foundation combine

RE: foundation combine

Kris Sathia — Fri, 19 Jun 2020 13:19:12 GMT

The unity check values that you see in the XML file are the allowable bearing pressure divided by the maximum actual corner pressure for each load case. A value greater than or equal to 1 means the footing is safe.

The zeros in the Moment and Reinforcement table look like an error. We will look into it.

RE: foundation combine

Aswathi A — Fri, 19 Jun 2020 08:51:03 GMT

For further queries, please create a Service Request at https://apps.bentley.com/srmanager/ProductSupport or contact us at 000 800 100 8434

RE: foundation combine

prashant kumar — Fri, 19 Jun 2020 07:16:34 GMT

communities.bentley.com/.../16.xml communities.bentley.com/.../16.sfa

for unity check it is more than 1, plz can u explain and i also want know why is xml file for many footing the spacing it is showing N/A.

RE: foundation combine

Kris Sathia — Fri, 19 Jun 2020 04:42:53 GMT

Look at the axial load (FY load) acting on the footing from the column. A positive load means the column is pulling the foundation upwards, which is termed as causing uplift. A negative load means the column is pushing down the foundation which will be resisted by the soil below. You can also see this from the graphical display. The yellow arrows pointing upwards indicate uplift.

On what basis are you stating that the footing is too big? Which footing are you referring to? What is your expectation for a reasonable footing size? Can you upload a calculation to back up that number?

RE: foundation combine

prashant kumar — Fri, 19 Jun 2020 02:20:38 GMT

how to know there is uplift pressure?

RE: foundation combine

Kris Sathia — Thu, 18 Jun 2020 16:34:05 GMT

Your footings are subjected to large uplift forces, with nothing except the selfweight to counteract them. Use the approach explained earlier to find out the reason for your current model. If you are still unable to determine the reason, please raise a service request.

RE: foundation combine

prashant kumar — Thu, 18 Jun 2020 13:51:51 GMT

why i am getting such big dimension.

RE: foundation combine

Kris Sathia — Thu, 18 Jun 2020 09:20:41 GMT

Here is the output from the current version - 9.3.0.14 that was released at the end of April 2020.

RE: foundation combine

prashant kumar — Thu, 18 Jun 2020 06:57:49 GMT

i have a same problem in other file i am upolading it. actually in design it shoe zero error but when i take detailed output it shows error and dimesion is also taken to long althoung i have updated the soil load to counter the effect.communities.bentley.com/.../phulwari-sharif3_5F00_foundation.sfa communities.bentley.com/.../10.xml

RE: foundation combine

Kris Sathia — Wed, 17 Jun 2020 11:53:45 GMT

Consider footing 1 and load case 2. There is an uplift force of 87.59 + 99.62 = 187.21 kN from the 2 columns. Since there is no soil on the footing, this entire uplift has to be counteracted by the selfweight of the footing. So, minimum weight of the concrete in the footing has to be 187.21 kN. But this will result in a net downward load of 0.0 kN. A bit more is required to satisfy the sliding check as described next.

In load case 2, there is a lateral load FZ of 12.46 + 12.62 kN = 25.408 kN. Since the factor of safety required in sliding is at least 1.5, and the coefficient of friction is 0.4, minimum additional downward force required is

(25.408 / 0.4) * 1.5 = 94.05 kN

Thus, the weight of the footing has to be at least 187.21 + 94.05 = 281.26 kNs

The program achieves this by keeping the thickness at 150 mm (the minimum value you specified) and increasing the plan dimensions to 13.107 m X 5.75 m, which gives a total weight of (13.107 * 5.75 * 0.15 * 25 = 282.62 kN) which is slightly greater than 281.26 kNs

Subsequently, during the concrete design phase, the 150 mm thickness is found to be insuficient, so it is increased to 250 mm.

That is how you end up with 13.107 m X 5.75 m X 0.25 m

If you start with a larger thickness, the plan dimensions will be smaller. Also, note that the plan dimension increment of 50 mm is more efficient than a 50 mm thickness increment from the standpoint of overall volume of concrete, so reducing the thickness increment to 10 mm will produce a more efficient design.

RE: foundation combine

prashant kumar — Tue, 16 Jun 2020 11:08:42 GMT

communities.bentley.com/.../work14_5F00_foundation.sfa

connect edition

RE: foundation combine

Aswathi A — Tue, 16 Jun 2020 09:17:05 GMT

Can you attach your .sfa file here? Also mention the version of STAAD Foundation Advanced you are using.