Bolt splicing at a single span. 2

[aun]

A steel bridge is a 150' simple span having a bolt splice location at 40' from its support. I know that a good place to splice is at or near the dead load contraflexure but it can't happen to this bridge. So why is a special consideration for this kind of splicing calculation??

 

[Lutfi]

My mentor always told me that if you have to splice a simple span beam, then splice it at the middle-third. His rational was it is an area of lower bending moment. However, when splicing, splice for the full section capacity (tension, compression and shear). I hope this answers your questions.

Good luck

 

[LPPE]

Uh, check me if I'm wrong, Sandy, but for a simply supported beam under uniform load, the maximum bending moment will occur in the middle third of the span.
Typically, multiple span beams are spliced at locations of zero or near zero bending moment. Since you have a simply supported beam, there are no zero moment regions except at the supports, where there would be no need for a splice. Therefore, it is reasonable to splice the beam nearer the supports than the middle.

 

[VoyageofDiscovery]

Hi aun,

I usually splice simple spans at 1/4 the span.

I have found that the reduction in moment here enables me to optimize the cross-section as well.

Regards

VOD

 

[rowe]

You could splice the simple span anywhere you like, as long as the splice is adequate to resist the max shear and moment at that section. I think in this case, 40 ft is a pretty good location. For a uniform load, (approx) M=0.75Mmax and V=0.5Vmax.

Note: Designing a splice for the full section capacity is not a bad idea. If your splice is too "efficient" (barely enough to be structurally adequate) you might need to consider changing the section property at the splice for another beam analysis.

 

[Qshake]

I agree with ROWE, you can splice it anywhere. I suggest that you investigate where erecting falswork will be utilized given the feature being spanned and work from there.

As for the capacity, AASHTO is clear on what is required. Even if you have an area of low stress, you will still have to develop a certain level of the original section. That is why some many State DOTs have prescribed splice designs. The designs are based on developing the material section not the load.

 

[aun]

thank you guys for the input..
from my understanding, I can splice anywhere I want and calculate in the same way even the splice loction is not near the dead load contrafluxure point.
Thanks again.