Seismic retrofitting is the adjustment of existing structures to make them more resilient to seismic activity, floor motion, or soil failing due to earthquakes. With better knowledge of seismic demand on structures and with the recent experience with large earthquakes near downtown centers, the need of seismic retrofitting is well acknowledged. Earthquake engineering is applied for the seismic retrofit of structures that involves alteration of existing structures to obtain level of resistance to seismic activity or soil failure due to earthquakes. Retrofit is now widely performed, particularly in the active seismic areas and specific zones.
Seismic retrofitting is a field of construction executive that targets the changes of existing structures to enhance their capacity to withstand earthquakes. It is gained by the inclusion of structural improvements that may prevent the building, people, and the equipment from damage by seismic dunes. In seismic zones, retrofitting may be essential for bridges, overpasses, tunnels, and buildings. While new structure would require compliance to seismic standards.
Seismic retrofitting may be executed on concrete masonry, unreinforced brickwork, soft story and solid tilt-up construction. Soft account building is a multi-story building with abundant open up space and in concrete floor tilt-up construction. Concrete is filled in the systems that form the wall surfaces of the structure. Because the concrete tilt-up walls are usually heavy, seismic retrofitting may be necessary. The objective for the concrete tilt-up retrofit is to prevent the separation of the roof from the building walls. Santa Monica soft story
There are several types of seismic retrofitting and their nature depends after the purpose which is why the retrofit is executed. The main form is the population safety retrofit involving strength reinforcement to save individuals life though some level of injury is suitable. Such retrofit is performed on structures which are not extremely expensive and for which a complete rebuild is not desired. A lower level re-fit may be selected to ensure earthquake endurance of the structure with some repairs needed after the earthquake. Extensive retrofit may be important for buildings that are important due to cultural, historical or other reasons. Mostly, retrofit is conducted on buildings that are extensively high, with a hazardous earthquake oscillation frequency. Roads also have a priority in re-fit because their service is vital during an earthquake in order that the function of emergency services.
There are numerous techniques that are being used for the seismic retrofitting of set ups. Their selection is centered on the objective of retrofit, form of structure, ground conditions and the expenses involved. Seismic retrofitting of buildings may reduce the earthquake damage by appropriate structural modifications, but no technique will completely eliminate the risk of seismic waves. Reinforcement of the buildings by the use of girders and trusses are normally implemented to make the buildings safe. Base isolators are used to decouple the structure from the shaking ground, thus reaching seismic vibration control. Supplementary dampers minimize the structure resonant effects, improve the energy dissipation and lessen the displacement of set ups. Other retrofit techniques are the use of absorbers and baffles to make the building protected from an earthquake.