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Are Singapore’s Buildings Earthquake Proof? Assessing Seismic Resilience

Goh Jun Cheng

Singapore has developed into a city filled with towering skyscrapers and massive developments. But given its location in seismically active Southeast Asia, an important question arises – are Singapore’s buildings designed to withstand earthquakes?

This in-depth article examines Singapore’s earthquake hazard risk, building codes and structural engineering practices to assess the seismic resilience of the city-state’s infrastructure.

Singapore’s Earthquake Risk Profile

While Singapore does not sit on active fault lines, it still faces some degree of seismic risk. Singapore lies about 250km north of the Sunda megathrust fault system where the Indo-Australian Plate collides with the Eurasian Plate.

The collision of tectonic plates generates stresses that occasionally rupture in large earthquakes, causing shaking over wide areas. Historically, large regional earthquakes like the 2004 Indian Ocean quake have been felt in Singapore.

Smaller, localized earthquakes closer to Singapore have also occurred. In 2005, an earthquake occurred just offshore of Sumatra around 270km south of Singapore, rattling buildings. While most local earthquakes have been too small to cause significant damage, larger magnitude ones pose a low-probability but high-impact risk.

Experts estimate that Singapore has a 2% chance of experiencing a quake of magnitude 6 or above in the next 50 years.

Seismic Design in Singapore Building Codes

To mitigate seismic risks and safeguard public safety, Singapore incorporated earthquake engineering requirements into its building codes and regulations. While seismic design only became mandatory in the late 1990s, today most buildings adhere to seismic-resistant design principles.

The code provides standards for designing different building structures – from residential houses to commercial skyscrapers – to withstand earthquake shaking and prevent collapse. Key seismic design specifications include:

  • Minimum horizontal seismic forces that the structure must be able to withstand. Stronger designs needed for taller buildings.
  • Ductility and deformation limits. The structure should flex and absorb shocks within safe parameters.
  • Stability checks for overturning and fatigue.
  • Anchoring and reinforcement of critical structural joints.

Codes require appropriate structural analysis and modeling to demonstrate seismic resilience. Buildings also need thorough planning to address earthquake risks like fires, power outages, etc.

Common Seismic-Resistant Design Features

Based on seismic codes, Singapore buildings utilize various earthquake engineering strategies and features to bolster resilience. Common seismic-resistant designs include:

  • Moment-resisting frames. Beam-column joints with rigid connections provide ductility.
  • Shear walls. Vertical wall elements strengthen the structural core against lateral forces.
  • Base isolation systems. The building is separated from vibrations via dampers/springs.
  • Tuned mass dampers. A heavyweight added at the top counteracts building swaying motions.
  • Buckling-restrained braces. Steel core braces deform without buckling to absorb earthquake energy.
  • Rocking cores. The core tips safely to dissipate seismic force.

Older Buildings Lack Seismic Design

Although today most buildings comply with seismic codes, older buildings constructed before the 1990s generally lack seismic-resistant design. This leaves them vulnerable to strong earthquake shaking. Some ways Singapore tries to mitigate risks in older buildings:

  • Selective retrofitting to strengthen critical structural weaknesses.
  • More regular structural assessments and maintenance regimes.
  • Lower occupancy limits and avoiding usage for critical functions.
  • Monitoring programs using sensors to detect damage early.

Ultimately, rehabilitation or rebuilding is the best approach for deficient buildings. But it is often costly or infeasible. Therefore, risks remain higher in older buildings.

Challenges in Seismic Assessment

While Singapore has made progress, some key challenges complicate seismic vulnerability assessments:

  • No major earthquakes have occurred locally to test Singapore buildings fully.
  • Building plans of older structures are sometimes unavailable for analysis.
  • Detailed structural simulations require time, expertise and resources.
  • Private owners may avoid voluntary retrofits due to high costs.
  • continuously evolving building codes and engineering knowledge.

Ongoing Research and Development

To enhance seismic resilience, Singapore spurs continued research and development:

  • Researchers are studying the performance of local building structures through shake table experiments and computer models.
  • New technologies like structural health monitoring systems and sensors are being developed and deployed.
  • Advanced materials like engineered timber and innovative dampers are being tested.
  • Construction firms are improving seismic construction methods and skills.
  • Outreach programs are conducted to promote community preparedness.

Adopting new research can help Singapore structures withstand future earthquakes. But it takes time to translate into real-world improvements.

Conducting Emergency Response Drills

In addition to long-term resilience, Singapore authorities also conduct emergency response drills to prepare for earthquake scenarios.

Multi-agency exercises simulate search and rescue operations, emergency communications, hospital surge capacity, etc in an earthquake crisis – testing coordination and identifying gaps. By rehearsing plans, agencies hone their readiness to handle seismic events.

Skyscrapers and Land Scarcity

While modern buildings have adequate seismic resilience, Singapore’s land constraints have led developers to build exceptionally tall skyscrapers in recent decades.

Skyscrapers introduce risks as they can oscillate more intensely, and pose greater hazards if damaged.

Implementing advanced damping systems and rigorous design checks is thus critical for super-tall buildings.

But safety comes at higher costs. With limited open space, Singapore has little choice but to build upwards – making resilience an even greater imperative.

Conclusion

In summary, Singapore has a moderate earthquake risk and most modern buildings incorporate requisite seismic-resistant designs following building codes.

However, older buildings represent a key vulnerability which can only be addressed through holistic upgrades or reconstruction. Ongoing research, assessment and preparedness programs are still needed to account for uncertainties and evolving knowledge.

While completely eliminating risks is impossible, Singapore has taken prudent steps to beef up seismic resilience. Moving forward, upholding rigorous building codes,

Constructing for safety over cost efficiencies, and raising public awareness are key to protecting Singapore’s infrastructure and citizens from future earthquake hazards.

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