Effects of temperature - Concrete Structures: Stresses and Deformations - page 364

Figure 10.8 Analysis of stress distribution due to temperature in a bridge girder
(Example 10.1): (a) elevation and cross-section; (b) rise of temperature;
(c) self-equilibrating stresses in any section; (d) released structure; (e)
continuity stresses at B; (f) total temperature stresses at B.

The cross-section area A is 0.877 m 2 ; the centroid O is at 0.969 m
above the so

t; the moment of inertia I about a horizontal axis
through the centroid is 0.1615 m 4 .
Hypothetical strain that would occur at any

fi bre if it were free to

expand (Equation (2.21) ) is:

y
1.2

5

ε f = 1.0 × 10 −5 22

where y is a distance in metres measured upwards from a point 0.2 m
above the so

t (see Fig. 10.8(b) ).
The stress necessary to prevent this expansion (Equation (2.22) ) is

y
1.2

5

σ restraint = − (30 × 10 9 ) 10 −5 × 22

= − (2.652 × 10 6 )( y ) 5 N-m 2 .

The resultants of this stress are (Equations (2.23) and (2.24) ):