Scaffolding Bracing of Composite Bridges during Construction

Relatively slight bracing of steel girders can significantly reduce the risk of buckling failures before the composite action between steel and concrete occurs. This paper aims at both experimentally and numerically, studying the torsional bracing performance of a typical type of scaffoldings that are commonly used in bridge construction. Minor improvements in the structure of the scaffoldings and in their connections with steel girders were needed for this purpose and are discussed in this paper. In the numerical investigations, the effects of different initial imperfections on bracing properties of the scaffoldings were also investigated. The study was extended to different bridge lateral-torsional buckling slenderness ratios and geometries. Results showed that the proposed system greatly increased the load-carrying capacity of the studied bridges with consideration of lateral-torsional buckling during the construction phase. Brace forces created in the scaffolding trusses were also measured in both the experimental and numerical investigations. Finally, indications of the brace moment versus in-plane moment values for different magnitudes of initial imperfections and lateral-torsional buckling slenderness ratios are given.