Prying action 2

[NitinPandharkar]

Does a second line of bolts (a second Gage) help for prying action on a "T" or single angle hanger, or is prying checked on the first bolt only?

 

[nutte]

First bolt only. The first bolt would have to elongate to engage the second bolt. The mathematical models used in the literature ignore the outer bolt for tension.

 

[JoshPlumSE]

Intuitively, I would think the 2nd row of bolts would help greatly. Though I do not have any literature to back up my claims.... I may try to research it over the next few days as I have an application for the same scenario. So, far I have been conservatively using the same prying formulas as single rows of bolts. But, it would be nice to find a more definitive source on the subject.

 

[nutte]

Kulak discusses this in “Guide to Design Criteria for Bolted and Riveted Joints.” The conclusion is that the flange has to be sufficiently thick and/or stiffened to fully engage the outer bolt. How thick is sufficiently thick? That's a good question.

 

[JoshPlumSE]

After some very cursory investigation of the issue, I have changed my stance. I don't think the outer bolts are going to help all that much. Unless, as nutte / Kulak says, the flange is pretty thick.

 

[dhengr]

NitinPandharkar:
How much can prying affect a second row of bolts, unless it has literally started to fail the first row of bolts? Worry about the bolts nearest the load application. If the plate were thick enough (stiff enough) you might start to get prying action which was proportional to the plate thickness and the distances from the load, i.e. the plate deflection under these loads. This leads to an additional stretch and bending action under the head of the bolt.

 

[johnbridge231]

Every bolts rows unedr tension should be checked for the development of prying forces. Prying forces occur when the steel plate thickness is weaker than the bolts. Prying forces reduce the tensile resistance of bolts and their existence should be almost always checked if the bolt is subjected to tensile loads.

Analysis and Design of arbitrary cross sections
Reinforcement design to all major codes
Moment Curvature analysis

http://www.engissol.com/cross-section-analysis-design.html

 

[NitinPandharkar]

Hi Guys ...
Thanks you for all your replies.
Suppose I am doing a clip angle connection for beam & column junction. Beam is connected with column web or flange & clip angle is having two bolts in vertical row for connection to column flange or web. In this condition bolt in second row will experience additional tension due to prying or not ?
If any one is having literature on this please upload.

Thanks & Regards,
Nitin