| Prefabricated simply supported T-beam bridge has become the most widely used bridge structure in China due to its simple stress,mature technology,fast construction and good economy.However,the wet joint connecting the precast bridge deck is prone to crack,collapse,fall off and other diseases in the structural use stage,which not only affects the beauty and driving comfort of the bridge,but also seriously threatens the safety of the bridge.In this paper,UHPC,a new material with superior mechanical properties,is used to replace NC as the wet joint of precast simply supported T-beam bridge deck.The purpose of this study is to explore the influence of the lap length of reinforcement on the bending performance of wet joint plate,and to verify the feasibility of UHPC replacing NC as wet joint material.The innovations of this paper are as follows: first,the material is "new" : UHPC is used as wet joint material;second,the reinforcement structure is "new" : the overlapping reinforcement of wet joint of bridge deck adopts the form of non overlapping(no need to weld or bind).Thirdly,the material "new" and steel structure "new" are applied to the wet joint for experiment and finite element analysis.The conclusions are as follows:(1)The ultimate bearing capacity of joint plate U3 is 16% higher than that of joint plate P1,and the bearing capacity of joint plate U3 increases with the increase of lap length of reinforcement in wet joint.(U1,U2 and U3: the wet joint material is UHPC,and the overlapping length of reinforcement is 150 mm,250 mm and 350 mm respectively,which are UHPC joint plate;P1: the wet joint material is C50,and the overlapping length of reinforcement is 350 mm,which is NC joint plate)(2)Through the study of the wet joint structure,it is shown that the tensile property(yield)of the steel bars can be fully exerted by the non lap form of the ring reinforcement,which indicates that the connection mode of the steel bars between the precast plates is reasonable.At the same time,it is found that the mechanical property of the wet joint structure of UHPC + tongue and groove joint + ring reinforcement non lap wet joint is the best.(3)The ultimate bearing capacity calculated by ABAQUS is U3 > U2 > U1 > P1,which is consistent with the test value.The maximum difference between the theoretical value and the finite element value of the ultimate bearing capacity of the specimen is about 10% and 5% respectively,which shows that the finite element simulation and theoretical calculation are more accurate.(4)The results show that there are no obvious cracks in the wet joint of UHPC(UHPC material)when the specimen is damaged,while there are more cracks in the wet joint of NC(C50 material),which indicates that UHPC has better crack resistance,and the durability of the real bridge will be improved when it is used in the wet joint of the real bridge;(2)the steel fiber in UHPC material can bond the uhpc-nc interface(UHPC concrete at the wet joint)with C50 precast segment There is a "delaying" effect on the cracking of the interface.(5)Through the study of local loading of simply supported T-beam bridge by finite element software,the UHPC wet joint of Tu bridge has better performance and better durability than C50 wet joint of TC bridge;Tu bridge also saves steel consumption,reduces on-site concrete pouring amount and greatly speeds up the construction progress compared with TC bridge.(TU bridge: the width of wet joint is 299 mm,UHPC+ ring reinforcement is not overlapped;TC bridge: the width of wet joint is 598 mm,C50 + closed ring welding)... |
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