RU2226593C2 - Composite multi-store building frame made of reinforced concrete - Google Patents

Abstract

FIELD: building structures, particularly concrete frames of buildings built in different areas, including seismic region. SUBSTANCE: frame includes composite or cast-in-place columns and flat composite floor discs formed by cast-in-place bearing and fastening beams made of reinforced concrete. Beams are united together with columns into closed frame cells. Composite walls of reinforced concrete are placed in groups within the bounds of frame cells. Composite walls are connected with each other by cast-in-place seams. Composite wall ends are supported by bearing beams. Continuous bearing beams in each span between columns have cross-sections with varying width. Cross-section width is changing from maximum value located near columns to minimum value in span center. Composite slabs within the bounds of each cell have different lengths. The outermost slabs positioned near fastening beams have the smallest lengths, slabs located in each cell center have the greatest lengths. EFFECT: reduced frame specific metal consumption, improved frame performance due to possibility of column grid spacing increasing. 6 cl, 13 dwg

Description

The invention relates to the construction, in particular, to reinforced concrete frames of buildings for various purposes and floors, erected in various regions, including seismic.

The reinforced concrete frame of multi-storey buildings is known, including columns and floor disks, consisting of multi-hollow slabs joined together by monolithic seams, and in the ceiling cells - monolithic reinforced concrete crossbars made with a construction hoist to the middle of their spans [1].

The frame is relatively easy to manufacture. However, the implementation of the construction lifting of the crossbars requires special care during the work, creates a flattened ceiling surface within each cell of the frame. This causes an additional need for the installation of suspended ceilings, and therefore the design of the frame is not economical enough.

Known reinforced concrete frame of the building, including columns, ceilings with channels of variable depth, made along the faces of the columns with prestressed reinforcement and monolithic concrete around the perimeter of the frame cells and filling the frame cells with monolithic or precast concrete slabs [2].

The frame design is characterized by low metal consumption. However, the frame during the construction is busy and multi-stage. First, a slab with channels is made, then after holding in time for concrete hardening (up to 20 ... 25 days), working reinforcement is pulled onto the slab concrete, which requires special equipment and technology. Then the bottom of the slab formwork channels and produce their concreting. This design and technology is very time-consuming, reduces the pace of construction of the building and therefore uneconomical.

Closest to the proposed is the reinforced concrete frame of a multi-storey building, adopted as a prototype and including columns and floor slabs, which consist of reinforced concrete continuous supporting crossbars, orthogonally conjugated in joints with columns with continuous connected crossbars, forming reinforced concrete closed frame cells in which prefabricated slabs are placed [3].

The frame is easy to manufacture, does not require prestressing in construction conditions.

The drawback of the frame is the difficulty of placing the longitudinal working reinforcement of the bearing crossbars in the zones of negative bending moments of the columns and the insufficient use of its strength. In addition, the support nodes of the precast plates at the columns are overstressed with large sizes of the grid of columns. In general, these shortcomings lead to an increased consumption of steel for reinforcing bearing beams and to a limitation of the size of the grid of columns.

The present invention solves the problem of reducing the specific metal consumption of the frame with a simultaneous substantial expansion of its consumer qualities, due to the possibility of increasing the size of the grid of columns.

The solution to this problem is achieved by the fact that in a reinforced concrete precast-monolithic frame of a multi-storey building, including precast or monolithic columns and flat precast-monolithic floor disks formed by monolithic reinforced concrete bearing and connecting crossbars connected in the plane of overlap in the nodes of the interface with the columns in closed frame cells within which prefabricated reinforced concrete slabs are placed in groups, interconnected on the sides by inter-plate seams and resting at the ends on load-bearing rigs whether the bearing crossbars in each span between the columns are made with cross sections of variable width, varying from the largest in the columns to the smallest in the middle of the span, and accordingly prefabricated slabs within each cell are made with the length shorter in the end plates of the connecting crossbars and the largest in the plates located in the middle of each cell.

Bearing crossbars can be made with the height of the section protruding upward relative to the top of the prefabricated plates by the thickness of the screed and with the width of the protruding upward part equal to the width of the cross-section of the supporting crossbar at the columns.

