chapter 3 rigid pavement - DOT On-Line Publications - Department ...

.A ::cleoier:Cai ?'.'3iU2::0:: Oi 5.e eifec: Oi ex:e?ied j;abs 3:. j:resj -34,. --. -- .... :;
.b--\.-L.. __
iJeriOi?Y. ed osing :he PC y..ersion or’ ILLSLXB. .A 14 ft bv 16 I: ,-;.j >v 4.3 mj siab
varving thiknesses was modeied on a subgrade 1~1th a ioati aF?iied’at :?,e j;ab’j 2:
,
midpoint on +he outer edge. The induced stress was then caicxiared at that zolr,: ;a
&in [lo1 mm] ocset, and at fur:her offsets from the edge oi 9 in, 26 in, and i: ir:
(203, 406, and 6iO l .~) by moving the load inward on the slab. AS is jhobT in
figure S, there is a !arge reductron in stress that results from movir,g loads ait’av ;ro;r:
the siab edge. ’32s reduction is greater ior thinner siabs. 5~2 stress is ;eiarei :o
fatigue ar.d, i;ltkmately, deterioration of the siab, this redution in jtiess 15 a desli2’2ie
goal.
CALCL’LATE~ STRESS. PSI
500 !
0
0 5
OFFSET &OM SLAtEDGE. IN
- : in srra - 9 in skia - 1OInsIab
+ :2mslm - 15inslaa
Figure 8
20 25
The effect of wheel load placement on pavement slab strains has also been
documented. As measured in test sections by the Minnesota Department of
Transportation (MnDOTI, pavement strains are shown to be greatest at the free edge
of the KC slab (see figure 9).‘6) The edge strain reduces quickly as the wheel load
moves inward from the edge of pavement, as shown in figure 10 (from a MMNDOT
laboratory test slab) and tends to level off when the applied load is 18 to 21 in (4Si :o
610 mm) from the edge of pavement.i6’ “In general, free-edge srrains were 36 percent
to 50 percent greater than interior strains.“‘6’
3.8.17