A MECHANISTIC BASED DESIGN PROCEDURE FOR JOINTED CONCRETE PAVEMENTS. PROCEEDINGS, 4TH INTERNATIONAL CONFERENCE ON CONCRETE PAVEMENT DESIGN AND REHABILITATION, PURDUE UNIVERSITY, APRIL 18-20, 1989

A procedure for mechanistic based design of jointed concrete pavements is presented. This includes both jointed plain (JPCP) and jointed reinforced (JRCP) pavements. The procedure was developed specifically for pavements in Illinois, but certain adaptations can be made to the procedure to include all environmental regions of the country. The basic design procedure is developed around the prevention of transverse cracking due to fatigue. Fatigue damage is calculated as a function of the shoulder type, traffic distribution, environmental factors and axle load. Material properties, joint spacing, and design reliability are also design inputs. Three shoulder types--bituminous, PCC tied shoulders, and extended width traffic lanes--are included in the design procedure. The basic failure criteria used in the design procedure is the number of slabs with transverse cracks. Since the joint system was modified to prevent the random cracking of the slabs with long joint spacing, any cracking of the slabs is considered to decrease the overall pavement condition. The procedure allows the design engineer to specify the percent of slabs with transverse cracks which constitutes failure. Pavements with a lower level of traffic, can tolerate a higher percentage of cracked slabs than pavements with high level of traffic. The analysis model used in the procedure is the finite element model, ILLI-SLAB. Since the model will permit the analysis of two layers either bonded or unbonded, the subbase is considered to be a part of the pavement system rather than a part of the support. Using this approach, the effect of stabilized subbases on the stress and deflections in the pavement system can be evaluated directly.