Experimental and Modeling Analysis of Load-Bearing Behavior in Concrete-Filled Steel Tubular Elements with Eccentric Loading

Abstract This research examines the behavior of long concrete-filled steel tubular elements under load, focusing on their deformation and failure mechanisms. The study employs mathematical modeling and laboratory tests to analyze concrete-filled steel tubes (CFST) and hollow pipes of 1600 mm length. The experiments introduce eccentric loading conditions with varying eccentricities of 0, 10, and 20 mm to simulate realistic scenarios. Mechanical properties of the steel and concrete are assessed through separate tests on short pipes and concrete prisms. Mathematical modeling using ANSYS software incorporates the Drucker-Prager model for concrete and bilinear isotropic hardening for steel, with frictional contact between materials. Three models are established: fully loaded CFST, hollow pipes, and CFST loaded only through the concrete core. The study assesses longitudinal and transverse deformations and stress distribution, revealing significant differences dependent on eccentric loading. Results indicate a strong correlation between model predictions and experimental data, validating the methodological approach. The research offers insights into stress concentration areas and interaction between concrete and steel, providing a basis for optimizing the design of tubular concrete structures under diverse loading conditions.