Monolithic beam floors, ribbed floors.

Reinforced concrete floors. Depending on the construction method, they are divided into monolithic and prefabricated. The advantage of such floors is their large bearing capacity. The compressive strength of concrete is used here since the dimensions of these floors can be accurately determined by static calculations. The disadvantage of reinforced concrete floors is high sound permeability.

Monolithic iron concrete floors manufactured at a construction site in formwork. Performing the function of transferring the load from the floor to the load-bearing walls, they also serve as stiffening elements in buildings with a massive frame. To manufacture monolithic reinforced concrete floors, formwork is required, made from a scarce material - wood. Monolithic reinforced concrete floors According to their shape, they are divided into slab, beam, ribbed and insulated ceilings (Fig. 84).

Monolithic slab floors. The simplest design of monolithic floors is the Monier slab, in which the reinforcement is placed in tension areas, i.e. in the lower part of the slab, since steel has 15 times greater tensile strength than concrete.

Rice. 84. Reinforced concrete floors a - monolithic reinforced concrete slab; b - reinforced concrete monolithic beam floor; 1 - transverse reinforcement of the beam; 2 - beam; 3 - longitudinal main reinforcement of the beam; c - reinforced concrete monolithic ribbed floor

The slab is usually laid on a load-bearing wall, and the length of the surface on which the slab is laid is 10 cm; When using slabs with a thickness of more than 10 cm, the length of the surface on which the slab is laid is equal to the thickness of the slab. Such floors can have a maximum span of 300 cm (see Fig. 84, a) . For larger spans, the reinforced concrete slab is concreted on steel load-bearing beams, covering a large span. Such floors are called slab monolithic reinforced concrete or combined floors with steel load-bearing beams.

Monolithic beam floors. For large spans, floors can have a maximum span of 300 cm. Reinforced concrete beams are laid on the wall; they are connected to a reinforced concrete slab and reinforced. Such floors, invented by the French engineer Ennabic, are called Ennabic floors. Beams are laid at a distance of 130-500 cm from one another. Length of beams to be laid on load-bearing beams brick walls should be 7.5% of the beam span, but not less than 22 cm. Typically, beams are anchored into monolithic reinforced concrete belts with brickwork.

Reinforced concrete beam floors are used in rooms where a flat ceiling is required (basements, warehouses, workshops, etc.), since the axial distance between the beams of this floor is too large to finish a flat ceiling.

The use of beam reinforced concrete floors is cost-effective if there are spans of 6 m (see Fig. 84, b).

Monolithic ribbed floors. If, when using reinforced concrete floors, it is necessary to make a flat ceiling, the axial distance between the beams should be reduced by 0.5-1 m. The cross-section of the beams is smaller, which is why they are called ribs. To prevent the ribs from bulging, they are reinforced over a span of 6 m with one transverse rib (see Fig. 84, c).

The flat ceiling is finished with hemming and lime-gypsum plaster or reed plaster. Before concreting a ribbed reinforced concrete floor, pins or wire with a diameter of 10 mm are placed in the reinforcement so that after concreting and stripping they protrude from the sides of the ribs. Planks 2 cm thick are installed on these embedded parts, the lower edge of which protrudes beyond the edge of the lower rib by 1 cm (Fig. 85, a).

Rice. 85.

a - side mounting; b - slab - base of the filing; c - finishing without slab; 1 - steel rod with a diameter of 8 mm; 2 - mesh

Another method is that when making formwork, the ribs are placed in it before the reinforcement is laid and the plank bottom is secured, after which both ends of the wire are monolied. To the base made in this way, a sheathing of slabs 12-20 mm thick, nailed, is attached. The joints between the plates should not be wider than 15 mm. Simple plaster is applied to the sheathing or lined with reed mat (Fig. 85, b). Sometimes wire is embedded into the slab and ribs and, after stripping, a chain-link mesh is attached to it and lime-gypsum plaster is applied (Fig. 85, c).

