RU2468167C1 - Method to reinforce support sections of beams - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: method to reinforce support sections of beams includes preparation of a surface, its treatment with an adhesive composition, performance of repair works, if necessary. Reinforcement is carried out due to fixation of corrugated metal sheets to support sections of the beam with permanent parameters of corrugations or alternately corrugated metal sheets. Corrugations may be arranged as transverse or inclined. Into all or only into some cavities formed between corrugated sheets and the beam a defect-clearing solution is or is not injected.

EFFECT: enhanced bearing capacity, reliability and durability of a beam.

4 cl, 8 dwg

Description

The invention relates to construction and can be used for load-bearing beams that require reinforcement in the supporting sections.

Reinforced beams can be made of various materials, while the maximum effect of the application of the invention is achieved for reinforced concrete, metal and wooden beams.

The closest in technical essence and the achieved effect is a method known from the prior art for reinforcing the supporting parts of beams (Matveev EP, Meshechek VV Technical solutions for strengthening and thermal protection of structures of residential and public buildings. M: Publishing center “Old Basmannaya”, 1998 .-- 209 p.: Ill. P.96). This method consists of a sticker on the damaged supporting parts of a sheet metal beam.

The disadvantages of this method are: the inability to pump a special solution to eliminate the defects (damage) of the beam under the glued sheet metal, because the method involves a snug fit of sheet metal to the beam over the entire area; a slight increase in the torsional rigidity of the beam; a relatively small increase in tipping stability and shape stability in the supporting sections (for beams (primarily metal), in which such a loss of stability is possible).

The technical result from the use of the proposed method of amplification is to increase the bearing capacity, reliability and durability of the beam.

The presented technical result is aimed at solving the problem of increasing the strength, stability and life of the beam by eliminating defects and strengthening the supporting sections in the case of repair or reconstruction work. Given the fact that a substantial part of the housing stock of the Russian Federation needs repair and reconstruction of load-bearing elements, this task seems urgent.

The specified technical result is achieved by the fact that traditionally or alternately corrugated metal sheets with a transverse or inclined arrangement of corrugations are attached to the supporting sections of the beam. A defect removal solution is injected into all or only some cavities formed between the corrugated sheets and the beam. The defect eliminating solution prevents or slows down the corrosion or decay of the elements, ensures the solidity of the cross section, and may have, in some cases, bearing capacity.

The scope of the invention provides a variant of the proposed method, in which the injection defect removal solution formed between the corrugated reinforcing sheets and the beam cavity is not provided.

The reinforcing corrugated sheets are fastened to the beam, as a rule, from two sides relative to the cross section of the beam (front and back of the beam). A variant of the proposed method, in which the beam is reinforced on one side (for example, with the front) of the corrugated sheet, and on the other, reinforcement is either absent or made in the form of a flat metal sheet.

When using reinforcing sheets with inclined corrugation, the expected optimal angle between the corrugation and the upper belt of the beam is 45 ° with an acceptable range of ± 10 °.

Variable corrugation of metal sheets implies the presence of corrugations with variable height, and / or pitch, and / or profile. A single corrugation along its length can be constant or variable (i.e., wedge-shaped or in the form of a half truncated cone) section. The corrugation can go to both edges of the metal sheet, only to one edge or not go to the edges at all - the stamped “blind” corrugation. The corrugations can be one-sided or two-sided relative to the median plane of the sheet element. When using sheets with “dull” corrugations or corrugations that extend only to one edge, it is preferable to use one-sided corrugation, which ensures continuous contact of at least one edge of the reinforcing sheet to the beam.

Traditional corrugation involves the constancy of the parameters of the corrugations within a specific reinforcing metal sheet.

The effectiveness of using metal corrugated sheets as reinforcing elements is justified by the features of their work, which is as follows: provided that the reinforcing corrugated elements are firmly attached to the beam, they perceive a significant part of the transverse forces that reach the greatest intensity in the supporting sections of the beam (for the vast majority of loads), significantly increase the torsional stiffness of the section, increase the stability of the shape and position of the beam. In this case, the variable-corrugated elements to the greatest extent correspond to the distribution of the intensities of the transverse forces and bending moments (for typical loading schemes), allowing optimal distribution of the material of the beam reinforcing elements.

The condition of reliable contact of the reinforcing elements to the beam is mandatory to ensure their joint work.

Reliable adjoining of the corrugated elements to the beam is carried out with the help of anchors looking for through coupling bolts installed in the holes drilled in the beam, as well as using transverse or inclined (depending on the type of corrugation) clips, clamps or bandages (including prestressed).

The pitch and locations of anchors, coupling bolts, clamps, clips and braces are set based on the joint work of reinforcing elements and beams. At the same time, at least two anchors or coupling bolts are installed along the height of the beam at the lower and upper zones, respectively. The pitch of the anchors and the coupling bolts is coordinated with the pitch of the corrugations, and in most cases it should not exceed 150 mm. A variable step is possible in accordance with a change in the intensity of the shearing forces, which in most cases reach their maximum at the beam supports.

