June 22, 2008
June 22, 2008
June 25, 2008
13.1032.1 - 13.1032.10
Reliability of Bridges: Significant Addition to Civil Engineering Curriculum
Rapid highway system development in the United States in the 1960’s and 1970’s has resulted in a large number of bridges reaching a stage in need of repair, rehabilitation, or replacement. Truck loads have also been steadily increasing since then. This has made the situation even worse. Many developed countries are currently experiencing a problem of aging and deteriorated bridge networks as well as observed growth of load in both magnitude and volume. These structures’ safety has been of concern. The bridges experiencing vehicular overloads are subjected to a higher risk of distress, damage, and even catastrophic failure that will jeopardize human lives. Evaluation, repair, and rehabilitation are necessary for the preservation of the load capacity and service performance of these existing bridges. To minimize cost of replacement or repair, the evaluation needs to accurately reveal the current load carrying capacity of the bridge and to cover future loads and further changes in the capacity. Note that this involves a significant amount of uncertainty. To this end, the reliability theory of structures can be a helpful tool to quantify the risk involved in this process of bridge assessment.
Addition of a semester-long course on reliability of bridges in the civil engineering curriculum can greatly help the students understand the fundamental concepts of bridge safety. Civil engineering graduates will have the capability in evaluating bridge safety which they can confidently use in their future career. As a result, this will encourage students to specialize in the field of bridge reliability and eventually the nation’s bridge assessment experts will grow in number. These experts will have the technical know-how to help maintain bridge infrastructures to avoid catastrophic failures and most significantly of all, save lives.
The load carrying capacity of highway bridges is clearly influenced by the standard design load used in their design. The design load also has a significant effect on the durability of these bridges. Highway bridges usually possess reserved strength to accommodate occasional overloads although they were designed for standard load. This additional amount may be substantial depending on a number of factors. However, many countries allow overloads on their highway systems. In some states of the U.S.A., for example, vehicles that exceed the national truck weight limit are allowed to cross the bridges. This issue becomes critical when actual truck loads are noticeably higher than the design load.
Safety and reliability of these bridges will be assessed using the reliability-based algorithms that will measure the safety reserve in a structure covering the focused uncertainty involved. The concept of structural reliability will be used for the assessment of bridges. Bridge reliability will be measured using the structural reliability index β, which has been used in several recent research projects related to bridge safety1, 2, 3, including NCHRP Project 12-33 Development of LRFD Bridge Design Specifications. In that project, the LRFD bridge design code was calibrated with respect to structural reliability index β. The design load can be examined in the
Pablo, R. (2008, June), Reliability Of Bridges: Significant Addition To Civil Engineering Curriculum Paper presented at 2008 Annual Conference & Exposition, Pittsburgh, Pennsylvania. 10.18260/1-2--3623
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