The U.S. Department of Housing and Urban Development (HUD) has specific requirements for seismic risk evaluations for HUD backed projects in seismic zones 3 and 4 based on the 1997 UBC seismic zone maps. A HUD seismic assessment must comply with ASCE 31 and is performed in accordance with the requirements set forth in HUD MAP Guide. It requires engineering input and design, and is much more comprehensive than a damage loss estimate study since it requires structural analysis and calculations.
The evaluation should be provided by a licensed civil or structural engineer with years of experience in seismic design of buildings. The engineer should also have post-earthquake reconnaissance experience and working knowledge of ASCE 31 “Seismic Evaluation of Existing Buildings” and ASCE 41 “Seismic Rehabilitation of Existing Buildings”. This ensures that the Engineer is familiar with the vulnerabilities of the type of structure and considers the workmanship of vintage buildings on their judgment.
HUD seismic risk assessments are comprised of a Tier 1 Evaluation (the Screening Phase), Tier 2 Evaluation (the Evaluation Phase), and Tier 3 Evaluation (the Detailed Evaluation Phase). The screening phase of the evaluation (the Tier 1 Evaluation) begins with a site visit and is used to verify existing data, collect additional data, determine the general condition of the structure(s), and verify or assess site conditions. This phase of the evaluation process is used to identify buildings that comply with the provisions of ASCE 31. When the Tier 1 evaluation identifies a non-compliant issue, the Structural Engineer uses appropriate provisions from ASCE 31 to determine if the building is deficient. In most cases, a "Deficiency-Only" Tier 2 evaluation that addresses only the deficiencies is needed. In some situations, however, a full building analysis and Tier 3 evaluation are needed.