Experimental Study on Mechanical Property of Bridge Deck with UHPC Joint
In order to master the mechanical characteristics of bridge deck with UHPC(ultra high performance concrete)joints under bending conditions,moreover,to investigate the proper width of UHPC joints and the effect of different joint cross-sections and reinforcement lap forms on the flexural performance of bridge deck slabs with UHPC joints,which have the same joint width,one cast-in-place slab and 3 prefabricated test slabs are designed and manufactured.Four-point bending tests are conducted to evaluate the flexural performance of the joints,and related study,such as load-mid-span displacement curve,load-main crack width curve,concrete load-tension strain curve,concrete load-compression strain curve,load-strain curve of tensile reinforcement,ultimate flexural capacity and crack propagation,are carried out.The result shows that(1)due to the excellent mechanical properties of UHPC,the load-mid-span deflection curves of the 4 groups of test panels are basically similar,and the ultimate load carrying capacity of the bridge deck with UHPC joints is better than that of the whole panel;(2)in the case of the same width of the joints and the same reinforcement connection,the funnel-shaped or wedge-shaped joints in the form of cross-section will not affect the ultimate load carrying capacity of the prefabricated decks,and the difference of the stiffness of each other is not large;(3)with the premise of guaranteeing the integrality of the decks and the load carrying capacity,the wet joints with UHPC can be reduced to 15 cm width;(4)with the premise of ensuring the integrity and load bearing capacity of bridge deck,the UHPC wet joint of precast bridge deck can be reduced to 15 cm width,the integrity of UHPC joint connection is good,which will not affect the tensile performance of the cast-in-place joint section and the connection interface.The initial cracks and main cracks of precast assembled bridge deck with UHPC joints are located in the ordinary concrete area,the high modulus of elasticity of UHPC makes the joint area locally stiff,and the compression zone of concrete at the joint area is improved.Compared with the concrete area around the joints,the compressive strain of the concrete in the compression zone and the tensile strain of the reinforcement in the tension zone at the joints are smaller.There is no cracks appeared in the joint area,and the cracks at the interface between the UHPC wet joints and the precast concrete slabs expand slowly.
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