| The American Society of Civil Engineers (ASCE) reported that approximately one-third of U.S. bridges are either in need of serious repair or functionally obsolete. Even as repairs are completed, the problem persists with more and more bridges being added to the list each year. In order to determine if repair is needed for a specific bridge, a condition evaluation is typically conducted. The selection of conditional evaluation method and the subsequent repair method has, to date, been based on the preference of the engineer and/or contractor and at times the equipment available.;The work presented in this dissertation represents a first effort to provide quantitative decision support for selection of the most economical evaluation and repair method. The two most commonly used condition evaluation techniques are non-destructive evaluation (NDE) and what is termed herein as semi-destructive evaluation (SDE). There are several repair and rehabilitation strategies readily available for bridge girders such as increasing the structural cross-section (CI), attaching steel plates (SP), external bonded fiber reinforced polymer (FRP), or external prestressing ( EP). The procedure presented herein used these above techniques for illustration and combines elements of structural reliability theory, optimization, and structural analysis. Included is the optimization (minimization) of a cost function which accounts for the approximate level of damage present in the structure, a decision diagram to ultimately select the method based on the lowest expected cost, and preference factors in the decision procedure that account for the availability of material, labor, and equipment.;Three illustrative examples for prestressed concrete bridge girders are presented. It is envisioned that, while the procedure still relies on some basic assumptions, it can be used eventually to develop a basic set of rules for the most common combinations of bridges and sites. |
