Girder Beam at Tilt panel

[NewbieStruct]

Do we always need to provide pilasters at girder beams?

I have 7.25" panel - 20'- long - 15' tall with a girder load of 100 k ultimate attaching to it. I spoke to my senior engineer and he told that they have not used pilasters at those loads (upto 150 k). I ran through the analysis myself and did not find the need for a pilaster. I want to make sure that I am not doing anything incorrect since the load seems to be quite high to me.

 

[ztengguy]

Usually it can be spread out over a distributed distance, thus a 1-0" column might only have 10-15K per foot. Obviously at mid height your max moment will be induced, so unless the bearing is at that location, you should be ok. Check your bearing stress at the girder bearing, check your bearing for the ecc & windload, any P delta effects...and put what steel you need.

 

[haynewp]

On a pinned base panel single-story panel with a high eccentric axial load at the top, the max moment can be at the top of the panel if the wind and seismic load on the panel is low in comparison.

 

[spats]

How are you doing your panel design? By hand? Which method? What program? Then I can give you more meaningful advise.

 

[NewbieStruct]

I ran the panel by hand using ACI 551 as a guideline along with an example in it. I rechecked my calculation with an office spreadsheet that my senior engineer has developed. I also ran the wall in Enercalc.

 

[spats]

If you're going by the ACI 551 Design Guide, the procedure is limited to Pu/Ag less than or equal to 0.06 x f'c. If f'c = 4000 psi, and using a 7 1/4" panel, you're limited to 20.88 kips per foot of panel. That means you need more than a 5' width of panel (once you include panel self weight) to participate in carrying the load.

 

[NewbieStruct]

I am using 5000 psi concrete and spreading the load to approximately 6'-0 to 8'-0" (I can't recollect the exact number since I don't have the calcs with me) using ACI 551. I remember the code allows for the load to be distributed approximately in two 30-60-90 triangles on both sides of bearing at half the unbraced height.

 

[a2mfk]

I hope you can use a bearing connection for that type of reaction....

If architecture allows, you can also bolt an HSS to the wall every few feet vertically to brace it and use that to carry the girder reaction. May be faster and easier than forming a pilaster into a tilt panel.