SOIL-STRUCTURE-WATER INTERACTION OF INTAKE-OUTLET TOWERS ALLOWED TO UPLIFT

A procedure that can be used for preliminary seismic analysis of intak e-outlet towers including soil-structure-water interaction is develope d. The formulation also considers the effect of partial soil-foundatio n separation, a phenomenon of considerable interest for the design of such systems that has not been addressed in the literature. The hydrod ynamic pressure of the water is accounted for through added masses giv en in concise closed-form expressions for easy use in analysis and des ign. The nonlinear equations of motion, based on foundation-soil bond conditions, are solved numerically. The effects of soil-structure-wate r interaction are evaluated for a representative intake-outlet tower. Parametric studies are also conducted in the presence and absence of s urrounding and contained water for typical cases of soil conditions an d tower height-foundation width ratios. The results indicate that hydr odynamic effects are significant and cause an increase in deflections, moments and shears and a decrease in foundation rotation. The study s hows that for short towers, foundation uplift is unlikely to occur. On the contrary for slender towers, uplift is more likely to appear, esp ecially for foundations supported by stiff soil, causing significant d ecrease in moments and deflections. (C) 1997 Elsevier Science Limited.