The floor disks behind the outer rows of columns can be made on the consoles of the bearing and / or communication crossbars, released for the outer columns, based on these consoles precast plates.

Prefabricated slabs in the floor disks can be made by formless molding, and flat reinforcing cages with through upper and lower reinforcement are placed in the interplate seams across the supporting crossbars for a length sufficient to anchor them in the concrete of interplate joints.

Prefabricated slabs can be made hollow with open voids at the ends.

Prefabricated slabs can also be made of a U-shaped cross section and supported at both ends by the upper shelf on the concrete dowels of the side faces of the bearing crossbars.

The implementation of load-bearing crossbars with a cross-sectional width greater than that of the columns makes it possible to optimally place the upper working reinforcement of load-bearing crossbars near the columns in the zone of action of the largest negative bending moment in absolute value and thereby ensure the most efficient use of the strength properties of reinforcing steel. At the same time, due to the broadening of the load-bearing crossbar at the columns, the resistance of the overlapping disk increases to the punching of the column and the reliability of the butt joint of the column with the overlap and the entire overlap increases. In addition, the reliability of the supporting joints of the prefabricated plates with the bearing crossbars is also increased, since their support on the bearing crossbars of a section wider at the columns reduces not only the vertical support reaction, but also the maximum torque in this node. As a result of a decrease in the value of shear stresses in the walls of prefabricated plates, the danger of the formation of oblique cracks and their brittle fracture is almost completely eliminated.

Due to the decrease in the length of the extreme plates in the cells, their relative rigidity increases. Due to this, the magnitude of the deflection of the extreme plates under load in the composition of the floor is reduced. In turn, the extreme plates, due to meshing on the inter-plate seams, restrain the vertical movements of both the middle plates of the cells and the entire floor under load. Thus, the proposed solution allows you to perform the frame without prestressing in building conditions and increase by 15 ... 20% the size of the spans of the crossbars without excessive steel and bring the step size of the columns of the frame to 8.5 ... 9.0 m using traditional prefabricated products.

The implementation of load-bearing crossbars with a section height that protrudes upward relative to the top of the prefabricated slabs by the thickness of the floor screed helps to solve the same problem of reducing the specific metal consumption of the frame while increasing the size of the grid of columns. In this case, in the supporting sections of the bearing crossbars at the columns, the shoulder of the inner pair of forces increases and the bearing capacity of these sections increases without increasing the number of working reinforcement. In the middle of each span of the bearing crossbar, in addition, effective T-sections with a shelf in the compressed zone are formed, which also leads to an increase in their bearing capacity.

The implementation of floor disks behind the outer rows of columns of the frame on the consoles of the bearing and / or connecting beams released for the outer columns, with the prefabricated slabs resting on these consoles, allows you to perform bay windows, balconies and loggias on these consoles, and create any required facade plastic using these consoles for placing floor-supported walls on them. At the same time, under the influence of the load on the crossbar arms, the values of the passing bending moments in the extreme spans of the crossbars decrease, which leads to a decrease in the steel consumption for the working reinforcement of the spans of the crossbars.

The use of formless molding in the floors of prefabricated plates can further reduce the consumption of steel for reinforcing floors and use products of advanced molding technologies. Placing reinforcing beams in the cross-seams across the supporting crossbars with through upper and lower reinforcement to a length sufficient for their anchoring in the concrete of the joints, allows to ensure the continuity of the working reinforcement of the floor along the entire span along the plates, to ensure the perception of the bending moments of both signs along the ends of the prefabricated plates . Thus, individual prefabricated plates are combined into continuous elements, which can further reduce the consumption of steel for reinforcing prefabricated plates and reduce their deflection.

The implementation of multi-hollow prefabricated plates significantly expands the capabilities of the frame, especially when it is used for residential and public buildings, providing smooth ceilings, as well as reliable interfacing of plates with load-bearing crossbars using concrete bolts of the crossbars placed in the voids open at the ends of the plates.

