3315 SEAWAY BLVD 2020-06-05 - Laserfiche WebLink

ENWSTRUCTURAL ENGINEERS Engineers Northwest Inc.,RS. 14.The structural calculations include the isometric view of the FEM used to perform the design. The FEM does not include the dead live loads on the platform from the stairways. The FEM shall be revised and the structural design re-evaluated. The structural drawings shall be revised as needed. See IBC Sections 1604.4 and 1613.1, and ASCE 7-10 Section 12.7.3. Response: The live and dead load of the stair has been added at the supporting columns. Please see attached 3D view of the design model along with comment response #12-a. 15.The structural calculations state that the lateral force resisting system is a steel ordinary concentrically-braced frame. However, the drawings specify moment frame connections between the beams and columns at Grids B/4, C/1, and C/4 on Plans 1/S1.1 and 2/S1.1. The connections are not provided to exclusively facilitate cantilever support of the stairway framing, and lateral bracing is not provided at locations specifying moment connections. The FEM in the structural calculations indicates two-way bracing at each level for the full height of the structure on Grids B/2- 4, 2/B-C, and 4/B-C. The FEM does not include moment frame connections. Furthermore, the use of moment frames is not permitted in Seismic Design Category D per ASCE 7-10 Table 12.2-1 Item C.4, and it does not qualify for use per Section 12.2.5.6.1. The structural drawings shall be revised for consistency with the structural calculations. See IBC Sections 1603.1, 1604.4, and 1613.1. Response: All the lateral force resisting system is a steel ordinary concentrically-braced frames. Please see revised plan and details. 16.The columns included in the lateral frames shall satisfy the requirements of AISC 341-10 Section D1.4a in addition to other load requirements. Calculations substantiating the design of the columns shall be submitted for review. See IBC Section 2205.2.1.2. Response: All the columns are designed including the amplified seismic factor, please see attached response. 17. Structural calculations substantiating the design of the diaphragm bracing and connections are not included in the calculations package and shall be submitted for review. The angles are connected to the connection plates though one leg. The design shall consider eccentric loading in the braces and the connections. The brace-to-connection plate design shall include shear lag. The connection plate-to-structural framing forces shall be determined using a generally-accepted method (e.g., Uniform Force Method, etc.). See IBC Sections 1604.1 and 2205.1, and AISC 360-10 Sections D3, E5, F10, and H1, and Chapter J. Response: Please see attached diaphragm bracing connection as well as the angle with shear lag factors. 18. Structural calculations substantiating the design of the tension braces and their connections are not included in the calculations package and shall be submitted for review. The design load for the brace connections shall satisfy AISC 341-10 Section 6a. The connection plate-to-structural framing forces shall be determined using a generally-accepted method (e.g., Uniform Force Method, etc.). The base plates connect to the faces of the HSS columns and shall verify the strength of the column wall per AISC 360-10 Section K1 and Table K1.2. See IBC Sections 2205.1 and 2205.2.1.2, and AISC 360-10 Chapters D and J. Response: Please see attached calculation of all bracing connection. 9725 Third Avenue NE•Seattle,WA 98115 206.525.7560.fax 206.522.6698 www. •ineersnw.com