ABSTRACT
Based on the cement concrete pavement fatigue test data under repeated flight loads during 1943 to 1973 by the USA COE, Salsilli et al put forward a fatigue equation for concrete slab under different failure probabilities. From this field testing pavement fatigue equation (Yao 1999), we can derive the computing equation for maximum loading frequency of a certain aircraft type under constant slab edge stress:
Where Nf is the accumulated loading frequency when the pavement fractures out of fatigue; S = σmaxfr is the ratio between slab edge stress and the anti-fractures strength; and Pr is the reliability. Related literatures show that the reliability of cement concrete pavement usually ranges from 0.5808 to 0.7130 (Jiang 2001). In this paper, we set that at 0.65. Based on equation (3), we get
According to Portland Cement Association (PCA), when stress ratio S≤ 0.5, loading frequency can be limitless (Len & Weng 1995), while in equation (4), S> 0.5. When S≤ 0.5, Nf is infinite, that is, we can ignore the fatigue loss.