The implementation of prefabricated slabs of a U-shaped cross-section with the support of their upper flange on the concrete dowels of the bearing crossbars can significantly reduce the load due to the own mass of the floors and thereby increase the size of the grid of columns. This is especially important for public and industrial buildings, the floors of which can be made with the installation of light suspended ceilings.

Comparative analysis with the prototype allows us to conclude that the claimed technical solution differs from the known one with new features: (1) continuous support crossbars in each span between the columns are made with cross sections of variable width, varying from the largest in the columns to the smallest in the middle of the span, (2) prefabricated slabs within each cell are made with a length shorter in the end slabs of the connecting crossbars and the largest in the slabs located in the middle of each cell, (3) continuous bearing crossbars are made with the height of the section protruding upward relative to the top of the prefabricated slabs by the thickness of the floor screed, (4) with the width of the protruding part equal to the largest cross-sectional width of the supporting crossbar at the columns, (5) the floor disks behind the outer rows of the columns are made on the consoles of the bearing and / or communication crossbars, issued for the outer columns, supported by prefabricated slabs on these consoles, (6) the prefabricated slabs in the floor disks are form-molded, and (7) flat reinforcing cages with a through bottom and the upper reinforcement to a length sufficient for anchoring them in the concrete of the inter-plate joints, (8) the prefabricated slabs are multi-hollow with openings at the ends, (9) the prefabricated slabs are made of a U-shaped cross section and are supported at the ends of the upper flange on the concrete dowels of the side faces of the bearing crossbars.

In general, the proposed technical solution meets the criterion of novelty, since the above characteristics of the proposed technical solution are not known in the above amount, and the technical results achieved by the proposed solution are superior to the known ones. This makes it possible to consider the proposed technical solution in accordance with the requirements of an inventive step.

The essence of the proposed solution is illustrated by drawings. Figure 1 presents the proposed frame, view in plan; figure 2 is the same as in figure 1, with load-bearing crossbars protruding upward; figure 3 is the same with the location of the bearing crossbars along the section of the house; figure 4 is the same, a fragment of the overlapping disk with the placement of the working reinforcement in the bearing and connecting beams, mezhplitnyh seams; figure 5 is the same, section aa in figure 4 when using prefabricated hollow core slabs; figure 6 is the same, a section bB in figure 4, the reinforcement of the bearing beams and the pair of beams with columns; in Fig.7 is the same, section bb in Fig.4 in the middle of the span of the bearing crossbar when multi-hollow plates are supported on it; in Fig.8 is the same, section GG in Fig.4 of the bearing beam at the columns when multi-hollow plates are supported on it; figure 9 is the same, a section aa in figure 4 when performing overlapping with the use of prefabricated U-shaped plates; figure 10 is the same, a section bb in figure 4 of the bearing beam in the middle of the span with the U-shaped plates resting on it; figure 11 is the same, section GG in figure 4 of the bearing beam at the columns with the support of prefabricated U-shaped plates; in Fig.12 - the same, a section bb in Fig.4 when performing the carrier crossbar protruding upward in the middle of its span; in Fig.13 is the same, section GG in Fig.4 of the bearing beam, which protrudes upward at the columns.

The proposed frame (Fig.1-13) includes columns 1, prefabricated slabs 2, interconnected at the sides by inter-plate seams 3 of monolithic concrete. In the cross sections of the columns 1 in mutually perpendicular directions, continuous monolithic reinforced concrete bearing 4 and connecting 5 crossbars are passed, forming closed frame cells in the plane of the overlapping disk, covering a group of multi-hollow plates 2 (Figs. 1-4). On the continuation of the supporting 4 and connecting 5 crossbars for the outer columns, consoles 6 of the crossbars on which the plates 2 are supported can be released. The supporting crossbars 4 are made with a variable cross-sectional width, increasing from the minimum in the middle of the span to the largest in the columns. The plates 2 in each cell have a variable length from the smallest length of the plates located at the connecting crossbars 5, to the largest in the middle of the cell. Through load-bearing crossbars 4, through-armature 7 is placed along their entire length, and in reinforcing zones near the columns, local reinforcement 8 is placed (Fig. 4). The number of fittings is determined by calculation. In the crossbars 5, through reinforcement 9 is made, the amount of which is also determined by calculation. Through longitudinal reinforcement 7 and 9 of the supporting 4 and 5 connecting bolts are anchored on the contour of the overlapping disk and it is performed without tension. Across the load-bearing crossbars 4, flat reinforcing cages 10 with through-through upper and lower reinforcement were placed in the interplate seams to a length sufficient for it to be anchored in the concrete of the inter-plate seams 3. In addition, a through reinforcement 11, anchored at one end in monolithic concrete of the extreme load-bearing crossbar, and to others - in the middle bearing beam closest to it (Fig. 4). The reinforcement 11 is designed to restrain the horizontal bending and torsion of the extreme bolt 4. The bearing bolts 4 are made to the height of the plates 2 (Fig. 5-11) or can be made in the same plane with the plates 2 on the lower surface and protruding upward (Fig. 2, 12, 13) relative to the upper surface of the plates 2 by the thickness of the floor screed 12.

