Large-Scale Wave Flume Experiments on Highway Bridge Superstructures Exposed to Hurricane Wave Forces

Recent failures of United States (US) coastal highway bridges during hurricane events have shown the need for improved modeling and analysis of storm induced wave forces. Failures mostly consisted of bridge superstructures being partially or in some cases completely removed from the supporting elements. Damage was attributed to elevated storm surges that enabled larger waves to reach the superstructure and to inadequate connection designs. Previous research on wave forces for bridge structures used small-scale experiments on the order of 1:15 to 1:20 with essentially rigid bridge models (neglecting realistic fluid-structure interaction). A new innovative large-scale laboratory setup has therefore been developed that enables realistic simulation of storm-induced wave forces on bridge superstructures. The experiment was conducted in the 104 m (324 ft) long wave flume at Oregon State University. The test setup employs guide frames attached to the flume walls that support a 1:5 scale reinforced concrete girder bridge superstructure model. The horizontal stiffness of the bridge substructure (bent columns and cap) can be varied by the guide system to represent different dynamic properties of the supporting structure to enable measurement of fluid-structure interaction. These experiments provide needed large-scale data for wave induced forces on bridges to validate design and analysis methods. First observations and a set of measurements for the rigid case (phase I) and a flexible case (phase II) exposed to a set of regular waves are presented and discussed.