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<br />-I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />. <br /> <br />given in Appendix D. A summary of the cases studied and their results are shown <br />on Table V. The compressive stresses in the dam are relatively low for all <br />cases studied and this can be attributed to the low height of the structure. <br />The maximum compressive stress of 215 psi for the repaired dam was obtained for <br />the case of minimum temperature and a full reservoir (unusual loading <br />condition). The U.S. Bureau of Reclamation (1977) recommends a factor of safety <br />of 2.0 for the specified compressive strength and a maximum allowable <br />compressive stress of 2,250 psi for the unusual loading conditions. Given the <br />average tested compressive strength of 5,000 psi and a specified compressive <br />strength of 4,000 psi for the repaired dam, the factor of safety for compressive <br />stresses is 18.6. <br />Tensile stresses in the dam are relatively high for the unusual and <br />extreme loading conditions. With the exception of the extreme loading <br />condition (earthquake) the high tensile stresses can be attributed to the very <br />low temperature of concrete in the dam. Tensile stresses as high as 235 psi were <br />calculated for the case of minimum concrete temperatures and a full reservoir <br />(unusual loading). The U.S. Bureau of Reclamation (1977) recommended that ten- <br />sile stresses do not exceed 225 psi for unusual loading combinations. <br />Tensile stresses for the usual loading condition were only 31 psi as <br />shown on Table IV. This analysis was for the normal water surface elevation and <br />June 14 temperatures. The Bureau recommends that tensile stresses for the usual <br />loading conditions not exceed 150 psi. <br />Although arch dams do not fail catastrophically from temperature induced <br />tensile stresses, cracking can occur in the concrete resulting in increased <br />rates of concrete deterioration. The open horizontal lift joints observed in <br />the dam could possibly be attributed to temperature induced tensile stresses. <br />However, no vertical temperature induced cracks were observed in the existing <br />structure. Any proposed repair scheme for the dam must primarily address these <br /> <br />-23- <br />