Prefabricated slabs 2 can be multi-hollow 13 or U-shaped cross-section 14 of formless molding with the ends resting on concrete dowels made on the side surfaces integrally with load-bearing crossbars 4. Moreover, before the slabs 2, 13 are installed in the ceiling, their voids are open ends up to 100 mm long. At the ends of the slabs 2, 13, 14, releases of working reinforcement (not shown) can be made, anchored in the monolithic concrete of the supporting crossbars 4.

With large spans of prestressed plates 2, when it is possible to vary in magnitude of their bending from compression by the prestressing force, a suspended ceiling 16 made of sheet products can be hemmed under the ceiling. With the proposed thin-walled U-shaped products, a sound insulation layer 17 can be placed in the ceiling.

The proposed frame operates under load as a single statically indeterminate multi-storey spatial structure with flat disk drives. On each floor, the vertical load is directly perceived by the prefabricated slabs 2, and distributed to the load-bearing crossbars 4, and the latter transfer the load to the columns 1. In this case, under the action of the vertical load, the extreme plates 2 located at the connecting crossbars 5 bend to a lesser extent and have a restraining effect on the vertical movements of plates located closer to the middle of the cell. Bearing crossbars 4 in the places adjacent to the columns 1, along with a significant value of the bending moment of the negative sign, are affected by the transverse force from the support reaction, and they can also twist from uneven bending of the prefabricated plates with different loads in adjacent cells, with different lengths of span of the crossbars 5 adjacent cells. Twisting is especially noticeable in the extreme and corner cells of the frame. Therefore, the implementation of the bearing crossbars 4 broadened at the columns 1 allows you to more fully and evenly redistribute the forces between the frame elements and provide a more uniform stress state in their sections. Along with increasing the efficiency of the carcass under the action of a vertical load, the resistance to twisting and shifting of the floor disks of the proposed carcass under the influence of horizontal load increases, the torsional rigidity of the carcass increases significantly. Thanks to the proposed design of the floor disks, vertical stiffness diaphragms are more efficiently included in the operation.

Thus, in comparison with the analogues [1, 2] and the prototype [3] in the proposed frame in the presence of the above characteristics, it is still possible to reduce and redistribute the efforts to the fullest extent between the frame elements. Indeed, if in the prototype without prestressing the monolithic elements of the ceilings, the maximum effective step of the columns is 7.2 m, then the proposed solution makes it possible under almost the same conditions to ensure spans overlap up to 8.6 ... 9.0 m. This significantly expands the possibilities of providing free space-planning decisions of buildings, which solves the problem of obtaining a universal frame for multi-storey buildings for various purposes (housing, public buildings, multi-storey garages, parking lots, etc.).

The proposed frame is erected in the following sequence.

