# AASHTO 8th 2017 Figure 3.12.3-2 Temperature Gradient

What AASHTO refers to as “Steel Girder Structures” implies composite as \(t\) is stated as the depth of the concrete deck.

\(H\) |
Depth of superstructure |

## Value of A

For composite sections:

\[
A = 12''
\]

For concrete sections:

\[
A = max(16'' - H, 12'')
\]

## Intersection between Segments 1 and 4

\[\begin{align}
\frac{t - 0''}{4'' - 0''} & = \frac{T_{seg1} - T_{1}}{T_{2} - T_{1}} \\
T_{seg1} & = \frac{t}{4''}(T_{2} - T_{1}) + T_{1}
\end{align}\]
## Intersection between Segments 2 and 4

\[\begin{align}
\frac{t - 4''}{A + 4'' - 4''} & = \frac{T_{seg2} - T_{2}}{0 - T_{2}} \\
\bigg(\frac{t - 4''}{A}\bigg)(-T_{2}) + T_{2} & = T_{seg2} \\
T_{seg2} & = T_{2}\bigg(1 - \frac{t - 4''}{A}\bigg)
\end{align}\]
## Value of \(T_{4}\)

\[
T_{4} = max(T_{seg1}, T_{seg2}, 0)
\]

## Intersection between Segments 3 and 4