This paper addresses the problem of estimating in situ the force output of fluid dampers when installed in structures for vibration reduction due to seismic and wind excitations. The paper first presents results from a comprehensive experimental program on medium and large-size fluid dampers in an effort to extract their force output during cyclic loading by simply measuring strains on the damper housing and the end-spacer of the damper. Subsequently, the paper discusses various practical issues associated with the proposed technology, including the use of weldable strain gauges, temperature effects, and the efficiency of commercially available velocity transducers. The experimental program concludes that the proposed technology is promising for monitoring in situ the force output of fluid dampers and detecting possible loss of their energy dissipation capability.
