Elevator Pit ANALYSIS!?

[NYILMAZ]

If you noticed, I wrote the word analysis in capital letters in the title. My goal in this is how the analysis of the pit drawings applied or drawn on-site, rather than how the elevator pit will be designed in terms of manufacturing. Or maybe it's how it isn't or even whether it is. Since this issue has come to the fore in different ways, I would like to bring it to the agenda again in this way. I would like to approach the event primarily from an engineering point of view rather than traditions, practices and programs. Then, respectively, programmatic, application, etc. We can continue as Now I will show two types of foundations: 1- The foundation is defined as flat, the pit has not been dug, the analysis was made in this way. Stress values are shown on the picture. In this case, as we observed in the forum, IdeYAPI; If it is modeled in this way, it recommends that the mat slab thickness be made in the main raft thickness, including the bottom of the pit. 2- A pit has been opened on the foundation, but the carrier elements (column or curtain) around the elevator press the edge of the pit, that is, the main raft. In other words; It is modeled as the side column (or curtain) pressing on the raft in the adjacent structure. The model and stress pictures related to this situation are as follows. A plaque will be drawn under the second model, again constructively, and its surroundings will be filled with concrete. Considering these two cases, the second model creates more unfavorable conditions in terms of both stress values and additional reinforcements, isn't it? (the strain value is seen to be 17 t/m² in one and 19 t/m² in the other) Isn't it a closer model? From this point of view, which of these two analysis choices is recommended. How does IdeYAPI look at this situation? In summary, I would like to talk about my own method: After making the second model and worshiping the analysis and additional reinforcements according to this unsuitable situation, I constructively draw ONLY the SECTION (ie the pit) THAT WILL SUITABLE FOR THE LIFT WORKER WORK. The drawing I made is as follows. Here, in terms of feeding the main foundation, the inclined section resulting from the excavation should either be filled very well or it should be filled with concrete as in the drawing. I can summarize the issue that I want to emphasize as follows. The point on which my model is based is that the main raft, which is strong and spread over a wider area, does not have any function and bearing capacity of the concrete layer underneath without being deformed. If it were, wouldn't we need to do something like this under the side columns as I mentioned above? I know that many of our friends are having trouble with this. I am facing such a problem right now. Although our project, which was modeled as I stated in the same municipality before, has passed, it is currently in the waiting phase. There is a phrase I use all the time: Not everything programs do is right, and everything they can't do is not wrong. Since some control mechanisms want to see everything ONE-TO-ONE in computer output reports and drawings, some mutual communication problems are encountered. Moreover, there are many programs that have been accepted and approved in the market, and the acceptance, modeling and even drawings of each program are different. For example, how to act when the project is brought with the SAP program, which is accepted as a reference. Such problems are generally encountered in small municipalities. Because big municipalities are already dealing with huge projects, such issues are not even ordinary. If that were the case, how would those beautiful projects we watch with admiration come to life? I look forward to your contribution to the subject. Especially the answers given by ideYAPI are even more important in terms of hearing by the relevant persons and all users. (since it is considered official?!) I wish all my friends good work.

 

[HakanŞahin]

Let me write for myself: All of the vertical carriers end at the raft level, I solved the raft by opening a space as big as the elevator pit and equipped it accordingly, let's say... Then I removed the soil to a depth of 2 meters in the area where there was a gap. In order to prevent the floor from slipping on the edges of the gap, I poured concrete on the edges and put reinforcement as much as raft reinforcement inside. I put concrete on the floor of the cavity to cover the floor and I put reinforcement in it as much as raft reinforcement. Do I need to change the raft reinforcement that I put in the first stage after these processes? I think it is not necessary.