Monolithic floors with liners. The big disadvantage of ribbed floors and especially floors with a flat ceiling is the complexity of their construction and the high consumption of wood for the manufacture of formwork and lining. Therefore, floors with liners are more often used. In the places of future gaps between the ribs, liners are placed, which serve as the formwork of the ribs and at the same time as the lower part of the slab formwork. The lower sides of the liners replace the lining with boards and serve as a base for plaster. Inserts are made from various materials of various shapes. The most common are rigid liners made of baked clay, the lower part of which extends to the shelves, forming the lower formwork of the ribs. The liners are placed in horizontal formwork and, after preparing the reinforcement for the ribs and slabs, they are concreted (Fig. 86).

Rice. 86. 1 - plaster; 2 - ceramic liner; 3 - rib reinforcement

The disadvantage of floors with liners is that they are characterized by greater sound permeability than the floors described above, since the liner, after adhesion to reinforced concrete, forms a continuous resonant slab.

When constructing brick, stone, concrete and slag concrete buildings, reinforced concrete floors are used. This is due to their durability, strength, relative ease of installation, as well as short construction time (if prefabricated reinforced concrete floors are used). Next, we will take a closer look at what their types are, and how you can perform the overlap yourself.

Types of structures

All existing reinforced concrete floors can be divided into two types:

• Prefabricated;
• Monolithic.

Now let's take a closer look at each type of structure.

Monolithic

Reinforced concrete monolithic floors, unlike prefabricated ones, are poured on site, directly at their location.

They come in several types:

• Ribbed– are a system of interconnected intersecting monolithic beams and slabs.
  These floors consist of the following elements:
  • Purlins (main beams)
  • Ribs (beams located perpendicular to the purlins).
• Caisson– are intersecting beams of the same cross-section that are monolithically connected to the slab. The recesses between these beams are called caissons.
• Beamless– are solid monolithic slabs laid on columns. At the top of the slabs there is a thickening (capital). Reinforcing bars are located at the bottom of the slab.
  The slab frame is placed at a distance of several centimeters from the formwork so that this space is filled with concrete. Such structures are used only in cases where the span does not exceed three meters.

• Beam reinforced concrete floor– used if the span is more than three meters. In this case, reinforced concrete beams are laid on the wall in increments of about 150 centimeters. The beams are connected to the reinforcement of the slab floor.
  It must be said that there are 16 types of reinforced concrete floor beams according to GOST 20372-90. Their longest standard length is 18 meters.
• Ribbed– can be used if the span length does not exceed 6 m. If the length is greater, then reinforcement is performed with a transverse beam. As a rule, this type structures are used in cases where it is necessary to obtain a flat ceiling. The distance between the beams should be no more than a meter.
  When installing such a structure, embedded elements are attached to the reinforcement frame, which makes it possible to hem the ceiling with boards. The disadvantages of this system include the complexity of its design.

Prefabricated

Reinforced concrete prefabricated floors are knitted and welded. The welded frame is made of straight reinforcement, which is connected by electric or gas welding. Making a knitted frame is more difficult. For these purposes, use a special knitting wire with a thickness of no more than 2 mm.

Prefabricated structures are divided into the following groups:

• Made from floorings weighing up to 0.5 tons.
• Floors on reinforced concrete beams with small-sized filling.
• Wide floor elements weighing 1.5-2 tons.
• Large-panel structures, which consist of elements made to fit one room.

Prefabricated structures include reinforced concrete hollow-core floor panels, which are very popular. They are monolithic iron concrete slabs, reinforced with reinforcement cage.

Inside the panels there are cylindrical voids that run along the entire length of the slabs. They can significantly reduce the weight of products and also increase the resistance to fracture deformation of the slabs. There are such panels different lengths and width.

Manufacturing of reinforced concrete slab

Now let's look at how to perform a beamless floor. It must be said that it is very rare to make reinforced concrete floor beams with your own hands.

Materials and tools

So, to erect the structure you need to prepare following materials and inventory:

• Steel reinforcement;
• Cement grade not lower than M400;
• Sand;
• Crushed stone or gravel;
• Welding machine;
• Boards, timber;
• Concrete mixer;
• Various power tools.

Manufacturing of formwork and frame

First of all, you need to do the formwork yourself. For the bottom of the slab, you can use plywood panels with a thickness of at least 2 cm, reinforced with bars, or board panels with a thickness of 4-5 cm.

