Thermal stress

When heated, substances expand in all directions. The main expansion of solids occurs in the direction of their largest dimension. Thus, for constructions as e.g. bridges, it is important to consider possible deformations due to thermal influences. If structural elements are subject to restraint, stress is caused that is harmful to the structural element and may even lead to total failure. Restraints can be provoked externally, e.g. by lack of expansion joints, or internally, e.g. by unbalanced temperature distribution or differing expansion properties of the compound materials as reinforced concrete, coatings on metal parts or concrete surfaces, etc.