Etabs and Sap2000 Column Design

[Ultra Zone]

If you use the Etabs or Sap2000 to design concrete columns, take this tip:

The Etabs and Sap2000 design the elements "columns" according to the ACI-318, however their don't check the next:

If the ultimate axial load (phi*Pn) < (0.10*fc'*Ag) , you should to design the element like a element in flexion (in both directions) without to considerer the axial load, I mean, you should design it like a beam.

where:
phi = strength reduction factor
Pn = nominal axial load strenght
fc' = compresive strength of concrete
Ag = gross area of section

This check is comun in the columns of the last story or with roof light.

(Reference: ACI-318, Appendix B: B.10.3.3)

[ptqc06]

Thank you. I think it 's very important to know. I never think about this problem. When you use software to analyse or design, sometime you don't care about special case of interior forces.

[brichard]

Karla,
Do you think with minimum 1% steel in column, it will govern the bending case when the column is lightly loaded?

[zbizafar]

Dear All,

Can anyone tell me how to assign parameter LZ, Ly Ct , CB in Sap and Etabs? As we do in Staad steel strucutre.

Secondly Do we have to assign them in SAP and ETAB, my guess is yes....

Please correct me if i am wrong and tell me the procedure.

[Ultra Zone]

Karla,
Do you think with minimum 1% steel in column, it will govern the bending case when the column is lightly loaded?

Not always.

If you design the column like a beam, you provide the steel reinforcemnt to the "face" of the column, so the 1% will doesn't apply.
Remember you should check the flexion design and satisfy the 1% of steel reinforcemnt (always is a column) and detail that govern.

[sonidero]

Dear All,

Can anyone tell me how to assign parameter LZ, Ly Ct , CB in Sap and Etabs? As we do in Staad steel strucutre.

Secondly Do we have to assign them in SAP and ETAB, my guess is yes....

Please correct me if i am wrong and tell me the procedure.

If possible but very tedious. These properties can be modified if once you run the analysis and design in ETABS or in SAP2000, select a member that interests you, to review the design parameters. So if the program in any default mark does not meet your needs, you have the option of rewriting it.

Imagine if you could not edit, so why would SAP and ETABS?

---

Karla,
Do you think with minimum 1% steel in column, it will govern the bending case when the column is lightly loaded?

Not always.

If you design the column like a beam, you provide the steel reinforcemnt to the "face" of the column, so the 1% will doesn't apply.
Remember you should check the flexion design and satisfy the 1% of steel reinforcemnt (always is a column) and detail that govern.

Absolutely. Remember that a column subject to biaxial flexocompresión therefore must satisfy the reinforcement in each direction. I think that 1% is for when you have little bending and axial force governs. Hope I'm not much mistaken

Care. In ETABS and SAP2000 have a horrible flaw: In the beams do not take the effect of biaxial flexocompresión therefore despises, unlike other programs like Staad or RAM if you take that into account. Because it only considers the actions beam in the direction normal to one of its main targets, such as in gravity loads, but if we push because arch roofs or other solicitation, not calculated. So in that part instead of defining them as beams, columns have to pass them.

[MOSS2000]

HI
HOW USE EFFECT BUCKLING MOMENT IN SAP2000?

[sonidero]

HI
HOW USE EFFECT BUCKLING MOMENT IN SAP2000?

For the critical buckling load on the installation CD or DVD is a video that illustrates how to use an analysis that relies on another to calculate a factor that reflects the critical buckling load. Also check the examples are a problem type. You can check it from Menu Help, Documentation, and Verification Problems. Greetings.