Excessive support reinforcement

[loggen]

Hello, in my 3-storey reinforced concrete project, I am getting excessive reinforcement, especially in the 1st floor beams (k06-07). Also, when I analyze the full rigid diaphragm solution by choosing a semi-rigid diaphragm, I see that the amount of reinforcement decreases. What are your suggestions? . Thank you..

 

[NYILMAZ]

Re: Excessive support reinforcement ?? You can solve with a semi-rigid diaphragm without changing the design. The attic floor D09 flooring is faulty.

 

[loggen]

Re: Excessive support reinforcement ?? Thank you for your answer.. In the semi-rigid option, the support reinforcement of those beams is reduced by almost half, which makes me nervous, frankly, about two different analysis results.

 

[Ismail Hakki Besler]

Re: Excessive support reinforcement ??

Thank you for your response.. In the semi-rigid option, the support reinforcement of those beams is reduced by almost half, which makes me nervous, frankly, two different analyzes on the results

Two clearly different methods give abnormally parsed results on some systems. This is very normal. Be alarmed, but not because of the program.

 

[denizbayram]

Are there any obstacles or disadvantages in regulations for making semi-rigid diaphragms?

 

[proisa]

I think the use of semi-rigid diaphragm has started to increase recently because it requires high analysis, that is, processing power. For this reason, TDY 2007 clearly does not have a semi-rigid diaphragm expression. Even if it did, there was no such possibility. But there is no word that prevents this. However, in most sections, there is the expression "in buildings where floor floors operate as rigid diaphragms..." or "in buildings where floor floors are idealized as rigid diaphragms...". Two items that may refer to the semi-rigid diaphragm; 2.7.3.2 - In buildings where the type A2 irregularity defined in Table 2.1 exists and the floors do not operate as a rigid diaphragm in the horizontal plane, an independent static displacement component sufficient to allow the horizontal deformation of the floors to be taken into account shall be taken into account in the calculation. For this reason, each of the equivalent seismic loads acting on the individual masses distributed at various points on each floor will be shifted by +5% and -5% of the story size in the direction perpendicular to the earthquake direction (Figure 2.8). 2.8.2.2 - In buildings with slab discontinuity defined under the heading A2 in Table 2.1 and where slabs do not operate as rigid diaphragms in the horizontal plane, sufficient dynamic degrees of freedom will be taken into account to allow the deformation of slabs within their planes to be taken into account. Each of the modal earthquake loads acting on the individual masses distributed at various points on the floor will be shifted by +5% and -5% of the storey size in the direction perpendicular to the earthquake direction (Figure 2.8)..... This means that a semi-rigid diaphragm can be used because it talks about the calculation and especially the deformations of the floors in their plane. Here is my conclusion; a method used in irregular irregular buildings can be used in any case for standard buildings without irregularity. As a result, if a fully rigid diaphragm is an acceptance and an idealization, a semi-rigid diaphragm is more of a consideration.

 

[Ismail Hakki Besler]

The calculation made with the assumption of a rigid diaphragm will lead you to huge errors in some structures. Check out this document.

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[ganymede]

Calculation with rigid diaphragm acceptance will lead you to huge mistakes in some structures. Check out this document.

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[/ quote] In the document, it is stated that "For the non-linear calculation of structures, the results obtained with the rigid diaphragm acceptance approach in cases where there is A2 slab discontinuity irregularity are not safe." As it is written there, for non-linear calculation A valid situation.For non-linear calculation it is necessary to define a new load and adjust the analysis settings accordingly.Idecad performs linear analysis when there is no intervention.In this case, do you think the result in the article can be considered valid for linear calculation as well?

 

[Ismail Hakki Besler]

Calculation with rigid diaphragm acceptance will lead you to huge mistakes in some structures. Check out this document.

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In the document, "For non-linear calculation of structures, the results obtained with the rigid diaphragm acceptance approach in cases where A2 slab discontinuity irregularities are not reliable." a result has been reported. As it is written there, it is valid for non-linear calculation. It is necessary to define a new load for Non-linear account and adjust the analysis settings accordingly. Idecad performs linear analysis when there is no intervention. In this case, do you think the result in the article can be considered valid for linear calculation as well?

Whether you do linear or nonlinear analysis, modeling your structure with the assumption of a rigid diaphragm is an outdated and slowly abandoned method. "Accept" above name. If your structure is a non-beamed or ribbed system or has A2 A3 irregularities, you should definitely consider the in-plane deformations of the floors. We have heard that this situation is taken into account in the new earthquake regulation to be issued. In order for you to be able to lay thinner than a certain floor thickness, a semi-rigid diaphragm modeling condition is imposed on the structure.

 

[ganymede]

In this case, the most realistic calculation method is the solution with the assumption of Semi-Rigid Diaphragm no matter what the structure is, although it does not make much difference in buildings where there is no irregularity. So, if we check the Create automatic rigid diaphragm regardless of connection option in the tile settings dialog, does it affect the results of this calculation method? Also, what are the issues to consider when choosing between Mode Combination Method and Eccentric Moment Loading and Response Spectrum?

 

[Ismail Hakki Besler]

In this case, the most realistic calculation method is the solution with the assumption of Semi-Rigid Diaphragm, no matter what the structure is, although it doesn't make much difference in buildings where there is no irregularity. i]Is ticking auto-rigid diaphragm whatever the connection[/i] will affect the results of this calculation method?Also, between Mode Combination Method and Eccentric Moment Loading and Response Spectrum What are the points we will consider when choosing?

