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Evaluation of numerical models and input parameters in the analysis of concrete dams

pubblicazioni - Memoria

Evaluation of numerical models and input parameters in the analysis of concrete dams

Sono documentate le analisi del caso studio dell’analisi sismica del concio più alto della diga a gravità di Pine Flat (USA) proposto nell’ambito del Workshop on Evaluation of Numerical Models and Input Parameters in the Analysis of Concrete Dams svolto durante la USSD Conference and Exhibition 2018), con l’obiettivo di confrontare i risultati delle analisi fornite da diversi partecipanti valutando i diversi metodi e approcci numerici nonché la dimestichezza nell’affrontare l’analisi sismica delle dighe in calcestruzzo.

The adoption of advanced models of structure-foundation interaction able to reproduce the propagation of seismic waves, taking into account the dissipation effects through the boundaries of the artificially truncated foundation, provides a reliable calculation of the seismic response of the dams, as confirmed in most cases by comparison with experimental measurements. On the contrary, the less complex interaction models used in the common practice nowadays, although well consolidated, reliable and widespread, tend to significantly overestimate the seismic response of dams. The use of such advanced interaction models requires the use of artificial (or absorbing) boundary conditions in order to simulate, using a truncated foundation, phenomena that actually occur in an unlimited domain, such as the propagation of seismic waves.

In the frame of the Workshop on Evaluation of Numerical Models and Input Parameters in the Analysis of Concrete Dams hosted by USSD (United States Society on Dams) Commitee on Concrete Dams and by USSD Earthquake Commitee during the USSD Conference and Exhibition 2018, the case study of the tallest monolith of Pine Flat gravity dam (USA) has been proposed with the aim to compare results provided by different participants to the Workshop, evaluating numerical methods and approaches and the confidence in advanced approaches for the seismic analyses of dam-reservoir foundation systems.The viscous-spring artificial boundary model has been used to solve the case study, using the spring and dashpot elements available in the finite element code Abaqus and computing the effective earthquake forces to apply on the foundation boundaries following a procedure reported in technical literature based on the theoretical solution of the wave vertical propagation problem in an elastic half-space.

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