What are the three types of reinforced concrete floors according to different construction methods?

According to the different construction methods, reinforced concrete floor can be divided into three types: cast-in-place integral floor, prefabricated integral floor and assembled integral floor.

1. Cast-in-place reinforced concrete floor slab

Cast-in-place reinforced concrete floors are mainly divided into four types: plate floor, beam floor, well-shaped multi-ribbed floor and beamless floor.

2. Precast reinforced concrete floor slab

There are two kinds of commonly used reinforced concrete floors: ordinary floors and prestressed floors.

3. Assemble the whole reinforced concrete floor.

Assembling integral reinforced concrete floor slab is to prefabricate and install some components in the floor slab, and then connect them into a whole through cast-in-place parts. This kind of floor slab has good integrity, which can save formwork and make the construction faster.

Reinforced concrete floor can be divided into two categories according to different construction methods: cast-in-place reinforced concrete floor and assembled reinforced concrete floor.

According to different structural arrangements, cast-in-place reinforced concrete floors can be divided into several categories. It can be divided into five categories: 1 and slab floor (1). One-way slab: the ratio of long side to short side of slab is greater than 2, and the reinforcement in slab is arranged along the short side direction. (2) Two-way slab: the ratio of long side to short side of slab is not greater than 2, and the load is transmitted in both directions, with large internal force in the short side direction and small internal force in the long side direction.

2. The multi-ribbed floor slab is provided with beams, which have main beams and secondary beams. The main beam is arranged along the room, and the secondary beam generally intersects the main beam vertically. The floor is placed on the secondary beam, the secondary beam is placed on the main beam, and the main beam is placed on the wall or column. Therefore, the load in the slab is transferred to the wall or column through the beam, which is suitable for large rooms such as factory buildings.

3. Cross-shaped floor slab (1 longitudinal beam and cross beam bear the load from the slab at the same time) (2) Generally, it is 6 ~ 10m, and the slab thickness is 70 ~ 80mm. The side length of well pattern is generally less than 2.5m (3), which is usually used for squares with a span of about 10m and a ratio of length to width of less than 1.5.

4. The beam-less floor column network is generally arranged in a square or rectangular shape, and the column spacing is about 6m, which is more economical. In order to reduce the span of the slab, improve the stress condition of the slab and strengthen the supporting function of the column to the slab, a column cap or supporting plate is generally arranged at the top of the column. Because of its large span, the thickness of the slab should not be less than 120mm, and it is generally 160 ~ 200 mm. It is suitable for shops, warehouses, exhibition halls and other buildings with heavy live loads.

5. The profiled steel plate of composite floor plays the role of permanent formwork for cast-in-place concrete; At the same time, the ribs on the plate can work together with coagulation, which can simplify the construction procedure and speed up the construction; Has the advantages of high rigidity and good integrity; At the same time, it can also be used to lay power or communication pipes in the inter-rib space of profiled steel plates, which is suitable for high-rise and multi-storey civil buildings and large-space and long-span industrial workshops.

C is used for reinforced concrete floors, that is, floors within 10 or 1 1 are C25, floors below the third floor including the basement are C30, floors above C25, 24th floor or 28th floor are C35, and floors above are C35 and must be C30. This is mandatory in the file.

Construction technology of cast-in-place reinforced concrete floor I. Construction requirements

1, corners should be fixed with planting bars, and the main girder is not easy to be damaged.

2. The steel bar must adopt the national standard rib, two or four layers are tied into a net, and the spacing is 150-200mm.

3. Choose qualified cement products and river sand. (Cement 425 # 600, river sand, rock, the ratio is 1:2:3, stir evenly, and vibrate with a special vibrator. Planting with steel bars)

4. Post-maintenance of the floor should be done well. (Not less than half a month is recommended)

5. When the span is too large, professional civil engineers should be asked to make calculations to avoid the danger caused by overweight.

6, reinforcement should be reasonable. As long as the design of concrete floor reinforcement is reasonable, it can play an early warning role even if there are major changes.

7, floor reinforcement points along the reinforcement, less reinforcement, super reinforcement.

(1) Applicable reinforcement category: The designed reinforcement quantity is within a reasonable range. Once the floor is about to be destroyed, cracks will appear.

(2) Less reinforcement means less reinforcement, so the bearing capacity of the floor is poor;

(3) Super reinforcement refers to the reinforcement beyond the specification scope. (In this case, the floor can't reflect the damage in time when there is a problem, so the more reinforcement, the better. )

Second, the cast-in-place floor form removal time

The strength of concrete rose fastest in the first three days, from 0% to more than 50%, and reached 95% on the seventh day.

