Loading Status - Rigid Diaphragm Question

[sdonder]

Hello there; Since our structures are generally connected with steel and mechanical equipment, we have to create new combinations in the idecad program. I wanted to ask about some of the points that we are stuck at exactly at these points, on the following example. Let's assume that we have a 2-storey structure and the equipment on the first floor of this structure, and a steel structure on the columns, on the second floor. E (equipment) status has been created for the loads to come from the equipment. (As you can see in the picture, the option to use in design has not been activated) Later, combinations with this loading status were added to the combinations section. ** Loads coming from the equipment on the 1st floor are entered in the middle of the beams under the E loading condition. While the moments in the combinations with E loading condition are used in the beam support regions, it has been seen that the opening moment is used in the design by taking the moment value from the combinations without the E loading condition (1.4G+1.6Q, which is not the largest opening moment). In case of loading, ticking "Use equipment loading in design" improves the opening moment. However, when this tick is checked, the program also designs with only the equipment load. Just having the equipment load without the structure takes an unrealistic approach. In summary; I want to design according to the beam span moment resulting from the combinations created by me, without making the loading cases use fixed loads, use live loads, not marked in the design, is there a way to do this? In addition, do the new installations and combinations I create seamlessly join the design in slab, column, foundation, pile design? *** At the 2nd floor of the building, a load of 100 t assumed to be made of steel (in G loading) has been added to each column. When we select the mode combining method from the analysis settings and create the diaphragm on the 1st floor, I see that the load of 100 * 4 = 400 t that I entered is included in the earthquake calculation. However, since I did not want to create a diaphragm on the 1st floor, when I did not create a diaphragm on the 1st floor using the response spectrum solution, I could not see that the 400 t load was added to the total weight of the structure in the earthquake calculation. Does the program include the loads we act under G in the earthquake calculation on floors where we do not create a rigid diaphragm?

 

[sdonder]

The ide file of the build is attached

 

[HakanŞahin]

hi; Checking Use equipment loading in design in case of loading, this situation in the span moment is corrected. However, when this tick is checked, the program also designs with equipment load only. It is unrealistic to only load equipment without structure.

Hello, User-defined loads are taken into account on the support. Span calculation is made from vertical load. Alternatively, you can define the value you add as E not as the loading state, but by multiplying G by 1.4. In this way, 1.4G+1.6Q is added to it.

Also, do the new installations and combinations I create participate in the design of slabs, columns, foundations, piles without any problems?

Yes they do

* ** On the 2nd floor of the building, a load of 100 t (in G loading) assumed to be made of steel has been added to each column. I see that the load of 100 * 4 = 400 t, which I entered when we created the diaphragm, is included in the earthquake calculation. However, since I did not want to create a diaphragm on the 1st floor, when I did not create a diaphragm on the 1st floor using the response spectrum solution, I could not see that the 400 t load was added to the total weight of the structure in the earthquake calculation. Does the program include the loads we act under G in the earthquake calculation on floors where we do not create a rigid diaphragm?

Yes, it agrees. Since there is no floor concept in a floor without a rigid diaphragm, the structural loads are activated at the ends of each element with the response spectrum. Good work

 

[sdonder]

*** On the 2nd floor of the building, 100 t load (in G loading) assumed to be made of steel has been added to each column. When we select the mode combining method from the analysis settings and create the diaphragm on the 1st floor, I see that the load of 100 * 4 = 400 t that I entered is included in the earthquake calculation. However, since I did not want to create a diaphragm on the 1st floor, when I did not create a diaphragm on the 1st floor using the response spectrum solution, I could not see that the 400 t load was added to the total weight of the structure in the earthquake calculation. Does the program include the loads we act under G in the earthquake calculation on floors where we do not create a rigid diaphragm?

Yes, it agrees. Since there is no floor concept in a floor without a rigid diaphragm, the structural loads are activated at the ends of each element with the response spectrum. Good work

How can we see the charges at the ends of these elements due to the response spectrum?

 

[Ismail Hakki Besler]

 

[sdonder]

In the attached file, I loaded 400 t loads on the top of the columns. When I solve it with the response spectrum without a rigid diaphragm, the shear force t each comes from 25 earthquake loads to the columns, while the sg fractionation ratio for the columns is 1.63. When I solve it with a rigid diaphragm using the mode coupling method, 50 t shear forces each come from earthquake loads on the columns, while the sg fractional ratio in the columns increases to 4.16. Why is there a 2-fold difference in earthquake loading between these two methods? I would be glad if you inform me.

