completed state is compared,and several methods are adopted It is necessary to analyze the ultimate bearing capacity of GFRP truss arch bridge with geometrically non-linear analysis method.(4)From the point of view of composite materials,this paper studies the influence of ply design angle and ply design layer number on FRP materials,that is,under a certain number of ply,it studies the ultimate bearing capacity of arch bridge with ply angle of 30 °,45 ° and 90 °;then it studies the ultimate bearing capacity of GFRP truss pedestrian bridge with ply number of three,four and five layers under a certain lay angle;On the basis of this,the size of GFRP truss arch bridge member section is optimized to get the most appropriate section size.Finally,suggestions are given for the value of bridge parameters.