Are You at Risk When the Next Earthquake Hits?
The New Building Code May Affect Your Answer!
By Perry A. Tabor, P.E.
In California, a building's structural ability to resist seismic activity is a key factor in its continued viability. Assuming that we have another seismic event similar to Loma Prieta - which many experts predict is inevitable - all buildings that suffer "earthquake" damage starting January 1, 2008, would require full engineering studies, including repair documentation in order to comply with the 2007 California Building Code (CBC).
The California Building Standards Commission has adopted the 2007 CBC (Title 24, Part 2), effective January 2008, which includes Chapter 34: Existing Structures, as well as the California Historic Building Code (Title 24, Part 8) and the Existing Building Code (Title 24, Part 10).
Under Chapter 34, all building structural repairs/additions (including seismic damage repairs) will require a complete structural engineering feasibility study of the entire building, both damaged and non-damaged. In addition to the required full documenta- tion and construction design documents, it is also required that the building be structurally upgraded to the 2007 CBC [qualified historic buildings are mandated to meet 75% times the seismic forces prescribed by the 1995 edition of the CBC].
Imagine the bureaucratic aftermath that may result from a 15-second seismic event? It may very well translate to a multitude of commercial/residential building owners awaiting engineering reconnaissance, analysis, design and governing agencies plan approval prior to making the necessary repairs. Meanwhile, businesses will be adversely impacted daily while remaining inoperable, and primary residences will remain uninhabitable with yellow or red tags hanging from their doors. There simply are not enough qualified engineers to meet this spontaneous need that a single seismic event can suddenly impose upon building owners.
Of course, building owners can take the chance that their buildings would not be impacted by a seismic event during their ownership and that they won't be subject to such challenging conditions. Alternatively, there are some reasonable steps that can be taken before the next seismic event occurs. Proactive measures to help mitigate the risk include:
Structural Risk Assessment: Structural site reconnaissance and report identifying the building assembly's structural "weakest links": whether deficient members, incomplete lateral system, insufficient foundation and/or inadequate connections.
Benefit Cost Analysis: Based upon the structural risk assessment, establish probable cost for repairs, economic construction repairs resulting impact upon the current operation, current building value, maintenance cost/extending building cycle, etc. versus probable seismic event occurrence and associated inoperation/repairs during the building's life cycle.
Thus, determine whether to proceed with structural rehabilitation as part of building retention or relinquish the building to reduce liability.
Buildings that were constructed or rehabilitated (entire building) more than 10 years ago will most likely benefit from having a structural risk assessment/benefit cost analysis. Establishing a current building assessment will certainly assist building owners to make the most informed, timely and intelligent decision whether to retain and repair their properties or to relinquish and reinvest.
When (not if) the next Loma Prieta occurs, will you be standing in line with the rest of the masses to hire an engineer to begin the process or have you been proactive by taking appropriate steps to reduce your liability under the current 2007 CBC?
January 2008 Builder Architect Edition Issue