Negative Base Pressure

M

miralay

New Member
Good work. In my project, I am getting negative base pressure error in the relevant combination in the reports. However, in the analysis model monitoring part, my base pressure values do not go negative in the relevant combination. How can I see where negative ground pressure occurs in my project? Project link and pictures are below.
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The image you added is the M11 moment. It has nothing to do with my question. I'm talking about ground pressure. Not from raft stretching.
 
We are not at the computer. But you probably have a rigid basement in your structure. While the raw results are displayed on the 3D result review screen, the increased stresses of the loads used in the foundation solution for the basement are printed in the report according to 4.10.1.5. Friends will write you detailed answers. If you remove the test-purpose rigid basement sign and solve it, the values printed in the report and the values printed on the review screen will be the same in buildings without a basement.
 
Ismail Bey, what you say is true. There is a rigid basement in the construction. But I don't have a negative value in raw results. How can a non-negative value be negative by adding amplification factors? I didn't understand this part.
 
Hi In structures containing rigid basements, the elements and foundations in the basement are joined as described in TBDY Section 4.10.1.5 (b). In this combination, Düst and Rüst are reduced in the dynamic analysis, where the masses in the basement of the building are not included and only the masses in the upper floors are included, as explained in TBDY Section 4.8.5, in the dynamic analysis, only the masses in the basement of the building are included and the masses in the upper floors are not included in the dynamic analysis. coefficients are used. In ideCAD v10, the results including the upper floor masses are seen as Ex and Ey, the results including only the basement floors are seen as ExB and EyB. The stress values that you look at on the 3D screen in the program and that you send as a screenshot are the raw results. In order to obtain the design results, it is necessary to combine as shown in the Earthquake regulation. The program reaches the result by making these combinations in the basic calculation. How this combination is done is shown numerically below. We will arrive at the design stress from the deformations of the foundation. Combination: 0.9G' + Ey + 0.3Ex - 0.3Ez G' = -2.83 mm Ey = 1.44 mm Ex = 0.743 mm ExB = 0.0389 mm EyB = 0.0907 mm Ez = -2.12 mm (-) slump (+) lift values, produces negative ground stress. Up = 3 Dalt = 1.5 0.9*N' + 0.6Up*( Ey + 0.3*Ex) + Dalt*( EyB + 0.3*ExB) - 0.3*Ez 0.9*(-2.83) + 0.6Up*( 1.44 + 0.3* 0.743) + Dalt*( 0.0907 + 0.3*0.0389) - 0.3*(-2.12) = 1.236 mm Since the displacement value of 1.236 mm is positive, we determined that there is an upward (negative ground stress) displacement in the foundation. If we multiply this displacement value by the Bearing Coefficient, we can obtain the stress. The bed coefficient is 3400 tf/m3. A value such as (1.236/1000)*3400 = 4.203 tf/m2 (negative ground tension) is output. The corner I am looking at is not the maximum value, but when we look at the other corners, the value in the report can be found. Best regards...
 
In this case, I have a request to you. If you add Normal loads as well as combinations to the base pressure tab, it will give us an idea of where the problem is at the base. If possible, it will be very useful if an option such as show the results with coefficients is put directly in the 3D result monitoring section. Thanks for your detailed answer. I wish you good work.
 
The request you specify will be handled together with the job you have requested before and will be presented to the users in the upcoming updates.
"miralay":2z8id2dh" said:
Mr. Yasin, I would like to give a brief information about what results I would like to see in item 3. Column capacity diagrams should be added to reports. Color scala graphics related to raft foundation should be added as a full page attachment. Regarding intermediate processes The transition between the raw values of the combination that the program finds as a result of static and dynamic analysis and the design values used in the reinforced concrete design should be as transparent and traceable as possible in the reports. In addition, Idecad has embedded some of the regulation items into the combinations in V10. These sections should be given in more detail in the reports. [/quote ] Thank you for your valuable contributions to the forum and program development.
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