Experimental study on crack resistance of stepped UHPC joints in negative moment zone of fabricated composite beams
In order to improve the crack resistance of deck slab in negative moment zone of assembled composite beam and simplify construction technology,a wet joint scheme of stepped ultra high performance concrete(UHPC)in negative moment zone of assembled composite beam bridge was proposed.Based on a fabricated composite beam bridge in Hubei province,a 1∶2 scaled model specimen was designed and fabricated for negative bending moment loading,and the crack resistance of stepped UHPC joints was experimentally studied.The section nonlinear calculation method was used to carry out the nonlinear analysis of the steel strain in the joint area.Based on the analysis results,the difference between the measured value of UHPC matrix crack width and the calculated value of the specification was discussed.The results show that the failure mode of the specimen is the buckling failure of the steel beam floor in the pure bending section.Under the action of negative bending moment,the maximum slip between the steel beam and the concrete bridge deck is 0.163 mm,and the strain distribution of the cross section in the joint area basically meets the plane section assumption,and the joint and the precast part have good joint force.UHPC and normal concrete(NC)have different crack distribution characteristics.The crack distribution of UHPC is dense,while the crack distribution of NC is sparse.In the joint area,the crack development of zone Ⅱ and joint section is the fastest,and the crack resistance of steel-UHPC section is stronger than that of steel-NC-UHPC section.When the crack width at the top surface of the bridge deck in the specimen joint area is 0.1 mm,the nominal stress at the joint interface exceeds 12.8 MPa,and the safety factor reaches 1.69.The nonlinear calculation method can effectively predict steel strain.The crack width of UHPC matrix in the joint area should be calculated by UHPC industry standard or French specification,and the tensile contribution of concrete should be considered in the calculation of steel strain.The stepped UHPC joint scheme has excellent safety and durability,convenient construction and meets the actual engineering requirements.
bridge engineeringultra-high performance concrete jointexperimental studynega-tive moment zone of composite beamcrack analysis
万方数据
维普
