Engineering Infrastructure to Support Societal Resiliency
Electric vehicle weights endangering parking structures.
Converting the US passenger vehicle fleet to electric power is a cornerstone of the national leadership’s proposed response to climate change. The electric vehicle tradeoff of reduced carbon emissions for increased vehicle weight creates a historic opportunity for the engineering and construction industries to adapt infrastructure to support societal resiliency.
While the opportunity is historic, it is not without precedent, and the examples are a call to action by engineers and builders. Recent history provides instances of promising technologies nearly eradicated by early failures. The liberty ships essential for the Allied victory in WWII had early catastrophic failures that only with rapid resolution of welding flaws avoided constriction of the war’s sea lifeline. The 1994 Northridge Earthquake brought a moratorium to welded steel moment frame construction after the temblor revealed the lateral system previously codified as the most ductile system to be brittle. Rapid engineering response produced retrofits of existing frames and developed new joint configurations to make welded steel moment frames reliable as originally believed. Failure to enable the shift to heavier electric vehicles (EVs) may impair one of the most broadly recognized remedial measures for climate change. Engineers and builders have an obligation to provide sound infrastructure for EVs to prevent early catastrophic failures from blighting adoption of the technology.
Obvious infrastructure vulnerable to damage due to increased vehicle weight are passenger vehicle parking garages. While there are other infrastructures, such as bridges and roads, that are also jeopardized by increased vehicle weight, we use parking structures to illuminate the need for action to compensate for the increased electric vehicle weights.
Significantly increasing passenger vehicle weights combined with recently reduced structural design requirements will result in reduced factors of safety and increased maintenance and repair costs for parking structures. The reduced factors of safety will increase the rate of structural deterioration and the frequency of structural failures. Parking structure maintenance and repair costs will increase from heavier wear on traffic coatings, concrete repair of cracking floors and beams, and/or necessary structural strengthening or retrofit of the overall structure. Serviceability will be impaired by increased floor vibrations, increased floor deflections, and visible concrete cracking. These deleterious effects are consequences for code-compliant design and construction; sub-standard parking structures will suffer more.
To develop practical and prudent approaches to mitigate the inexorable increase in passenger vehicle weights, we review the structural effect of the added loads to quantify the risks imposed on parking garage owners, users, and stakeholders. Many existing parking structures need repair, and there is a high probability that they do not meet current or historic code-loading requirements. There are many cases of parking structure failures, and the growing demand for EVs will only increase the probability of failure.