THE CONCRETE BRIDGE MAGAZINE

WINTER 2015

ASPIRE is a quarterly magazine published by PCI in cooperation with the associations of the National Concrete Bridge Council. The editorial content focuses on the latest technology and key issues in the Concrete Bridge Industry.

Issue link: http://www.aspiremagazinebyengineers.com/i/439391

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CONCRETE BRIDGE DESIGN Design of concrete bridges has changed in a number of ways, but one of the most significant for complex structures is the introduction of computers to do the many calculations that are necessary for more complex bridges such as box girders erected as cantilevers and cable-stayed structures. These and some other types of bridges have ever changing loads and stresses during construction that must be tracked and adjustments made if the final product is to perform as intended. The long-term effects of creep and shrinkage along with the effects of temperature changes and gradients are now evaluated to provide better solutions. Without the increased computational speed of computers, it would be nearly impossible to successfully build these complex structures. CONCRETE BRIDGE CONSTRUCTION As advances in materials and designs have occurred, the construction industry has kept up by finding ways to construct these longer-span bridges. Concrete bridge construction has made advances in many ways as materials, techniques, and equipment have steadily developed, allowing the construction and handling of longer spans and larger elements. Erection equipment has also been developed to allow construction of cable-stayed concrete bridges. PUBLIC EXPECTATIONS The public has begun to raise their expectations for bridges. In some situations, they now expect aesthetics to be incorporated into new structures that occupy prominent places in public spaces. They also expect bridges to be constructed more quickly, so they will not be inconvenienced by the delays caused by construction. Fortunately, concrete bridges can address both of these expectations by the ability of concerte to take many attractive forms and also to be used in ways that accelerate bridge constructions, such as prefabricating elements. CONCLUSIONS Much has changed since 1914 in concrete bridge construction, making possible remarkable advances in the life span and span length of concrete bridges. There is no reason to think that the pace of innovation will slow. Instead, there are many areas in which further improvements are on the horizon. I am confident that we will be able to use these advances to improve concrete bridges so that this amazing material will remain a key part of transportation structures for the next 100 years. For the summary report of the FHWA National Bridge Inventory (NBI), see www.fhwa.dot.gov/bridge/nbi/no10/yrblt_yrreconst.cfm

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