Experimental Research on the Bearing Capacity of a Steel and Concrete Joint Section in a Hybrid Tower

To investigate the bearing capacity and force mechanism of a steel and concrete joint section in a hybrid tower and on the basis of analyzing the stress of the front bearing plate, rear bearing plate, and plug-in joint section, finite-element models concerning the back bearing plate based on a specified pylon joint section of Yuejiang Bridge in Zhaoqing City were conducted to study the mechanical behaviors of the joint section. According to the calculation results of the model, the shear force of the shear studs in the back bearing plate joint section increases gradually from top to bottom. The farther away from the bearing plate, the greater the shear force borne by the shear studs, and the peak value was reached at the bottom of the joint section. The axial force transmitted by the bearing plate accounts for 68% of the total axial force, and the other axial forces are transmitted through shear nails, which has a good force-transmission effect. An experimental specimen with back bearing plate and with a reduced scale at 1:4 of the single limb of a tower was conducted, and structural deformation and stress distribution were measured. The results show that the existence of a bearing plate and its position in the connection will lead to a different shear force distribution of the shear connectors. The joint section with back bearing plate has an excellent bearing capacity and can transfer force fluently from the steel tower to the concrete tower. The tested specimen basically kept a linear behavior in the whole loading process. The steel plates in the connection hold a gradually decreasing stress distribution downward, while the distribution of concrete is opposite. The maximum relative deformation between steel and concrete was about 0.1 mm in this test. The hybrid connection with a back bearing plate has a good application in engineering. In view of the test results that the stress level of the concrete under the bearing plate was slightly higher, the C60 concrete with steel fiber in the steel–concrete joint section was used to improve the compressive capacity of the structure. At the same time, to improve the stress-concentration phenomenon of concrete at the corner of bearing plate and wall plate in steel–concrete joint section, the trial mixing test and grouting were used to ensure the compactness between steel and concrete, and good use effect was achieved.