CIVIL ENGINEERING 365 ALL ABOUT CIVIL ENGINEERING



AbstractBridge design values for axle load and truck volume have increased since the 1960s, following the introduction of modern vehicle configurations, such as those of permit, special hauling, and emergency vehicles. Many highway bridges in the U.S. are estimated to be structurally inadequate, especially with respect to the shear capacity of the superstructure to carry these loads, and there have been numerous efforts to consider strengthening options for such older shear-deficient bridges. Techniques for enhancing the shear capacity of concrete bridge girders range from traditional approaches using steel and concrete (e.g., bolted steel plates) to newer approaches that utilize novel concepts and advanced materials, such as fiber-reinforced polymer (FRP) composites and shape-memory alloys. This paper reviews these shear strengthening techniques from a practical application standpoint, particularly with respect to their structural efficiency and constructability. The conceptual basis of each technique is described along with a summary of the advantages and shortcomings of each technique, followed by an overview of some representative field implementations and relevant design guidelines, if available. Finally, the concept of developing an assessment rubric is introduced to aid in identifying a potential shear-strengthening scheme for a particular project.



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