Laserfiche WebLink
<br />Design <br /> <br />If the floor diaphragm or connections are determined to be <br />unable to withstand the increased loadings, the designer <br />could strengthen these components by: <br /> <br />. adding a new plywood layer on the bottom of the <br />existing floor diaphragm; <br /> <br />. increasing the number and size of bracing within the <br />floordiaphr.agDn;and <br /> <br />. increasing the number and size of connections. <br /> <br />Step 4: Analyze existing foundation, <br /> <br />The existing foundation should be checked to determine its <br />ability to withstand the increased gravity loads from the <br />elevation, the increased lateral loads due to soil pressures <br />from potential backfilling, and the increased overturning <br />pressures due to seismic and wind loadings. The designer <br />should tabulate all of the gravity loads (dead and live loads) <br />plus the weight of the new foundation walls to determine a <br />bearing pressure, which is then compared with the allowable <br />bearing pressure of the soil at the site. Not including <br />expected buoyancy forces in this computation will yield a <br />conservative answer. <br /> <br />If the existing footing is insufficient to withstand the addi- <br />tionalloadings created by the elevated structure, the design <br />of foundation supplementation should be undertaken. The <br />foundation supplementation may be as straightforward as <br />increasing the size of the footing and/or more substantial <br />reinforcement. The designer may refer to the ACI manual <br />for footing design, recent texts for walls and footing design, <br />and applicable codes and standards. <br /> <br />Engineering Principles and Practices of Retrofitting Flood-Prone Residential Structures <br />January 1995 <br /> <br />VI- E,41 <br />