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Turkish First of all, good evening. After analyzing the project, the number of mods gave an insufficient error. After many attempts, I increased the number from 18 to 100. The analysis did not give an error. my question is what does it mean if the number of mods is less or more? If I buy too much, will I do something wrong? How does it affect the account? How else can I solve this problem? Or what could be causing the error? Thank you for your interest. I am attaching the project. A ready-made prefabricated house will be placed on the foundation.
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Insufficient number of mods
- Thread starter actombo
- Start date
Levent Özpak
New Member
Hello, Mode number is insufficient in dynamic analysis according to Tdy 2007 item 2.8.3 It means that sufficient mass participation rate is not provided. It is normal to need high modes because there is no rigid diaphragm even if the floor is not considered rigid. In the project, the mode calculation method "Ritz vectors" can be selected in the modal analysis status window, and sufficient mass participation rate can be achieved with a lower mode number."actombo":8zx8ohnd" said:first of all, good evening. After analyzing the project, the number of mods gave an error that was insufficient. After many attempts, I increased the number from 18 to 100. The analysis did not fail. ?Will I do something wrong if I take too much? How does it affect the account? How else can I solve this problem? Or what could be causing an error?
HakanŞahin
Administrator
Hello, The project you added does not have an insufficient number of mods message. The reason for this is that by changing the rigid basement number, you may have added your project by making a single-floor rigid basement. If there is a rigid basement in a single-storey building, the earthquake forces to be applied to that floor are found according to the equivalent method (FBk=Ao* I *Wbk / 1.5) as specified in the TDY (See TDY article 2.7.2.4 and Figure 2.6.) Dynamic analysis is not performed in projects because the floor forces are determined by equivalent load. The mode insufficient warning you ask is revealed when a rigid basement is not accepted in your single-storey project. There is no flooring in your building and therefore there is no rigid diaphragm. In structures without rigid diaphragms, the masses are at the ends of each element It is calculated and more modes are needed to reach sufficient mass participation rate depending on the number of nodes. If you use the Ritz vectors method instead of the Eigen method, you can reach 90% mass participation rate with less modes. In version 8, the Ritz method has been added to the program. Mode calculation in the modal analysis status window You can choose the method as "Ritz vectors", or you can use more than 100 You can also use the eigen method with more mods. For Ritz and Eigen, you can refer to the following link:
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