Natural Hazards

Back to Risk Mitigation

Climate change continues to be a top concern globally, as observed weather patterns and associated weather-related events have become increasingly severe in recent years. Natural hazards associated with extreme weather events pose a serious risk to people and critical infrastructure, and industry remains challenged to continue adjusting design-basis hazard parameters and associated design approaches to follow the upward trend in event severity. Examples include updated seismic and wind hazard maps, new hazard maps for coastal storge surge and tsunami threats, new performance-based design techniques for buildings and infrastructure, and re-evaluating and revising design-basis events for critical infrastructure such as nuclear power plants.

At PEC, we are striving to help industry and our clients cope with the increasing risks associated with natural hazards. We help owners assess the vulnerability of their safety-related or mission-critical assets. We integrate seamlessly with design teams in need of specialized technical support or peer review services for protective design solutions. From developing seismic risk rating systems and designing windborne debris barriers to employing advanced computational modeling techniques to look at things like soil-structure interaction and wind-induced vibrations, we stand ready to help you meet your personnel and asset risk objectives to ensure resiliency in the face of natural hazards.

Wind and Windborne Debris

High-wind events, such as tornadoes and hurricanes, produce two distinct and potentially damaging load effects: dynamic wind pressures and windborne debris impact. The dynamic wind pressures induce large lateral loads on buildings and structures, the effects of which can be amplified in urban settings and by certain terrain features. In the case of tornadoes, the wind loading environment is further complicated by the presence of differential pressure drops associated with the rotational nature of the wind event. Windborne debris can come in all shapes and sizes from 2×4 lumber and steel balls to wooden utility poles and automobiles. Once windborne, the debris can gain significant velocity before striking buildings, structures, or people.

PEC engineers leverage advanced computational modeling tools, such as computational fluid dynamics (CFD) and nonlinear dynamic finite element analysis (FEA), to help clients characterize these load effects and quantify asset and personnel vulnerabilities. Once these vulnerabilities have been identified, we can work with your team to devise risk mitigation measures. We have helped commercial nuclear power plants assess vulnerabilities to safety-related structures, systems, and components associated with design-basis tornado events and designed and installed novel debris protection barriers on site. We have used CFD tools to quantify wind pressures on complex building facades in urban environments and evaluated wind-induced vibrations of structural and non-structural components. We also assist clients with storm shelter design, testing, and peer review in accordance with the International Building Code (IBC) and ICC 500 criteria.


The destructive effects of earthquakes on buildings, transportation and lifeline structures, and people present a significant risk both domestically and abroad. Recently in the U.S., seismic risk has experienced a notable and unprecedented uptick in some regions due to the manifestation of non-natural (or induced) seismic events that are believed to be related to landside oil & gas operations. Whether induced or natural in nature, the mechanism by which a seismic event loads buildings and structures is quite different than that for conventional dead, live, and wind loading conditions. Earthquakes shake the ground imparting a kinematic excitation to the base of a structure. This base excitation accelerates the mass of a structure, which, in turn, generates inertial forces and flexes structural members in a dynamic, cyclic manner. Unlike blast events, the cyclic motion of structural members during an earthquake event can last on the order of seconds to minutes and can lead to time-dependent stiffness and strength degradation.

Prescriptive design requirements for seismically resistant structural systems are well-established and often addressed without much difficulty as part of the typical design process. However, situations arise where specialized skills are needed to address seismic hazards. PEC engineers provide owners, contractors, and design teams with these specialized skills, to ensure challenging seismic hazard issues are addressed adequately and do not derail core assessment or design processes. The PEC team has experience conducting ASCE 41 seismic evaluations, developing unique seismic risk rating systems, performing soil-structure interaction and site response analysis, utilizing advanced nonlinear analysis tools to quantify structural and non-structural vulnerabilities, developing in-structure response spectra for design and equipment qualification, and designing complex building façade systems for seismic loading conditions.

Related Resources

Computational Wind Engineering: Modeling Wind Effects in Urban Terrain

Collaborating to Deliver a New Seismic Risk Rating System for the General Services Administration

Beyond-Design-Basis Hazards Assessment and Mitigation at Nuclear Power Plants


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