A Case for Adding an Inspection Level Related to SHM for Bridge Evaluation by CHBDC

The Canadian Highway Bridge Design Code CHBDC), Section 14, uses the concept of a target reliability index (Beta) for evaluating the load carrying capacity of existing bridges. This target reliability index, which is based on the probability of failure and the risk to human life, is related to three aspects of uncertainties inherent in a bridge: those related to (a) element behaviour, (b) system behavior, and (c) inspection level. It is assumed that all bridge inspections are being carried out manually and without using the structural health monitoring (SHM) instrumentations. Citing examples of tests on many instrumented bridges, this paper proposes another level of inspection, which is done with the help of electronic instruments and tests under controlled vehicle loads. The paper proposes simple additions to the clauses of the CHBDC, which can be used to determine the optimum load carrying capacities of existing bridges where structural health monitoring information is available. Using the new value of the target reliability index, the load carrying capacity of bridge can be calculated and being compared to the capacity calculated based on other inspection levels. In this work, using the suggested target reliability index and live load factor, the load carrying capacity of a steel girder bridge is calculated. In this calculation, the available data from structural health monitoring has been used