RU2728055C2 - Wood-concrete self-stressing covering - Google Patents

Abstract

FIELD: low-height construction.

SUBSTANCE: invention relates to wood-concrete self-stressed roofing of a building. Wood-concrete cover includes reinforced non-metallic rods, glued two-wall wooden beams filled with expanding concrete, reinforced with non-metallic mesh concrete slab, connecting beam and anchors. In the lower zone of the glued two-girder beam rectangular cross-section is glued across and in the middle zone of its cross section—stepped lamellar nails, forming in middle section of cross-section through rectangular stepped holes with length increasing to supports, filled with monolithic concrete, creating "keys" of variable cross-section.

EFFECT: technical result consists in increasing the rigidity of the beam.

1 cl, 3 dwg

Description

The invention relates to the field of low-rise construction and can be used as floors of residential and public buildings.

Known wood-concrete flooring, including load-bearing wooden beams and a reinforced concrete slab, the lower plane of which is located at the level of the upper edges of the beams, connecting the beam and the plate with steel anchors installed with a certain pitch (see RF patent No. 115796, IPC E04B 5/16, publ. 05/10/2012, bulletin No. 19).

The disadvantages of the known wood-concrete floor are the relatively low rigidity and strength, due to the lack of prestressing, low tensile strength of the foam concrete slab.

Known wood-concrete floor, including wooden beams with a sample of the depression in each beam and a monolithic ribbed slab with a fixed plank formwork, formed by pouring concrete into the depression of the beam and anchoring rods located at the bottom of the depression and in the walls of its forming (see Canadian patent A2094995 A1, 1993).

The disadvantages of this invention are the presence in the stretched zone of the rib of concrete, weakly working in tension, the inefficiency of the anchors located at the bottom of the hollows due to the smooth-bore pipes and side anchors along the wall - due to the coincidence of the shear lines "concrete-wood" with the longitudinal fibers of wooden plates. Also, the disadvantages should be considered the laboriousness of the selection of grooves of complex configuration in a solid section, in contrast to the manufacture of glued beams with specified parameters under the current load.

The closest is a wood-concrete floor, including load-bearing wood-concrete beams and a reinforced concrete slab, where ordinary concrete is replaced by concrete with expanding cement, and the lower zone of the beam and slabs are reinforced with plastic reinforcement (see RF patent No. 177801, E04B 5/23, publ. 13.03 .2018, bul. No. 8).

The disadvantages of this wood-concrete floor are: ineffective use of the strength properties of materials (concrete) in a wood-concrete beam (filling the zone below the neutral axis with concrete to a greater extent) the absence of structural elements that prevent unwanted stretching (destruction) along the wood fibers of the lower zone of the beam and preventing the beam walls from buckling. The execution of the ribs of the wall in the upper zone of the beam for the entire thickness leads to the need for additional formwork to ensure the impermeability of the concrete during its laying.

The invention is aimed at increasing the rigidity and strength of the beam by transverse reinforcement of the lower flange and the beam wall, at improving the work of the floor layers for shear by creating "dowels" in the beam of different lengths, increasing towards the supports, at approaching the stress-strain state of the structure to the plastic fracture pattern (in which the flange and the rib collapse simultaneously).

The result is achieved by the fact that in a wood-concrete floor, including load-bearing wood-concrete beams, a monolithic slab according to the invention, concrete on expanding cement is used in load-bearing beams and a slab, moreover, non-metallic plastic reinforcement is installed in the stretched zone of the beam, and the slab is reinforced with plastic mesh reinforcement. To improve the adhesion of concrete, slabs with a wood-concrete beam in the contact zone of the beam walls are ribbed by a quarter or half of their width and non-metallic anchors are installed with a step a ₁ , a ₂ , a ₃ , decreasing to the supports. The result is also achieved by the fact that in the lower zone of the beam and in its walls with a certain pitch, transverse wooden plate pins are glued in, preventing the transverse stretching of the lower zone of the beam and the buckling of its walls from the action of expanding concrete. In addition, lamellar pins, connecting the walls with a certain pitch, form through rectangular holes with a length increasing to the supports for the passage of monolithic concrete, thus forming concrete "dowels" of different sections, increasing the bearing capacity of the beam for shear.

