Advanced Cyber-Physical Test Method for Seismic Assessment of a Retrofitted Motorway Bridge

Abstract eng:
An upgraded hybrid cyber-physical technique was introduced to assess the seismic response of a reinforced concrete motorway bridge and the effectiveness of the friction-pendulum seismic isolation. The two independent roadway bridge was built in the 1960s in Italy and it spans over twelve couples of portal frame piers. Two of the piers (scale 1:2.5) and two seismic isolators setups detached from the piers were constructed at the European Laboratory for Structural Assessment (ELSA). Altogether eighteen actuators where installed, of which six controlled horizontal displacements and twelve ensured vertical loading on the piers and isolators. To obtain the dynamic response of the whole bridge, the part not present physically in the laboratory was modelled numerically. In the upgraded cyber-physical technique, two processes were running in parallel, one for the numerical model and the other controlling the motion of the physical model in the laboratory. These two processes had different time steps and ran two different time integration schemes. This way the physical structures were in continuous movement following an explicit time integration scheme whereas the numerical model could have a huge number of degrees of freedom and high non-linearity and use the implicit time integration scheme. The deleterious effect of control errors in the obtained response for the hybrid test was quantified by assessing the frequency and damping distortion in the obtained response as identified from equivalent numerical models. The models were based only on the measurements done during the experiment, which increases the generality and applicability of the reliability assessment method.

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