Computational Fluid Dynamics Model for Tacoma Narrows Bridge Upgrade Project

The purpose of this work was to validate and apply a commercial computational fluid dynamics code with a hybrid RANS/LES turbulence computational model for a flow past a bluff body ultimately to help in the design of the caisson anchoring system during construction of a new adjacent span of the Tacoma Narrows Bridge. INTRODUCTION The new Tacoma Narrows Bridge will be designed as a suspension bridge and operated parallel to the existing Tacoma Narrows crossing in Tacoma, Washington (see Figure 1). This is the largest suspension bridge built in the USA in the last 40 years, and the first time a major suspension bridge has been constructed parallel and so near to an existing bridge. Fig. 1 Rendering of future new span (shown on left) of Tacoma Narrows Bridge Tacoma Narrows Constructors has commissioned a study involving the use of CFD modeling in support of the Tacoma Narrows Bridge Expansion Project. During the construction of the new caissons a complex, cable-supported anchoring system will be used to control the positions of the caissons located 65 feet from the existing bridge piers. During installation, the caissons will be subjected to current-driven loads and vortex shedding. The CFD model results for the East and West pier configurations will provide input data to the dynamic mooring analysis of the flow-structure interactions to determine the expected and maximum forces on the anchoring system cables. CFD is an especially important tool in this case due to the lack of relevant field measurement data for similar structures or experimental scale model data for similar configurations. PROBLEM DESCRIPTION The forces and moments determined from the CFD analysis are used to guide the dynamic simulation and design a cable-supported anchoring system. A preliminary design of this anchoring system at the east side of the span is shown is Figure 2 with the new caisson (square cross section) on the left Fig. 2 Anchor system design layout for the East side