Estimation of deflections of bridge by two-step model updating approach based on ambient acceleration measurements

For the deflection measurement of a bridge, sensor inaccessibility due to the reference point (fixed point) may cause lots of inconvenience and increase of installation cost and time. Therefore, an alternative indirect deflection estimation method is proposed utilizing the FE model updating with measured acceleration data from an ambient vibration test. For the fast and stable optimization during the model updating, two step model updating approach is additionally proposed. To investigate the effects of used modal quantities and their weighting factors, extensive model updating was carried out by applying several kinds of data sets: using only natural frequencies, using only mode shapes, and using both of them, By simulating the load test on each of the updated model, deflections were estimated and compared with the real measured deflection data in the load test.