For the side walls, ordinary boards 2-3 cm thick are suitable; you can, of course, use plywood, but its price is higher.

The formwork is assembled in the following order:

• First of all, the bottom panels are laid. For their installation, supports and cross beams should be used.
• Then the sidewalls are installed.
• The inside of the formwork is covered with roofing felt. Synthetic film can also be used for these purposes.
• The next step is to assemble the frame, which should be located at a distance of 2-3 cm from the bottom of the formwork. To do this, you can use special liners, or use bars. The diameter of the reinforcement should be at least 10-12 mm, and the mesh size should be 150x150 or 200x200 mm.
  The thickness of the frame is calculated in such a way that protective layer the solution was at least 2 cm below and above. Those. its thickness should be 4 cm thinner than the thickness of the slab.

Fill

To fill the slab, you should make the solution in the following proportion:

• One part of cement M400;
• Two parts sand;
• Four parts with a fraction diameter of no more than 20 mm;
• Water until the required consistency is obtained.

Filling is performed without interruption, starting from one corner and ending with the opposite. In this case, the solution is compacted using a deep vibrator.

After pouring, the concrete is protected from rapid drying. To do this, cover it with damp burlap and sawdust. For the first 8-10 days, the surface is periodically moistened.

After 2-3 weeks, after the solution has collected about 80 percent of its content, remove it. However, the slabs can only be used after 28 days.

Advice!
After completing the slab, it may need to be machined.
It is most effective to perform procedures with a diamond instrument.
In particular, reinforced concrete can be cut with diamond wheels, polished with diamond cups or diamond drilling holes in concrete.

It must be said that in some cases it may be necessary not to build a slab from scratch, but to repair reinforced concrete floors. It consists of strengthening the structure with additional elements in the form of slabs, beams, shells, etc. The procedure is quite complex, so it must be carried out by specialists.

Conclusion

As we found out, there are many types of concrete floors that are designed for different cases. Therefore, in each individual case, you need to choose the right type of structure. In private construction, you can make reinforced concrete floors with your own hands, using the technology indicated above.

From the video in this article you can get additional information on this topic.

Most often in country houses Of course, wooden floors are installed. But in cottages with 2-3 floors, this structural element of the building can also be poured from concrete. Such floors can withstand heavy loads and at the same time are reliable. However, the construction of such structures, in comparison with wooden ones, is, of course, more expensive. In addition, the technology itself for arranging floors of this type is considered relatively complex. Concrete structures of this type can be poured, for example, using a profiled sheet.

Characteristics

Monolithic floors can be erected using corrugated sheets not only in private houses, but also, for example, in industrial buildings, garages, warehouses, etc. The weight of such structures is quite large. But since in in this case Corrugated sheets are used as formwork; pouring them requires less concrete than installing a conventional monolithic slab. Consequently, the weight of the ceiling is reduced. Accordingly, such a slab puts less load on the supports.

The advantages of such structures, in comparison with conventional monolithic ones, also include:

no need to use multi-row reinforcement;

possibility of installing the ceiling in short terms;

no need to dismantle the formwork.

IN production premises A ceiling filled in this way is usually not even further finished. The profiled sheet looks quite aesthetically pleasing.

Design

Before you start constructing a monolithic floor using corrugated sheets, of course, you should compose it detailed drawing and do everything necessary calculations. Designing such structures is a very complex and responsible matter. Errors in calculations monolithic floors can lead to their rise in price, reduced service life, and in some cases even to the collapse of the structure.

Therefore, the design of such slabs is usually entrusted to specialists. The owner of a house can independently calculate a monolithic floor using corrugated sheets only if he has special education. You can also create a project for such a slab using software developed for this purpose.

Requirements for floors

In most cases, I-beams are used as beams for such slabs. When designing a monolithic floor using corrugated sheets, the following factors are taken into account, among other things:

each sheet must rest on at least three beams - at the edges and in the center;

beams should be laid at a distance of 1.5-3 m from each other;

along the length, the sheets can be mounted end-to-end when assembling formwork for floors;

the width is overlapped by at least 1 wave;

layer concrete mixture after pouring, it should rise above the waves of the material by at least 5 cm;

The reinforcement frame for such a slab should be knitted from 12-8 mm rod.

