>Foundation treatment for stopping excessive vortex shedding vibrations of two 75 meter stacks

Two 75 meter high stacks at gas refinery of Iran showed excessive vibrations due to vortex shedding. The amplitude of vibrations reached 80 centimeters during the last vibration episode. Foundation has been on compacted sandy soil. Further due to the rise of the ground water after construction, induced softening and probable liquefaction in the foundation soil. After remedial action, several episodes of high wind speeds have happened in the sue the last one lasting for two days and going up to 54 km hr and passing around the critical speed of 38 km’hr for more than two hours and did not result in vibrations of more than two centimeter amplitude Deux chemineux de 75 meters d’altitude dans un rafinery de gas avait vibrations excessive de vortex. Eamplitude de vibrations attainait 80 centimeters dans la dernier episode. La foundation etait basee sur la sable compressée. En plus, la monte de l’eau soustrain aprés la construction a abouti a la liquidation probable de la foundation. Apres quelque remedication ily a eu, plusieurs episode de forte wends de vitesse de 54 km/h qui durêait deux jours. La vitesse critique de 38 km/h a durée deux heurs. L’amplitude pendant ce temps ne depasse pas de 2 centemeters.