Fragility curves for baffled concrete cylindrical liquid-storage tanks

摘要

Annular reinforced concrete ribs, or baffles, have been used effectively for suppressing liquid sloshing due to earthquake motion in large cylindrical tanks. Meanwhile, these added structural elements may change the structural characteristics of tanks and negatively affect their seismic behavior. In this paper, effects of baffles on the seismic behavior of concrete cylindrical tanks are evaluated. Regarding aspect ratio, three types of tanks including short, medium and tall structures are examined under 9 earthquake ground motions. Seismic fragility curves are calculated for liquid sloshing, vertical crack width due to the tensile hoop force, and bending moment of the tank wall at the base. The results display the structural benefits and costs of baffles in liquid storage tanks. While use of baffles largely decreases the sloshing wave height, it results in a minor increase of the vertical crack width and the base bending moment of the tank wall. The benefit of the decreased sloshing height seems to govern the cost of the minor increase of the mentioned responses.