The surface of the finished slab can be 3 cm vertically away from the edge of the sheet waves. However, pouring in this way is allowed only if a screed is subsequently intended to be poured on it.

Concrete floors, including corrugated flooring, are installed only in buildings with heavy walls. Supporting slabs on metal sheets is allowed only on brick or block enclosing structures. Constructions of this type cannot be installed in wooden structures.

Installation of monolithic flooring on corrugated sheets: installation technology

Corrugated ones are laid on I-beams in such a way that their waves are perpendicular to the latter. Most often used for pouring floors roofing material, marked N. It is believed that a sheet with a not too high wave is best suited for the installation of such structures. It is advisable to use such corrugated sheeting under a monolithic floor, primarily because in this case it turns out to be the most durable.

Ribbed ones are fixed metal sheets on I-beams when installing formwork with reinforced self-tapping screws. When using such fasteners, there is no need to pre-drill holes in the decking and beams. Screw in the screws with a drill at low speeds in increments of about 30 cm. The width of the corrugated sheet overlaps is usually additionally secured with rivets.

Attic passage

After the entire opening of the building is closed, vertical formwork walls made of boards are installed along the edges of the future slab. The same elements are installed where it is planned to make an exit to the attic in the future. Experts advise covering the boards before assembly. plastic film. This will make dismantling them much easier later.

After removing the boards from the finished slab, at the point where the attic exits, the corrugated sheeting is simply cut with metal scissors. The operation is very simple and can be performed in a few minutes.

Reinforcement

At the next stage, reinforcement is installed on the formwork made from corrugated sheets and boards. When knitting it, a thicker rod of 12 mm is usually placed parallel to the waves. Perpendicular elements are made from 6-8 mm reinforcement. If desired, you can also purchase a ready-made reinforcing mesh for such an overlap. However, pouring the slab in this case will, of course, cost a little more.

Of course, after pouring the monolithic floor over the corrugated sheet, the frame should be in its thickness. Therefore, the associated reinforcement is lifted above the sheet using special plastic clamps. According to the standards, the connected mesh should be located above the bottom of the metal formwork at a height of at least 1.5 cm. This will allow for a fairly reliable and durable floor to be poured.

When installing a slab on a corrugated sheet, both self-made and purchased reinforcement cages are mounted using the same technology. For knitting mesh with your own hands, you should use strong wire, 1.2-1.4 mm thick.

Additional supports

After the reinforcement frame is connected and installed, the actual pouring of the slab begins. Previously, if necessary, additional steel or wooden vertical supports are installed under the sheets between the beams. Such structures are used if the distance between the I-beams was chosen to be large enough when drawing up the project for a monolithic floor on corrugated sheets. After the slab hardens, the additional supports are simply dismantled.

Pouring the slab

In the vast majority of cases, ready-made concrete mixtures for constructing monolithic floors on corrugated sheets are used in the vast majority of cases. The fact is that such structures must be poured in one step. Concrete is placed in parts into the formwork mainly only during installation large floors, for example, production workshops.

Of course, cook it yourself right away large number cement mortar and pouring it onto sheets will be extremely problematic. Therefore, concrete is laid when installing monolithic floors on corrugated sheets, usually using the following technology:

a concrete truck is ordered to the work site;

feed the solution into the formwork from a steel hose;

As the mixture spreads, all resulting defects are smoothed out manually.

Also, during the pouring process, it is advisable to pierce the concrete with a shovel from time to time. This will avoid the appearance of voids in the finished slab, reducing its strength.

Final stage

Monolithic floors on corrugated sheets, like any other concrete structures, take quite a long time to harden. The slab will gain sufficient strength only 4 weeks after pouring. At this point, you can remove additional supports from under them and begin, for example, building a roof.

While the slab is hardening, you need to carry out proper care. For the first two weeks, the ceiling should be watered at least once a day. Otherwise, surface cracks may form on the slab. And this will certainly lead to crumbling of the top layer in the future. For reliability, the wetted slab can also be covered with plastic film. It is especially important to carry out this procedure in hot weather.

