47.5 MB - The Whole Building Design Guide

prior to the onset of this level of flooding. Level 4 is applicable tofacilities affected by all types of flooding, including those that resultfrom failure of dams, levees, or floodwalls.Planning and design to achieve an appropriate level of flood protectionfor critical facilities should include avoidance of floodhazard areas and adding a factor of safety (freeboard) to theanticipated flood elevation. Performance evaluation of a facilityaffected by flooding needs to include consideration of thebuilding response to the following load conditions (fragility functionsmust be developed to relate calculated response to actualdamage states):m Lateral hydrostatic forcesm Vertical (buoyant) hydrostatic forcesm Hydrodynamic forcesm Surge forcesm Impact forces of flood-borne debrism Breaking wave forcesm Localized scour1.3.6 Performance-Based High-WindDesignThe performance objectives for wind hazards, outlined in FEMA424, have been expanded and generalized for performance-basedflood design of critical facilities as follows:Level 1 (Operational): The facility is essentially undamaged and canbe immediately operational.Level 2 (Moderate Impact): The facility is damaged and needs somerepairs, but can remain occupied and be functional after minorrepairs to nonstructural components are complete.CRITICAL FACILITY DESIGN CONSIDERATIONS1-23