The inventory of existing buildings in geographical areas subject to potential strong earthquake ground motion is enormous. The Seismic Risk division at MHP assesses the vulnerability of these buildings to assist clients in making informed decisions concerning valuable building assets. These due-diligence evaluations provide earthquake loss or Probable Maximum Loss (PML) estimates, and when appropriate suggest strengthening options, allowing the consideration of seismic risk of commercial assets in real estate transactions.
Considering both site hazards and building features, MHP’s experienced team of licensed engineers uses the latest tools and data available in evaluating building seismic risk. In addition to first hand experience gained through conducting post-earthquake evaluations following the San Fernando, Whittier, Loma Prieta, Northridge, and Nisqually earthquakes, this dedicated team has extensive in-house resources at their disposal. Built on the backbone of MHP’s evaluation of thousands of commercial properties these resources include: ATC 13, FEMA and ASTM E-2026 procedures and guidelines, numerous geologic hazard maps, city and agency seismic safety elements and on-line site hazard references. Significant in-house expertise in detailed, non-linear computer modeling of buildings enhances MHP’s ability to effectively predict building behavior and assess potential risks.
Led by Lance Kenyon and Brad Ferris, the combined experience and resources of MHP enables the firm to complete projects of any size and complexity, from small industrial and retail to high-rise and large portfolios, with capabilities that few firms can match.
The strength of MHP’s seismic risk group lies in the experience and knowledge developed while working on traditional design projects. The firm’s commitment to maintaining an active design emphasis allows those assessing building risks to gain continued insight into current design and construction practices. This interaction between the risk and design groups is a unique benefit that most firms providing seismic risk services cannot offer their clients. The design and building evaluation experience allows MHP engineers to develop and implement seismic strengthening programs that are efficient, appropriate and consistent with the desired performance objectives and risk tolerance of the client.
SOUTHERN CALIFORNIA RETIREMENT
HOTEL
Southern California
Seismic Risk Evaluation-Level 3
TYPE
Level 3 Evaluation
STRUCTURE SPECIFICS
The site consisted of an 8-story concrete framed retirement hotel built over subterranean parking.
CHALLENGES AND NEEDS
An initial, Level 2 evaluation indicated a high seismic hazard and potential limitations in the original structural design. An SEL estimate was produced that exceeded the client’s benchmark. To better determine the seismic risk and potential seismic retrofit solutions, a detailed Level 3 loss evaluation was completed following ASCE/SEI 31-03 (FEMA 310) procedures. Three-dimensional computer modeling of the structural frame was prepared using ETABS™ computer analysis software.
SCOPE OF SERVICE
Earthquake Loss Evaluation (Level 3) for acquisition and potential seismic strengthening. Scenario Expected Loss (SEL) results provided for the 475-Year return period event.
EVALUATION FINDINGS
The results of the in-depth structural analysis indicated that the building meets the Life Safety and Immediate Occupancy performance levels as defined in FEMA 310 and should perform reasonably well in a 475-year return period event. The results allowed a downward revision in the SEL estimate, releasing the client from earthquake insurance or seismic retrofit obligations.
The modeling indicated isolated vulnerabilities in some concrete columns where seismic strengthening would be beneficial. Voluntary strengthening measures were investigated, including carbon fiber-wrap of selected reinforced concrete frame columns and increasing the capacity of the same columns by adding reinforcing steel and concrete around the existing sections.
