Improved Finite Beam Element Method to Analyze the Natural Vibration of Steel-Concrete Composite Truss Beam

Based on Hamilton's principle, this study has developed a continuous treatment for the steel-concrete composite truss beam (SCCTB). It has also deduced the SCCTB element stiffness matrix and mass matrix, which include the effects of interface slip, shear deformation, moment of inertia, and many other influencing factors. A finite beam element method (FBEM) program for SCCTB's natural vibration frequency has been developed and used to calculate the natural vibration frequencies of several SCCTBs with different spans and different degrees of shear connections. The FBEM's calculation results of several SCCTBs agree well with the results obtained from ANSYS. Based on the results of this study, the following conclusions can be drawn. For the SCCTB with high-order natural vibration frequency and with short span, the effect of the shear deformation is greater. Hence, the effect of the shear deformation on the SCCTB's high-order natural vibration frequency cannot be ignored. On the other hand, the effect of the interface slip on the SCCTB's high-order natural vibration frequency is insignificant. However, the effect of the interface slip on the SCCTB's low-order natural vibration frequency cannot be ignored.