Seismic Response by Variable Damping Finite Elements

The procedure permits the use of strain-dependent modulus and damping values for each element in a finite element representation of the deposit. The use of this procedure is illustrated for a 100-ft layer of sand. The results are compared to those obtained by a one-dimensional wave propagation solution, which also incorporates the use of variable damping. This comparison indicates that the variable damping finite element provides response values in reasonably good agreement with the wave propagation solution. The use of this procedure is illustrated and its results compared to recorded values and to computed values using constant damping finite element solutions. These comparisons indicate that the variable damping solution provides response values that are in somewhat better agreement with recorded values for earth banks than those obtained by a constant damping solution and improved results for deposits underlain by sloping rock boundaries having greatly varying material characteristics.