What you need to know

Flood interfloor ceilings Recommended only at positive temperatures. Otherwise, such a design will not turn out to be too strong. Sometimes concrete slabs are made on corrugated sheets in winter. However, in this case, a mixture of a special composition is used for filling, which increases the cost of the work.

Monolithic ceiling on corrugated sheets: manual pouring guide

During the production of slabs, concrete is supplied to the formwork, thus, in most cases, from a tank using a hose. However, there is a technology for self-filling such structures. In this case, additional sectional adjustable formwork is installed above the corrugated sheet.

In this case, each part of such a structure should be filled at a time. The sections must be positioned across the I-beams in such a way that each individual slab is subsequently supported by at least three beams.

The cutting walls of such formworks are not statically attached to the main frame. After pouring each section, the board is simply rearranged to the same distance. This formwork element is configured in such a way that adjacent finished slabs, after pouring, are interlocked using the tenon/groove lock principle.

Do you need a screed?

The technology for installing a monolithic floor on corrugated sheets is therefore relatively simple. Compared to concrete structures slabs cast on a metal ribbed sheet usually have a smaller thickness. After all, in this case formwork gives them additional strength. However, when using a hose to supply the solution, the surface of such ceilings, unfortunately, is usually not particularly smooth. After all, it can be quite difficult for builders to correct it during pouring.

Therefore, after the slab has hardened, in most cases, a concrete screed. You can prepare the mixture for such a leveling coating yourself. Concrete mixed in a cement/sand ratio of 1/3 is usually used to fill the screed. The minimum permissible thickness of such a leveling coating is 3 cm.

Operating rules

The service life of monolithic floors, including those cast on a profiled sheet, corresponds to the durability of the main load-bearing elements of the house. That is, this design will never have to be changed in the future. However, such floors can last so long, of course, only if they are used correctly.

The service life of structures of this type may be reduced due to:

exposure to aggressive environments;

frequent changes in humidity.

To ensure that such a monolithic ceiling on corrugated sheets does not have to be repaired or dismantled in the future, communications - heating and water supply pipes - should be laid in the attic in strict compliance with all required technologies. This is especially true for slabs that serve as floors or ceilings for bathrooms, steam rooms, etc. Any leaks over such floors must be repaired immediately.

Wooden formwork boxes are used to construct columns. The formwork box is usually sewn together on three sides. Installation begins with the installation of a frame, which is pressed against plugs laid in advance in fresh concrete.

The frame is installed in such a way that the axes marked on it during manufacture coincide with the axes drawn in the concrete of the structure, and the surface into which the box is installed is at the same level as the marks on the outlets of the reinforcement.

The assembled formwork boxes are installed in frames and secured with braces or inclined joints, which are nailed to plugs previously laid in concrete, or to joists laid spaced between adjacent columns. 'The verticality of the boxes is verified using a frame plumb line. The fourth panel of the box and the clamps missing in the column formwork box are installed after installing the reinforcement cages. The formwork has holes for supplying concrete mixture inside the structures.

Reinforcement of columns is carried out using a crane. The installed frames are aligned and temporarily secured using clamps. Clamps are used for alignment and axial alignment of column frames. Removal of temporary fastenings is carried out after electric welding of the frames to the outlets of the reinforcement of the lower columns.

Dismantling of the formwork is carried out in the reverse order after the concrete reaches the stripping strength. The formwork is dismantled with shields, which are then moved to workplace for cleaning and lubrication.

The installation of formwork and reinforcement according to SKM No. 1 is carried out with a gantry crane, and according to SKM No. 2 - with a tower crane, i.e., with the same lifting means used to lay the concrete mixture. According to SCM No. 3, the installation of formwork and reinforcement is carried out using a tower crane, used only for these works. The concrete mixture is supplied using portable bunkers. Bunkers are supplied by gantry cranes according to SKM No. 1 (Fig. 95) or tower cranes according to SKM No. 2 (Fig. 96). The supply of concrete mixture according to SCM No. 3 is carried out by a concrete pump (Fig. 97, tables 68, 69).

