# Civil and Environmental Engineering Department (DOC)

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```					Lecture 29 Temperature Steel Requirements
Temperature steel is used in concrete pavements to control
cracks that naturally occur. The basic approach used is based on
a summing of forces where the resistance force of the concrete
and temperature steel is set equal to the friction force that
develops between the slab and the soil
Longitudinal and transverse steel

Friction force -                        English units with
h in inches and f = the friction factor = 1.5
Concrete force - Fconc  Aconc f conc
Steel force -
Assume the force carried by concrete is zero and the
steel force is set equal to the friction force and solved
for L (the length between joints) the result is

For example with
h=9 in
Asteel=.25 in2
f=1.5
gconc= 150 pcf
fs=30000 psi

24 x.25x30000
L                  89 _ ft
150x9 x1.5
Spacing of this amount is large MDOT uses 43 ft
according to their standard plans

Another more likely approach would be to give the
spacing and find the amount of steel required.
For typical spacing see standard plans. Standard
Plans . Remember the areas of steel required for
both longitudinal and transverse direction are required
41x150 x9 x1.5
Aslong                      0.115 _ in 2 / ft
24 x30000
12 x150 x9 x1.5
Astrans                     0.0.34 _ in 2 / f
24 x30000

Tie bars - spacing is determined by dividing the area of the
selected tie bar by the transverse area of steel per foot of
slab as done above. The result is spacing in feet.
Aact
S
ARe q
Using a ½ in diameter bar the spacing is
0.25 2

S       4  2.89 _ ft
0.034
use _ 36 _ in

The length of the tie bar is determined by setting the bond
force developed along the bar to the force in the steel

where  is the perimeter of the tie bar and  is the bond
stress and t is the length of tie bar

Using the variables defined above the length is
x.5 2
2 x30000x
t             4              21.4
350xx.5
use _ 24 _ in
Dowel bars - size of dowels is determined by considering them as
cantilever bars. The development of dowel bar size is beyond the
scope of this course.

A Calculator for determining temperature steel requirements is
available at
Calculator for Temperature Steel

```
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