10721 19TH AVE SE 2023-04-07 - Laserfiche WebLink

Jeff Heilman,Development Technician--Public Works Department RE: Owner: Wong-- 19'1'Avenue SE ne 20 2018 ages b) The structure is assigned to Seismic Design Category(SDC) D. The walls shall be designed as special reinforced concrete shear walls(SRCSW)with a response modification factor of R=5 per ASCE 7-10 Table 12.2-1 Item A.1. The forces from the wood-framed walls above shall be scaled per ASCE 7-10 Section 12.2.3.1 Item 1. See IBC Section 1613.1. c) The walls shall comply with the reinforcement requirements for SRCSW per ACI 318-14 Section 18.10. See IBC Section 1901.2. d) Performance of the lateral system requires rotational resistance of the concrete walls at their bases by the foundation system. Calculations shall be submitted substantiating that the foundation system provides adequate strength and stiffness to resist design loads from the structure above. See IBC Section 1604.1, 1604.4,and 1613.1, and ASCE 7-10 Section 12.7.3. e) Continuing with the previous comment,the foundation system shall comply with the seismic detailing requirements of ACI 318-14 Sections 1813.2.1. The thickened slab edge shall be designed as a grade beam per Section 18.13.3.1 as needed to provide flexural restraint for and resist uplift on the wall piers. See IBC Section 1901.2. f) The thickness of the wall is not specified on Sheet S2.1 or Detail 12/S4.2. The wall thickness should be specified for clarity. See IBC Section 1603.1. g) The holdowns are anchored in thin walls with minimal resistance to breakout. It is recommended that the top of the wall be reinforced per the requirements of ACI 318-14 Section 10.7.6.1.6. See also comments below regarding the hold own design. See IBC Section 1901.2. a) See added sheet C-28 for garage portal design. b) See response to a) c) See response to a) d) See response to a) e) The holdown anchor bolts are embedded into the footing. The footing is design to resist uplift from the wall piers. J) Sheet S2.1 has been updated to specify the wall thickness. g) The holdown are embedded into the footing. See added sheet C-39 for anchor bolt calculations. 16. The structure includes 2-foot long wood shear walls at the first story on the south side per Sheets S2.1 and A2.1.The following comments should be addressed: a) Structural calculations page C-25 indicates the wall piers are 2.2-feet long.At least one pier in each bay is limited to 2 feet. The calculations should be revised considering the actual length. b) Continuing with the previous comment,the calculation of the holdown force is based on the gross wall length. The placement of the holdowns significantly reduces the moment arm and increased the required tension force,especially for the side with the(4)-stud boundary element per Detail I2/S4.2. The holdown force should be revised. a) The shearwall lengths have been updated. b) The moment arm lengths have been revised. See calculation sheet C-26. 17. The orthogonal shear walls at the southwest corner of the structural appear to share a holdown per the foundation plan on Sheet S2.1. The holdown is positioned to provide direct resistance for the