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Turkish We have a Basement Floor + Ground Floor + 14 Floors (2 Blocks) project. I am publishing the project in roughly jpg format as the site plan. I want to make the raft foundation design of this project. My question is; As seen in the design, there is no dilatation in the raft foundation. Since the ground safety stress is 10 t/m2, bored piles will be used. The structure is in the 4th earthquake zone. I divided the foundation into 3 sections. 2 foundations for 2 blocks and 1 foundation for the car park. Only on the foundation under the building I want to use piles. I want to connect the raft foundations with a slope. Is it possible to design in this direction in İdecad? Soil safety stress control; divide the building load by the total m2? Or is it per square meter of the foundation I defined for each audience? If so, what kind of design should I design? If you have any suggestions for pile placement, I would be glad if you share them. When I define the soil layers, I get a warning that they are incompatible with the pile length. For example, I have 3 layers of 5 meters and my pile length is 15 meters. I enter as 1st layer 5mt-2nd layer 5mt-3rd layer 5mt. I would appreciate if you explain where I made a mistake. I would be glad if you have different suggestions about design. Good work...
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Raft Foundation Design
- Thread starter haliltek
- Start date
Hello, you can make the basic design according to the plan and section you added with IdeStatik. However, this design is not as you say, dividing the superstructure load by the base area (an illogical and primitive method). It is done by taking into account the superstructure loads coming from the columns and walls with advanced finite element methods, as well as information such as raft foundation stiffness and soil parameters. Since there are basement floors in your building, you should pay attention to the 0 (zero) level when defining the ground layers. Best regards.
Hello there; The raft foundations, which are defined by being separated from each other by the slab edge, are analyzed by taking into account the meat formed during the analysis. There will be changes in the bearing coefficient of the ground under the building due to the piles, it is possible to take this change into account by using the Bearing Coefficient Multiplier under the Raft Foundation Properties/Static heading added to the program with V7. Thanks to this feature, it will be possible to use different bearing coefficients for each raft foundation piece and to create a more realistic analysis model. Best regards.
Since we used pile foundation in the project, we enter the value of the bed coefficient as zero. Instead, we define ground layers. I have 3 ground layers. Soil layers will be taken into account in pile foundations. So will ground layers be taken into account in non-pile foundations as well.
Since we normally assume that the piles carry the structure, we enter zero (or a small value) in the raft foundation bearing coefficient when making the pile solution. In your project, since some of your foundation will be designed with piles and some without piles, it will be problematic to enter the general bearing coefficient as zero (the raft pieces on the non-pile place will act like a console). Instead, enter the general bearing coefficient of your project as normal, but by entering a small value such as 0.001, from the properties of the rafts to be designed with piles, you can calculate your raft in the form of modeling with winkler spring in the piled part and winkler spring in the non-pile part, it will be a more realistic approach.
Do I still need to define soil layers? If necessary, should I ignore the warning "bearing coefficient in pile foundation system is not zero". If I am not going to define a soil layer, should I ignore the warning "pile foundation elevations are incompatible with soil layer"? Also, how should I do modeling with winkler spring in the piled part and with winkler spring in the piled part? I wish I could send the project, but the size is too big. We are also having a problem with the internet in a place like Iraq. I would be very happy if you could help me solve the project. Thanks for your interest so far...
To make a pile solution, you must define the soil layers. The program takes the stiffness of the springs to be modeled along the pile from the soil layers. If you are going to model as I mentioned, you do not need to take into account the warning "bearing coefficient is not zero", because you will reduce the bearing coefficient in the pile lattice by multiplying it. You should also consider the warning that the pile foundation elevations are incompatible with the ground layer. The point you need to pay attention to here is that the ground layer heights should be taken from the project zero, not under the raft. (If your raft is not at zero elevation, add the bottom of the raft to the thickness of your top layer) The program gives this warning because it cannot find a layer corresponding to the piles. You will not model without spring in the piled part and with spring in the piled part, there are winkler springs under the entire raft area. The reason why we give a factor of 0.001 to the raft under the pile is to simulate the real behavior of the building by reducing the stiffness of the raft springs in this region and transferring the load to the piles.