First, precast columns 1 with a height of 1-2 floors are installed in the foundations, then support devices with formwork on top for monolithic load-bearing crossbars 4 are mounted in the alignment of columns. Prefabricated plates 2, 13, 14 of various lengths are supported on the supporting devices. At the same time, longer plates are placed in the middle of the spans, and the shorter ones are placed at the columns. Along the outer slabs in the alignments of the columns to the installed slabs, the formwork of the tie rods is suspended 5. After that, in the resulting volumes, span reinforcing frames 7 and 9 of the crossbars are installed in the alignments of the columns, the reinforcement of the crossbars 8 in conjunction with the columns is installed. Under interplate seams 3 hang inventory stripe formwork. Flat reinforcing cages 10 are placed across the inter-plate seams 3 across the load-bearing crossbars, and reinforcement 11 is also placed in the extreme overlapping cells. The concrete mixture is laid simultaneously in the supporting 4 and connecting 5 crossbars and in the inter-plate seams 3 with continuous supply by a concrete pump or cyclic feeding by tubs. After a set of concrete monolithic structures of the required strength, support devices and formwork are removed from under the finished floor and installed on it to erect the floor of the next floor, and the cycle repeats.

In the case of the use of monolithic columns, the reinforcement and formwork of the columns 1 are first installed at the height of the floor. Then, the columns containing the outlets of their longitudinal reinforcement on the upper floor are concreted at the top. After that, the order of the device for overlapping each floor is similar to that described above.

The floor-mounted exterior walls of the building are arranged simultaneously with the construction of the frame and use them as the formwork of the external crossbars of the floor disks.

The presented technology of the construction of the frame complements the advantages of its design and provides all-weather and high pace of construction of a multi-storey building.

The proposed technical solution will be implemented in the construction of multi-storey buildings for various purposes in Belarus and Russia, as well as in other CIS countries. It will contribute to the distribution and development of technological equipment for formless molding, increasing the efficiency of the construction industry. Such re-equipment of enterprises in the construction industry is carried out as part of the implementation of the state scientific and technical policy to ensure the competitiveness of construction products in these countries.

Sources of information

1. RF patent No. 2052591, E 04 B 1/18, E 04 H 9/02, BI No. 2, 01.20.1996.

2. RF patent No. 2166032, E 04 1/18, BI No. 12, 04/27/2001.

3. RF patent No. 2118430, E 04 B 1/18, E 04 H 9/02, BI No. 24, 03/05/1996.

Claims (6)

1. Reinforced concrete precast-monolithic frame of a multi-storey building, including precast or monolithic columns and flat precast-monolithic floor disks formed by monolithic reinforced concrete load-bearing and connecting crossbars, united in the plane of overlap in the nodes of the connection with the columns into closed frame cells, within which groups are placed prefabricated reinforced concrete slabs interconnected by interplate seams and resting at the ends on load-bearing crossbars, characterized in that continuous load-bearing crossbars in each span m Each of the columns is made with cross sections of variable width, varying from the largest in the columns to the smallest in the middle of the span, and accordingly the prefabricated plates within each cell are made with the length smallest in the outer plates at the connecting crossbars and the largest in the plates located in the middle of each cell. 2. The reinforced concrete frame of the multi-storey building according to claim 1, characterized in that the continuous load-bearing crossbars are made with a section height that protrudes upward relative to the top of the prefabricated slabs by the thickness of the floor screed and with a width of the protruding part equal to the maximum width of the cross-section of the load-bearing crossbar at the columns. 3. The reinforced concrete frame of a multi-storey building according to claim 1 or 2, characterized in that the floor disks behind the outer rows of columns are made on the consoles of the bearing and / or communication crossbars released for the outer columns, based on these consoles of prefabricated plates. 4. The reinforced concrete frame of a multi-storey building according to any one of claims 1 to 3, characterized in that the prefabricated slabs in the floor disks are made by formless molding, and flat reinforcing cages with through and through lower and upper reinforcement are placed in the interplate seams across the supporting crossbars for a length sufficient for their anchoring in concrete of interplate joints. 5. The reinforced concrete frame of a multi-storey building according to any one of claims 1 to 4, characterized in that the prefabricated slabs are multi-hollow with voids open at the ends. 6. The reinforced concrete frame of a multi-storey building according to any one of claims 1 to 4, characterized in that the prefabricated slabs are made of a U-shaped cross section and are supported at the ends of the upper shelf on the concrete dowels of the side faces of the bearing crossbars.

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