Static Experimental Study On Splice Joints Of Composite Lower Rib Of Assembled Steel-concrete Open-web Sandwich Plate

The assembled steel-concrete open-web sandwich plate is a more advantageous assembled combined structure developed on the basis of the cast-in-place reinforced concrete open-web sandwich plate.The assembled steel-concrete open-web sandwich plate uses U-shaped steel as the steel elements,and frictional high-strength bolts and WL twin-screw sleeve connectin.It has high bearing capacity,good fire-resistance,good ductility,convenient construction,and green environmental protection Etc.However,in the assembled steel-concrete open-web sandwich plate structure,the splice joint is between the two shear keys and the lower rib bears a large tensile force,so splice joint belongs to the weak link of the structure.Therefore,this paper systematically studies the mechanical properties of the splice joint of composite lower rib under eccentric tension,and mainly completes the following work:(1)Summarizes the calculation theory of assembled steel-concrete open-web sandwich plate structure.Based on the theory of sandwich plate analogy method and practical analysis method,through the analysis of basic calculation examples,the connection and difference between sandwich plate analogy method and practical analysis method,The internal force distribution characteristics of the two analysis methods were compared,it is found that the maximum internal force appeared near the middle of the plate.The results of the practical analysis method were used as reference to design the splice joint of the composite lower rib.(2)The mechanical property test of 7 full-scale splice joint of composite beam with U-shaped steel plate under eccentric loads was completed,and the effects of stud layout and concrete strength on the mechanical properties of splice joint of composite lower rib were studied.By analyzing the load-stress curve and experimental phenomena,it is clear that the splice joint of the composite lower rib has the only one failure mode that the side plate is separated from the concrete,the concrete at the loading end splits,and the steel plate produces large plastic deformation.And the transfer mechanism of splice joint of the composite lower rib under eccentric tension is analyzed in detail.It was found that the stress of the side plate and the displacement of the side plate at the assembly site decreased with the increase of the number of studs and the concrete strength(C40 and C50).(3)Through the problems encountered in the splice joint test and in the actual project,the construction feasibility of the general sleeve connection,welding connection and WL twin-screw sleeve connectin was investigated.It was found that compared with the general sleeve,WL twin-screw sleeve connectin not only can realize the connection of two fixed and non-rotating steel bars,but also allow a alrage tolerance,which greatly reduces the construction difficulty.Compared with the welding connection of WL twin-screw sleeve connectin,the WL twin-screw sleeve connectin can greatly shorten the construction period,the connection is reliable,and there is no welding residual stress.(4)The ABAQUS finite element software was used to simulate the performance of splice joint of the composite lower rib under eccentric tension,and the conclusion that the side plate stress decreases with the increase of concrete strength(C30 to C60)and gluten diameter is obtained.The test results are analyzed and compared to verify the correctness of the finite element model.