This Small Business Innovation Research Phase I project investigates the feasibility of developing a fiber optic deflectometer. The deflectometer will consist of laser, mounted on a stationary object near the bridge, and an array of fiber optics attached to the area of the bridge where the deflection measurements are desired. Real time structural monitoring of bridges requires a new way to measure deflection. Current deflection measurement methods generally use linear potentiometers that are mounted on the bridge and attached to the ground directly below with a cable. The ground below the bridge acts as a reference against which bridge deflection is measured. This method does not work in most real time applications since bridges usually have traffic or water underneath. This project will develop a new, low cost, deflectometer that does not require access to the ground below the bridge. The fiber optic array can be configured to provide varying degrees of sensitivity. Individual fiber optic strands will be laser interrogated and any vertical displacement of the bridge, while subject to static or dynamic loads, will be detected and recorded. The new deflectometer will provide advancement in technologies for bridge condition assessment and reliability investigations. New sensors, including fiber optic strain gauges have recently been applied to bridge structural monitoring. These devices have proven successful in monitoring strain in structural components of the bridge but do not provide displacement data. A reliable deflectometer, in addition to strain gauges, is needed to measure displacement of the bridge in order to make a full structural evaluation. The research will provide a method to measure deflection in bridges and any other civil engineering structure that requires deflection measurements. Government, research institutions, Universities, and construction companies are potential users of the instruments.