Yes, 14 days can reach more than 1 10%, and then it grows at a very slow speed.

In the Building Construction Manual, there is a simple agreement on the time when the formwork can be removed:

Load-bearing floor formwork can only be removed after reaching the following strength:

1, with a span of 2m or less, reaching 50% of the design strength;

2, span 2 meters to 8 meters to reach 75% of the design strength;

The span over 3.8m reaches100% of the design strength; When the strength of the demolished floor does not reach 100%, it is forbidden to pile up redundant building materials. Therefore, it is not advisable to pile too many tiles on the floor within 14 days after concrete pouring on the floor, and normal decoration works can be carried out. After 14 days, 350kg/m2 can be released.

4, the choice of floor thickness:

(1) In general, the ratio of the length of the long side to the short side is less than or equal to 2.0, which shall be calculated as a two-way slab;

(2) According to the China People's National Standard Code for Design of Concrete Structures, the minimum thickness of cast-in-place reinforced concrete slab is not less than 80mm. Generally, the thickness of the bottom plate is100 mm.

(3) According to the design specification, the spacing of the reinforced bars in the slab should not be greater than 200mm when the slab thickness h≤ 150mm; When the thickness h> 150mm, it should not be greater than 1.5h, and it should not be greater than 250 mm. The span of a family is generally small, so if secondary threaded steel bars are used, the spacing can be 200 mm, which is generally a double-layer bidirectional steel mesh. In the middle of the floor, the upper reinforcement can be disconnected, but the surrounding upper reinforcement needs negative bending moment. Negative moment reinforcement is not distributed, and cracks will appear, which will affect the use.

Third, the construction process

Professionals measure users >: engineers of design department design projects for users and issue design drawings > accurately locate floor elevation according to users' requirements > construct by professional construction team using technology and materials > pour concrete with formwork, rebar planting, spacing 15-20CM > make old and new concrete labels consistent > do post-maintenance and remove formwork > end of the project.

How long can the cast-in-place reinforced concrete floor be constructed? The strength of cast-in-place concrete reaches 12MPA before construction. Generally, the temperature is above 25 degrees, and construction can be started after 12 hours. But it is not allowed to pile up heavy objects and vibrate the newly poured floor strongly.

Cast-in-place reinforced concrete floors can be divided into _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.

According to the stress direction: unidirectional stress plate and bidirectional stress plate.

According to the support type: single-sided embedded, double-sided, three-sided and four-sided. It can also be subdivided into two adjacent sides and two pairs.

Edge; Brackets can also be subdivided into simply supported and embedded, and there are many combinations.

Textbooks, specifications and atlas all say that cages are not allowed, and cast-in-place reinforced concrete floors can be divided into four categories.

Construction method and steps of cast-in-place reinforced concrete floor slab 1 survey and setting out (if you start from the first floor, when building the foundation of the whole house, you should reserve the reinforcement of the stairs-that is, the reinforcement of the stairs must be "rooted |" in the foundation).

2 stair bottom molds (including rest platform bottom molds)

3. Tie the rebar at the bottom of the stair slab (including horizontal and vertical, and pay attention to the rebar sequence when binding).

Side formwork for 4 stairs

5 Tie the negative reinforcement and the upper reinforcement of the stair board.

Six-step template

7 Concealed acceptance

8 pouring concrete

9 maintenance

10 form removal

1 1 Continue to save water.

That's probably all the steps.

Reinforced concrete lintels can be divided into precast lintels and cast-in-place lintels according to different construction methods. The length of precast lintel extending into the support is: brick wall 10cm, and the length of cast-in-place lintel support is 25cm.

What are the classifications of reinforced concrete floors? According to different construction methods, reinforced concrete floors can be divided into three types: cast-in-place, assembled and assembled integrally.

Reinforced concrete floors are made of concrete and steel bars. This kind of floor is durable, with high rigidity, high strength and good fire resistance, and is widely used at present. According to the construction method, it can be divided into cast-in-place reinforced concrete floor and assembled reinforced concrete floor.

Cast-in-place reinforced concrete slabs are generally solid slabs, and cast-in-place slabs are often poured together with cast-in-place beams to form cast-in-place beams and slabs. The common types of cast-in-place beam and slab are ribbed slab, crossbeam slab and beamless slab.

Except for a few solid slabs, prefabricated reinforced concrete floor slabs mostly adopt round hole slabs and slotted slabs (divided into positive slotted slabs and reverse slotted slabs). Assembled reinforced concrete floor slabs generally extend steel bars at the end of the slab, and the joints are filled with concrete after on-site assembly to strengthen the integrity.