Tips For Making Existing Structures More Resistant Against Earthquakes

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The structural integrity of buildings is key for ensuring the safety of occupants and mitigating property damage caused by earthquakes. This is especially true in countries that are prone to seismic activity like New Zealand.

This high incidence of earthquakes is also what pushed New Zealand to introduce the most recent changes in the Building Amendment Act 2016, which are aimed at improving the quality, safety, and resilience of buildings throughout the country. However, older structures built before these new regulations may be more vulnerable to collapse and structural failure simply because they’re following older standards. 

Fortunately, retrofitting existing buildings with earthquake-resistant techniques or structures can help improve their resilience and reduce the potential impact of earthquakes. With the help of professional builders, they assess existing structures for seismic risks and identify areas that require reinforcement. 

If you’re concerned about the structural integrity of your home or office building in the Dunedin area, consider contacting a Dunedin builder to help strengthen the structure. Additionally, check out these retrofitting techniques and additional reinforcements that can fortify existing structures against seismic hazards.

Strengthen Foundations

One of the fundamental retrofitting techniques for existing structures is the strengthening of foundations, usually through underpinning and adding concrete jackets.

Underpinning involves extending the existing foundation to a greater depth or width, which provides additional support and stability. Meanwhile, applying concrete jackets to existing foundations can enhance their load-bearing capacity and resistance to ground movement during earthquakes. It’s also crucial to ensure the proper anchorage of the foundation to the ground, as this helps prevent displacement and ensures the stability of the entire structure.

Add Lateral Bracing

Another effective technique to make existing structures more resistant to earthquakes is the addition of lateral bracing systems. During earthquakes, buildings are subjected to lateral forces that can cause sway and structural instability. With robust lateral bracing systems providing additional support and stiffness to the structure, buildings can better mitigate these often-destructive forces. Some examples of lateral bracing systems are cross bracing and moment frames. 

A cross brace consists of diagonal braces installed between structural elements, such as beams and columns. These are designed to distribute seismic loads and reduce sway, ultimately minimising the risk of structural damage and collapse. On the other hand, moment frames utilise rigid connections between beams and columns to resist lateral movement, enhancing the overall stability of the building.

Improve Building Connections

Weak connections between structural elements pose a significant risk to the overall stability of buildings during earthquakes. These connections can be improved or strengthened using suitable retrofitting techniques to enhance the structure’s seismic resilience. 

Usually, retrofitting techniques for this purpose involves upgrading connections between beams, columns, and other structural components to withstand increased loads and prevent failure. Reinforcement methods—such as the addition of steel plates, anchor bolts, and epoxy injections—can also effectively strengthen connections and enhance the structural integrity of an old building. 

Add Shear Walls

Shear walls are vertical structural elements designed to resist lateral forces and enhance building stiffness. With the strategic addition of shear walls throughout a building, you can optimise the distribution of seismic loads. This reduces structural deformations and improves overall stability. 

In the case of external shear walls, they are installed on the exterior of the building and connected to the foundation to distribute lateral forces and reduce building sway during earthquakes. These walls can be constructed using various materials, such as reinforced concrete, steel, or engineered wood. 

Consider Base Isolators

A new and innovative approach to retrofitting existing structures for seismic resilience is base isolation technology. It makes use of base isolators, which are devices installed between the building foundation and the ground that essentially decouples the structure from seismic waves. 

During earthquakes, base isolators absorb and dissipate seismic energy, which significantly reduces the transmission of vibrations to the building above. This minimises structural damage, as well as enhances occupant comfort and safety, by reducing the intensity of ground motion experienced within the building.

Enhance Non-structural Elements

In addition to strengthening the structural components of buildings, it is essential to address non-structural elements to minimise damage and ensure occupant safety during earthquakes. These include furniture, fixtures, and utilities, which are prone to displacement and damage when subjected to seismic forces. 

Retrofitting non-structural elements involves securing them to the building structure using anchors, straps, or other fastening devices, when possible. Additionally, protective measures such as reinforcing glass windows and facades with laminated glass or impact-resistant coatings can help prevent shattering and reduce the risk of injury from flying debris.

Making existing buildings more resilient to earthquakes is crucial to safeguarding lives and property. Consider these earthquake-resistant techniques and additional reinforcements when retrofitting existing structures. Most importantly, hire expert builders when you plan to invest in seismic retrofitting. These professionals have the expertise to implement proactive measures and ensure the structure passes local building safety standards.

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