OPTIMIZATION OF LARGE-SPAN STEEL TRUSSES THROUGH MODIFICATION OF STRUCTURAL FORM

This study addresses the problem of improving the structural efficiency of large-span steel trusses, which are widely used in construction due to their simplicity and adaptability but are often associated with increased material consumption and complex stress states under non-nodal loading. A key issue arises when concentrated loads act between nodes, generating additional bending moments (M) and shear forces (Q) in the upper chord members, leading to unfavorable stress–strain conditions.
To overcome this limitation, the research proposes a constructive approach based on the local reverse bending of the upper chord panels. The knowledge gap lies in the insufficient exploration of how modifying the geometric form of truss elements can influence internal force distribution and reduce material usage. The study investigates two variants of a 36 m span pentagonal steel truss: a conventional model with a straight upper chord and a modified model with pre-bent upper chord panels.
Using numerical analysis in the LIRA-SAPR 2017 environment, both models were subjected to identical static and dynamic loading conditions. The results demonstrate that reverse bending significantly reduces bending moments and shear forces in the upper chord members, leading to a more efficient stress distribution. The optimal performance was achieved at a bending height of f=12 cm.
The findings confirm that this method enhances load-bearing capacity, reduces structural deformation, and decreases steel consumption by up to 10–11% overall and 20–21% in upper chord elements. The proposed solution offers a practical and economically efficient approach for optimizing large-span steel truss design.