Effect Of Pavement Layer On Steel-concrete Hybrid Beam(SCHB)Analysis Of The Effect Of The Continuous Rigid Bridge Structure

The subject of this paper is a steel-concrete hybrid beam(SCHB)continuous rigid frame bridge.Unlike ordinary continuous rigid frame bridges,the SCHB continuous rigid frame bridge uses a steel box girder instead of a concrete box girder section in the middle of the main span and interconnects the concrete and steel box girder sections in the structural plane to form the main girder section of the continuous rigid frame bridge.In this paper,the mechanical properties of a normal continuous rigid bridge are used as the basis,and the concrete girder section of equal length in the middle of the span is replaced by a 46 m steel box girder in the main span,and then the structural analysis of this new bridge is carried out.The research in this paper includes the following aspects:(1)Creation of a simplified mechanical model for describing a specific SCHB rigid bridge girder.Analytical expressions for the internal forces and displacements of the basic sections are obtained using the principles of structural mechanics and advanced mathematical knowledge.By controlling the changes in pier and girder stiffness ratio,edge-to-medium span ratio,and main span diameter,a brief mechanical comparison is made to analyze the changes of the bridge structure under constant load and effective live load in the mid-span lateral moment at the top of the pier,edge-to-medium span lateral moment at the top of the pier,mid-span moment at the main span and unbalanced moment at the top of the pier for the SCHB rigid bridge.The results show that the pier-beam stiffness ratio has a small effect on the internal force distribution of the critical section,while the side mid-span ratio and the main span diameter have a large effect on the internal force distribution of the critical section.(2)A 3D model of the SCHB continuous rigid bridge with asphalt concrete pavement and cement concrete pavement was established using Midas/civil software to verify the constructed model.The steel box girder section is tested for strength,shear stress,and commuted stress,while the concrete girder section is tested for endurance limit state,endurance normal use limit state,and endurance member stress.The test results conform to the requirements of relevant codes.(3)The three-dimensional models of asphalt concrete pavement and steel box girder sections of cement concrete pavement were established by using ABAQUS software.The stresses and displacement changes of the steel box girder section under the lane load and vehicle load were analyzed.The results show that under the same conditions,the stress values of the steel box girder section under asphalt concrete pavement,the cross-sectional plate,and the U rib(4)Comparative static and dynamic analyses of the asphalt concrete pavement and cement concrete pavement SCHB continuous rigid bridge were conducted to compare the stresses and displacement changes in the concrete girder section,steel box girder section,and steel box girder and concrete girder section joints,and to analyze the self-vibration of the bridge under both pavement layers.The results show that the stresses and displacements at the concrete girder section of asphalt concrete pavement,steel box girder section and steel box girder connected with the concrete girder section are larger than those at the concrete girder section of cement concrete pavement,steel box girder section and steel box girder connected with concrete girder section at the same location.The free vibration frequency of the SCHB continuous rigid frame bridge with cement concrete pavement is much lower than that of the SCHB continuous rigid frame bridge with asphalt concrete pavement.In comparison,the mechanical properties of the SCHB continuous rigid frame bridge with cement concrete pavement layer are better,and the SCHB continuous rigid frame bridge with cement concrete pavement layer has better load-bearing capacity.