Model test verification on structural failure modes observed in Hyogo-ken Nanbu earthquake 1995

Main concern is placed on the effect of vertical thrust from the bottom of footing on a viaduct pier column failure. Small scaled model tests were carried out using an underwater explosion method. In the method, a pulse-like vertical thrust was induced to the bottom face of footing by an explosion of a thin steel wire or a thin aluminum foil charged with high voltage in water. Specimens of RC pier models with a circular, a square or a rectangular column cross section were made by plaster or cement mortar with steel wire reinforcements. Furthermore, specimens of steel tubular pier models were also made of aluminum. Parametric tests were carried out concerning surcharge mass, charged voltage and capacity of condenser. Discussion was made by comparison of the observed failure modes in the Hyogo-ken Nanbu earthquake with those in the test models.