3315 SEAWAY BLVD 2020-06-05 - Laserfiche WebLink

Ms. Nadia Azarova Craft Architects Plan Check Number: B1808-012, First Review October 1, 2018 Structural General: 1. It is understood per discussions with the project architect that the design for the area between Grids E.3-F.6/2.9-4.6 may be revised. The architect has indicated the area will-be revised to provide an independent structure with a 125 psf storage area above the office/laboratory space. Structural drawings showing the revised construction of this area should be submitted for review. Criteria for the design of the structure, including but not limited to the proposed lateral system, shall be stated in the Structural General Notes on Sheet S1.0. Based on the proposed storage loading, it is presumed that the 6-inch slab may not be sufficient for the revised design and should be provided with new foundations as needed. At least two columns for the existing building are located within the footprint for the proposed independent structure; the columns should be seismic isolated from the structure. Calculations substantiating the design of the structure should be submitted for review. Additional comments may be provided pending the review for this portion of the project. See IBC Sections 1603.1, 1603.1.5, 1604.1, 1604.1, and 1613.1,and ASCE 7-10 Sections 12.12.3. Gravity System: 2. Sheet A2.4 indicates that the Second Floor will include blackout curtains. The structural plans do not appear to include framing to support the curtain. The support requirements for the curtains should be clarified. Drawings and calculations for supplemental framing should be submitted for review as needed. The calculations should evaluate the existing roof structure to support the additional loads as needed. See IBC Sections 1603.1 and 1604.1. Lateral System: 3. The lateral forces for the mezzanine are calculated on page 2. See IBC Section 1613.1 and ASCE 7-10 Section 12.7.2. The following comments should be addressed: a. The exterior tilt-up concrete walls include an architectural stud framed wall. The wall weight should be increased. b. The mezzanine area appears to include interior partition walls. The floor seismic weight should be increased to 32 psf to include the 10 psf partition weight. 4. Note 3/S2.1 specifies that the sheathing nailing is 0.131" nails (i.e.,8d). Calculations page 5 considers 0.148"nails (i.e., 10d). Note 3 should be revised. In addition, verify that the grade of the truss top chords is equal or greater to DF-L. See IBC Section 2306.1 and AWC SDPWS- 15 Table 4.2C including Footnote 2. 5. The diaphragm has been designed to span in the east-west direction between shear walls on Grids F.6 and G.9 per calculation page 5. The diaphragms provide out-of-plane support to the concrete wall panels and include one half of the wall height in the effective seismic weight for the diaphragm. Based on the relatively shorter height of the mezzanine level and shorter span of the mezzanine diaphragm, in comparison with the roof diaphragm, it appears that the mezzanine level may result in a substantially-stiffer lateral load path that attracts additional seismic weight from both the panels and potentially the roof diaphragm. A stiffness analysis of (Page 3 ofiTh CITY OF EVERETT • 3200 Cedar Street • Everett, WA 98201 • (425) 257-8810 • Fax(425) 257857