Single bolt subjected to bending..

[qks]

hi.. I need to determine the tensile load carrying capacity for 10.9 grade M30 dia bolt.
Shear force is 75 kN
Tensile force is 12 kN
also I am applying some moments to the bolt that is 15 kN-m.
I have only one shear plane available
I just want to know how this moment is distributed in the bolt as I am applying this perpendicular to the shear plane of the bolt.
Please help me on this..
Thanks..

 

[briancpotter]

I'll let others handle the issues of inducing a moment on a bolt (of which there are many), and just say that stress due to bending = M*y/I, where M is your bending moment, y is your distance from the neutral axis, and I is your moment of inertia. Add/subtract this to your tensile stress to get your resultant tension.

Brian C Potter, PE

http://simplesupports.wordpress.com

 

[qks]

thanks for your reply, Brian. but while computing..

I got confused while using bending equation M*y/I the stress developed is nothing but bending stress.. which is not tensile stress so how can I add/ subtract it.. also how to find the design bending strength for 10.9 bolt??
Thanks..

 

[Bagman2524]

Bending stress is just tension on one half of the member and compression on the other. Which is why the bending stress should be added to the tensile stress

 

[briancpotter]

This sounds like a school assignment, which is not permitted here.

Brian C Potter, PE

http://simplesupports.wordpress.com

 

[qks]

As I am designing the curtainwall(façade) to support it to the spaceframe where I have only one bolt support access point
so I am trying to connect it with M30 10.9 grade bolt.

I tried with the bending equation but the stress ratio is more than the allowable ratio..
were the allowable tensile stress for 10.9 grade bolt is 700 N/mm2
As I am trying to fix 14 meter unsupported curtainwall with this one bolt both the ends .. I have provided pin joint but still due to some eccentricity in the structure this moment is created..

Please excuse me for not providing the enough information..

 

[TLHS]

Yeah, this just isn't going to work. Without doing any math, consider the fact that you're basically saying this bolt needs to be able to hold up a 15m long cantilever with a big guy standing at the end of it.

 

[hokie66]

Your solution has no chance of working, and if you don't know how to calculate the stress on a bolt, you need help. Seriously.

 

[connectegr]

I also commented on your other post.

I do not recommend using hardened structural bolts (A325/A490) bolts in bending. Quenched and tempered material has very little ductility, related to moment/bending forces. These are intended for shear and tensile forces.

http://www.FerrellEngineering.com

Providing fabrication and erection efficient structural design of connections. Consulting services for structural welding and bolting.

 

[rb1957]

considering combining tension and bending stresses, use an interaction formula, something like Rb+Rt = 1/(MS+1)
Rb = bending stress/allowable stress (ftu or plastic bending?)
or applied moment/allowable moment
and Rt = tension stress/ftu or tesnion force/allowable tension

usually it's a bad idea to combine bolt bending with bolt tension. usually you provide enough preload so the joint doesn't gap and the moment isn't carried by the bolt.

Quando Omni Flunkus Moritati

 

[gobsmacked]

In the UK, ....If the bolt is in shear, it will also be in bending apart from the bending moment you are superimposing. The code values for shear resistance come from tests that include an allowance for the bending associated with clearance holes. Engineers are not expected to calculate this bending.What you are proposing sounds unwise, to say the least.