MODEL FOR DETERMINING THE OPTIMUM REHABILITATION CYCLE FOR CONCRETE BRIDGE DECKS

The optimum rehabilitation cycle for concrete bridge decks is determined by calculating the average annual cost of patching the deck for a number of years and then rehabilitating it to extend life but not enhance the original functional characteristics. The model used to carry out the necessary calculations is based on the fact that every operation performed on the deck gives rise to a stream of future maintenance obligations. It relies on five user-defined inputs and makes specific provisions for the fact that patched areas fail in terms of a deterioration profile different from that exhibited by the original deck. A spreadsheet is developed to perform sensitivity analysis studies using different values for the user-defined inputs. The results are tabulated. It is found that physical life as defined by the deck deterioration profile and economic life as defined by the rehabilitation cycle must be balanced to achieve the best results. The limitations of the model are discussed. The user is cautioned about the use of relatively simple models in a complex environment.