HYDRODYNAMIC ANALYSIS OF A CIRCULARCONCRETE TANK, LAYING THE GROUND
Abstract
A survey run on an assessed large tank farm revealed awidespread pathology [10]: the defect found is a diagonalcrack on the tank wall, not parallel to the main axes of thewall. These cracks located at the link-strike through-wall inreinforced concrete change over time, thus compromising thetightness of structure. According to the classification of G.Mathieu [8], this condition has a severity rating of D (defaultreveals an evolution of advanced degradation of structure incontact with the liquid). These storage tanks meet the vital needs of the population.Their study should allow them to remain functional during andafter an earthquake. This task becomes even trickier when youknow that in a tank partially filled the seismic excitation makesa part of the fluid in motion (which leads to the formation ofsurface waves, resulting in the birth of constraints on thewalls, which can cause damage to the dome and the wall). Thisphenomenon is called the hydrodynamic effect, and itsassessment is difficult. In France, the only normative reference tool was for long theIssue 74 [7] until the advent of the Eurocodes. The latterremained silent on the issue until July 2005, date ofavailability of Eurocode 8, which devotes its part 4 to tanks. InAlgeria, the Regulation imposes taking into account thehydrodynamic effect only for reservoirs whose capacity isgreater than 1500 m3in areas of average and high seismicity. Through this study which is illustrated by a numericalapplication, we will attempt to link cause and effectrelationship between the pathology encountered on the tanksand the fact of not taking into account the hydrodynamic effectin the design calculations of tanks.
