Caused due to temperature that induces stresses in bearings and deck joints.

• A. Deformation Stresses
• B. Thermal Stresses
• C. Bridge Loads
• D. Live Load

Answer: (B)

When temperature changes, materials want to expand or contract. If their movement is restrained by bearings and deck joints, this tendency to change size is converted into internal forces within the structure. That conversion of thermal strain into stress is what we call thermal stresses. In bridges, expansion joints and bearing connections control movement; if those restraints are present, temperature variations induce stresses even without any external loads. This is different from deformation stresses, which come from loads bending or compressing the members, or from live loads, which are the weights of traffic. So the described cause is thermal stresses.