STRUCTURAL DESIGN OF PCC SHOULDERS

A structural design procedure for plain jointed portland cement concrete (PCC) highway shoulders has been developed. The procedure can be used to provide PCC shoulders either for rehabilitation of existing pavement or for new pavement construction. All major factors that are known to affect the behavior of PCC shoulders are considered in the mechanistic design approach, including encroaching moving trucks, parked trucks, foundation support, load transfer across the longitudinal joint, shoulder slab thickness and tapering, width of shoulder, and traffic lane slab. The finite-element structural analysis technique was used along with a model for concrete fatigue damage to sum damage for both moving encroaching trucks and parked trucks. A relation was established between accumulated fatigue damage and slab cracking. The shoulder can thus be designed for an allowable amount of cracking, which can vary depending on the performance level desired. Procedures for tying the PCC shoulder to the mainline PCC slab are recommended to provide adequate load transfer and avoid joint spalling. Long-term, low-maintenance performance of the PCC shoulder, as well as significant improvement in the performance of the traffic lane, can be obtained if the shoulder is properly designed. (Author)