FORMULATION OF HYDRODYNAMIC PRESSURES IN CRACKS DUE TO EARTHQUAKES INCONCRETE DAMS

A new analytical development of the seismic hydrodynamic pressure insi de pre-existing cracks on the upstream of concrete dams is presented. The finite control volume approach is utilized to derive an expression for the seismic hydrodynamic pressure using the continuity principle and the linear momentum theorem for the fluid inside the crack. The de rived pressure expression is a function of the relative crack-opening acceleration and velocity. The acceleration and velocity terms are the n recast in the form of added mass and damping matrices which can then be included at the nodes inside the discrete crack of a finite elemen t model. This procedure linearizes the solution of the problem. A dam, 55 m high and having an initial crack opening of 2 mm at the base or near the crest and subjected to two different accelerograms, is analys ed. For high-frequency ground motion, the seismic hydrodynamic pressur e inside the crack, at the base of the dam, appears to be 50 per cent higher than the corresponding hydrostatic pressure.