Deployable Tool to Facilitate Cross-Frame Installation in Highly Skewed and Curved Steel Girder Bridges

Abstract

This paper introduces a novel, cost-effective deployable tool for the construction of highly skewed and curved steel girder bridges that will provide the necessary geometrical adjustments to the adjacent girders for the fit-up and installation of cross-frames. This tool consists of two cables and one hydraulic jack and would be deployed near the location where a cross-frame needs to be installed. The jack would be extended or contracted to rotate the girders such that they are approximately parallel to one another to achieve the desired geometry for the installation of the cross-frame without requiring force-fitting. After the cross-frame is installed, the deployable tool would be released and reused elsewhere. This paper presents a numerical investigation of the efficacy of this deployable tool in facilitating the installation of cross-frames for two prototype bridges: a highly skewed and a curved steel girder prototype bridge. Three-dimensional (3D) finite-element (FE) analyses of the prototype bridges under steel dead load at the construction increment just before the cross-frames would be installed were performed to first understand the challenges in cross-frame fit-up. The deployable tool was then incorporated into the developed FE model to determine the forces in the system throughout its deployment and the installation of the cross-frames. A control sequence for the deployment was developed and evaluated. For the prototype bridges considered in this research, the peak force in the hydraulic jack was 26.6 kN (5.97 k), meaning that off-the-shelf technologies could be used. The peak von Mises stress in the installed cross-frame was 22.4 MPa (3.25 ksi), indicating that the procedure is not overstressing the system. Overall, this research demonstrates the promise of a new tool to facilitate cross-frame installation in highly skewed and curved steel girder bridges and culminates in recommendations on the use of this technology in the field.