UHPC Application Research On Negative Moment Area Of Steel-Composite Composite Continuous Beam Bridge

The steel-concrete composite structure has been widely used in bridge construction in China and the world due to its large rigidity,good seismic performance,convenient construction and steel saving.Throughout the existing steel-concrete composite continuous beam bridge bearing,the section is greatly affected by negative bending moment.The durability of the structure is not guaranteed well,because of that ordinary concrete slabs are subjected to less tensile stress and exit from work.It is a solution to use ultra-high performance concrete for negative bending moments to resist tensile stress.UHPC is a brand-new high-performance cement-based composite material.Adding fiber into UHPC has high tensile strength and durability.It is a future development trend in bridge construction.In this paper,the characteristics of the steel-concrete composite continuous beam bridge and the great mechanical performance of UHPC are combined to tidy up and summarize the relevant literature.UHPC's ultra-high tensile performance is applied to the negative bending moment zone of steel-concrete composite continuous girder bridge to resist tensile stress,and combined with different construction techniques to analyze the overall force of the bridge.Taking a steel-mixed continuous open box girder bridge as the research object.Establishing the MIDAS Civil finite element model of the normal concrete bridge deck combined with the falling beam construction process and the UHPC bridge deck combined with the simple supported continuous construction process in the negative bending moment zone.The comparative analysis of the mechanical behavior of steel box girder and concrete slab is carried out to discuss the superiority of continuous construction process with simple support and super high performance concrete applied to the bridge.Using MIDAS Civil to change the length of the UHPC bridge deck in the negative moment zone of the steel-concrete composite continuous open box girder bridge,so as to explore the better arrangement length under the condition of structural stress.The MIDAS FEA local finite element model is established to analyze the mechanical behavior and force transmission mechanism of the UHPC and ordinary concrete joint sections in the negative moment zone.Comparative analysis was performed using a total life lycle lost lnalyze through the initial construction cost,operation cost and user cost,the general life economics of the UHPC deck combined with the simple support continuous construction of the ordinary concrete deck combined with the falling beam construction and the negative bending moment zone are set in the negative bending moment zone.Through all the analysis,it can be seen that the UHPC in the negative bending moment zone combined with the continuous construction process of the simple support can fully utilize the UHPC super high tensile performance,which can reduce the stress of the steel box beam to a certain extent,and also reduce the deflection of the bridge during the construction phase.Although the negative bending moment area adopts the high construction cost of the UHPC in the early stage,it has a good economic significance in the long run time.