Structural System Of Super Span Suspension Bridge And Mechanical Properties Based On High-Performance Materials

This paper combined with the completion of the key program "Theories and methodologies for structural design and wind-induced catastrophe of super-long span cable-supported bridges with high-performance materials"(51938012).The schemes of 3300-meter-suspension based on Ultra-highperformance Concrete and Carbon Fiber Reinforced Polymer were proposed.The static performance of the schemes is analyzed,the local model of the segment is constructed,and the flexural performance of steel-UHPC composite slabs is studied by experimental research and numerical simulation,the main work is as follows.(1)Structural scheme design of suspension bridge.Based on different materials and beam forms,four suspension bridges with a main span of 3300 m,are constructed,which including steel cable + steel box girder + UHPC tower,CFRP Cable + steel box girder + UHPC tower,steel cable + steel truss-UHPC composite girder + UHPC tower and CFRP Cable + CFRP truss girder + UHPC tower.(2)Structural static performance analysis of suspension bridge.The whole model and local model of the four schemes are established to analyze the static performance of each scheme.The results show that the main cable axial force of steel cable suspension bridge(schemes 2)is about 2.32 times that of CFRP cable suspension bridge(schemes 1)under dead load;The lateral displacement of CFRP cable suspension bridge is greater than that of steel cable suspension bridge under the extreme cross wind,and the lateral displacement of scheme 1,scheme 3 and scheme 4 can meet the requirements;The use of CFRP cable or CFRP truss-UHPC composite beam can effectively reduce the stress level of the main cable,and has a large safety reserve.The whole analysis shows that scheme 4 has better static performance.The elastic buckling stability safety factor of the four schemes is greater than 4,which meets the specification requirements.The buckling safety factor of scheme 4is the largest.Scheme 4 has better static performance and buckling stability than the other three schemes while meeting the code requirements.(3)Twelve steel-UHPC composite bridge decks were tested under hogging moment,the failure mode of specimens,the load-midspan deformation curves,load-steel and concrete strain curves,post-cracking stiffness and crack width,and ultimate capacity were studied.Based on the plastic analysis theory,the cracking moment and ultimate bearing capacity of composite slab were calculated,and the contribution of UHPC is assessed by parameter k.Through regression analysis,it is found that while the k value is 0.35,the calculated result with plasticity theory were in good agreement with the test result.Referring to the calculation of crack width of composite slabs in national codes,a formula for calculating the crack width and reinforcement stress of composite slabs in this test is proposed(4)The numerical simulation of 12 composite bridge decks is carried out and compared with the test results to verify the accuracy of the finite element model.Based on the verified finite element model,the parameter analysis is carried out to explore the influence of shear key form,stud spacing,stud arrangement,PBL plate thickness,height,PBL spacing,PBL hole diameter,hole spacing and side length of wet joint on the transverse flexural performance of composite bridge deck,based on the verified finite element model.