Thermo-mechanical response of layered perlite beams under transient thermal loading

This paper presents a combined numerical and experimental study on the transient thermo-mechanical response of layered perlite concrete beams subjected to unilateral heating. The motivation arises from the growing application of lightweight, thermally efficient materials in structural elements exposed to temperature gradients, where time-dependent thermal effects may significantly influence deformation behavior. An in-house computational framework is developed that explicitly couples transient heat transfer through the beam thickness with a shear-deformable Timoshenko beam model extended by an axial degree of freedom. The temperature field is reduced to section-level thermomechanical quantities, namely effective axial thermal strain and thermal curvature, which are introduced into the mechanical problem in a transparent and physically interpretable manner. Spatially nonuniform thermal loading along the beam length is accounted for through position-dependent boundary conditions. The numerical model is validated against laboratory experiments conducted on a layered concrete-perlite-concrete beam subjected to controlled top-surface heating up to 35 °C. Measured time-dependent midspan deflections show good agreement with numerical predictions, indicating that the model is able to capture delayed thermal response and thermally induced bending governed by transient heat conduction and material heterogeneity. In addition, a small illustrative nonlinear extension is presented in a purely numerical setting by introducing temperature-dependent stiffness degradation within the same framework. This additional example is not experimentally validated and is included solely to demonstrate the extensibility of the proposed formulation beyond the linear thermoelastic regime. The study should therefore be interpreted as a benchmark linear validation case, complemented by a concise numerical proof-of-concept for extensibility toward nonlinear thermo-mechanical analysis.