FIG. 1 shows a self-stressed reinforced monolithic slab with a wood-concrete beam, FIG. 2 is a top view of a glued board beam, FIG. 3 is a fragmentary section of FIG. 2.

The overlap includes wood concrete load-bearing beams 1, concrete slabs 2 are supported on the beams 1. Wooden load-bearing beams 1 are made of glued boards in the upper part of the wall, have depressions to the height of the compressed zone of the working section filled with expanding concrete 5. In order to increase the rigidity and strength of the wood-concrete floor at the bottom zone 10 of the beams installed non-metallic reinforcement 4, and slab 2 made of expanding concrete 5 is reinforced with mesh reinforcement 6. To hold the walls 7 of the beam 1 in the design position from the expansion of the expanding concrete 5 in the middle and lower zone of the beam, plate pins 8 and 9 are installed. variable pitch b ₁ , b ₂ , b ₃ plate pins 8, form rectangular holes 10 of different lengths, increasing towards the supports for the passage of in-situ concrete during its "pouring". The joint work of the beam 1 and the concrete slab 2 is provided by the ribs 12 of the wall 7 in the upper level. Non-metallic anchors 11 are installed on the protrusions of the ribs, with different pitch a ₁ , a ₂ , a ₃ . The formation of rectangular concrete dowels of different lengths 10, thanks to the lamellar dowels 8 of stepped section, which increase the shear area of the concrete dowels 10 and the installation of dowels 11 (with a step decreasing to the supports) increases the load-bearing capacity of the beam for shear.

The order of installation of the floor is as follows. First, wooden load-bearing beams 1 with lamellar dowels 8 and 9 are installed in the design position, then a removable plywood formwork is mounted, the upper plane of which is at the level of the upper edges of the beams 1, the formwork is attached to the side edges of the beams. Non-metallic bar reinforcement 4 and reinforcing mesh 6 are mounted, concrete is laid on expanding cement 5. Monolithic concrete 5 filling depressions 3 and lower voids 13 of beam 1 forms a plate 2 reinforced by beams 1 (Fig. 1). When the expanding concrete hardens, the reinforcement 4 of the beam 1 and the mesh reinforcement 6 of the slab 2 are prestressed. The presence of lamellar dowels 9 prevents the formation of cracks in the lower boards of the beam 1 and the dowels 8 - the buckling of the walls 7.

The assembled wood-concrete self-tensioned overlap, due to the presence in the wall of the beams of depressions and ribs in the upper part, filling of the depressions 3 and lower voids 13 of the beam 1 with expanding concrete, the presence of dowels of stepped section 8, has increased rigidity and strength, as a result, provides a decrease in material consumption. The use of such beams in the floors reduces their material consumption, the use of expanding concrete in the slab and beams increases the bearing capacity and rigidity of the slab and floor due to the prestressing of the reinforcement of the beam and the mesh of the slab. In addition, the presence of ribs at the beam at the upper level (at the junction with the slab) increases the anchoring capacity of the shear-receiving elements of the beam and slab.

Claims (1)

Self-tensioned wood concrete slab, including glued double-walled wooden beams reinforced with non-metallic rods, filled with expanding concrete, reinforced with a non-metallic mesh, a concrete slab connecting the beam and the anchor plate, characterized in that in the lower zone of the glued two-wall beam transversely, pins of a rectangular cross-section are glued in the middle zone of its cross-section (along the line of the neutral axis) - stepped lamellar pins, forming in the middle zone of the section through rectangular stepped holes with a length increasing towards the supports, filled with monolithic concrete, creating "dowels" of variable cross-section, and in the zone of contact with the slab the walls of the beams are ribbed by a quarter or half the width of the wall, on the protrusions there are non-metallic anchor rods with a step decreasing towards the supports.

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