Panel formwork was used to construct the beams. First, the bottoms of the beam formwork are placed in the column formwork cutout and fastened with nails. Then, inventory racks are placed under the bottom of the formwork and wedged from below. After adjusting the position and construction lifting of the bottom of the beams, install the side panels of the beam formwork into the frames of the column cutouts and attach them to the lower ribs of the bottom.

Dismantling of the formwork is carried out in the reverse order after the concrete reaches the stripping strength. The formwork is dismantled with shields. First, the inventory racks are removed, then the side and bottom shields are torn off.

Reinforcement of beams begins with laying the reinforcing cage into the beam formwork. Before laying the frame, clamps are installed on its lower part to create a protective layer. Installation of clamps is carried out in checkerboard pattern in increments of 1 m. Installation of reinforcement and formwork of beams is carried out using a KB-100 crane from mobile platforms.

The concrete mixture is laid using portable bins installed in the crane's operating area, which are transported to the concreting site by a tower crane (Fig. 98). As the beam formwork is filled, the concrete mixture is compacted using deep vibrators.

Installation of floor formwork is carried out in the following sequence. Before installing the formwork, supporting scaffolding is installed with a flooring 1.8 m below the bottom of the floor formwork. The installation of floor slab formwork is carried out simultaneously with the installation of beam formwork and is carried out in accordance with the work project.

When dismantling the formwork, first remove the supporting posts, then tear off the panels. Reinforcement of floors begins with laying reinforcing mesh into the floor formwork. Before laying the nets, clamps are installed on them to create a protective layer. Installation of clamps is carried out in a checkerboard pattern with a step of 1 m.

Installation of formwork and reinforcement is carried out using the same lifting mechanisms as laying the concrete mixture.

The concrete mixture is supplied to the place of laying in the floor formwork using portable hoppers using a gantry crane according to SKM No. 1 (Fig. 99) or a tower crane according to SKM No. 2 (Fig. 100, Tables 70-73).

Panel formwork is used to construct walls. The formwork of the walls is installed in two steps: first, the formwork of one side of the wall is installed to its entire height between the floors, and after reinforcing the wall, the formwork of the other side is installed. In this case, holes are provided in the formwork to supply concrete mixture through them into the structure.

Formwork outside The walls are secured to the inside with tension bolts or wire ties.

To maintain the design thickness of the walls, wooden or concrete spacers are installed inside them, placing them in the places where the tie bolts or wire ties pass. Wooden spacers are removed during the concreting process. Reinforcement of walls begins with the installation of frames using a crane and manual installation of rods. The ratio of frames to rods is 85 and 15%. The installed frame is aligned and temporarily secured using clamps. A clamp is used for alignment and axial alignment of the wall frame. Removal of temporary fastenings is carried out after electric welding of the frames to the outlets of the reinforcement of the lower tier of the wall.

Dismantling of the formwork is carried out in the reverse order. The formwork is dismantled using shields: the ties are removed, first the shields of one side of the wall are torn off, then the other. All shields are moved to the workplace for cleaning and lubrication. Stripping the walls is carried out after the concrete reaches stripping strength.

Laying the concrete mixture into the wall formwork is carried out according to SKM No. 1 using a gantry crane (Fig. 101), according to GRM No. 2 - tower crane(Fig. 102), according to OKM No. 3 - concrete pump (Fig. 103, tables 74, 75).

In construction practice, prefabricated monolithic frame structures multi-storey buildings with spatial stiffening cores made in monolithic reinforced concrete.

Structurally, the creation of a solid box-shaped stiffener core instead of flat shear walls increases the rigidity of the entire building, allowing a significant reduction in reinforced concrete consumption. Thus, the consumption of reinforcement in a monolithic core of a house is 3-4 times lower than in a similar house with prefabricated reinforced concrete walls rigidity. In addition to the stiffening core, the weight-bearing and enclosing elements of a building are usually carried out in prefabricated products.

Monolithic stiffening cores are also combined with prefabricated panel structures of internal and external walls. It is recommended to erect rigid cores with a height of more than 15 m in sliding formwork or in formwork with a tear-off device (Fig. 104). The stiffening cores currently being built are made of heavy monolithic concrete brand M300. In plan they can be rectangular, cylindrical, cruciform or a more complex configuration. The thickness of the walls ranges from 20-80 cm.

