Bending Model Experiment of Local Heightened UHPC with Formwork-free Wet Joint
In order to simplify the on-site construction technology of wet joints of assembled bridges(formwork-free and welding-free),simplify the reinforcement structure of joints and improve the crack resistance of joints,this paper proposes a kind of Ultra-High Performance Concrete(UHPC)formwork-free wet joint structure with the local heightened part of normal concrete(NC)precast bridge deck as the bottom formwork.In order to test the mechanical properties of this structure,seven test beams were designed,including two integral beams,one conventional joint beam and four formwork-free joint beams.The steel fiber content,inter-layer shear reinforcement and interface reinforcement ratio were used as test parameters.The four-point loading method was used to complete the flexural performance test of the test beam,and the key test results such as cracking load,crack distribution,failure mode and stress-strain state of the test beam were obtained.The test results show that both the joint beam and the integral beam have bending failure.The main cracks of the heightened joint beam without interlayer shear reinforcement are located in the joint section,and the main cracks of the other test beams are located in the precast section.With the increase of steel fiber content,the crack resistance of the heightened joint beam is also improved.The crack resistance of the heightened joint beam with interlayer shear reinforcement is second only to that of UHPC integral beam.At the same time,it has the advantages of simple structure,simplified construction and economical cost,which shows that the joint structure is feasible and reliable in practical engineering.The steel fiber content of UHPC is recommended to be 1.0%.
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