Seating roof design shortcomings

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mustafadisci

New Member
my teachers asked me to build a sitting roof at the place where I did my internship, I designed something roughly, but it seemed a bit strange to me. Could you please tell me the cons and extras about the roof I made? i am ignorant about this?
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Hello there ; First of all, since you are using a box profile, you should analyze with AISC 360-10 ASD or LRFD, not with TS 648 in analysis settings. Another problem is that the snow load you affect on the pavements is quite high. You entered a load of 2 tf/m2. I recommend you to review TS 498. Snow load data are available in tabular form according to regions and height. I see in your model that the intervals of the purlins are quite frequent. Some changes have been made, I would like you to examine your model. Apart from that, Prof. I recommend you to review Hilmi DEREN's book on steel structures. For joints, you can use the welded joint at the bottom in the Constructive Joints tab, or you can use the welded joint for pipe/box profiles. You will see different results due to the changes I made in your model. You can compare the modeled version with this version in terms of design results and building behavior. Just an important point. Due to an error in the program, the material elasticity module is faulty in the box profiles. There is a second fe 37. The elasticity module needs to be 21000000 tf/m2. Examine the fe 37s from the building tree and correct the one with the lowest modulus of elasticity. Good work.
 
Hello there; In box profiles, a material is displayed as fe 37 for the second time in the building tree. Correct the elasticity modulus of this Fe 37, which is 100 times smaller than it should be, as 21000000 tf/m2. Also, your model had a modeling error in purlins and skins. I fixed them. It is one of the reasons why you are having problems. Finally, your cladding unit weight is quite high, and an image taken from the internet will give you an idea of the sandwich panel unit weights available. When you right-click after the analysis on the 3D screen and switch to the analysis model, examine the element end freedoms under the structure title in the tab that will appear on the screen. Articulated joints appear on your frame in both directions. The main frame direction should remain moment transmitting. Therefore, I removed a few welded joins that you will see in your model. Completely remove welded joints in that direction.
 
Hello there; In the analysis results, you should check not only the pmm rates, but also the other sub-tabs in the result tab. You also need to check the steel element reports by getting them. In the reports, it is explained in more detail why it is not sufficient. The cross-sectional conditions stipulated by the earthquake regulations in your columns do not seem sufficient. After reviewing the report, it will be useful if you examine the Earthquake regulation 2007. Good work.
 
Hello sir, forgive my ignorance, when I look at the column reports, it says that the column sections are insufficient in this project and the number of modes included in the calculation is insufficient, I increased the number of mods to 50, but for a bi-story building, this needs to be solved in 4 modes or something, so in the system you solved and sent me, 10 boxes you have provided it by using a profile, why can't I get a check in the 20 box profile, why does it give me a lack of cross-section, while yours provides everything including the pmm ratio, and I tried it by removing the coating and purlin weights, and it gave an insufficient error again:/ . As you said, I fixed the fe 37 material and even though I closed the element end freedoms.
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Hello there; First of all, the material error in the program is renewed every time the program is closed and opened. Check the material every time. In this way, you can see that only the cross-sectional conditions arising from the earthquake regulations are not met. If we come to your other question, for manual calculation and dynamic analysis, the masses are gathered to the center of the structure and you operate with 1 bar representing each floor, and at this point, you proceed with the assumptions, the elongation and deformation of the structure in the other direction is neglected. The operation is performed assuming that there is a rigid diaphragm movement on the floors. In the program, if a rigid diaphragm, that is, a floor in the floor, is not defined in the structure, it is not possible to be sufficient in 4 modes. The deformation of the structure in the other direction will also be effective. Good work.
 
When I convert the 200 box profiles to IPE 200 profiles, it resolves, but I wonder why the 200 box profile gives an insufficient cross-section error for these loads.
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is providing right now, but even if I translate a column of 200 box profile, I couldn't understand the reason why, in my opinion, 200 box profiles should carry it easily, I couldn't provide it somehow but even if I use 10 pcs of I profiles, I couldn't get square and rectangular profiles while solving.????
 
"mustafadisci":2ykkfl4x" said:
It resolves when I convert 200 box profiles to IPE 200 profiles, but I wonder why the 200 box profile gives an insufficient cross-section error for these loads?
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currently provides, but even if I rotate a column of 200 box profile, I couldn't understand why, in my opinion, box profiles of 200 should carry it comfortably, I couldn't provide it, but even if I use 10-gauge I profiles, square and rectangular profiles are used when solving I couldn't provide it.????
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Hello; Please examine the elasticity module of the material of the box profile of 200. When the program is defined, the elasticity module of this box profile is 100 times lower than it should be. This error has been fixed for the next version, but V8. For 030, you need to enter the material section of the building tree and enter the elasticity module of the material correctly. The value should be 21000000000 kgf/m2. Best regards
 
Hello there; First of all, in the analysis settings, your ductility level is high and your R carrier system coefficient is 8. The regulations you choose are designed according to AISC 360-10 ASD and Earthquake regulations 2007. The purpose of the earthquake regulation is to provide a building design with a high level of ductility so that your structure is damaged under the effect of the earthquake, but no loss of life occurs, or no damage depending on the importance of the buildings or an informed collapse. At this point, there are special conditions brought by the regulation in buildings with high ductility level and for these conditions, the ductile behavior of materials and sections is important, not strength. There are coefficients determined as a result of the experiments. If you do a literature review, you will have the chance to examine different situations. Compared to other regulations, the coefficients in our earthquake code are similar, but slightly higher. The reason why your sections are not sufficient is not their strength but their ductility. In the section you see in the image, if you manually check with the coefficients in the high ductility level tab for box profiles, you will see that your H profile meets this requirement. You can find powerpoint presentations about ductile steel structure design on AISC's site. I recommend you to review Fema as well. You can access comprehensive data on steel structures. Good work.
 
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