Mechanical responses of Boeing 747 running on runways

Based on the large amounts of measured strains and deflections of runway pavement at Denver International Airport, the main characteristics of deflections and strains at different positions of pavement were analyzed when Boeing 747 was running on runway, and the load transfer capacities of different joints, the residual deformations and strain rates of pavement at the typical positions were researched. Analysis result shows that the edge and middle of slab have 2 strain peaks respectively, which corresponds with the number of aircraft's main gear axles. The transverse strain (perpendicular to the running direction of aircraft) only has one type, while the longitudinal strain (parallel to the running direction of aircraft) shows 2 times' transformation between tension and compression. The peak-strain recovery between gear axles at the bottom of longitudinal joint edge is significant, its peak strain and peak-strain recovery are 1.2 times and 2.5 times as much as the values at the top of longitudinal joint edge respectively, which means more prone to cracking and fatigue damage. When the aircraft is running, the maximum strain rates occur at the joint, and the maximum tensile and compressive strain rates are 9.1×10-4 s-1and 7.6×10-4 s-1 respectively, and belong to quasi-static strain rate, so their impact on the deformation of concrete slab are ignored. The deflection curves at the slab's middle have 1 peak, but there are 2 peaks at the slab's corner and transverse joint edge. The relative residual deformation at corner of slab is largest, the deformation at the middle of slab is least, the relative residual deformation rate at the corner of slab is 2.60-4.59 times as large as the value at the middle of slab, and compared with other locations, the corner more easily occurs void with base. The load-transferred coefficient of hinged joint is about 1, the load-transferred coefficient of dummy joint is lower compared with hinged joint, the load-transferred characteristic of dummy joint has directionality, but the load-transferred characteristic of hinged joint is non-directional. © 2016, Editorial Department of Journal of Traffic and Transportation Engineering. All right reserved