上弦杆 upper chord ; top chord ; top boom

底弦杆 bottom chord ; lowest chord

下弦杆 lower boom ; lower chord ; bottom chord

桁架弦杆 chord ; chord member of truss

受压弦杆 compression chord ; compression boom ; compressive chord member

下弦杆应力 bottom chord stress

平弦杆桁架 flat chord truss

上弦杆件 upper chord member

桁架的下弦杆节点 lower chord panel points