Earthquake Engineering
Earthquake engineering is a specialized field of engineering which primarily deals with the analysis and design of structures that are exposed to earthquake forces. Earthquake engineering is also known as seismic engineering or structural seismology. The basic concepts of structural earthquake engineering are as follows:
Seismic Response of Structures
The primary objective of earthquake engineering is to identify and reduce the seismic risk of a given structure. This requires an understanding of the behavior of structures under the combined action of ground shaking and gravity forces. Seismic design is based on principles of lateral force-resisting systems, which are typically categorized as either “rigid” or “flexible.” Rigid structures, such as moment-resisting frames, are designed to resist seismic forces by virtue of their strength and stiffness. Flexible buildings rely primarily on layers of reinforced concrete to absorb the energy of the earthquake. Both design approaches require that the buildings be able to withstand and dissipate the earthquake energy in a safe and effective manner.
Seismic Design and Analysis
A variety of methods are used in earthquake engineering to determine the seismic response of a structure. These may include static and dynamic analysis, experimental testing, and computer simulation. The overall goal of these techniques is to ensure that the structure is designed to withstand the maximum seismic forces generated during an earthquake without exceeding its load-bearing capacity. When all of the appropriate parameters and constraints are considered, an optimal design solution is then derived.
Performance Based Seismic Design
In recent years, the concept of performance based seismic design has become increasingly popular. This approach involves the identification of physical failure modes and the specification of acceptable levels of damage and repair costs. The seismic design is then tailored to meet these objectives within the context of a risk management framework. As such, a performance based design relies heavily on the expert judgment of a structural engineer for the selection of structural systems, materials, and details that will achieve the desired level of seismic performance.
Earthquake Engineering Research
Earthquake engineering research continues to be an extremely important part of structural engineering. New techniques are allowing scientists and engineers to gain greater insight into the behavior of structures during an earthquake, and to develop better design techniques to reduce the potential damage caused by seismic events. Earthquake engineering research is particularly important in parts of the world that are less seismically active, as it can help ensure the safety of buildings in the event of an earthquake.
Seismic Isolation
Seismic isolation is another relatively recent innovation in earthquake engineering. This technique involves the use of elastomeric or elastoplastic materials to isolate the structure from seismic waves. By decoupling the structure from the ground, the structure experiences less force as the seismic waves pass through. This reduces the potential for damage and allows the structure to remain in service following an earthquake. Seismic isolation can also be used in combination with other seismic design tools such as base isolation and dampers.
In conclusion, earthquake engineering is a complex and ever-evolving field of engineering. While there is still much to be explored and understood, advances in the field are providing structural engineers with more sophisticated design tools to ensure that buildings are safe and effective occupants when exposed to seismic forces.
