In statically indeterminate structural systems, thermal strain (given by the coefficient of thermal expansion multiplied by the temperature change) and misfit-induced pre-strain both generate internal forces and stresses when free deformation is constrained, requiring simultaneous solution of equilibrium equations, geometric compatibility equations, and constitutive stress–strain relationships. Thermal stress is defined as the modulus of elasticity times the thermal strain, arising because restrained members cannot freely expand or contract with temperature change; pre-strain arises analogously when a structural member's fabricated length differs from its required length (misfit) or is deliberately introduced (e.g., via a bolt or turnbuckle with a defined pitch), inducing stress in indeterminate assemblies but not in determinate ones. This belongs to the mechanics-of-materials domain of strain and stress analysis in compound (multi-material) bar and truss systems.
In statically indeterminate structural systems, thermal strain (given by the coefficient of thermal expansion multiplied by the temperature change) and misfit-induced pre-strain both generate interna…