Basically negative stress

[mert2044]

Greetings 10.20 version 16 . Added negative displacement control for combinations containing item 0.9G, will negative control be done after this process? In the last question, we were given an incomplete information, I think, we said that if the load with 0.9 is below half of the carrying capacity, we said that there is no problem, but how much below zero and half the carrying capacity should be below half, otherwise, a value below half of the carrying capacity at -100 will not fall below zero, which we understand from here. when you do it, it throws a value multiplied?? As a result, what should be the solution when minus the base thickness will be increased or what kind of solution would you suggest in terms of cost?

 

[Levent Özpak]

greetings 10.20 version 16. item 0.9G negative displacement control has been added for combinations, will negative control be done after this process? We said that there is no problem with the value, but how much should it be below zero with half the bearing capacity, otherwise a value below half of the bearing capacity at -100 will not fall below zero, which we understand from here. What kind of solution would you suggest in terms of cost?

Hello, -With the negative displacement control added in Ver 10.20 version, if there is still margin to save in positive base pressure in combinations with 0.9G, negative base pressure error is not given. It is important to examine the combination and in how much area it occurs. we risk. Negative values can be neglected if they are small and occur in small areas relative to the base area. If the negative base pressure consists of 1.4G+1.6Q loading, then we recommend a balanced arrangement of the structural system of the structure. As a result, negative ground pressures are a situation that should be reviewed by the project owner and decided. Good work

 

[mert2044]

Mr. Levent, I found the article on this subject in ismail brain Re: Negative Ground Stress Message by Ismail Hakki Besler » 19 May 2019, 02:49 In the combination of negative ground tension, if the maximum positive stress value is half or less of the ground bearing strength, you do not need to deal with negative stress. . Also (negative stresses area/total raft area) <0.20 you don't need to bother. The values I have given are very rough values. Negative stresses should be reviewed and evaluated by the engineer. If the ground stresses due to vertical loading are not abnormally asymmetrical, you can ignore negative stress at all. If vertical loads create abnormal asymmetric stress, it is a more important issue to first make the load-bearing system of your structure symmetrically balanced and correctly arranged in terms of vertical loads. In general, negative tension exists in a 0.9 load combination. When we talked to Mr. Emrah, look at the values in the 0.9 load combination. He said that if it is below half of the carrying capacity, it would not be a problem, if I remember correctly, but positivity and negativity were not talked about much thanks ismail in the brain article ''' Negative ground tension came out If the maximum positive stress value in the combination is half or less of the ground bearing strength, you do not need to deal with negative tension '' With this statement, he explained many situations, generally in the 0.9 load combination (in the combination where the negative stress occurs) MAXIMUM POSITIVE If the STRESS VALUE is half or less of the soil bearing capacity , it usually comes out less than half , but he mentioned positive values , so negativity will not be a problem .