 

[Ismail Hakki Besler]

In order to understand which options you are solving in the analysis settings dialog, either save both projects separately and send them as Question3-Rigid diaphragm and Question3-Without diaphragm, or in the analysis settings. Save and share pictures of options. We couldn't create the situation you mentioned here.

 

[sdonder]

The files you requested are attached. During the analysis, the program gives a diaphragm warning in both files because it cannot find tiles. In the file with diaphragm, create the default diaphragm on these floors, and in the file without diaphragm, solve the structure without diaphragm options, the solution is made. Good work.

 

[Ismail Hakki Besler]

In case the floor masses are applied to the diaphragm center, the equipment load you enter as 400 tons from the outside affects the floor diaphragm center as a mass of 1600 tons. In the other model, the 400 tons of equipment load you enter on the columns is applied equally to the end and lower end of the columns at floor level. In this case, the solution you made without a rigid diaphragm is solved with half the masses compared to the other solution. This difference is more obvious in a single storey building. You get the closest to reality when you divide the columns into more elements. In multi-storey structures, there is less difference between the effect of the masses on the rigid diaphragm and the spreading of the masses in the form of dispersed masses. good work

 

[sdonder]

Have a nice day; Since I will ask a similar question, I wanted to continue under this title. In the attached project, I loaded a load of 300t under the name E (Equipment Load). I assume that this equipment will consist of; I loaded the earthquake force on the x-axis as 100t under the name Dx, and as 100t on the y-axis under the name Dy. I created combinations G+E+Dx and G+E+Dy. I solved the structure without a diaphragm using the response spectrum method. I could not use the 300 tm moment that I saw in the frame results - moment diagram, which is formed at the lower end of the column due to the 100t shear force under the names Dx and Dy, and the 300t axial load under the name E in the column design.

 

[Ismail Hakki Besler]

You have not selected the option to use the E (Equipment) load you defined at constant load. Or you should enter the direction as G to use it in the design. You entered as Z.

 

[sdonder]

Use fixed loads: These are the options that determine whether loads from fixed or live loads are included in the loading situation. If you mark "Use fixed loads", fixed loads such as walls, dead weights and floor coverings are included in the related load situation. Do not tick this option if you are defining seismic loading. Due to the expressions in the description; This tick is not marked because it is not requested to automatically combine with this load. It is thought that dead loads will be added in the G+E+Dx combination. In addition, when this tick is marked, a load of 307.35 t comes to the column axially at G+E+Dx loading, as can be seen in the table, but it does not use this in the design. In addition, while the 300tm moment consisting of Dx horizontal loads appears in the moment diagram, it does not appear in the table and is not included in the design. It was added in the G axis while adding the load to the column. In the change loads section, it appears as FZ=-300 t. I could not see any problem in the image where we saw the loads.

 

[Levent Özpak]

Hello, in the case of a solution without a rigid diaphragm in version 7, unchecking the "Use in design" option in the Loadings section will enable the design to be made according to user-defined load combinations. Good work

 

[sdonder]

When I combine the beam question I asked before and the column question, I get the following results in summary. In order to be used in the design of all structural elements, regardless of the analysis method of the extreme forces and moment effects that occur depending on the loading conditions that I have created; **Use in design must be checked in the loading cases created for vertical loads **Use in design must not be checked in the loading cases created for horizontal loads.

 

[HakanŞahin]

When I combine the beam question I asked before and the column question, I get the following results in summary: For the use of the extreme forces and moment effects, which occur depending on the loading conditions that I have created, in the design of all structural elements, regardless of the analysis method; * *Use in design should be checked in the load cases created for vertical loads **Use in design should not be ticked in the load cases created for horizontal loads.

No, to summarize: 1. In order to take the vertical load combinations you added into account in the beam spans, you should load your loads in the beam openings. In G loading, we define it by multiplying it by 1.4 if necessary. (Aperture calculation is made from vertical load. You can define the value you add as E not as the loading condition, but also by multiplying G by 1.4. In this way, you add 1.4G+1.6Q.) 2. If without a rigid diaphragm if you are making solution, check "use in design" don't suck. (This is only valid for 7 version users) Note: If necessary, you can contact me on 0 224 220 67 17.