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8 <br /> • <br /> Drew Martin <br /> From: Drew Martin <br /> Sent: Monday,April 02, 2018 4:51 PM <br /> To: 'Gary.oleary@skotdal.com' <br /> Cc: Tony Lee <br /> Subject: 2828 Colby(Permit#61801-002): Second Review <br /> Gary, <br /> I've reviewed the responses for the structural portion of the design. There are still some items that the structural <br /> engineer needs to address. I called Dale Kaemingk at ENW and discussed the items with him. He said his team can <br /> address the remaining items. Please forward these comments to ENW. Comment numbering generally matches the <br /> original letter. <br /> In addition to the comments below,we are requiring structural observation to be performed on this project due to the <br /> past modifications and complex load paths. A note requiring structural observation by the structural engineer should be <br /> added to Sheet S0.1 in accordance with IBC Section 1704.6.1 Item 5. <br /> Remaining Structural Comments <br /> i.. The spacing of the foundation anchor bolts should be specified. See Detail 5/S1.1. <br /> t/5aAcalculation for the connection, most notably the breakout of the bottom of the beam, should be provided. The <br /> design should address how the connection affects the shear capacity of the existing concrete moment frame beam, <br /> particularly for shear. The additional comments are provided for the EOR's consideration: <br /> i. We recommend that the detail specify solid-grouting of the holes around the through-bolts. <br /> ii. Depending on fabrication and fit-up,the vertical angles may not bear uniformly on the through-bolts. One <br /> way to address this is to provide welded washers that can be placed in-contact with the top-sides of the throughbolts, <br /> and field-welded to the angles prior to installing the structural framing and flooring,to ensure uniform loading of all <br /> through-bolts. Detailing and sequencing, whether by field-welded washers or another approach,shall be determined by <br /> the EOR. <br /> 5437The existing concrete beam on Grid F/2-3 must act as a self-supporting member spanning between columns once the <br /> in-fill is constructed and the support from the existing W14x61 is removed. It appears possible that the beam may be <br /> supported by the adjacent construction rather than supporting itself. However, it is noted that there is limited <br /> connection between the concrete beam and the hollow-core floor panels. Additional calculations for the beam should <br /> be submitted for review verifying the strength and integrity of the spliced beam to span between the columns. The <br /> following comments and recommendations are provided: <br /> i. The flexural strength of the beam should be checked considering the reduced lap length (i.e.embedment <br /> depth) of the reinforcement. The reinforcement should be placed sufficiently near the existing reinforcement to provide <br /> an effective lap. The reinforcement strength should be based on the existing steel and concrete properties as these will <br /> limit the capacity. The design should consider loads that are expected to be tributary to the beam (e.g., in-fill, etc.) <br /> ii. The shear strength of the beam should be checked. Due to the stepped cut in the existing beam,the shear <br /> capacity should be based on the minimum beam depth at any point. The capacity should be based on the steel and <br /> concrete properties of the existing section as these will limit the capacity. Note that the shear capacity through the <br /> interface is a concern since the existing stirrups are not full-height. It is recommended that the existing beam be <br /> demolished back to a planar surface to provide improved splicing. <br /> 1.„ <br />