Single Bolt carrying bending.. 1

[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..

 

[CoryPad]

I recommend using VDI 2230 to help calculate this joint.

 

[qks]

hi.. I just want to know how to design the bolts in spaceframe structure as the bolts are subjected to two way bending also two way shear and axial force..
I don't have any idea about "VDI 2230"
please suggest me some basic engineering formulae for designing this bolt...

 

[TDIengineer]

The shear can be checked on its own.. Check combined tension and bending. I suggest using the effective diameter of the shank rather than the nominal diameter for determining the effective area for tensile stress. I would just calculate the Sx of the round shape with Sx=piD^3/32. fbending = M/S, Faxial = T/A.. then simply combine the bending and axial stress to get your maximum tensile stress. I like to work in ASD and let your allowable tensile stress by 0.75Fy.
I am more familiar with English units or I would calc out your SI for you...

 

[TDIengineer]

qks said,"...the bolts are subjected to two way bending also two way shear and axial force"

For shear in two directions, simply find the resultant by taking square root of sum of squares. For the bi-axial bending, calculate bending in two orthogonal axis and simply combine each bending stress with your axial to find the maximum net tensile.

Shear is checked separetely from tension, they are in different planes.

 

[hokie66]

The answer I gave in the other forum still applies. An M30 bolt won't take 15 kN-m in bending. You need some experienced help.

Spaceframe? Bolts in a spaceframe don't have to cope with anywhere near that amount of bending. Perhaps if you posted a picture of your intended joint, we could help.

 

[connectegr]

I would not recommend using hardened (quenched and tempered) bolts in bending. These bolts are intended for shear and tensile forces. They have very little ductility, for moment/bending forces.

http://www.FerrellEngineering.com

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

 

[qks]

here I have attached pdf copy of the details I am going to provide.. as the moment was heavy due to wind load I released it using pin connection as you can find it in the attached file.. so the horizontal loads coming upto 20 kN (you can find the location of the force acting in the detail)
also due to the eccentricity in the details provided there is a possibility of the moment 20000kN-mm
to arrest this moment I am fixing the 80 mmx 5 mm dia pipe to the node (without welding)by giving sufficient pre stress to the bolt.
again I can't increase the bolt diameter it should be M30 only to fix it to the steel sphere.

Please advice me on this detail, will work??

 

[hokie66]

No, that won't work. You can't rely on either the bolt or a prestressed pipe to take the bending.

You are apparently trying to mimic a proprietary spaceframe system which uses steel balls at the nodes. There are a number of these systems in the market. The ones I have seen use a special node at the supports, and the ball is welded to a fitment which is in turn bolted to the supporting column. A pinned connection like you have shown would transfer the moment into the spaceframe, and you don't want that. The spaceframe members are axial only members. The moment needs to be taken into the supporting structure, not into the spaceframe.

Perhaps I have misunderstood your problem. At any rate, you are not making clear what you are trying to design, and you need experienced assistance in your office, not on the internet.