Steel beam anchoring and bearing seat (supports)

[mats12]

Lets say we are dealing with a steel beam that is simply supported and there is no upward forces acting on a beam.

How do you guys determine anchor bolts when there is no horizontal load and no vertical load on bolts? How do you design those anchors/bolts - Based on what?

Support 1 – normal holes for bolts/anchors
Support 2 – elongated holes which allow horizontal displacement (so there is no tension in steel beam when it comes to its expansion because of temperature differences. That also means no shear on bolts).

What about horizontal loads on beam (bolts in shear as a result)? Lets say that horizontal loads are caused by occupants and thermal expansion of a beam.

Im also wondering what is minimal bearing seat width (support dimension b)? How do you guys determine what is a minimal required bearing seat? I was thinking about commpresion forces on a beam/concrete support, but that usually gives small values.

 

[BigInch]

For thermal loads the bolts on support 1 must be able to resist friction shear load in order to direct all movemet of the beam toward the slotted bolt hole slide. Otherwise movement might be in one or both directions.

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[mats12]

That makes sense. Thank you.

What about minimal bearing seat width (support dimension b)? Anyone has a suggestion/advice about this?

 

[DayRooster]

Take a look at your AISC Steel Manual specifically pg 2-13 of the 13th Edition & 2-17 of the 14th Edition & Figure 2-1. This will explain why you need anchor rods or something similar for stability. As for sizing the bearing plate for compression see Part 14 of the Manual Section 14-3 "Beam Bearing Plates". Also, I agree with BigInch on the hole layout.

 

[canwesteng]

Minimum bearing width will generally be governed by your anchors edge distance requirements, minimum size so you can place rebar, etc... Pretty uncommon for concrete bearing or web yielding/crippling to govern but it should be checked if you don't have a good feel for it.

 

[ALEXZ0622]

mats12:

If you're using plain concrete columns there, ACI318-14 Chapter 14 gives you the minimum thickness of "bearing wall", let's say your floor height is 12 ft, then the interior columns may have 6'' x 6'' size(not sure, plz check the plain concrete requirement). then you can choose the notional loads concept either from ASCE7-10 Chapter 1.4, or AISC notional loads under direct design method, whichever is greater, as your lateral loads, to design what ever you want.