3315 SEAWAY BLVD 2020-06-05 - Laserfiche WebLink

MIME 111110111111111 MEI MINI the west wall of the office. The total for each end will be about 20 pounds. This loading can easily be included in the miscellaneous portion of the loading used in the structural design. The ceiling grid will support this loading and transmit the loading to the floor joists. 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. DCI Response:The weight of the exterior wall has been increased to include the furred-out wall.The mezzanine seismic weight has also been increased by 10 PSF for the partition loading. The seismic design has been updated to account for the increased seismic mass. See updated calculations sheets 0-2 thru 0-10. 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. DCI Response: Plan note 3 on sheet S2.1 has been updated to require 0.148"diameter nails to match the structural design. DCI Engineers has contacted Red-Built and they have confirmed that the top chords have a minimum specific gravity of 0.50 which matches the specific gravity of DF-Larch. 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 the diaphragms should be performed to determine their deflections and verify if additional load will be attracted to the mezzanine level. See IBC Sections 1613.1 and ASCE 7-10 Section 12.7.3. DCI Response: For loading in the E-W direction there are building shear lines on grids A, F, G and M. The shear lines on grids F and G greatly reduce the"span"of the roof diaphragm and stiffen the roof diaphragm such that the roof diaphragm is roughly equivalent in stiffness to the mezzanine diaphragm. DCI Engineers is satisfied that assigning 50%of the wall height seismic mass is acceptable for the design submitted. 6. Sheet S2.1 specifies connection of the diaphragm to the concrete wall panels using 5/8"diameter threaded rods with a 5"embedment at 18"on-center. Calculations substantiating the connection should be submitted for review. Note that the connection forces have been calculated using ASD load combinations; LRFD-based loads shall be used to verify the anchorage design. See IBC Section 1901.2 and ACI 318-14 Section 17.4, DCI Response:Anchorage calculations for the strapping of the wall to the floor diaphragm has been performed. See updated calculations sheets 0-11 and 0-29 thru 0-35.