5631 10TH DR W 2021-09-02 - Laserfiche WebLink

Thank you, • • Nathan Crawford On Wed,Jan 8, 2020 at 12:36 PM Drew Martin<dmartin@everettwa.gov>wrote: I Mr. Crawford, la We are working on finalizing the structural review for the proposed project. There are several items that the structural engineer needs to address. At this point, scanned copies of the revised documents may be emailed directly to me. The structural engineer-of-record (EOR)should address the following: 1. The proposed project includes structural design requiring the services of a licensed design professional (i.e.,the design has not been performed using the prescriptive procedures of the IRC). The construction drawings will need to be sealed and signed by the EOR. Note that the structural review stamp included on the drawings is not sufficient;the EOR's WA State-issued engineering seal must be used. See RCW Chapter 18.08.410. 2. The structural design has been performed using seismic design criteria that appears incorrect in our judgement. That said,we are not going to require the EOR to revise the design. However,we are bringing this to the EOR's attention at this time in the event that he agrees and would like to make changes to comply with the criteria listed below. Alternatively,the EOR should submit a statement affirming that in his judgement the seismic design criteria listed in the structural general notes(i.e.,Simplified Procedure per ASCE 7-10 Section 12.14.8,Ss=1.25g,51=0.4, R=6.5) are appropriate for this design. Here are the seismic criteria that should be reconsidered: a. The design has been performed using the Simplified Method per ASCE 7-10 Section 12.14.8. However,the proposed lateral system for attached roof system is not an extension of the main building system (i.e., discontinuity between the roof diaphragm and the main building). The appropriate design criteria for this project is ASCE 7-10 Chapter 13 b. Continuing with the previous comment,the method of attachment is not a shear panel, and therefore does not have the seismic performance characteristics intended by the light shear wall response modification factor of R=6.5 (i.e.,the system does not comply with one of the standard systems Listed in ASCE 7-10 Table 12.2-1). The roof system is an attachment on the primary structure,and therefore the correct seismic design parameters are Rp=2.5 and ap=2.5. Seismic design forces shall be determined using Equation 13.3-1. This will significantly increase the design loads on the bracket and anchorage to the building(e.g., load increase of approximately 6.5x) c. The site-specific seismic design parameters for the project site,as determined using the American Technology Council (ATC) hazard mapping application, are Ss=1.431 and S1=0.545. This 2I