In the preliminary design, the designer studied the functions, advantages and disadvantages of various software in detail, and finally decided to adopt ANSYS software through comparison. Because ANSYS has a rich cell library first, the beam and shell shells commonly used in civil engineering have mature units to choose from. Secondly, ANSYS has node coupling and set the rigid domain function, which can simulate the relationship between some components in the calculation model. ANSYS also has the life and death function of the unit, and achieves the purpose of simulating the structural construction process by setting the life and death of the unit. What designers appreciate most is that ANSYS is an open finite element platform that provides APIDL, UIDL and other development tools that allow users to develop professional modules themselves. The calculation comparison program uses Sap2000. Table 1 Structure cycle and frequency Table 1 structure cycle and frequency Serial number Frequency (HZ) Period (s) Serial number Frequency (HZ) Period (s) 1 0.7410 1.34953 16 1.2876 0.77664 2 0.74119 1.34918 17 1.3886 0.72015 3 0.74815 1.33663 18 1.3893 0.71979 4 0.74948 1.33426 19 1.5137 0.66063 5 0.77800 1.28535 20 1.5151 0.66002 6 0.88401 1.13121 twenty one 1.5435 0.64788 7 0.88668 1.1278 twenty two 1.5543 0.64338 8 0.94100 1.0627 twenty three 1.6024 0.62406 9 0.94378 1.05957 twenty four 1.6027 0.62395 10 0.97805 1.02244 25 1.6144 0.61943 11 0.98842 1.01172 26 1.7748 0.56344 12 1.06030 0.94313 27 1.7780 0.56243 13 1.06160 0.94197 28 1.8070 0.55340 14 1.18530 0.84367 29 1.8155 0.55081 15 1.28690 0.77706 30 1.8162 0.55060 Next page ceiling fan on wall,wall ceiling fan,wall Ceiling Fan With Light ceiling fan on wall,wall ceiling fan,wall ceiling fan with light JIANGMEN ESCLIGHTING TECHNOLOGY LIMITED , https://www.jmesclightingfan.com
introduction
The National Stadium is located on the east side of the central axis of Beijing, on the south side of Chengfu Road, in the central area of ​​the Olympic Park. The National Stadium is the main stadium of the 29th Olympic Games in 2008. It undertakes the opening and closing ceremonies of the Olympic Games and the track and field competition. The total construction area is about 250,000 m2. The design of the building is 100 years old, and its "Bird's Nest" structure will become an important landmark in Beijing. The plane above the ground of the building is elliptical with a long axis of 332.3m and a short axis of 296.4m. The main structure consists of a reinforced concrete stand and a large-span steel roof with a convertible roof. The main structure of the roof consists of 48 trusses and intermediate ring beams supported on the surrounding 24 combined columns. The top of the roof is saddle-shaped with a maximum height of 68.5m and a minimum height of 42.8m. The main truss is arranged radially around the ring beam in the middle of the roof. Together with the secondary structure of the roof and the façade, the special structure of the "Bird's Nest" is formed. The main stadium stands with reinforced concrete frame-shear wall structure system and large span steel. The structure is completely disengaged.
Structural analysis
Calculation program selection 
Main content of structural analysis
Calculation model and assumptions
1) All components in the overall model use the beam4 unit in ANSYS.
2) Curved beam and arc beam are simulated by multi-section linear beam element.
Static analysis
The main loads of the structure include: constant load, live load, snow load, wind load, temperature action. The constant load includes structural self-weight, ceiling, sink and horse-course equipment, etc. The live load is determined by the “Building Structure Load Specification†(GB5009-2001) without the roof of the man. The snow load is determined by the “Building Structure Load Specification†(GB5009-2001). Take the 100-year snow pressure in the design base period, wind load report data is used for wind load, and the temperature effect is determined according to the climate statistics of Beijing for nearly 30 years. The building safety level is one level, the importance coefficient is taken as 1.1, and the partial coefficient and combination coefficient are selected according to the Code for Loads of Building Structures (GB5009-2001) and the Code for Seismic Design of Buildings (GB50011-2001).
Seismic analysis
The fortification intensity of the structure is 8 degrees, and the design earthquake group is grouped as the first group. The project site is of Class III. Seismic analysis uses the mode decomposition reaction spectrum method, and the seismic action effect uses the CQC method. The overall model has 120 vibration modes, and Table 1 shows the frequency and period of the first 30 modes. Figure 2 is its main vibration pattern.