Grouting fastener size calculation for applied seismic forces.

[Babups]

HI Team,

I would like to know your suggestion and guidance for the analysis case i work on,

Scenario:

There is a machine structure grouted to the floor that needs to withstand the seismic forces.

Load path :

1.The self weight of the structure is around 40 kg, 20 kg is transferred to the LH tube frame and remaining 20 kg is transferred to RH tube frame.

2.From the tube frame the load is transferred to the floor.

3.The U Bracket is mounted to the LH and RH tube which are then grouted to the floor.

Applied External Load :

1. The applied seismic force in Horizontal and vertical forces are applied to the machine structure at the CoG of the machine structure.


Hand calculation:

1. Free Body diagram.

2. Need to calculate whether the applied point load on the bottom of tube section is capable to withstand the self weight of the structure.( Need to
freeze the sections)

3. Need to calculate the effect of seismic force applied to the CoG of the structure for sliding, Rocking and Toppling of the structure( Basically
calculating the moment of the structure due to the applied seismic forces about the grouting ). From the design the U Bracket with grouting is
responsible to resist the Generated moment.

Outcome :

Need to choose the appropriate size of the grouting bolts which can resist the moment.


FEA Simulations:

Have to perform the same in FEA as well to validate the hand calculations.


Please share your thoughts and your guidance to calculate the grouting fasteners that may be suitable to withstand the applied seismic forces in terms on accelerations applied at CoG of the structure.

Seismic force : Vertical and Horizontal acceleration are applied at the CoG of structure.

 

[desertfox]

Hi

Can you provide a sketch showing heights, widths, hole pitch and dimensions to the CofG from some reference plane.

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[Babups]

HI deserFox,

I have attached the sketch with dimension details. Pls check

 

[desertfox]

Hi Bapups

Thanks for the updated picture, so it will help if you can show the magnitude of the loads and the direction that they act in on the seismic forces do they all act simultaneously?
Regarding the bolts I would assume that the frame is ridged and the bolts take all the load in bending and in shear, see this site and scroll down till you see the heading bolts withstanding bending forces.

https://roymech.org/Useful_Tables/Screws/Bolted_Joint.html

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein