Experimental Study On Mechanical Properties And Connection Mode Of GFRP Tube

This study is based on the research project of the force mechanism and design method of the FRP-concrete composite box section double deck traffic structure system(project number: 51578263),and the GFRP tube composite plane truss is part of the project.The pultrusive GFRP pipe,as the drawing member of the composite plane truss,has the characteristics of light weight,high strength,corrosion resistance and so on,so it can reduce the weight of the structure and improve the corrosion resistance of the structure.However,the anisotropy of the pultrusion GFRP pipe is more serious,and there are some key problems in its application in the composite structure.In this paper,the mechanical properties of GFRP pipes and the three kinds of connection modes are studied.The main research category is as follows:(1)The mechanical properties of GFRP pipes were tested.The tensile strength,tensile modulus,compression strength and compressive modulus of elastic modulus of GFRP pipes were obtained,and the protection mode of the end of the specimen was suggested according to the experiment.The end of the tensile specimen was suitable for the use of impregnated fiber cloth to protect the specimen,and the loading end of the compressed specimen was suitable for the use of internal and external steel rings.Protection.(2)In the adhesive bonding experiment,the distribution characteristics of the shear stress along the length direction,the treatment mode of the bonding interface and the influence of the bonding length on the connecting bearing capacity are investigated.It is known from the experimental results that the shear stress distribution in the length direction is uneven along the length direction,and the high stress occurs at the two ends of the joint,and most of the connection length has a lower transfer load capacity.The bonding interface can greatly enhance the connection strength and the stability,with the "migration method" treatment,and the load bearing force is not linear with the bonding length,and the length of bonding is limited to the lifting capacity.(3)In the bolt connection experiment,the influence of e/d(end / bolt diameter)and bolt number n on the connection performance is explored.The experimental results show that the e/d ratio in single bolt connection parameters has an important influence on the bearing capacity and failure mode of the bolt connection.When e/d is more than 7,the bearing capacity reaches the maximum value,and the damage occurs to a partial safety failure form-extrusion damage,according to the existing research and reality The test results show that the multi bolt connection parameters are set up,and the experimental verification is carried out.The bearing capacity of the multi bolt connection does not increase linearly with the increase of the bolt number,which is more different from the traditional material connection.(4)The experimental study of the new type of corrugated pre tightening tooth connection is carried out,which has the characteristics of high connection efficiency,convenient disassembly and so on,and discusses the combination of the connection and other connection forms.Finally,three kinds of connection methods are applied to the composite truss structure of GFRP pipe,which are adhesive connection,bolt connection and ripple pretending tooth connection.The connection performance is studied,and some reference basis is provided for the follow-up project.