Study On Flexural Behavior Of RPC Segmental Beams With Keyed Joint Connected By Prestressing Tendons And Bolted Connection

The application of Reactive Powder Concrete(RPC),the material with excellent mechanical propert y,is increasing graduall y in the bridge engineering.However,the total acquisition of excellent mechanical propert y requires high-temperature curing for RPC,which indicates that RPC is more applicable to the pre fabricated assembly bridge in bridge engineering.The joint plays an important role in the bearing capacity of pre cast segmental beams in assembl y bridges,the usual joint between precast segmental RPC beams of assembly bridges consist of two forms,one of which is wet joint,built by cast-in-place construction,and the ot her is dry joint,which is connected b y the prestress ing tendons.The wet joint built by cast-in-place construction is usually cured in a natural environment,which increases the period of curing,and leads to the nonidentity of mechanical propert y and volume stability caused by the curing condition between RPC built b y cast-inplace construction and prefabrication.The precast segment al beams of bridge is discontinuos in the location of dr y joint connected b y prestressed tendons,which may leads to the corr osion of prestressing tendons under the long-time exposion to the natural environment,and the failure of the dr y joint may occur earlier due to the corrosion.A kind of keyed joint connected by prestressing tendons and high-strength bolted connection,bas ing on the usual connecting form of joint,the outstanding toughness of RPC and the form of bolted connection in steel structure,was promoted in order to promote the safet y,durability and mechanical propert y of joint in prefabricated assembly bridges,flexure tests,theoretical analyses and finite element analyses were conducted to investicate the flexure performance of the composed joint connected b y prestressing tendons and bolted connection,the accomplished work and conclusion is as follows:(1)Material testing of RPC,reinforcement and bolted connection adopted in the flexure test were conducted,three segmental RPC joint beams with composed joint and seven RPC beams with different experiment parameters were designed for the flexure test.The result s show that the phenomenon of failure of joint connected b y prestressing tendons and bolted connection consists of the crush of RPC in the top region of joint,the shearing failure of high-strength bolts in bolted connection and the obvious opening in the bottom region of joint.(2)The epoxiy glue daubed in the RPC surface of joint can not only increase the opening load,slipping load and flexural capacit y of joint,but also can promote the latter flexural rigity of RPC beams with composed joint,however,the anomalous enlarging of bolt holes in connecting steel plates will apparentl y weaken the flexural behavior of composed joint.(3)Simplified computational formulas for the opening load,slipping load and flexure capacit y of joint connected by prestress ing tendons and bolted connection were proposed basing on the bearing feature of the joint,whose results in general agree with the characteristic load when being compared,the computational formulas can give conservative prediction of characteristic load to the composed joint due to not giving consideration to the contribution of bonding effect b y epoxiy glue daubed in the RPC surface of joint,more flexure test of the joint connected by prestressing tendons and bolted connection are suggested to the appli cability of the formulas.(4)Finite element models were set for the specimens,basing on the data of material testing of RPC,reinforcement and bolted connection adopted in the flexure test and the modeling approach es of relative research es,and the analytical results were able to show the bearing feature and to predict the characteristic load of the composed joint.