What is Seismic activity?

Seismic activity is the frequency and type of earthquakes in a geographical location over a time period. This assessment also involves understanding the severity of the earthquakes. The movement of the tectonic plates below the Earth’s surface results in the release of energy in the form of earthquakes. Structural design ensures that the seismic activity is considered especially in industrial projects. 

Implications of seismic activity on structural design

Seismic activity profoundly impacts structures and hence needs to be considered while designing. Industrial structural consultants understand the implications and design accordingly, not only for compliance but also for the safety of occupants, operational continuity and protection of the assets.

In the case of seismic activity, the consequences of not considering it are catastrophic. The collapse of the structure, economic losses, loss of finished products, production downtime, and the release of hazardous materials are some of the consequences. However, the most disastrous is the loss of a life.

Seismic Activity – a non-negotiable factor in Structural design

Structural consultants understand the implications of seismic activity on industrial structures and, hence, consider the seismic load on the structure. The seismic hazard assessment ensures that structural consultants design the structures accordingly.

1. The design process starts with analysing seismic hazards at the project site. Seismic zoning helps understand the seismic activity at the site. The National Building Code. IS1893 specifies parameters for seismic design. IS1893-Part 4 specifically provides guidelines for plant and related structures. Some critical industries may need site-specific studies based on geographical conditions and soil types. It takes into account various soil types that amplify seismic waves. The consultants also factor in the possible damage due to seismic activity and ensure that there is no collapse and minimal damage.
2. Structural Integrity: Structural consultants design structures to resist and dissipate seismic forces. They consider the lateral load resistance provided by braced frames, shear walls (made of concrete or steel), and moment-resisting frames.
3. Ductility: Designing for ductility allows structural elements to deform without losing their load-carrying capacity, thus absorbing seismic energy as per IS 13920.
4. Continuity and Integrity: The structural design ensures that all structural elements and their connections work together.
5. Foundation Design: The foundation design must ensure stability. The foundation must be able to transmit the seismic forces from the superstructure to the ground without excessive settlement or failure.

Protecting Critical Assets:

Industries have many valuable non-structural components. Their seismic design is equally critical. Anchorage and bracing help heavy machinery, tanks, pipelines, and HVAC equipment from sliding, overturning, or rupturing during an earthquake. The piping and conduit design must ensure flexibility to prevent breaks or leaks.

Compliance with Codes and Standards

Compliance with codes and standards is mandatory. Moreover, these codes provide guidelines for seismic-resistant structures.

The Economic Perspective

The seismic design may be expensive, but the long-term benefits and safety cannot be overlooked.

Conclusion:

Although translating seismic compliance into a structure depends entirely on structural consultants. So the structural design must consider the seismic activity in industrial projects. However, the safety of the entire industrial facility is a multi-disciplinary effort.