Comparative Structural Assessment of Pratt and Warren Steel Truss Bridges under Combined Vertical and Horizontal Loading

This study presents a comparative finite element investigation of six-span Pratt and Warren steel truss bridges subjected to simultaneous ۲۰۰ kN vertical and ۲۰۰ kN horizontal loads. The numerical results indicate that both configurations maintain high structural stiffness and remain within the elastic range under the combined loading condition. The Pratt truss exhibits a maximum vertical displacement of −۵.۳ × ۱۰⁻⁵ m and a peak Von Mises stress of ۸.۶ × ۱۰³ Pa, with stresses primarily concentrated in diagonal and lower chord members near the mid-span region. In contrast, the Warren truss shows slightly asymmetric vertical displacements, with maximum downward and upward values of ۲.۸۱۹ × ۱۰⁻⁵ m and ۲.۳۶۰ × ۱۰⁻⁵ m, respectively, and a maximum stress of ۶.۸۱۳ × ۱۰³ Pa. The addition of horizontal loading introduces secondary interaction effects in the Warren configuration, leading to minor amplification of vertical response due to load redistribution mechanisms. Overall, both systems demonstrate adequate stiffness and safety margins, the Pratt truss exhibits slightly higher stress concentration, whereas the Warren truss provides more uniform stress distribution under multi-axial loading conditions.

کلیدواژه ها:

Pratt and Warren steel truss bridges ، load redistribution mechanisms ، stress distribution