Alpha S >0.75 Condition in a Curtained Normal Ductile System

I

ilkem

New Member
Hello there; In a 4 storey project (there are elevator curtains in one direction) in the 3rd degree earthquake zone, the ductility level is normal, when I choose R=4; I get the warning "Normal system is selected, but the ratio of the sum of the wall shear forces to the total shear force is less than 0,75". The regulation allows the normal system of ductility level without curtains in the third and fourth degree seismic zones under the conditions (height limit) specified in paragraphs a and b of 2.5.1.6. And again in 2.5.3.te, it can be done above the height limits, but it makes it necessary to use SDN or SDY curtains. Then 2.5.3.1. In the case of using SDN curtains, Alpha S >0.75 is required. According to the aforementioned articles of the regulation, I think that the Alpha S > 0.75 condition should not be sought in this project. Because, in case of using SDN curtains in TDY Article 2.5.3.1, Alpha S >0.75 requirement is stipulated in Article 2.5.1.6. I think it is desirable if the height limits defined in paragraphs a and b are made. (This is what I understand from the regulation) I wonder if I'm wrong! Thank you in advance for your comments and suggestions.
 
Re: ALPHA S >0.75 CONDITION IN WRAPPED NORMAL DUCULAR SYSTEM HK. Hello Sir; If we examine the relevant articles of the regulation; (Picture-1) 1. Ductility Level Normal to carrier systems only in 3rd and 4th degree earthquake zones... (Article: 2.5.1.6) a) mushroom, cassette, gear, SDN for structures with load-bearing elements...H<13 mb) for slab flooring systems.....H<25 m 2. SDN systems over the above-mentioned limits (Hn>13 and/or Hn>25) can be done in two ways... (Article:2.5.3) a) In case of using Curtains with Normal Ductility Level*.... Alpha s > 0.75 b) In case of using Curtains with High Ductility Level*... Mixed Carrier System... (2.5.4.1) (* ductility on element basis) If SD Normal is selected based on the report letterhead of the program; (Picture-2) 1. Alpha s >= 0.75 .... R=4 2. Alpha s < 0.75 .... Mixed System Evaluation: 1. Since the structure is in the 3rd degree, the Normal Ductility Level System can be selected... 2. Since the building height is Hn< 25m, there is no obligation to use a curtain... [b ]3.[/b] Curtains used in the building; a) SD High curtains; Mixed System can be selected, but it is not mandatory since Hn<25m... (optional) b) If SD Normal curtains; Alpha s>0.75 condition should be sought, but since Hn<25m this condition should not be sought... 4. In the table in the report letterhead of the program (Picture-2) Building Height Requirement (Hn)' I think you have come across such a warning... Thanks to the friends who will contribute to the discussion with their comments and opinions on this issue.... Good work, respect...
 
Re: ALPHA S >0.75 CONDITION IN WRAPPED NORMAL DUCULAR SYSTEM HK. Thank you very much for your detailed contribution to the subject, my master. ''4. I think that the Building Height Requirement (Hn) is not taken into account in the table (Picture-2) on the report letterhead of the program, therefore you are faced with such a warning... '' I agree with you. I wonder if the ide officials are of the same opinion as us. ''a) SD High pitches; Mixed System can be selected, but it is not mandatory since Hn<25m...(optional)'' Now in such cases, the ductility level can be selected mixed in the direction where the elevator curtains are located, in this case it will be SD Normal in one direction and SD Mixed in the other direction.( High-High, High-Hash can also be selected) SD Normal in one direction, SD Mixed in the other; Does it contradict the statement "Systems with a high ductility level in one earthquake direction or mixed and normal in the other earthquake direction," in the article 2.5.1.2 of the earthquake code, will be counted as systems with normal ductility level in both earthquake directions? Does this expression result in Normal-Mixed non-selectable? What is your opinion on this? Thank you again for your valuable contribution. Best regards...
 
Re: ALPHA S >0.75 CONDITION IN WRAPPED NORMAL DUCULAR SYSTEM HK. Hello Sir; I think the expression in the aforementioned article (2.5.1.2) is clear and as you know, Ductility Levels can be selected for each earthquake direction in the following ways; 1. High-High 2. High-Karma 3. Karma-Karma However; 1. If High-Normal....all structure:Normal 2. If Mixed-Normal....whole structure:Normal To put it briefly; If SD in any direction is defined as Normal, on the other hand, we can say that Normal SD should be defined for the Entire structure regardless of whether it is Mixed and/or High... Good work, regards...
 
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