About raft foundations, what is raft foundations?

Note: I'm really sorry, but I read your question again, it may be a design problem with the equipment foundation. At that time, I did not understand the content of your question correctly, and I did it according to the budget, and now I have deleted the content and apologize to you for my recklessness.

If it is an equipment foundation design, whether it is designed according to the raft foundation depends on the equipment load, the thickness of the foundation and the aspect ratio of its plane. If the equipment load is not very large, or the thickness of the foundation is fully guaranteed to resist punching and shear (the general equipment foundation, due to the anchor bolts to be anchored, the thickness is larger), only according to the structure of the foundation under the skin with two-way steel bars, too thick to consider the design of steel cage.

However, if the foundation is thin and the aspect ratio of the foundation is less than 2:1, it can be designed as a raft foundation. It should be noted that when designing according to the two-way plate, it is necessary to analyze whether the placement mode of the equipment on the foundation meets the stress conditions of the two-way plate, that is, the fulcrum condition of the foundation version (therefore, it is calculated according to the uniform load of the foundation reaction force of the plate, and the place where the equipment contacts the foundation plate is the support of the plate), if the equipment and the foundation are in surface contact or at least three sides are linear contact, you can consider designing according to the two-way plate.

If the equipment is concentrated in a certain part of the slab, or the equipment is in contact with the foundation at several points, it is not suitable to design according to the two-way plate, and it is necessary to consider the independent foundation plate under the column (which may still be eccentric) or the beamless plate.

I don't know if this understanding is reasonable or inappropriate, please give me advice with all netizens. Once again, I apologize to you for your reckless actions at the time. Have a nice day.

It can be calculated on an independent basis.

It should never be calculated as a two-way board!

Raft foundation(raft foundation) refers to when the upper load of the building is large and the bearing capacity of the foundation is relatively weak, it is used simplyIndependent foundationOr the strip foundation can no longer adapt to the needs of foundation deformation.

This often connects the foundation under the wall or column, so that the load of the whole building is borne on a whole plate, and this kind of full-hall slab foundation is called raft foundation.

The raft foundation is divided into plate type and rib beam type, because of its large bottom area, it can reduce the pressure of the foundation, and can also improve the bearing capacity of the foundation soil, and can more effectively enhance the integrity of the foundation, adjust the uneven settlement.

Principles for the selection of raft foundations:

1. On the soft soil foundation, the strip foundation under the column or the cross-beam strip foundation under the column can not meet the requirements of the superstructure for deformation and the bearing capacity of the foundation.

When required, raft foundations can be used.

2. When the column spacing of the building is small and the load of the column is very large, or the load difference of the column is large, it will produce a large settlement difference, and the overall stiffness of the foundation needs to be increased to adjust the uneven settlement, the raft foundation can be used.

3. When the building has a basement or a large liquid storage structure (such as a pool, oil depot, etc.), a raft foundation can be used in combination with the requirements.

4. Wind load.

and multi-high-rise buildings where the load plays a major role, when the foundation is required to have sufficient stiffness and stability, raft foundation can be used.

Raft foundation is also known as sheet raft foundation and raft foundation. When the upper load of the building is large and the bearing capacity of the foundation.

When it is relatively weak again, with a simple independent foundation or strip foundation can no longer adapt to the needs of foundation deformation, this often connects the foundation under the wall or column, so that the load of the whole building is borne on a whole plate, and this full-hall plate foundation is called raft foundation. Due to its large bottom area, the raft foundation can reduce the base pressure, improve the bearing capacity of the foundation soil, and more effectively enhance the integrity of the foundation and adjust the uneven settlement.

The raft foundation is divided into flat plate type and beam plate type, which is generally determined according to the soil quality of the foundation, the superstructure system, the column spacing, the load size and the construction conditions.

Flat raft foundation.

The floor of the slab raft foundation is a reinforced concrete slab of equal thickness. The thickness of the plate is generally between. Flat foundations are suitable for situations where the column load is not large, the column spacing is small and the column spacing is equal.

The thickness of the bottom plate can be preliminarily determined according to the raw layer of 50mm, and then the punching strength of the plate is checked. The thickness of the bottom plate shall not be less than 200mm. Usually for civil buildings with less than 5 floors, the board thickness is not less than 250mm; The plate thickness of a 6-storey civil building is not less than 300mm.

Beam-plate raft foundation.

When the spacing between the column network is large, the beam-plate raft foundation is generally adopted. According to the setting of the rib beam, it is divided into two forms: one-way rib and two-way rib. The one-way ribbed plate raft foundation is to connect two or more strip foundations under the column with a base plate in the middle to form a whole, so as to expand the bottom area of the foundation and strengthen the overall stiffness of the foundation.

The two-way rib plate raft foundation is to arrange the rib beams under the columns in the longitudinal and transverse directions, and the secondary rib beams can also be arranged between the column nets to reduce the thickness of the bottom.

Raft foundation: It is composed of a base plate, beams, etc. The building load is larger, the bearing capacity of the foundation is weak, the concrete bottom plate is often used, the building load is beared, the raft foundation is formed, its integrity is good, and the uneven settlement of the foundation can be well resisted.

Raft foundation: Full hall slab foundation.