Updated Port Wave/Flood Load Building Code Provisions

The Port of San Francisco (POSF) like most other jurisdictions has its own building code for its engineers and consultants to follow during structural design of its piers, wharves, seawalls and other waterfront structures. In 2008, the Port adopted the 2007 California Building Code (CBC, based on the 2006 International Building Code) that contains provisions for wave and flood forces by reference to other standards such as ASCE 7-05 and ASCE 24-06. The 2007 FEMA draft Flood Insurance Rate Map (FIRM) for the San Francisco Bay showed all of the piers within POSF jurisdiction along the waterfront to be located in a Special Flood Hazard Area (V Zone), i.e. area subject to flood risk. Following issuance of the 2007 draft FIRM, FEMA provided a comment period during which the POSF began evaluation of coastal conditions at the POSF waterfront and prepared an appeal for modification of the draft 2007 FIRM. The POSF structural engineers performed calculations of wave and flood forces on waterfront structural elements as part of this appeal using provisions in ASCE 7-05 that provided estimates of wave forces. For some structural elements, the loads provided in the CBC were not sufficiently detailed to evaluate structural impacts, and formulations were not present to evaluate every relevant type of wave loading. The calculated forces were not sufficiently detailed and in some cases over-conservative in determination of wave loads for San Francisco waterfront structures. In order to provide more detailed, complete and realistic wave load provisions for San Francisco waterfront structures and coastal conditions, the Port decided to develop an addendum to the 2007 CBC for its engineers and consultants. The addendum provides more detailed wave and flood load formulations that are typically used in the coastal engineering industry. The POSF commissioned a site-specific coastal engineering analysis and review of waterfront structures present on Port property subject to wave/flood forces. The code addendum contains modern wave/flood force formulations with approximations to ensure a stand-alone section of the building code with an appropriate level of complexity that does not require outside formulations or computer programs. The code development also included coastal engineering analysis of winds, waves and currents and their variability throughout the POSF jurisdiction, and tabulation of these factors for use in design by POSF staff according to the code formulations.