WRK Engineers 12/7/2018 - Laserfiche WebLink

The methodology utilizes a series of checklists to screen for possible seismic deficiencies (i.e. Tier 1 Screening). Checklists are included in the Standard for all of the major structural systems, nonstructural elements and geologic and site hazards. The evaluating engineer addresses each statement and determines whether it is compliant or non-compliant. Compliant statements identify conditions that are acceptable. Non-compliant statements identify conditions that need mitigation or further investigation. WRK anticipates using the previously completed Tier 1 Screenings as the basis for starting their evaluation. However,the WRK evaluation will use the Tier 2 deficiency-based procedures in ASCE 41-17 to address all known non-compliant Tier 1 statements and determine appropriate, cost-effective strengthening measures. As required by ASCE 41-17, nondestructive examination of connections and conditions will be performed during our site walk-through. In addition, default material properties will be used in lieu of performing in-situ destructive testing. The WRK evaluation, and subsequent strengthening recommendations, will consider the BSE-1N earthquake event (10% probability of exceedance in 50 years aka 475 yr. mean recurrence period). In other words, WRK will evaluate the buildings for compliance with a seismic hazard level consistent with the Washington State Building Code for new Risk Category II Buildings. The WRK evaluation will not incorporate a reduced hazard level (i.e. using 75%of BSE-1N) as the City of Everett would like existing and new buildings evaluated using the same seismic force levels for direct comparison. Based on the ASCE 41-17 evaluation, WRK will provide estimates of the expected seismic performance using three critical measures; Safety, Damage (Cost) & Recovery Time. WRK will use the methodology developed by the United States Resiliency Council (USRC) Building Rating system in conjunction with the Earthquake Performance Rating System (EPRS) developed by the Structural Engineers Association of Northern California (SEAONC). The USRC Building Rating system identifies expected consequences of earthquake hazards affecting buildings and translates these consequences into a clear and understandable 1-star(worst)to 5-star(best) ratings for the three critical measure areas. The USRC Building Rating considers the performance of a building's structure, mechanical, electrical and plumbing systems, and architectural components such as cladding,windows, partitions, and ceilings.The performance of these elements significantly affects occupant safety, the cost and time to carry out necessary repairs, and when you can begin using the building again following an earthquake. Building Ratings are based on ground shaking intensity expected to occur during the lifetime of the building and is consistent with the benchmarks in the Building Code. • The SAFETY rating describes the potential for people in the building to get out of the building unharmed after a major earthquake. • The DAMAGE rating(expressed as Repair Cost)describes the estimated cost to repair the building after the earthquake as a percentage of the building's replacement cost. • The RECOVERY rating(expressed as Time to Regain Basic Function) is an estimate of the minimum time required to effect repairs and to remove safety hazards and obstacles to an extent necessary for using the building. Additional time might be needed to restore the building to provide the functions and operations at levels prior to the earthquake. For your reference, the USRC Building Rating definitions for the three critical performance metrics are included below. Highlighted, is the performance expectations that correspond to the 3-star rating,which is consistent with Life-Safety performance. Page 2 of 7