Walls are reinforced with both rigid and flexible reinforcement. The working one is the longitudinal reinforcement. Flexible fittings placed both from the outside and from inside barrel made of steel classes A-II and A-III. The diameter of the reinforcement is established by calculation and decreases with the height of the core (for example, from 28 to 16 mm).

Horizontal reinforcement is not designed and is installed structurally.

Monolithic tank structures are made of concrete grade M200, rectangular in plan with a height of up to 2 m and round - up to 6 m. The thickness of the bottom is 25-70 cm. Reinforcement is carried out with meshes or frames made of class A-II or A-III steel with a diameter of 10-16 mm.

The walls are made of monolithic concrete using conventional methods or shotcrete. With generally accepted concreting methods, the wall thickness is 25-30 cm.

Shotcrete is applied to the outer formwork of the walls under a pressure of 0.45-0.5 MPa, with a thickness of 4-5 cm in three passes. The formwork and reinforcement are immediately set to full height. Reinforcement made of steel classes A-II and A-III.

Prefabricated monolithic structures can be rectangular or round in plan with a height of up to 5 m. The bottom is made of monolithic reinforced concrete with the same design characteristics as for the monolithic version.

Monolithic reinforced concrete floors are still of limited use due to their high labor intensity. They are used in cases where it is necessary to cover an atypical room with atypical dimensions, as well as in monolithic buildings.

Monolithic floors are made with beams (ribbed) and without beams in the form of a smooth slab (Fig. 5.4).

Fig.5.4. Structural diagrams of monolithic reinforced concrete floors:

a – ribbed; b – caisson; c – beamless; 1 – plate; 2 – beams; 3 – columns; 4 – column capital

5.1.4. Floors on beams

Beam floors are used in low-rise construction (in wooden and stone buildings), during the reconstruction of old buildings by replacing wooden beams with more durable metal or reinforced concrete ones.

Based on the material, beams are divided into wooden, reinforced concrete and metal.

Floors on reinforced concrete beams. Floors on reinforced concrete beams consist of beams laid on load-bearing walls with axial distances of 600, 800, 1000 mm, inter-beam filling and a floor (Fig. 5.5).

The depth of support of the ends of the beams on the walls or purlins is taken to be at least 150 mm. The ends of the beams on the supports are anchored, and the gaps between the beam and the walls of the nest to a depth of 40-60 mm are sealed with mortar. The inter-beam filling (Fig. 5.6) consists of a ramp, which is a flooring of lightweight concrete slabs and a sound-insulating (heat-insulating) layer. The seams between the knurling elements and the beams are carefully filled with mortar or glassine is laid on top of the knurling. Sound insulation is usually made from a layer of slag or sand at least 60 mm thick. From below, the bevel and beams are rubbed with mortar. This design is used for plank floors along joists. When installing other types of floors, for example cement, requiring a continuous gesture

Fig.5.5. Prefabricated reinforced concrete beams and their supporting parts:

a – plan for the location of floor beams; b – general view beams; 1 – beam;

2 – steel anchor; 3 – steel structure; 4 – mounting loop; 5 – sealing with concrete

After preparation, the space between the beams is filled with slag, on which a layer of slag concrete with a thickness of at least 40 mm and a floor are laid (Fig. 5.6d). More appropriate in these cases are roll-ups made of double-hollow lightweight concrete stones - liners, which have sufficient soundproofing properties and require only careful filling of the joints with mortar (Fig. 5.6 d).

Floors on metal beams. Currently metal beams are used only in exceptional cases during the repair and reconstruction of buildings.

Steel beams (usually I-beams) are located at a distance of 1-1.5 m from each other. The depth of support of their ends on the walls is 200-250 mm.

Fig.5.6. Prefabricated beam structure

reinforced concrete elements:

a – general view; b – lightweight concrete slab; c – lightweight concrete liner stone; d,e – flooring options with mineral floors; 1 – reinforced concrete beam; 2 – roll-up made of lightweight concrete slabs; 3 – waterproofing layer; 4 – sound insulation; 5 – soundproofing gasket; 6 – logs; 7 – plank floor; 8 – slag; 9 – slag concrete thickness

40 mm; 10 – cement floor 20 mm thick; 11 – grouting with mortar

To increase the area of ​​pressure on the masonry in order to protect it from crushing, concrete pads or steel pads are placed under the ends of the beams. The ends of the beams are anchored into the masonry walls and, if necessary, insulated with felt, followed by sealing the gaps around the perimeter of the nest with concrete (Fig. 5.7).

