Earthquakes are natural disasters that can cause devastating damage to buildings and infrastructure, especially in densely populated areas like Kathmandu, Nepal. According to the National Seismological Centre, Nepal has experienced more than 500 earthquakes of magnitude 4 or higher since the 2015 Gorkha earthquake, which killed nearly 9,000 people and injured more than 22,000. Therefore, homeowners and builders must design and construct earthquake-resistant homes that can withstand seismic forces and minimize the risk of collapse and injury.
In this article, we will discuss the principles and techniques of earthquake-resistant design and construction, as well as the benefits and challenges of implementing them in Kathmandu. We will also provide some examples of typical floor plans and architectural features for earthquake-resistant homes, as well as some tips and checklists for homebuilders and homeowners who want to make their homes safer and more resilient. Finally, we will introduce Multisewa, a company that offers a range of services for home repair and maintenance, including earthquake-proofing solutions.
What is Earthquake-Resistant Design and Construction?
Earthquake-resistant design and construction is the process of applying scientific knowledge and engineering principles to create structures that can resist the effects of earthquakes without significant damage or loss of function. The main objectives of earthquake-resistant design and construction are:
- To prevent structural failure or collapse that can endanger human lives and property.
- To limit structural damage and deformation that can impair the functionality and serviceability of the structure.
- To reduce non-structural damage and hazards that can affect the safety and comfort of the occupants.
Earthquake-resistant design and construction involves considering various factors that influence the seismic performance of a structure, such as:
- The seismic hazard level of the site depends on the frequency, intensity, duration, and type of earthquakes that can occur in the area.
- The soil conditions of the site, affect the amplification, attenuation, and transmission of seismic waves from the ground to the structure.
- The structural system of the building includes the type, shape, size, material, configuration, and connection of the structural elements that support the building’s weight and loads.
- The non-structural components of the building, which include the walls, windows, doors, ceilings, floors, partitions, furniture, appliances, utilities, and equipment are not part of the structural system but can affect its behavior or pose hazards during an earthquake.
- The occupancy and use of the building determine the level of safety and serviceability required for the structure.
To achieve earthquake-resistant design and construction, various methods and technologies can be used, such as:
- Base isolation: This is a technique that isolates the structure from the ground motion by placing flexible isolation components between the foundation and the superstructure. This reduces the transfer of seismic forces from the ground to the structure and allows it to remain relatively motionless during an earthquake1.
- External reinforcement: This is a technique that adds external steel or concrete structures to reinforce the existing structure and make it more resistant to lateral forces. This increases the strength and stiffness of the structure and prevents excessive deformation or failure2.
- Retrofitting: This is a technique that modifies or upgrades an existing structure to improve its seismic performance. This involves strengthening or stiffening the structural elements or connections, adding seismic restraints or bracing systems, or repairing or replacing damaged or deteriorated components2.
Why is Earthquake-Resistant Design and Construction Important for Kathmandu?
Kathmandu is one of the most vulnerable cities in the world to earthquakes due to its location in a seismically active region, its high population density, its poor soil conditions, its low-quality construction practices, its lack of building codes and enforcement, its inadequate infrastructure and services, and its low level of preparedness and awareness. According to a study by GeoHazards International, a major earthquake in Kathmandu could result in:
- More than 100,000 fatalities
- More than 300,000 injuries
- More than 600,000 displaced people
- More than 60% of buildings were damaged or destroyed
- More than $10 billion in economic losses
Therefore, Kathmandu must adopt earthquake-resistant design and construction as a means of reducing its seismic risk and enhancing its resilience. Some of the benefits of earthquake-resistant design and construction for Kathmandu are:
- Saving lives and preventing injuries by preventing or minimizing structural collapse and non-structural hazards.
- Preserving property and assets by reducing or avoiding structural damage and repair costs.
- Maintaining functionality and serviceability by ensuring the continuity of essential functions and services, such as water, electricity, communication, health, education, and transportation.
- Improving the quality of life and well-being by enhancing the safety and comfort of the occupants and reducing the psychological and social impacts of earthquakes.
- Promoting sustainable development and growth by increasing the durability and longevity of the structures and reducing the environmental and economic impacts of earthquakes.
How to Implement Earthquake-Resistant Design and Construction in Kathmandu?
Implementing earthquake-resistant design and construction in Kathmandu is not an easy task, as it faces many challenges and constraints, such as:
- Lack of awareness and education among the public, policymakers, builders, and homeowners about the importance and benefits of earthquake-resistant design and construction.
- Lack of technical expertise and resources among the engineers, architects, contractors, and workers involved in the design and construction process.
- Lack of financial incentives and support for the homeowners and builders to invest in earthquake-resistant design and construction.
- Lack of regulatory framework and enforcement for the implementation and monitoring of building codes and standards for earthquake-resistant design and construction.
- Lack of coordination and collaboration among the various stakeholders, such as government agencies, non-governmental organizations, the private sector, academia, media, and community groups.
To overcome these challenges and promote earthquake-resistant design and construction in Kathmandu, some possible actions are:
- Raising awareness and education among the public, policymakers, builders, and homeowners about the seismic hazard level of Kathmandu, the potential consequences of a major earthquake, the principles and techniques of earthquake-resistant design and construction, the best practices and examples of earthquake-resistant buildings, and the available resources and services for earthquake-proofing solutions.
- Developing technical expertise and resources among the engineers, architects, contractors, and workers involved in the design and construction process by providing training programs, workshops, seminars, manuals, guidelines, tools, software, equipment, materials, etc.
- Providing financial incentives and support for homeowners and builders to invest in earthquake-resistant design and construction by offering subsidies, grants, loans, tax breaks, insurance discounts, etc.
- Establishing a regulatory framework and enforcement for the implementation and monitoring of building codes and standards for earthquake-resistant design and construction by adopting or updating national or local codes based on international or regional best practices; creating or strengthening institutions or agencies responsible for code development, implementation, inspection, certification, etc.; conducting regular audits or surveys to assess the compliance level of existing or new buildings; imposing penalties or sanctions for non-compliance or violations; etc.
- Enhancing coordination and collaboration among the various stakeholders involved in earthquake-resistant design and construction by creating or strengthening platforms or mechanisms for information sharing, consultation, partnership, coordination, etc.