Structure System And Load Performance Research Of A New-type Fabricated Steel Box-concrete Composite Bridge

Based on clustered studs connection, a new-type prefabricated steel box-concrete girder bridge has been studied. Through the full-prefabricated technology, this type of bridge can improve the level of bridge industrialization and overcome the distress in concrete box girder, usually caused by weak transverse connection. According to structural characteristics of this new type of bridge, experiment and theoretical studies are carried out. The main work and research results are as follows:(1) Reasonable structural system and details of the prefabricated steel-concrete composite box bridge have been studied, which is composited of open steel box girders and full-depth precast deck panels by clustered studs. A series of standard designs are also provided.(2) Four composite beam specimens are tested to study the influence of the spacing of shear pocket, the degree of shear connection, and the amount of transverse reinforcement. It shows that the sectional normal strain distribution is in accord with plane-section hypothesis in the elastic stage, regardless of the degree of shear connection. With the increase of loading to the plastic stage, the interface slip is increasing. The degree of shear connection has an effect on the beam’s flexural performance. Compared with Beam-B (n/nf=1), Beam-C’s (n/nf=0.65) flexural bearing capacity is reduced by 17%, and Beam-D’s (n/nf=0.74) is reduced by 9%. With the reduction of degree of shear connection, the slip between steel girder and concrete plate is increased. The distribution of slip from the supporting point to mid-span is declining and the slip in shear span is relatively stable, in accord with the distribution of the shear force.(3) According for the influence of partial shear connection, design approaches of the bending capacity and the bending deflection are proposed, which are suitable for the fabricated steel box-concrete composite bridges.(4) A reasonable layout of clustered studs in prefabricated steel-concrete composite box bridge is given. It is suggested that the degree of shear connection should be not less than 0.7, and the spacing between shear pocket should not be greater than 1200mm.(5) Through the beam test and two groups of push-out test, the loading transferring mechanism of clustered studs shear connection is discussed. Trough strut-and-tie modelling, the design method for the transverse reinforcement of shear pockets is proposed.