EFFECT OF TRIDEM-AXLE LOADING ON CONCRETE PAVEMENT PERFORMANCE

A field program of strain and deflection measurements was conducted. The objective of the program was to evaluate the effect of frozen support, tied-concrete shoulder, and tridem-axle loading on concrete pavement performance. Results of the study on the effect of tridem-axle loading are presented in this paper. Field measurements were obtained during October 1982 and February 1983 at five pavement project sites located on I-90 in the State of Minnesota. Measurements included edge and corner deflections and edge strains. Loadings applied were 20 kip single-axle, a 34 kip tandem-axle, a 42 kip tandem-axle, and a 42 kip tridem-axle. Theoretical analysis was also conducted using a finite element program. Study results also indicate that for application to the ASSHTO thickness design procedure, a tridem-axle can be considered as equivalent to a single-axle weighing about 50 percent of the tridem-axle and to a tandem-axle weighing about 80 percent of the tridem-axle. Traffic equivalence factors are presented for tridem-axles on concrete pavements. (FHWA)