Use of tilt sensing equipment for monitoring long-term bridge movement

Accurate monitoring of long-term movements in bridges can be difficult primarily because of the relatively long time period over which the movements occur and inadequate instrumentation and technique. A stable reference point for measurements is difficult to obtain over these long time periods. Two bridges were monitored for long-term structural movement; the results are presented here. Instrumentation including temperature transducers and tilt sensors placed on and near piers determined the pier movement. The results of the study indicate that a superstructure expansion pier on one of the bridges monitored actually behaved as a fixed pier. The equipment used in the study, including data acquisition components and tilt sensors, proved reliable and accurate.