Study on effect of piston system on seismic performance for cylinder gasholder

The cylinder gasholder is a large size complicate mechanic equipment. The weight of piston system increases evidently with cylinder gasholders tends to be large capacity and high pressure. In design, conventional calculation model of seismic response takes the weight of piston system into the main mass, regards the piston system as the negative factors on the seismic performance of gasholder. Bearing the gas pressure, the piston system actually suspends in the cylinder shell with the oil sealing between the piston side and cylinder shell. The spring idler pulleys are set at the ends of piston trusses to fulfill the flexible contact between the piston and the columns in cylinder shell. In this paper, based on the actual construction, taking the piston system as suspended mass, the SM calculation model for seismic design of cylinder gasholder is established. Taking a 300,000 m(3) cylinder gasholder as an example, selecting 3 earthquake waves, the seismic responses for conventional and SM models are calculated. The calculation results show that the piston has a remarkable positive damping effect on the seismic performance of gasholder.