Understanding Steel Truss Arch Structures

Steel tube truss arches are categorized into planar truss arches and spatial truss arches. Spatial truss arches may feature triangular, rectangular, or trapezoidal cross-sections; among these, the equilateral triangular cross-section is preferred due to its balanced load distribution and superior torsional rigidity. Chord and web members may be constructed from circular steel tubes, rectangular steel tubes, or other structural steel sections, with the angle between diagonal web members and chord members ideally maintained between 30° and 60°.

Truss structures are derived from simply supported beams and exhibit similar internal force distribution patterns: internal forces in chord members are highest at mid-span and decrease toward the supports, whereas internal forces in web members are lowest at mid-span and highest near the supports.

Multi-span truss arches experience negative bending moments at intermediate supports, causing internal forces in chord members to reverse sign or increase significantly; consequently, these areas require special reinforcement. For spatial truss arches, particular attention must be paid to overall stability and torsional performance; for long-span structures, safety must be ensured through appropriate cross-section design and bracing arrangements.