 

[NYILMAZ]

Let me write for myself: All of the vertical carriers end at the raft level, I solved the raft by opening a space as big as the elevator pit, and equipped it accordingly, let's say... Then I removed the soil to a depth of 2 meters in the area where there was a gap. At the edges, in order to prevent the floor from slipping, I poured concrete on the edges and put reinforcement in the amount of raft reinforcement. I also poured concrete at the bottom of the cavity to cover the top of the floor and put reinforcement in as much as the raft reinforcement. After these procedures, do I need to change the raft reinforcement that I put in the first step? I don't think it's necessary. .

Dear Hakan, Did you actually mean this: I leave the gap, I warn you that the edges should be kept (just like the outer columns), the rest is already details. Isn't it? Isn't it enough to do this as an analysis? Isn't it an admission in the provinces?

 

[Ismail Hakki Besler]

The important thing here is not whether there is a gap, but the presence of a vertical plate equal to the thickness of the raft under the curtain. The sample detail should be as you give in the drawing. Even if there is no elevator pit, it would be useful to thicken the raft a little on this forehead.

 

[NYILMAZ]

In fact, I expect opinions from other friends within the framework of the analysis perspective. The main topic of discussion is is there a need to make a carrier plate under the pit? In other words, does the plate under the pit have an effect, a function like a foundation? (I don't think so)

 

[2m proje]

Hello there; I think that both calculation methods are acceptable depending on what is wanted to be done in practice. as follows; In the first analysis model, since the analysis is done without leaving a gap in the raft, an application detail with the least raft stiffness in this region should be given in the application detail. If a production is to be made here just to prevent the soil, the modeling and solution will be wrong. In the calculation to be made by leaving a gap in the second analysis model, it is assumed that the manufacturing in the elevator pit does not contribute to the raft foundation in the transport of vertical loads. In this case, the ground under the pit should not be disturbed at all, or the production to be made should be at least as careful as in the 1st method, otherwise, we will create weaknesses in the ground under the main raft, which we accept to carry the entire load. From this we can deduce that in both methods it will be necessary to prepare a detailed application drawing with at least the main raft stiffness. If the curtains around the pit and the raft under the pit can be included in the calculation model without any problems, it should definitely be done like this. The problem starts here, usually this situation cannot be added to the model as desired. So, after preparing the application details as necessary, both admissions are safe and sufficient in itself. Best regards.

 

[NYILMAZ]

....... From this we can deduce: in both methods it will be necessary to prepare a detailed application drawing with at least the main raft stiffness If the detail to be prepared appropriate, that is, if the curtains around the pit and the raft under the pit can be included in the calculation model without any problems, it should definitely be done like this.The problem starts here, usually this situation cannot be added to the model as desired. And it's enough.

Thank you for the comment. Everyone agrees on the above. The issue was how accurately this could be done in analysis. Your sentence I quoted sums up a lot. Here you go, you will understand, interpret, comprehend and be an engineer. Brains are needed to decide. If there are friends who will write other comments, I would like to take them. Especially about which approach is more reasonable in terms of analysis..

 

[engineer_yildiz]

Since the elevator shaft is at a lower level than the foundation, we expose the elevator perimeter wall (wall, wall close to the foundation properties or how we define it) to lateral soil thrust. So how do we idealize a surcharge load or additional load originating from the structure while calculating this soil thrust? Basically, how can we include the effect of dynamic water level in the system. Unfortunately, if academic studies on this were done using LVDT or Strain gages, we would be able to find answers to most of our questions. While manufacturing the elevator shaft, what should we take as bearing capacity, since the part that we fill the excavation that we opened wider than the project (the part that will come under the foundation of the building) is the sub-basement floor? In fact, there may be more questions to consider. My suggestion would be to go from the result to the beginning. Whether it's the alternatives you mention or the questions I've included, not to start with them, but to examine the elevator shaft of a building with an elevator shaft that we think was built in accordance with the Project for which we have the data. Depending on the result, we may confirm or correct our acceptances. We're like saying this is a bit difficult. Then our brainstorming on this issue will not end. The results we think we have achieved remain relative.