Boeing 757

4000

3000

2000

1000

50 x 103

0

10

20

30

40

PCC Modulus (MPa)

5000

MD DC 9

4000

3000

2000

1000

50 x 103

0

10

20

30

40

PCC Modulus (MPa)

results. We used partial basin areas, but found no bet-

ter correlation. The following equation can be used to

Joints are generally weak points in jointed concrete

determine σh from the total basin area

pavements. Although the load transfer across joints has

a great effect on the stress at the bottom of the slab, and

σh = 7.35 AT

therefore on the performance of the pavement, it is

largely ignored in most evaluation schemes because of

The ISM can also be used to estimate σh, as shown

the difficulty of measuring these stresses (Foxworthy

in Figure 36. A power relationship was found to best

describe the relationship between ISM and (σh)

amount of deflection on both sides of the joint when a

load is applied on one side of the joint. The FWD, sim-

σh = 357,068 ISM0.8165

ulating a wheel load on one side of a joint, can be used

29