topic Re: Combined footing: Problems with reinforcement and pier (RSA 2022) in Robot Structural Analysis Forum

Combined footing: Problems with reinforcement and pier (RSA 2022)

mikelt6CWRJ — Fri, 03 Jun 2022 11:35:53 GMT

Hi all,

I am designig the following truss:

As you can see, the columns are close to its other, therefore I want to design a combined footing. Then I select the 2 nodes of the columns and enter in the RC design module and I select yes to design one spread footing with two columns. I do not want piers, so I put the initial numbers like this:

When I calculate the example I get "Problems with the reinforcement patterns" So I am doing something wrong. Also I do not want to have any pier, just column bolted to the footing. But I have not much of a idea of the steps to get that.

Thanks

See attachment.

Regards

Re: Combined footing: Problems with reinforcement and pier (RSA 2022)

Krzysztof_Wasik — Fri, 03 Jun 2022 13:36:09 GMT

Hi @mikelt6CWRJ

Open Analysis > Reinforcement pattern >Pier tab

Switch off all patterns for pier

then calculate reinforcement again

Re: Combined footing: Problems with reinforcement and pier (RSA 2022)

mikelt6CWRJ — Sat, 04 Jun 2022 15:05:11 GMT

Thanks @Krzysztof_Wasik , I did not see the option.

Now I have calculated the model again and entered the loads in the RC module. I have selected the following options:

Then I run the calculation and I get the following result:

Am I penalizing too much the checkings? I am thinking about burying it more and giving it more thinkness, but right now the dimensions are too big.

Another question, the load definition option is when there is no previous model and we just have the reactions, right?

Thanks.

Re: Combined footing: Problems with reinforcement and pier (RSA 2022)

Krzysztof_Wasik — Sat, 04 Jun 2022 21:08:10 GMT

Hi @mikelt6CWRJ

You allowed all dimensions to be optimized. You can block some diameters with checking dimension box an Apply. Then only not checked out diameters will be optinized.

You have imported loads from calculated 3D model. Loads definition works when RC footing is design in "stand alone mode", regardless results calcualted in your 3D structure model.

Re: Combined footing: Problems with reinforcement and pier (RSA 2022)

mikelt6CWRJ — Sun, 05 Jun 2022 15:51:30 GMT

Thanks @Krzysztof_Wasik .

Just one more question. I have been testing some fixed dimensions and I get the following results.

Apart from the uplift, which I can solve it giving more weight of putting deeper the footing, I do not understand well the "Safety factor" error. I went to "calculation options" and I see them ok as I want to put reinforcements from 12 mm.

Re: Combined footing: Problems with reinforcement and pier (RSA 2022)

Krzysztof_Wasik — Sun, 05 Jun 2022 19:41:20 GMT

Hi @mikelt6CWRJ

When tere is error in soil capacity, sliding or overturning program does not generate reinforcement. This is the reason for those (reinforcement) errors. Allow uplift, or switch off forces position verification in Analysis >Geotechnical options. Then stability condition will be satisfied and reinforcement will be generated.

Re: Combined footing: Problems with reinforcement and pier (RSA 2022)

mikelt6CWRJ — Mon, 06 Jun 2022 09:40:38 GMT

Thanks @Krzysztof_Wasik ,

How do you allow uplift in this case? I guess you are not referrering to define an uplifth in the supports.

I algo thinking about giving an eccentricity:

But doest not seem to have an effect.

Re: Combined footing: Problems with reinforcement and pier (RSA 2022)

Krzysztof_Wasik — Mon, 06 Jun 2022 09:47:20 GMT

Hi @mikelt6CWRJ

Activate 1/3 in Geotechnical options.