ANALYTICAL SOLUTION FOR STRESS WAVES OF HOLLOW CONCRETE FILLED STEEL TUBULAR PILES SUBJECTED TO AXIAL IMPACT

The dynamic equilibrium equation of a thick wall hollow cylindrical shell subjected to axial impact is presented within the framework of the theory of three-dimensional axisymmetric elastodynamics. With the boundary conditions on the interfaces, the equal wave speed condition determines that the Bessel function and modified Bessel function are suitable for describing the wave of concrete tube and steel tube, respectively, whereas the equal particle displacement and equal shear stress conditions determine the relationship of the eigenvalues. Analytical solutions of wave speed and stresses of hollow concrete filled steel tubular (CFST) piles are obtained, which are close to those of FEM results. The analysis results show that the maximum interaction shear stresses of generally used hollow CFST piles are much less than the bond strength of concrete tube and steel tube obtained by the experiments.