Starting with the supported jacks, this area is trapezoidal;
Area of the Trapezoid = �
+ 1
2
�
d=setback = 7'
b=span of #1 hip = 30'
b1=span of #1 hip – setback (d) = 23'
Area of Trapezoid = 7�
30+23
2
� = 185.5 ²
Next, calculate the rectangular area;
Area of the Rectangle =
( )
( )
L = distance from the #1 hip to the adjacent common truss = 2'
W = span of the #1 hip = 32'
Area of the Rectangle =
(
2
)(
32
)
= 64 ²
Once the two load areas are known, the girder reactions can be calculated.
(
185.5 + 64
)(
40
)
4
= 2495