The inter-beam filling can be made of prefabricated reinforced concrete or monolithic slabs, and in some cases from brick vaults.

Fig.5.7. Floor construction on steel beams:

a – supporting the ends of the beams on the walls; b – anchor fastening detail; c – floor filled with reinforced concrete monolithic slab; d – the same, with brick vaults;

1 – steel beam; 2 – steel anchor; 3 – concrete pad; 4 – bolt; 5 – sealing with cement mortar; 6 – reinforced concrete monolithic slab; 7 – lightweight concrete; 8 – ceramic tiles over a layer of cement mortar; 9 – brick vault; 10 – soundproofing layer; 11 – two layers of roofing felt; 12 – plank floor along joists; 13 – steel mesh; 14 – plastering with cement mortar

Floors on wooden beams. Currently, wooden floors can only be used in low-rise buildings and only in areas where wood is a local building material. Their advantages are the simplicity of the device and relatively low cost. Disadvantages are combustibility, the possibility of rotting and relatively low strength.

All wooden floor elements are made from coniferous species forests (pine, larch, spruce, etc.) Beams are made mainly in the form of rectangular beams, the dimensions of which are determined by calculation. (Fig. 5.8). The distance between the axes of the beams is taken from 600 to 1000 mm.

To support the inter-beam filling, bars with a cross-section of 40 x 50 mm, called cranial ones, are nailed to the sides of the beams (Fig. 5.8). The depth of support of the ends of the beams in the nests of stone walls must be at least 150 mm (Fig. 5.9). The ends of the beams are antiseptic with a 3% solution of sodium fluoride or coated (except for the ends) with resin, and when embedded in external walls, they are additionally wrapped in two layers of roofing felt. On internal walls or purlins, two layers of roofing felt with tar mastic are laid under the ends of the beams. The gaps between the walls of the nest and the ends of the beams to a depth of 40-60 mm are tightly sealed with mortar. The arrangement of wooden floor beams, as well as their anchoring, are similar to reinforced concrete beam-type floors (Fig. 5.1 c).

The filling between the beams (Fig. 5.10) consists of a panel board roll, lubrication along the top of the roll with a clay-sand solution 20-30 mm thick and a soundproofing layer of slag or calcined earth 60 mm thick. The floors are made of planks on joists with metal ventilation grilles installed in the corners of the rooms. The ceilings are plastered with lime-gypsum mortar over the shingles or hemmed with sheets of dry plaster.

Fig.5.8. Structural solutions for wooden beams:

1 – single beam beam; 2 – a beam composed of two solid wood blocks; 3 – beam made of laminated wood; 4 – cranial block

Rice. 5.9. Details of supporting wooden floor beams on

stone walls:

a - on outer wall; b – on the inside; 1 – external load-bearing wall; 2 – external self-supporting wall; 3 – internal load-bearing wall; 4 – wooden beam; 5 – thermal insert; 6 – two layers of roofing felt on tar mastic or an antiseptic zone of the beam; 7 – anchor made of strip iron; 8 – crutches or nails

Fig.5.10. Floor construction on wooden beams:

a – with a board panel roll; b – the same, from hollow blocks; c – the same, from lightweight concrete blocks (slabs); d – floors in bathrooms; d – types of roll-ups; 1 – beams; 2 – roll-up (panel); 3 – plaster; 4 – clay lubricant; 5 – backfill; 6 – lags; 7 – soundproofing gasket; 8 – plank floor; 9 – hollow lightweight concrete block; 10 – cranial block; 11 – solution; 12 – gypsum board; 13 – floor made of ceramic tiles; 14 – cement screed 20 mm; 15 – concrete preparation; 16 – two layers of roofing felt on mastic; 17 – plank floor; 18 – plates; 19 – boards; 20 – false ceiling