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November 5, 2015
The seismic design of fire stations and essential facilities demands that the structural engineer clearly understand the importance of these facilities and the role they play in the disaster resilience of our communities.
Engineering for resilience
Fire stations house apparatus such as engines, ladder trucks, hazmat response and paramedic vehicles, along with their most important asset: the firefighters, paramedics and rescue personnel who live and work there. Consequently, these facilities need to be robustly designed to keep them operational and functional after a severe earthquake.
Our building codes provide minimum force-level and structural detailing requirements, but sometimes the minimum is not good enough.
Engineering for performance
Performance-based seismic design standards have been available to engineers for over 20 years. These standards allow the structural engineer to select a specific level of earthquake shaking and determine the seismic performance of the structure with varying levels of analysis complexity.
The performance-based seismic design standards were initially designed to evaluate and upgrade existing buildings seismically, but they can also be applied to the design of new buildings as a check on the expected level of seismic performance for the building-code level design. Performance-based seismic design standards were originally intended to evolve into the codes for new building design, and their development is moving in this direction.
Essential community facilities, such as fire stations, police stations, emergency services facilities, hospitals, schools and critical infrastructure deserve this level of design analysis for reliability and community resilience.
Learning from failure
Designing fire stations and emergency services facilities to better withstand the effects of extreme events like earthquakes, tsunamis and hurricanes requires that we pay particular attention to how our designs perform in these extreme events. By studying failure, we learn what worked well and what didn’t work so well and how to apply those lessons learned to our designs.
Earthquake reconnaissance is one such tool that allows structural engineers to investigate damage to buildings, bridges and essential facilities, such as fire stations, to determine how to better design these facilities to be reliable and resilient to extreme events.
Communities struck by these extreme events provide a real world example of disaster performance that must be observed and studied to help our profession improve our design capabilities. This firsthand experience then becomes a useful tool to better understand how to design these facilities for better performance.
Collaboration is key
Resilient design is all about effective collaboration among the owner, user, architect and engineers. Fire station programming leads to determination of the type, size, shape and siting of the facility. Station size and shape leads to selection of structural systems that are integral to the architecture and building function. Other building systems such as HVAC, electrical and fire protection play a central role in a fire station designed to continue performing immediately after a significant earthquake. This design for resilience is a collaborative process.
Collaboration also requires effective communication among these multidisciplinary design teams to meet design objectives for the overall facility design and its various systems and components. Over the last decade, building-information modeling (BIM) has provided an excellent tool for the design team to collaborate visually on the design. BIM allows designers to see detail long before it is constructed. As structural engineers, BIM can help us see where other building systems will need to penetrate our structural systems so we can plan for their effects on the performance of the structural systems.
The overarching goal of all of this work is to make our communities more disaster resilient. When fire station and essential facility design teams understand the importance of these facilities and the role they play in the disaster resilience of our communities, we can be more prepared to address their unique seismic design needs.
David Swanson is director of structural engineering at Reid Middleton. Corbin Hammer is a structural engineer at Reid Middleton specializing in the design of essential facilities.