Experimental seismic testing of a controlled rocking bridge steel truss pier

The experimental seismic testing of a 1/5-length scale model, slender bridge steel truss pier was conducted to investigate the use of a controlled rocking approach as a means of seismic protection. The controlled rocking approach allows the pier to uplift from its base, partially isolating the structure, while passive energy dissipation devices (steel yielding devices, fluid viscous dampers) are implemented across the uplifting location to control the response. The controlled rocking approach for seismic protection limits the force demands placed on the bridge pier and deck and can allow the structure to remain elastic during an earthquake, preventing damage, and increasing the probability that the bridge remains operational following the earthquake. The experimental specimen’s design, set-up, and selected testing results are presented. The testing program included the use of three sets of steel yielding devices and a set of fluid viscous dampers while the model was subjected to ground motion records using three components of motion. Experimental results are presented and compared with the expected fundamental behaviour (self-centering, hysteretic behaviour, higher mode participation) which is evident in the experimental results. Comparisons between the experimental results with design predictions and advanced analytical methods (nonlinear time history analysis) are made that show reasonable prediction of response.