Question

4.27 A rigid pavement on a multilane highway (two lanes each direction) has been conservatively designed (for its design-lane traffic). The pavement engineer uses an 11-inch slab, Ec of 4 x 106 lb/in2, a concrete modulus of rupture of 695 Ib/in2 a load transfer coefficient of 2.8, an initial present serviceability index of 4.2, and a terminal serviceability index of 2.5. The overall standard deviation is 0.6, the subgrade CBR is 20, and the drainage coefficient is 1.0. The pavement was designed for four hundred 30,000lb triple axles, nine

Answer 1

Given that E_c = 4 times 10^6 lb/in^2 concrete modulus of rupture = 695 lb/in^2 load transfer co efficient = 2.8 service ability index = 2.5 standard deviation = 0.6 subgrade co efficient = 1.0 prevent is design = 30,000 lb = 30 kip 400 - 30 k i p therefore equivalency factor for flexiable moment 30 k i p Transform a xis = 0.695 log_9 = 1300 times 0.695 log_9 = 278 log_9 = zR_50 + 9.36[log_10 (SN + 1] - 0.2 + log_10 [AFSi/2.7]/0.4[log 4/ s N + 1)^5 - 1) therefore log k/9 = 3878689.85 therefore No of years = 3878689.85/365 times 278 = 38.22 year = 38.22