Minimum angle for X bracing

How can we know the minimum angle of an X bracing before
it becomes unefficient ?

anyone have an answer ?

thanks

 

[dlew]

regis lacroix,

The angle of a brace should be kept within the range of 30-60 degrees to be efficient. This is a rule of thumbs I have read in some books on structural design. I do not believe it is specified in any code.

AEF

 

thank you for answering !

 

Ive done a lot of work on communication towers. Most of the time we look to go no less than 20 degrees in an X brace before we go to a K type configuration or other.

 

[inspectorjeff]

20 degrees from horizontal?why is this better than the standard 45-60 degrees? Inspector Jeff in Florida

 

[whyun]

inspectorjeff, i think Towerdude is saying that 20 degree is the minimum angle. Per dlew, 30 to 60 is ideal but 30 degree is not the absolute limit.

 

[dlew]

whyun,

I do not think there is a limit on the magnitude of the angle. It is a matter of economics. The lower the angle with the horizontal, the lower the force (and section required) but more length of brace is needed.

If the angle is too large, the force (and the section required) becomes too big.

Regards

AEF

 

[whyun]

dlew, i am with you 100%. think of the extremes. brace with 0 degree incline will take 100% of the lateral force. brace with 90 degree incline takes 0%. any angle in between takes components based on basic trigonometry.

i think keeping it between 30 to 60 degrees is recommended for economy and structural efficiency.

 

[trainguy]

30 to 60 degrees also enables feasible connection layouts.

GA