A significant portion of the total risk mitigation cost is being expended on retrofits of insufficient earthquake resilience of existing buildings. It is therefore necessary to accurately identify buildings that need to be repaired seismically and to make the repair cost-effective. When a decision has been made, seismic retrofitting may be carried out in a number of ways, for example by increasing the load of the system, deformation, and/or energy dissipation capabilities. Standard and emerging retrofit methods will be explored briefly in the following chapters.
Multinational refurbishment methods
Two methods are used in structural revision: a) conventional tactics based on the seismic resilience of existing structures and b) non-traditional approaches to seismic demand mitigation.
1. Past-seen methodology
Refitting is a method to enhance the seismic resilience of existing structures by minimising or reducing the detrimental effects of the construction or building. Any of the methods employed include shear walls, filling walls and steel braces.
2. Adding new shear walls.
One of the most common means of improving the side strength of reinforced cement buildings is by the provision of extra shearing walls. Infill/add new shear walls are also known to be the best and clearest way to improve seismic effectiveness. As a result, non-ductile reinforced concrete frame structures are frequently retrofitted. Additional elements can be used as cast-in-place or precast concrete parts.
3. Steel Bracings in the Design
Steel bracing is another way to reinforce a structure, and it offers similar benefits.
The structural features of the bracing and column attachment are seen below. Where wide openings are needed, steel bracing members may be a cost-effective solution.
4. Non-Traditional Approach
In recent years, some alternative methods to seismic retrofitting have been used. The most common methods are seismic base isolation and the installation of supplementary devices. The use of these techniques in retrofitting is still in its infancy, as evidenced by the scientific literature on the topic.
5. Seismic Base Isolation
The placement between the foundation and the superstructures of flexible insulating systems is part of the technology of seismic basis insulation. The insulating systems reflect and absorb parts of the earthquake energy, which is entirely transferred to the superstructure by reducing their flexibility and energy absorption requirements in a superstructure.
Jacketing is the most common process for strengthening columns. The most popular type of jacket are steel jackets, strengthened jackets, plastic polymer fiber jackets and jackets constructed from high-tension equipment such as carbon fiber, glass fiber and others. The main aim of the jacketing is to: – increase the containment of concrete through transverse/reinforcing fibers, in particular for circular trans-sectional columns; – increase the containment of concrete by transverse/reinforcing fibres, in particular for circular trans-sectional columns.
7. Ground care
Surface treatment has developed largely through trial and error as a common technique. Any of the techniques used for surface preparation are ferro cement, enhanced plaster and shotcrete. This treatment preserves the exterior of the maçonnery, by its very nature, and affects the architecture. Ferro cement consists of a few layers of closely spaced fine rod hardware mesh.
Seismic retrofitting is an important way to protect a number of buildings. Professionals in this field want to write correct design codes as practice code. Earthquake-prone structures have been updated and the different strategies for the seismic upgrade have been addressed briefly.