ABSTRACT
The support structures for the second stage 3#, 4# boiler fan are both two-storey reinforced concrete frame structures. There are two transverse spans, 3.5 m and 11 m long respectively, and four longitudinal spans, 7 m, 12.23 m, 12.23 m, and 7 m long respectively. The total length of transverse spans is 14.5 m and that of the longitudinal spans is 38.46 m. The height of the first storey is 9 m, with no floor slab; and the height of the second story is 10.4 m; therefore the total height is 19.4 m. In the original design, the frame beam columns of the upper part all adopt C40 concrete. Concrete cover for beam and column is 25 mm thick. Cross-sections of the frame columns are all rectangular sections in the dimensions of 700 mm*800 mm. The longitudinal and transverse cross-sections of the main frame beam are in the dimensions of 500 mm*1300 mm, and the crosssection of beam in secondary floor is in the dimensions of 450 mm*700 mm and 500 mm*1200 mm. There’s no maintenance structure. The foundation is of pile foundation with six piles rectangular bearing platform, and the pile is precast concrete square pile with the section size of 450 mm*450 mm and vertical bearing capacity of 2000 kN for a single pile. The section size of bearing platform is 2600 mm*4200 mm and 2800 mm*4000 mm, the height of bearing platform is 1500 mm. In the original design, the strength grade of concrete for the pile foundation bearing platform is C35, while the that for cushion is C10; the bearing platform foundation cover is 35 mm thick, and the bearing platform foundation is buried 3.0 m deep under the outdoor floor. In this area, the seismic intensity scale of structure isVII, design earthquake group is group II, and site category is category III. So it is considered as
a seriously liquefied site, and vibro-replacement stone pile is used to avoid liquefaction.
