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Synthesis of Information Related to Highway Problems. Topic 47-01. Control of Cracking in Concrete Bridges

项目名称：	Synthesis of Information Related to Highway Problems. Topic 47-01. Control of Cracking in Concrete Bridges
摘要：	Despite many advances in bridge design, concrete technology, and corrosion-resistant reinforcement, cracking of concrete continues to be a concern for bridge owners; particularly for bridges exposed to severe environments. The presence of cracks provides a direct path for water and chlorides to penetrate the concrete and reach the reinforcement. This in turn, can lead to freeze-thaw damage to the concrete or corrosion of the reinforcement. However, there appears to be little or no correlation between crack width, corrosion, and service life. The American Association of State Highway and Transportation Officials Load and Resistance Factor Design (AASHTO LRFD) Bridge Design Specifications provides requirements for minimum amounts of reinforcement and maximum spacing of reinforcement to control crack widths. In some cases, these requirements are based on in-depth research, while others are based on experience. Nevertheless, bridge owners find the need to supplement the AASHTO provisions with their own requirements. The control of cracking for aesthetic, durability, and structural reasons becomes increasingly important as service life goals are extended and higher strength concrete, higher strength reinforcement, and different types of reinforcement are used in bridge construction. The overall goal of the synthesis is to provide a compilation of methods used to control cracking in concrete bridges and the influence of cracking on long-term durability. Specifically, the synthesis will address the following types of cracking: (1) Flexural cracks in nonprestressed members; (2) Shrinkage cracks in nonprestressed concrete bridge decks; (3) Splitting cracks in pretensioned anchorage zones; (4) Vertical cracks in pretensioned beams prior to transfer of the prestressing force; and (5) Reflective cracking in cast-in-place partial-depth decks and overlays. The synthesis will include information related to the use of steel reinforcement with specified yield strengths from 60 to 100 ksi, corrosion-resistant steel reinforcement, and fiber-reinforced polymer reinforcement. The selection of concrete constituent materials and construction methods to reduce the potential for shrinkage cracking will be addressed. Finally, the synthesis will address remedial measures that may be taken after cracks occur. The synthesis will be beneficial to bridge owners and designers and the AASHTO Subcommittee on Bridges and Structures in their Grand Challenges to extend bridge service life and advance the AASHTO specifications.
状态：	Proposed
资金：	45000.00
资助组织：	National Cooperative Highway Research Program
项目负责人：	Williams, Jon M
开始时间：	20150701
预计完成日期：	0
实际结束时间：	0