This option was put in order to solve the system according to a single rigid diaphragm in case there is a gap between the floor masses and more than one rigid diaphragm is detected. That is, this option will be effective if you have a child with the "Rigid diaphragm" acceptance. Eccentric moment The difference between the loading and the response spectrum is the displacements and end forces for each mode and are found and combined in the response spectrum solution, while the mode combining method finds and finds the floor Fs by making a modal analysis. Displacements and end forces are found by applying these floor Fs to the system. The most realistic solution is Response Spectrum with Eccentric Moment Loading with the Semi-rigid diaphragm option. Only positive results are obtained in the response spectrum calculation. ideCAD considers all positive and negative combinations of internal forces associated with all loading states when incorporating response spectrum results into the design.

 

[proisa]

Mr. İsmail, I also have the following question in my mind; In the analysis with the response spectrum, for example, when examining the general reports of earthquake regulations, +5% and -5% shift of the storey masses are not given separately, but +-5% at once? That's all we can notice from the reports. What is the reason for the difference in the analysis infrastructure?

 

[admin]

In response spectrum analysis, the values of interest (internal forces, displacements, etc.) are combined in the final step using the contribution of each mode, so they do not have a sign. Physically, there is no direction information in the sense of earthquake movement. They only contain information such as "the value we are interested in can be this much" only in the earthquake. For this reason, to take eccentricity into account in this analysis method, ideCAD separately applies a static torsion load (eccX and eccY loads) to the system for each direction. Additional values due to eccentricity are calculated along with the signs (direction) of this loading result. Since there is no direction information in the response spectrum results, subtracting the signed values calculated from the eccentricity can have a reducing effect. appended[/b]. Eccentricity in two directions (+5% and -5%) is taken into account at once. Then, at the combination stage, these earthquake effects are combined as both (+) and (-) and calculations are made for both directions of the earthquake. Since the maximum values consisting of +5% and -5% eccentricities for each direction (X and Y) are calculated at once, the information is given as +-5% at once in the reports. In the story force loading, the earthquake force calculated for each floor is applied to the floor by shifting the center of mass of the floor by 5% in the positive direction, and the other time by shifting it by 5% in the negative direction, and a static solution is made. For this reason, +5% and -5% statuses appear separately in the reports.

 

[sereze]

In this case, the most realistic calculation method is a semi-rigid diaphragmSemi-Rigid Diaphragm[ Resolution with /b] acceptance. So, if we check the Create automatic rigid diaphragm regardless of connection option in the tile settings dialog, does it affect the results of this calculation method? Also, what are the issues to consider when choosing between Mode Combination Method and Eccentric Moment Loading and Response Spectrum?

This option is the space between the floor masses and more than one rigid diaphragm is detected. was put to solve the system according to a single rigid diaphragm. So this option will be effective if you make a child with the "Rigid diaphragm" acceptance. Difference between eccentric moment loading and response spectrum ; In the response spectrum solution, displacements and terminal forces for each mode are found and combined. The mode combination method, on the other hand, finds the floor Fs by making a modal analysis and applying these floor Fs to the system, the displacements and end forces are found. The most realistic solution is Response Spectrum with Eccentric Moment Loading with the Semi-rigid diaphragm option. Only positive results are obtained in the response spectrum calculation. ideCAD considers all positive and negative combinations of internal forces related to all loading conditions while adding the response spectrum results to the design.

When we examine the mode shapes according to the mode shapes, we see that the building is twisted in some modes. In this case, we see that the modal analysis is not two-dimensional, but a calculation that takes into account torsion. In a torsional building, some columns get more load depending on their direction. In this case, how accurate is it to find the floor F's and distribute them? Is he relying on 5% eccentricity here to represent torsion? Is it possible for you to open this issue a little more? Thanks .

 

[Ismail Hakki Besler]

In this case, the most realistic calculation method, although it does not make much difference in buildings where there is no irregularity, Anyway, it's a solution with the acceptance of Semi-Rigid Diaphragm But will we tick Create automatic rigid diaphragm regardless of connection in the tiling settings dialog, does it affect the results of this calculation method? What are the points to consider when choosing between the Mode Combination Method[/b] and Eccentric Moment Loading and the response spectrum?

this option is a space between the slab masses and in case more than one rigid diaphragm is detected, the system will be single-handedly. It was put to solve with respect to a rigid diaphragm. So this option becomes effective if you assume "Rigid diaphragm". The difference between eccentric moment loading and response spectrum is the displacements and end forces for each mode in the response spectrum solution and are found and combined. The mode combination method, on the other hand, finds the floor Fs by making a modal analysis and applying these floor Fs to the system, the displacements and end forces are found. The most realistic solution is Response Spectrum with Eccentric Moment Loading with the Semi-rigid diaphragm option. Only positive results are obtained in the response spectrum calculation. ideCAD considers all positive and negative combinations of internal forces related to all loading conditions while adding the response spectrum results to the design.

When we examine the mode shapes according to the mode shapes, we see that the building is twisted in some modes. In this case, we see that the modal analysis is not two-dimensional, but a calculation that takes into account torsion. In a torsional building, some columns get more load depending on their direction. In this case, how accurate is it to find the floor F's and distribute them? Is he relying on 5% eccentricity here to represent torsion? Is it possible for you to open this issue a little more? Thanks .

You are quite right, so it would be more accurate to use "Response spectrum solution with Eccentric Moment Loading". The effect of the torsion modes you mentioned in the response spectrum calculation comes into play in three dimensions. Even if only the response spectrum analysis is performed, the effect of the torsion modes you mentioned is reflected on the columns and beams. On top of that, 5% eccentricity of the earthquake regulation is added in this case.