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Project No.: 219.007-24 DATE : 02/05/24 <br />PROJECT: Vietnamese Alliance Church PV BY : ESY <br />2022 CEBC Existing Structural Elements Carrying Lateral Load <br />CEBC Section 502.5 for Existing Structural Elements Carrying Lateral Load states that existing structural <br />elements subject to lateral loading (seismic) are permitted to remain unaltered if the percent increase of the <br />demand-capacity ratio of that element does not exceed 10%. This is relevant to work that involves adding <br />seismic mass to the rooftop of existing structures, like equipment or photovoltaic panel systems. <br />Seismic loads at the roof level are calculated by multiplying the weight of the roof and half the height of walls <br />perpendicular to the direction of loading by a seismic coefficient, dependent on site seismicity and building <br />properties. The weight of the components contributing to seismic loading is the “seismic mass” of the existing <br />structure. This means that the seismic mass is directly proportional to the seismic demand on existing <br />structural elements resisting seismic loading of the existing structure. This also means that the weight of the <br />new PV system on the roof is directly proportional to the added demand on existing structural components. <br />The critical element that experiences the largest increase in seismic demand is the diaphragm of the structure. <br />When considering the percentage increase of demand-capacity ratios to all existing structural elements for <br />seismic loading, this analysis compares the added seismic mass of the new PV system to the existing seismic <br />mass of the building to verify that the percent increase of seismic demand to the diaphragm does not exceed <br />this 10% allowance. <br />BRIDGEORIE 2 <br />STRUCTURAL <br />BRIDGEORIE 2 <br />STRUCTURAL <br />BRIDGEORIE 2 <br />STRUCTURAL <br />BRIDGEORIE 2 <br />STRUCTURAL <br />BRIDGEORIE 2 <br />STRUCTURAL <br />Page 5 <br />2130 N Grand Ave <br />10/1/2024