Predicting bridge bearing demands through a probabilstic framework

The age at which bridge bearings are replaced is determined through field inspection and engineering judgement with no real information on remaining performance. Bridge bearings are expected to be replaced once during a bridge's lifetime; however, having a more specific timeline will aid in forecasting maintenance schedules and costs. Quantifying and compiling the cyclic load demands of a bearing, such as horizontal displacement and vertical compression, is the start to determining the life expectancy of bridge bearings. Temperature fluctuation and seismic events represent the major demands on bridge bearings within Ontario, with contributions of each depending on location. A framework for quantifying the probabilistic lifetime demands for cyclical displacement of bridge bearings is presented by combining the effects of the loading types on a model of a multi-span girder bridge. The probabilistic lifetime bridge loading combines the multiple loading scenarios specific to a location. The output will represent the annual displacement cycles experienced by the bridge bearings, with information on the relationship between the number and amplitude of cycles. By obtaining the lifetime displacement demands on a bridge bearing the replacement time can then be projected.