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Experimental Study on UHPC “T-shaped” Wet Joints in the Negative Moment Zone of Continuous Concrete Beams after Simple Support
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    Abstract:

    In order to improve the crack resistance of wet joints in the negative bending moment area of ordinary concrete continuous beams and simplify the construction process,a new type of UHPC wet joint scheme for the negative bending moment area of concrete beam bridges was proposed. Taking a common concrete continuous beam bridge with a span of 30m as the background,according to the French UHPC structural design regulations and Chinese Specification for Design of Highway Reinforced Concrete and Prestressed Concrete bridge and Culverts(JTG 3362—2018),the reinforcement design of the bridge under normal service limit state is carried out. Based on the results of reinforcement design,the 1 ∶ 2 scale model test of UHPC new wet joint structure was carried out. The test results show that the crack resistance and load-bearing capacity of the UHPC new wet joint scheme without reinforcement welding and prestressed strands in the negative bending moment area are all in line with the engineering requirements. The test values are well fitted with the numerical simulation values. The introduction of UHPC can effectively limit the crack width of normal concrete(NC),significantly increase the rigidity of NC section,and reduce the redistribution of internal force and vertical deflection of the continuous concrete beam in the mid-span. Compared with the traditional wet joint structure without negative bending moment prestressed tendon,the new UHPC joint structure can reduce the redistribution coefficient of the internal force and vertical deflection of the continuous concrete beam to about 30%~50%. The parameter analysis shows that: for the concrete continuous beam bridge with UHPC new wet joint structure in the negative bending moment area,the length of UHPC along the longitudinal direction of the bridge should be taken to be 0.27 times the calculated span. The diameter of the longitudinal tensile main bars in the negative bending moment area can be unified to 20 mm,and the thickness of the UHPC layer can be 60 mm.

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History
  • Received:
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  • Online: March 23,2021
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