Research On Mechanical Performance Of Steel-Concrete Composite Continuous Beam-V Leg Continuous Rigid Frame Bridge

With the development of steel-concrete composite structures and the pursuit of bridge aesthetics,steel-concrete composite continuous beam-V-leg continuous rigid frame bridges have been applied as emerging bridge types in some scenarios.The characteristics of the steel-concrete composite continuous beam-V-leg continuous rigid frame bridge are:The main beam adopts a steel-concrete composite section.The steel main beam is continuous from the longitudinal bridge to the full bridge,and at the same time,it is consolidated with the V-legs to form a V leg rigid frame system.Because the support of the V-leg pier to the main beam can reduce the calculated span of the main beam,the span of the steel-concrete composite continuous beam-V-leg continuous rigid frame bridge is significantly larger than that of the steel-concrete composite beam bridge with vertical pier It is beneficial to increase the spanning capacity of the steel-concrete composite structure.However,there are very few studies on the factors affecting the mechanical performance of this bridge type.Therefore,this paper analyzes and studies the actual project of a steel-concrete composite continuous beam-V-leg continuous rigid frame bridge.The main work and research contents are as follows:1)Through reasonable simplification,the Midas civil and Midas FEA software were used to establish the comparative verification of the rod and solid finite element analysis models considering the construction process.The initial stress state of the main construction stage and the completion stage of the bridge is analyzed and studied,and the stress variation law of the structure during the construction process is studied.Furthermore,through parameter analysis,the reason for the difference in compressive stress reserve between the negative bending moment area of the V-leg pier top and the negative bending moment area of the vertical pier top was studied.The stress on the upper flange of the steel girder in the pier top is established after the construction of the cast-in-place concrete is completed.Thereafter,the second-stage pavement has no significant effect on the stress on the upper flange of the steel girder.The steel V leg will bring additional tensile stress to the lower flange of the steel main beam.When the vertical stiffness of the steel V-leg is weakened,the effect of using the weight method to improve the stress of the bridge deck will also be weakened.2)Based on the construction process and the characteristics of the V-leg structure,the timing of dismantling the temporary support of the V-leg is analyzed and studied.From the perspective of improving the stress of the bridge deck,the temporary support of the V-legs should be removed as much as possible before the deck deck is paved,and it should not be later than the construction of the cast-in-place section at the latest.Using parameter analysis and stress state analysis,the effects of different V-leg angles on the stress state of the steel girder and bridge deck were investigated.The results show that different V-leg angles have a significant effect on the stress of the steel girder.If the vertical stiffness of the V-legs is not considered,the different V-leg angles have little effect on the stress in the bridge deck.At the same time,the characteristics of stress redistribution in the steel-concrete composite main beam under long-term shrinkage and creep are analyzed.From the perspective of the whole bridge,the top of the V-leg pier is easy to become the control section of the tensile stress in the concrete slab.3)Through the analysis and research on the structural natural vibration characteristics and lateral distribution,it is found that the steel V-legs have a significant contribution to the rigidity of the full bridge.When the pier beams are consolidated,the lateral distribution of the load on the cross section of the double main beams has been significantly improved.Through the actual bridge test,it is verified that the bridge structure is normal,and the physical finite element simulation of the bridge is more accurate.