There were many KK-type joints with double chords made of welded square hollow sections in the National Stadium under construction,which is formed by two trusses from different directions.

• 正在建设的国家体育场两两斜交的主桁架构成了许多双弦杆焊接方管KK型节点,该节点连接焊缝密集,构造极其复杂。