This paper presents results from a comprehensive experimental program on medium-size and large-size fluid dampers in
an effort to extract their force output during cyclic loading by simply measuring the strain on the damper housing and the
end-spacer. The paper first discusses the stress path within the damper and subsequently via the use of linear elasticity
shows that the experimental data obtained with commercially available strain gauges yield a force output of the damper
that is in good agreement with the readings from the load cell. The paper then examines the performance of a portable
data acquisition system that can be used to collect and transmit data from a damper installed on a bridge to a nearby
location. The data show that the proposed arrangement is promising for monitoring in-situ the force output of fluid
dampers and detecting possible loss of their energy dissipation capability.