The objective of this study is to obtain and compare stress based load transfer efficiency [LTE(S)] and deflection based load transfer efficiency [LTE(d)] of rigid pavement airfield joints measured during the full scale testing of airfield pavements at the Federal Aviation Administration's (FAA's) National Airport Pavement Test Facility (NAPTF). FAA current rigid pavement thickness design procedure assumes LTE(S) of 25% as an aircraft traverses a joint. Since, it is not convenient or practical to measure LTE(S) in field, the current FAA specification determines LTE(S) from LTE(d) which suggest that LTE(S) of 25% is equivalent to LTE(d) of 70-90%. Fallingweight deflectometer (FWD) generally serves the purpose of measurement ofdeflections and LTE (d). However, the equivalency of LTE(d) and LTE(S) depends on the effect of single plate loads of FWD versus multiple gear loads of aircraft and short duration impulse loads of FWD verses a comparatively longer duration dynamic aircraft wheel loading. The paper presents the results of the analysis from FWD and slow moving wheel load tests. The results showed that the deflection based load transfer efficiency was similar between single wheel loading and 4-wheel loading. However, a noticeable difference in the value of LTE(S) was observed between 4-wheel static load and 4-wheel moving load. The study thus infers that the commonly usedcorrelation for estimating LTE(S) from LTE(d) measured by FWD is valid only for static load. The same correlation significantly underestimates theLTE(S) of dowelled joints under moving aircraft loads.
Samenvatting