Product Overview:

In this tutorial, we examine the simulation of a composite beam, composed of concrete and steel, under fire conditions using Abaqus for thermal and stress analysis. Both the concrete and steel components are modeled as three-dimensional solid parts.

When reinforced concrete (RC) structural members are exposed to high temperatures, as in fire scenarios, they experience a reduction in structural capacity due to the degradation of the mechanical properties of both the reinforcing steel and the concrete. The composite beam showcases significant advantages over standard bare steel or RC beams, primarily due to the synergistic action between the core concrete and the steel beam.

To effectively simulate the heat transfer behavior of the concrete and steel in this analysis, key material properties such as thermal conductivity, specific heat, and density are utilized. A heat transfer step is employed to model the fire conditions, considering three modes of heat transfer: conduction between the concrete and steel, convection on the outer surface exposed to fire, and radiation. All these heat transfer mechanisms are accounted for, and a fine mesh is essential for obtaining precise results. Following the heat transfer simulation, outputs like nodal temperatures and heat flux are generated.

In the subsequent simulation, we analyze the elastic-plastic behavior of the concrete and steel beams, incorporating the expansion coefficient for both materials. A general static step is employed, along with adjustments to the convergence model. Surface-to-surface interactions with defined contact properties are utilized. The nodal temperatures obtained from the first simulation are applied to the second model to represent the fire conditions during analysis. As the simulation progresses, the fire condition induces stress and strain in both the concrete and steel components.

Upon completion of the simulation, a variety of results—including temperature distributions, stress, and strain profiles—are available for interpretation.