In order to increase the earthquake resistance of existing structures, seismic retrofitting of buildings is an essential structural procedure. Since seismic events like earthquakes are unpredictable, a seismic retrofit protects properties and lives by minimising damage and ensuring structural integrity. This blog explores what is retrofitting in construction, its importance and different seismic retrofitting techniques to increase a building’s resistance to earthquakes.
What is Retrofitting in Construction?
Seismic retrofitting strengthens a building’s foundation and structure to handle earthquake forces. When earthquakes hit, older buildings face more risk of damage as they were built before modern quake-resistant rules came into play. To boost a building’s ability to resist seismic pressures and cut down the risk of collapse or major structural problems, retrofitting makes changes to the structure. In earthquake-prone areas, retrofitting can help building owners and residents in several ways. Rather than reconstructing an entire building, retrofitting turns out to be a more cost-effective solution and an instant fix for such issues. Additionally, the retrofitting of structure also helps to withstand other natural hazards such as tornadoes, tropical cyclones, and severe thunderstorms and winds.
Why is Seismic Retrofitting Necessary?
For older buildings which have been built before modern seismic codes were implemented, seismic retrofitting is important to increase its capacity to withstand seismic forces. In addition to saving lives and property, retrofitting helps protect important structures from seismic shocks and conserve priceless architectural history.
Seismic retrofit guarantees the protection and safety of a facility, personnel, equipment, inventory, and structure. It helps in minimising risks and damages of non-structural components. It is necessary to reinforce important structures, such as hospitals, whose services are crucial immediately following an earthquake.
Benefits of Retrofitting:
Here are some benefits of seismic retrofitting:
1. Makes Structures Safer
Buildings that have undergone seismic retrofitting are safer to occupy because they strengthen the structure and increase the building’s resistance to seismic activity. Since buildings may experience intense shaking and ground motion during an earthquake, seismic retrofitting of building lowers the chance of building collapse. Building damage or failure is less likely when structures are retrofitted to withstand stresses and deformation.
2. Prevents Death and Property Damage
Retrofitting reduces the chance that a structure may collapse and therefore reduces the number of casualties and injuries associated with earthquakes. Seismic retrofitting protects property damage, since an earthquake can shake the components of a building in addition to its structural integrity
3. Lowers the Cost of Maintenance and Repair
Since retrofitting reduces the damage caused by seismic events, it can greatly save on the restoration and repair costs after an earthquake.
4. Cultural and Architectural Preservation:
Preserving architectural legacy and cultural identity by retrofitting historic and culturally significant buildings helps ensure that these priceless treasures are preserved for the enjoyment of future generations.
5. Raises the Value of Real Estate
A retrofitted building’s increased safety makes it more appealing to renters and buyers, raising its market value. A structure’s eligibility for insurance coverage can also be improved and compliance with more stringent building codes granted by retrofitting of buildings.
Seismic Retrofitting Techniques and Methods:
Structures can be retrofitted using a variety of methods and strategies, depending on the age, kind, and state of the building. These include strengthening the walls with steel frames, adding reinforcements like braces, beams, and columns to brace the structure, and installing base isolators, dampers, and shock absorbers to absorb seismic energy. Let’s have a closer look at the different techniques of seismic retrofitting.
Base Isolation:
Base isolation is among the most popular retrofitting techniques. As the name suggests, the superstructure and base structure are separated in the base isolation method. This is done by providing a number of bearings or shock absorbers that will absorb movement during seismic activity. By doing this, the building’s chance of collapsing is decreased because it won’t move significantly during an earthquake. It is the most effective method to control passive structural vibrations.
Installing Shear Walls:
Installing shear walls, which are made to absorb and disperse lateral energy during earthquake activity, is another seismic retrofitting technique. Shear walls are frequently positioned in between a structure’s floors and are usually composed of steel, concrete, or reinforced masonry.
Column Jacketing:
The most commonly used technique for retrofitting of building columns is called jacketing, or local retrofitting. There are different types of jackets available, such as steel jackets, fiber-reinforced polymer composite (FRPC), reinforced concrete jackets, etc. Jacketing increases the shear and flexural strength of the structure.
Incorporating Steel Bracing:
Steel bracing serves as a popular method to strengthen buildings against earthquakes. Engineers can place steel braces at key points to give structures more support and stability. This approach cuts down the risk of building collapse when an earthquake hits.
Installing Dampers:
The energy of seismic waves is absorbed by dampers, which lessen the amount of vibration that reaches the building. They are often included into the components of the building, like in the roof or between levels, to lessen the harm that seismic activity can do.
Reduction in Mass:
Seismic forces exerted on a building are lessened when its total weight is reduced. To achieve this, heavy structural elements are eliminated or heavy materials are replaced by lighter alternatives.
Strengthening the Foundation:
Buildings with weak foundations collapse during seismic events like an earthquake. Retrofitting techniques include adding reinforced concrete footings, micropiling, and deep foundation reinforcement.
Anchoring Walls:
In the event of an earthquake, masonry buildings can avoid wall separation and collapse by using steel anchors and ties to secure their walls.
Soft Storey Retrofitting:
Structures with soft stories, or open ground floors, are more likely to collapse. In order to make such constructions more stable, steel frames, shear walls, or diagonal bracing are added.
Conclusion
Seismic retrofit plays a key role in protecting buildings, people, and property from earthquake damage. Thanks to new tech and better engineering, we can now use different seismic retrofitting techniques on buildings based on their weak spots. Besides making structures safer, these upgrades help to increase their durability. As earthquakes remain a threat worldwide, it’s crucial to do retrofitting of buildings before a disaster strikes. Apart from that, seismic retrofitting can cut down on repair costs for buildings after an earthquake. They can also make a property more valuable and attractive to possible renters or buyers.
Mithali Konety