Study On The Negative Moment Region Performance Of Steel-UHPC Continuous Composite Beam

Steel-concrete composite beam structure has the advantages such as large bearing capacity,small cross section height and light deadweight,etc.Therefore,it is widely used in the field of bridge structure.The prefabricated composite beams are made in the factory,it has the advantages of the construction speed and the quality.However,in the continuous steel-concrete composite beam,there are negative moment zone,some disadvantages such as steel beam compression and concrete tension occurs.In addition,in the period of normal working,the continuous composite beams will suffer temperature change humidity and uneven settlement of the support and other problems which test the ductility of the concrete more than the tensile strength.In view of this,this paper adopts the precast fabricated steel-composite beam constructed of Ultra-high performance concrete(UHPC)with nature curing and Ultra-high toughness cementitious composite(UHTCC)are used to conduct experimental research on the performance of negative moment area.The main work is as follows:(1)According to the steel structure in the specification for composite beams that made from autoclave curing of prefabricated steel-UHPC composite beams,and compared with ordinary steel-concrete composite beams with the bending performance in the negative moment region test.By analyzed the result of the experiment,found the steel-UHPC composite beam in such combination interface slip,cracking load,stress of concrete,and concrete slab crack width which are influencing the negative bending performance has certain improved.(2)Steel-UHPC composite beam was added with Post-combined prestress and the bending performance test in the negative moment region was carried out.Some differences in the test process and test results between the steel-UHPC beam and the post-bond steel-UHPC beam were compared and analyzed.According to the result,after adding prestressed the steel-UHPC composite beams in the cracking load,the plate steel yield load and so on have greatly improved.(3)Out of consideration for the problem of crack width,the concrete creep,and slab ductility of the negative moment region.This article introduces a kind of high toughness of concrete(UHTCC)material and do a negative moment region performance test of the steel-UHTCC composite beam,compared with normal steel-concrete beam,steel-UHPC beam about the advantages and disadvantages of the negative moment area.Although the steel-UHTCC composite beam is not as good as the steel-UHPC composite beam in cracking load,it performs very well in crack width control.