Seismic load refers to the force exerted on a structure during an earthquake. Seismic load is an important consideration in the design of structures in earthquake-prone regions, as it can cause significant damage or failure if not properly accounted for. Seismic load is calculated based on the expected ground motion during an earthquake, the characteristics of the structure, and the location of the structure.
Different types of seismic load with examples are:
- Inertial load: This is the force exerted on the structure due to the mass of the structure and the acceleration caused by the earthquake. Inertial load is calculated based on the seismic acceleration, the mass of the structure, and the stiffness of the structure.
- Damping load: This is the force exerted on the structure due to the energy dissipation caused by the internal damping of the structure. Damping load is calculated based on the damping ratio and the seismic acceleration.
- Pounding load: This is the force exerted on the structure due to the impact between adjacent parts of the structure during an earthquake. Pounding load is calculated based on the size and location of the adjacent parts of the structure and the seismic acceleration.
- Torsion load: This is the force exerted on the structure due to the rotation of the structure around its vertical axis during an earthquake. Torsion load is calculated based on the eccentricity of the center of mass of the structure and the seismic acceleration.
To calculate seismic load, various factors such as the expected ground motion during an earthquake, the characteristics of the structure, and the location of the structure must be considered. Building codes and standards provide guidelines for calculating seismic load based on the type of structure and its location. The load calculations are typically based on the seismic hazard analysis, which involves the estimation of the earthquake ground motion and its effects on the structure. Engineers may also conduct computer simulations and tests to verify the safety and performance of the structure under different seismic load scenarios.