Optimized Design of Concrete Curb under Off Tracking Loads

摘要

Most research studies in the portland cement concrete (PCC) pavement area focused on addressing distresses related to pavement structure itself. As a result, the design and construction of other structural elements of the concrete curb and curb and gutter (CCCG) system have been overlooked and not much research has been done in this area. Visual inspection of damaged CCCG systems was conducted in the field. All damaged CCCG systems were the TxDOT Type II system and almost all damaged CCCG systems were found at U-turn curbs due to excessive off tracking of traffic. Although geometric changes of the curb design are the fundamental solutions for the off tracking failure, such changes are not feasible in most cases due to economic and space limitations. Extensive finite element analysis was performed based on the new U-turn curb design of the TxDOT Houston district. The horizontal loading is the most critical loading condition to evaluate the structural adequacy of a CCCG system. The structural capacity of CCCG can be enhanced by increasing the curb width and/or by inserting the curb dowel further from the traffic face of CCCG. The use of the new U-turn curb design from the TxDOT Houston district is highly recommended for areas affected by the off tracking of heavy vehicles. It is recommended to position the curb dowel further from the traffic face of a CCCG system for better performance when the new U-turn curb design is applied. The use of an epoxy-grouted curb dowel is also recommended instead of a manually inserted straight dowel bar to ensure better bond performance between dowel bar and concrete in a CCCG system.