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[� SFA Design Group, LLC <br />®� STRUCTURAL I GEOTECHNICAL I SPECIAL INSPECTIONS PROJECT IMFR23-236 SHEET NO. <br />PROJECT <br />DATE <br />Bankston Residence Underpinning <br />3/1/2024 <br />SUBJECT <br />BY <br />Push Pier Design Requirements <br />CAF <br />Q Structural Narrative <br />The structural calculations and drawings enclosed are in reference to the design of the foundation underpinning of the 1-story <br />residence located in Everett, WA as referenced on the coversheet. The round steel tubes and retrofit brackets are used to <br />stabilize and/or lift settling foundations. The bottom and back portion of the bracket is securely seated against the existing <br />concrete footing. Using the weight of the existing structure, pier sections are continuously hydraulically driven through the <br />foundation bracket and into the soil below until a load bearing stratum is encountered. Lateral earth confinement and a driven <br />external sleeve with a starter pier provide additional stiffness to resist eccentric loading from the foundation. Once all piers are <br />installed, they are simultaneously loaded with individual hydraulic jacks and closely monitored as pressure is applied to achieve <br />desired stabilization and/or lift prior to locking off the pier cap. The piers are required to resist vertical loading from the roof <br />framing, wall framing, floor framing, concrete slab on grade, and concrete foundation. Underpinning the structure will remove <br />lateral resistance provided by soil friction acting on the concrete foundation. Lateral resistance will be provided by passive earth <br />pressures acting on polyurethane backfills encasing piers and soil friction acting on the unpiered portions of the concrete <br />footing/concrete slab on grade and passive pressure acting on the buried footings perpendicular to the piered gridlines. <br />There is no ICC-ES report currently approved for underpinning systems within Seismic Design Category D or higher, thus the <br />entire underpinning system has been reviewed and analyzed and is therefore a fully engineered system complying with all current <br />codes and stamped by a licensed design professional. Deep foundation guidelines, load combinations, special inspection and <br />testing requirements per IBC 2018 have been included. Axial and bending capacities of the external sleeve, analysis of the retrofit <br />foundation bracket, design reductions, and corrosion considerations have been incorporated in all required calculations per AISC <br />360-10. Concrete foundation span capacities have been analyzed per ACI318-14. Bracket fabrication welding has been performed <br />by SafeBasements Mfg Co. conforming to AWS D1.1 performed by CWB qualified welders certified to CSA Standard W47.1 in <br />Division 2. In addition, SafeBasements Mfg Co. has received US99/1690 certification meeting ISO 9001:2008 requirements by <br />ANAB accredited SGS. <br />General <br />Building Code Conformance <br />' g e (Meets Or Exceeds Requirements). <br />2021 International Building Code (IBC) <br />2021 International Residential Code (IRC) <br />2021 Washington Building Code <br />2021 Washington Residential Code <br />Loads <br />Floor Dead Load <br />Wood Wall Dead Load <br />Interior Wall Dead Load <br />Concrete <br />Live Loads <br />Roof Snow Load <br />Floor Live Load (Residential) <br />Soil Parameters <br />Reference Stands <br />Allowable Foundation Pressure (Assumed) <br />City of Everett........ <br />15.0 psf <br />15.0 psf <br />12.0 psf <br />9.0 psf <br />150.0 pcf <br />25.0 psf <br />40.0 psf <br />Conform to IBC Chapter 18 <br />"Soils & Foundations". <br />1500 psf <br />