The Beijing National Stadium is designed to resist both typical building loads and earthquake loads.
The structure must resist a total of 56,625 tons of vertical load. The Steel structure itself must resist its own load of 42,000 tons and 11,625 tons of live load, totaling in 53,625 tons. The Plinth type of the foundation is essential to carry such a load, which is fairily evenly distributed.
Each member of the steel “Nest” is designed carefully to carry its own weight of 42, 000 tons loads. The overall shape appears to be random, but in reality it follows strict geometric rules.
The loads at each intersection are split between the members and transferred downward as indicated below.
The red points indicate the transfer connections were load impact is felt most significantly. The below image identifies the primary and secondary members. the secondary members had to be welded on two sides of primary members. The steel envelope is constructed of 22.5 miles of steel and it took about 700 welders to complete the task.
The core portion of the building carries the dead load of the concrete structure as well as the live load of people totaling to 13,122 tons. The load is transferred directly to the plinth foundation as distributed load as shown below.
The massive steel structure resists lateral loads in a similar manner as the horizontal ones. In addition, instead of the loads hitting the structure and following it downwards and upwards it is broken down through the lattice of steel while being weakened and providing natural ventilation in the building.
The Beijing National Stadium was designed with earthquake loads in mind, because Beijing is prone to seismic events. The outer steel structure is completely separate from the inner stadium seating area and is placed 50 feet apart. this placement allows the two structures move independently in case of an earthquake. Steel has a rather high modulus of elasticity as compared to the concrete, therefore the entire outer structure could be put together as a unit and withstand earthquakes. The core of the stadium was constructed out of the pre-cast reinforced concrete. Because concrete has significantly lower modulus of elasticity, it was decided into eight individual sections. this division allows each portion of structure to move independently of the other in case of seismic motion causing minimal amount of damage. Beijing Bird’s Nest is designed to withstand earthquakes rated at 8.0 on Richter Scale.
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