Hurricane Andrew: Whatever Happened to My Argument to Abolish Prescriptive Building Codes?

摘要

At the first forensic engineering congress, shortly after investigating damage to residential structures from Hurricane Andrew, I presented a paper on the shortcomings of the prescriptive building code. Specifically, I argued that a prescriptive code is typically based upon past experience, that this experience is out of date as soon as it is acquired, and that prescriptions will always break down at the margins of design innovation. I concluded by proposing that all residential structures in areas of severe hazard be engineered to withstand the expected loads. As noted, Hurricane Andrew damaged houses throughout southern Dade County, Florida. Despite a strict building code, after a 31 year hiatus from major hurricane damage, the region's housing stock proved much more vulnerable than expected. However, setting aside the prevalence of lost roof covering, broken windows, and the complete destruction of mobile homes, relatively few wood-frame houses suffered severe structural damage. Consequently, those that did suffer damage became objects of intense investigation and engineering scrutiny. The results of that scrutiny included changes to the Building Code. While these changes are welcome and necessary, they repeat the historical pattern of codifying elements necessary to fix problems observed in the housing stock that suffered damage. Among these, damage to gable-end walls stands out among issues that led to Code revisions. Presently, with an additional 23 years of experience since Hurricane Andrew, and with more recent experiences from other storms, Florida retains a largely prescriptive Residential Building Code. However, for High Velocity Hurricane Zones, the Code directs the building designer to use the performance standards of the Florida Building Code for Buildings, based upon the International Building Code. Therefore, at least for those areas considered to be High Velocity Hurricane Zones, Florida does not allow for the use of the prescriptions contained within the Code. This paper reviews the Code evolution briefly, and revisits the question of whether and how well a prescriptive code can adequately insure the integrity of residential structures in Florida.