Design Calculation This project uses a program based on the space bar finite element method for design calculation. The 7 areas of the grid are designed separately, that is, the A, D, and G areas are classified as the first type according to the size of the frame, and the B, C, E, and F areas are designed as the second type of frame. Each node is considered as a hinge, and each member is considered according to the axial force bar. The yield stress of steel is 235N/mmZ, the design stress is ZOON/mm, and the allowable slenderness ratio of the rod is 150.
The rod, the node and the support are designed with the high-frequency welded pipe of the bolt ball node grid structure using 60X3.5, medium 7.6X3.75, medium 89X4.O, medium 114X4.0, medium 159x6. The bolt ball is forged with 45 steel; the high-strength bolt is selected with 40Cr steel; the sealing plate, the support and the support block are made of A3 steel; the sleeve is made of Q235, 16Mn, 45 steel. The support of the grid system is a key to the design of the grid. The support adopts the pressure bearing as shown, which can withstand the pressure and the tensile force, and can ensure the hinge characteristics of the upper grid.
Deflection observation Zhuhai International Circuit's large grandstand roof is a large-span cantilever structure. The sides are asymmetrical and the cantilever span is 22m. The design and construction of the grid is difficult. To verify the safety of the grid, the deflection test is carried out. . The coordinates of the grid support are observed by the Leica TC170O total station. The horizontal angles are observed in two rounds. The side length observation is a four-time reading and the average value is taken. The elevation of the grid support is measured by the Soka BZ. precision level according to the accuracy and observation method of the fourth level.
(1) Coordinate observation of grid support: After the grid support is completed, measure the elevation, axis coordinates and offset of the grid support. (2) Grid deflection measurement: After the truss is assembled, the roof is not covered once; after the roof is searched, it is measured again. (3) Observation of settlement and displacement: The observation is started after the roof of the grid is completed, and it is observed once every half month, and once after the strong typhoon.
Each measuring point is arranged on the upper chord node. Each zone is divided into four deflection lines along the longitudinal direction, and four measuring points on the y deflection line from the right are A, Ai: A13 and Ai respectively; As shown by the CI deflection line. The deflection observation results of each point in the C and D regions are as shown. The values ​​in parentheses in the table are calculated values. It can be seen that: (1) the observation result is close to the design calculation result, and the maximum error is 28mm; (2) According to the calculation structure, the symmetry of each area is about symmetrical. From the measured results, the deflection of the C area and the right side is slightly larger than the left side deflection. The description is slightly tilted left and right.
Since the upper chord is not visible, each measuring point is arranged on the roof. Each section takes two edges and three deflection lines in the longitudinal direction. The numbering is similar to the front of the roof covering, but it is not the same. Due to the loss of the reference point, the relative deflection of 3 points is measured based only on the elevation difference between the average elevation of points 2 and 4 and the intermediate point of 3 points. The relative deflection results of the front C deflection line before roofing are shown. The values ​​in parentheses in the table are calculated values.
It can be seen that: (1) Observed deflection and calculated deflection have large errors at individual points, other points are still small, and may be affected by large deformation in strong typhoon; (2) except for E area, each area is still There is a tendency that the right side deflection is greater than the left side deflection, indicating that a certain degree of inclination occurs to the left and right of the frame.
Conclusion This paper introduces the characteristics of the large grandstand grid of Zhuhai International Circuit: (1) The grid is a large cantilever bolt ball node grid structure, which can be designed and calculated by the program of space rod finite element method. (2) The deflection of the grid structure was observed. The upper chord node was observed before the roof covering: the relative deflection of the middle of the cantilever was observed after the roof covering, and the observed deflection error was smaller than the calculated value. (3) It was observed by observation that a certain degree of inclination occurred to the left and right of the frame, but the entire grid was still safe.
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