5901 23RD DR W PROVIDENCE 2023-05-22

• ! slab as adequate, we have identified this plywood lid to not have any storage, a 10 PSF ceiling load has been assigned, signage"No Storage"are indicated to be added around the perimeter of this lid. Analysis found the longest 16' span above the oxygen storage was the highest loaded, in particular the 225 pound point load at the mid span of a single joist(2 joists required to carry a 300#point load. Note this highest loaded area does not have any mechanical load. The DL used includes a 5 PSF collateral load for sprinklers, electrical, and HVAC in the dead load. The HVAC ductwork is above the plywood dust lid, not suspended below as there is limited height between the ATC and the framing. Maximum hanger spacing is 6 feet. With the largest 16"duct weighting 5.5 PLF this causes a 33 pound point load on the deck. See M-2 for this support. Design of each support includes the lateral seismic load and overturning moment applied to the ceiling joists. All joists were checked for the worst case of the ductwork. Mechanical equipment of each type has details provided to show the anchorage of such to the dust lid structure, including the seismic forces combined with the vertical loads. All mechanical equipment weighing more than 20 pounds are checked. 4a. Continuing with the previous comment, the interior equipment appears to be both suspended from and mounted on interior wall-ceiling structures that are presumed to be constructed of light-framed walls with GWB sheathing. It is not clear if these structures have sufficient capacity to support the proposed equipment. In addition, these structures likely lack adequate lateral strength for the induced seismic loads. Note that it is not clear how many levels are occurring inside the building. Based on the drawings and photography of the building, it appears there are two levels in the area where the units are being installed. The following comments should be addressed: a. The gravity and lateral framing supporting the units should be specified in the drawings. b. Calculations substantiating the vertical and lateral load paths should be submitted for review. c. Additional structural reinforcement of the interior structures may be required. This will require a separate building permit application to be submitted for review. All structural work should be shown in this submittal if required. Drawings M-1 to M-3 show the framing provided under the primary building permit, with the details showing the attachment of mechanical equipment. M-3 shows the as-built conditions of the wall ceiling/dust lid structures constructed by others. The reviewer is correct that these are 10 foot high light gauge stud framing with plywood lid locating within a large warehouse. Lateral analysis is based on a in house Excel spreadsheet used for 25 years by our office (updated with each code change) regularly used on projects at Naval Base Kitsap and NAS Everett. Recently used for a 10,000 SF 2 story NSST trainer within B2200 at NAS Everett, seismic values are based in the UFC criteria,which exceeds the IBC18 and ASCE 7-16 so some values may be slightly high compared to within the City of Everett. No adjustment for better than Site Class D conditions assumed. Total mechanical equipment weight on the project including ductwork is 1.40 kip. Lateral analysis of the portion of the dust lid supporting our HVAC found a total weight for walls above the mid height and all ceiling/ sheathing loads is 61.26k, so the 1.4 K for mechanical is 2.5%of the total W. Walls resisting seismic forces range from 32%to 98%of the allowable loads. This assumes shear forces resisted by GWB, if a design from our office we would include so sheathed walls, however on this project the HVAC equipment is only 2.5%of the base shear. No structural alterations of this dust lid structure are proposed. Refer to the Excel spreadsheet for vertical loads. All stud properties in the calculations are based on the SSMA Technical Guide. 5. The engineer's response that the reinforcement is spaced at least 18 inches is not correct. This is the common spacing for temperature reinforcement used in