A1 irregularity in basement curtains

I

ingegnere

New Member
Hello, I'm new to İdecad and I'm trying to learn. I will be grateful if you, my experienced engineer friends, comment on the project and show any errors. The point that I came across and could not get out of the work; A1 irregularity appears too much in the basement curtains. On the other hand, the relative translations are normally very low. I couldn't understand why. The project is a little big. Thanks in advance to those who helped
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Re: Subbasement Problem My friend, before looking at your project, I will ask you something, did you put the sign "panel with no continuity in the subbasement, which does not continue on other floors" for the sub-basement curtains?
 
hello, Your system satisfies the alphas>0.40 condition in both directions. You can select the ductility level mixed (high pitch-normal frame). KEMAL YALVAC
 
Hello. Will it be a problem if I choose the system as high ductility? Which is more suitable? Other than that, is there anything you see missing? @Sarıdurmus Teacher, as you said, I defined it as subbasement.
 
hello, In the high ductile solution you have to provide the relevant regulation items. you move away from economical design (you have to deal with greater forces in shear safety, you must carefully meet the conditions of joint shearing, strong column). The regulation allows you for a mixed solution. It doesn't say that you can't dissolve high ductile.... Good work, KEMAL YALVAÇ
 
It would be correct to say this situation is not A1 irregularity in the basement curtains, but A1 irregularity on the floor where the basement curtains are located. A1 irregularity is handled in the plane of the floor diaphragm. However, the elements that cause maximum displacement and irregularity may be the basement/basement curtains. I personally take care to place these elements symmetrically, even if it is a basement or basement curtain. Marking the curtain elements as 'flooded' in ideCad only serves to exclude the base shear forces of these elements from the effective shearing area in the AlfaS calculation and B1 irregularity control. It does not change the analysis. Choosing the system ductility is at the discretion of the project author. In order to be able to design a mixed or normal ductile structure, the regulation has set some conditions. Ductility may not always be a correct ratio of economy. It is generally accepted that seismic forces are more damped as a result of the 'high ductile' behavior in highly ductile designs. According to this assumption, the value of the earthquake load reduction coefficient R is higher than normal and mixed in high ductile structures. In order for the structure to behave highly ductile, some criteria have been introduced in the column-beam junction areas and stirrup design. In mixed and normal ductile structures, on the other hand, the seismic loads that the structure can bear linearly elastically are increased by decreasing the R coefficient. The system and elements dissolve under greater lateral load, but are exempted from certain highly ductile design considerations such as column-beam junction security, strong column control, and stirrup tightening. Good work everyone.
 
Hello, the system shared by Mr. Ignegren provides the boundary conditions for high ductile-R=7 (alphas<0.75) and mixed-R=6 (alphas>0.40) solutions in terms of shear-frame sharing of earthquake loads. R coefficient values defined in earthquake regulations are upper limit values. When the engineer deems it necessary, the R coefficient can be lower than the value specified in the regulation in terms of safety. .) However, I did not want to interfere with Mr. Ingegren's choice of R coefficient. may have implications for security. In my previous article, I stated that an economy would be achieved in case of switching from R=6 high ductile system to R=6 mixed system. I agree with myself on this. However, if an R=7-high ductile solution is to be made, we cannot make a definite judgment, as you say, from an economic point of view, in terms of reducing the design forces but also introducing high ductility conditions (capacity moments in shear safety, etc.). We need to solve the system both ways and look at the results. It can be economically positive or negative... good work. KEMAL YALVAC
 
Dear proisa, "You said that marking the curtain elements as 'Basman' in ideCad will not change the analysis. alphas and B1 irregularity coefficient are the parameters closely related to the R coefficient. What exactly are you trying to express in this sentence? I would be glad if you inform me. Good work. KEMAL YALVAC
 
If you have chosen the rigid basement floor number correctly, marking the curtains as sub-basement or not does not change the calculations.
 
Hi Omer, I totally agree with you. However, a general statement such as "does not change the analysis" is not correct in my opinion. Depending on the situation of the building, sometimes we may cause erroneous results if we do not accept rigid floors and do not introduce these curtains into the program as sub-floor walls in buildings where only a part of the wall does not continue on the top. otherwise, these curtains may not be marked if they are defined in the rigid basement floor and the rigid floor is defined correctly in the program. however, as a habit, I favor marking this option on the curtains that do not go up to the top of the building in order not to cause errors. I wish you good work. KEMAL YALVAC
 
Greetings, In my project, as my friend said, I preferred high ductile and got the R coefficient of 6. The reason is that the ground is very bad and even if jetgrouting is done, the structure will increase the period of the building due to some uncertainties in the ground interaction and this will lead to unexpected effects. I even thought about buying the R 5 for a while, but I didn't know how accurate it would be. Do you think I'm doing right? Your recommendation? Which R coefficient should be solved with? Secondly, due to the layout of the elevator curtain in my project, the distance between the center of rigidity and the center of mass is too large. Despite many attempts, I could not get them closer together. As a result, I am not afraid of additional torsional moments. Just in case, it made more sense to me to choose high ductile and lower R to solve it with high earthquake forces. I didn't know what else to do to stay on the safe side. Again, I'm waiting for your suggestions. Do you think this obvious difference between the center of stiffness and the center of mass creates a problem? What precautions should be taken? Waiting for your valuable opinions. Thanks in advance.
 
Dear ingegnere, We already define the ground in the spectrum curve. In this sense, I don't think you need to go for an additional increase, taking into account the ground condition. The regulation takes this into account. We intervene in the R coefficient in cases where we feel the need for additional security related to the superstructure (eg soft floor). However, if you have doubts within the scope of the regulation-ground, I don't know, you may find the spectrum coefficient S(T)=2.5 insufficient in the TA-TB range (if your building period is in this range). It's also normal to want to clear this doubt by reducing R. However, it would not be right for us to give a definite opinion for R to get this. However, my own opinion is that you should not take less than 6. because you already reduced by taking 6 when R=7. The main way to clear all these doubts is to move your structure away from the resonance effect. Check your build 1st period after your superstructure interactive solution. If not, make some concessions on rigidity and move the period of your structure away from this range. This should be the primary path you should follow. Otherwise, no matter how much you reduce the R coefficient, it will be very difficult for your structure to resist the resonance effect. Good work... KEMAL YALVAÇ
 
I would like to express my personal opinions, but I have not had the opportunity to examine your structure, but I can say the following. The regulation has taken measures to detect a very wide range against the possibility of resonance. This has made us on the safe side. If the ground is Z4 class, we define a ground characteristic period between 0.2-0.9 sec between Ta and Tb. .This interval Z1 is between 0.1-0.30 sec. As you know, what we call the resonance effect is the coincidence of the period of the structure and the dominant period of the ground. As we imagined, when the ground and the structure oscillate to the same side, the earthquake impulse creates a double effect. When viewed from the seismic report, this value may increase if the transmission speed is low. But as I said, in order to achieve this range, let's say between 0.2-0.9, our ground dominant period is 0.6, and if the first period of our structure is 0.6s, even then the regulation takes the necessary precautions by increasing it by 2.5 times. The reason why I am against taking these values in the regulation the absence of open cases. The other issue is torsion effects are important in cases where the center of mass difference is caused by the elevator bulkheads. For this, it can be a problem if the first mode of your structure is in torsion mode. Regards OMER FARUK ÇAKIL
 
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