Steel truss bridges - Computational Analysis and Design of Bridge Structures - page 307

Truss section property calculation

Input data:

Overall height, y t = 25.3750 (measured up from global x -axis)

Overall width, x t = 22.5000 (measured to right from global y -axis)

No. of k n own shapes = 4

Data: Shape #1 Shape #2 Shape #3 Shape #4

A = 5.3100 5.3100 5.3100 5.3100

I x = 19.30 19.30 19.30 19.30

I y = 6.91 6.91 6.91 6.91

x c = 1.5100 1.5100 20.9900 20.9900

y c = 2.5100 22.9900 22.9900 2.5100

No. of rectangles = 5

Data: Rect. #1 Rect. #2 Rect. #3 Rect. #4 Rect. #5

Length, l x = 0.5000 20.0000 0.5000 20.0000 12.0000

Length, l y = 24.0000 0.3750 24.0000 0.5000 0.5000

x c = 0.2500 11.2500 22.2500 11.2500 11.2500

y c = 12.7500 25.1875 12.7500 0.2500 0.2500

+ y

22 1/2″ o. to o.
21 1/2″ b. to b. Ls

4 ∠ 5 6 × 4 × 9/16
2 Web Rs. 24 × 1/2
1 Top Cov.R 20 × 1/8
1 Bott. Cov.R (20-12) × 1/2

Rectangle

Known shape

+ x

+ z

Nomenclature

Results:
Centroid location and area:
x c (left) =

Centroidal axes properties:
I x =

Principal axes properties:
I x ′ = 13.493 4048.93 4002.44

x c (right) = 9.007 S x (top) = 346.46 I y ′ = 4251.64

y c (top) = 11.687 S x (bot) = 295.79 I xy ′ = 0.000

y c (bot) = 13.688 I y = 4205.15 r x ′ = 9.316

A = 46.120 S y (left) = 311.66 r y ′ =

θ =

9.601
−25.588

S y (right) = 466.87

I xy = −97.072

r x = 9.370

r y = 9.549

Figure 10.10 Calculation of a sampling truss member cross section.