An Expansion Joint is a joint that is installed at a position where cracks are expected to occur in a linear structure such as underpass. It is used for the purpose of inducing cracks in resistance to shrinkage and expansion of concrete, prevention of...
An Expansion Joint is a joint that is installed at a position where cracks are expected to occur in a linear structure such as underpass. It is used for the purpose of inducing cracks in resistance to shrinkage and expansion of concrete, prevention of temperature cracks due to temperature gradient, and locations where foundation settlement is expected. The expansion joints installed in the underpass where the vehicles are directly loaded cause many defects such as potholes due to the road surface water, which deteriorates the road surface flatness and driving stability. Nevertheless, the length of extension joint of underpass has conventionally applied to 20~30m without improvement study or detailed structural analysis.
In this study, it was confirmed through field surveys that most of the underpass flaws occurred in the joints and that the main cause, the penetration water, degraded the durability of the concrete and the pavement layer. In order to eliminate the infiltration water, it was suggested to use guided drainage and replace the steel support plate with a glass fiber reinforced plate and replace the sealant finishing material with a drain bar, which is an advantageous alternative in terms of durability and maintenance. In addition, through the thermal stress analysis, the appropriate length of expansion joint was numerically confirmed to be safe because the maximum tensile stress of the Box-Type and the U-Type did not exceed the allowable stress up to 35m. The maximum displacement occurs in the U-Type part directly affected by the external temperature, and the U-Type part shows a larger displacement amount about 2.07mm than the Box-Type part. Therefore, it was indicated that the expansion joint length is dominated by the displacement of the U-type part.
In this study, it is considered that the durability is secured by applying the improvement method to each defect cause of the weakest expansion joint in the underpass structure, and it is safe to extend the arrangement interval of expansion joint to 35m as the result of numerical analysis. It is expected to improve the stability and durability of running and improve the maintenance cost by improving the problems caused by the installation of the expansion joint.