钢桁架桥是一种介于梁与拱之间的一种结构体系，它是由受弯的上部梁结构与承压的下部柱整体结合在一起的结构。由于梁和柱的刚性连接，梁因柱的抗弯刚度而得到卸荷作用，整个体系是压弯结构，也是有推力的结构。

永久性轻型钢桁架桥指的是以桁架作为上部结构主要承重构件的桥梁。桁架桥一般由主桥架、上下水平纵向联结系、桥门架和中间横撑架以及桥面系组成。在桁架中，弦杆是组成桁架外围的杆件，包括上弦杆和下弦杆，连接上、下弦杆的杆件叫腹杆，按腹杆方向之不同又区分为斜杆和竖杆。弦杆与腹杆所在的平面就叫主桁平面。大跨度桥架的桥高沿跨径方向变化，形成曲弦桁架；中、小跨度采用不变的桁高，即所谓平弦桁架或直弦桁架。

Steel truss bridge is a kind of structural system between the beam and the arch, a structure that combines the bending upper beam structure with the compressed lower pillar as a whole. By the rigid connection between the beam and the pillar, the beam is unloaded due to the bending stiffness of the pillar, making the whole system a compression-bending structure as well as a thrust structure.

The permanent light steel analysis bridge is a bridge with persimmon frame as the main load-bearing member of the superstructure. The persimmon frame fold is generally composed of the main bridge, the upper and lower horizontal longitudinal load junction system, the bridge gantry frame and the middle cross brace frame and the bridge deck system.