Reinforcing rods made of steel of a periodic profile can be used as anchors. The recommended diameter of the rods is 8-16 mm, the length of the rods is 100-200 mm. The rods at the points of attachment to the corrugated sheets have a local thickening, for example a nut, and are connected to the reinforcing sheets by welding.

Anchors are fixed in the beam using structural polymer solution or adhesive bonding.

For metal and thin-walled wooden beams, rivets and bolts can be used.

The criterion for choosing the profile of the corrugations of the reinforcing elements can be the degree of damage to the reinforced sections of the beam:

in the presence of a significant number of defects or structural damage (for example, developed inclined cracks in reinforced concrete beams), a wavy profile may be most effective, since minimal contact is made (at the corrugation tops) of the reinforcing element and the beam and, accordingly, a large contact surface of the injected defect eliminating solution;

in the case of a small amount of damage, the use of a trapezoidal profile can be effective, in particular, the use of a profiled metal sheet (corrugated board) is possible.

Corrugations of reinforcing metal sheets may contain stamped ribs on the edges (additional corrugations) that increase the "local" stability of the element.

The defect removal solution is injected through holes drilled in the corrugated sheets (usually at least one hole per corrugation), through natural holes between the corrugated sheet and the beam (for elements whose corrugations extend at least on one face), and also through holes in the upper elements belts (including reinforcing) beams.

The composition and type of the defect removal solution is determined by the specific amplification conditions. A cement-sand mixture, compositions based on resins (epoxy, polyester, etc.), polymers, etc., known from the field of repair work, can serve as such a solution.

If a cement-sand mixture is used as a defect-removing solution, the formed layered structure (corrugated metal sheet, hardened volume of the cement-sand mixture and the section of the reinforced beam) works as a single section, i.e. the hardened volume of the cement-sand mixture takes part of the effort, increases the stability of the corrugated sheet. For this reason, it is effective to use a mixture based on non-shrink or expanding cement, which allows to reduce defects from shrinkage deformations and reduces the volume of voids.

The proposed method of reinforcing the supporting sections of the beams allows the possibility of using as an additional reinforcing elements of inclined go transverse clamps, glued reinforcing bars, tie rods, bandages. Additional reinforcing elements can be located both between the beam and the corrugated reinforcing sheets (sheet) - internal additional reinforcing elements, and on top of the corrugated sheets (sheet) - external additional reinforcing elements.

The pitch and cross-sectional area of additional reinforcing elements is determined by calculation and design features - coordination with the direction, step and height of the corrugations of the reinforcing sheets.

At the ends of the beam, to better fit the reinforcing sheets and minimize leakage of the defect removal solution, it is possible to use end elements in the form of vertically mounted corners of rolled steel, which are fastened with one shelf to the sheet and the other to the end of the reinforced beam. Fastening is carried out by welding, and / or anchors, and / or adhesive bonding.

The thickness of the metal corrugated sheets, as well as the physicomechanical characteristics of the metal from which they are made, are determined by calculating the shear strength taking into account the multiplicity of the thickness of the metal and the technological features of the equipment for organizing corrugations. The step and height of the corrugations is determined by calculating their stability ("local" and "general" stability of the corrugated element) according to formulas known from the literature on the design of metal structures, taking into account the joint work of the corrugations with the beam. When determining the perceived corrugated elements, as well as the defect eliminating solution, which has a bearing capacity (as in the case of a cement-sand mixture), the most important is the principle of the distribution of forces in accordance with the linear stiffness of the elements. Those. an element with comparatively greater rigidity in the section under consideration perceives a large proportion of the forces acting in this section.

The length of the reinforcing elements, including corrugated metal sheets are installed from the conditions of loading the beam and the size of its damaged sections. In the case of loading the beam with a distributed load, it is most advisable to use reinforcing elements per ¼ span, counting from the supports. In the case of loading the beam with concentrated loads, the length of the reinforcing elements should be at least the distance from the support to the nearest concentrated load. In any case, the length of the reinforcing elements is coordinated with the structural conditions and the results of strength calculations, and, if necessary, stability and crack resistance.

The reinforcing elements of the belts, made, as a rule, of sheet metal, are connected to the beam, for example, according to the nail scheme using anchors or coupling bolts. The step, number and type of such joints are determined by calculations for shearing and shear, as well as by the structural requirements of specific conditions of application and operation, while taking into account that the cutting forces in the split hinged beams reach the greatest intensity at the supports.

If reinforced concrete flooring is adjacent to the reinforced beam from above or from below, then the reinforcing elements of the belt (respectively, of the upper or lower) can be attached to the ceiling in the immediate vicinity of the beam (Fig. 7).

The proposed method is applicable for beams with a rectilinear, curvilinear and broken axis plan. The cross-sectional shape of the beams can be rectangular, tee, I-beams. The curvilinear cross-sectional shape of reinforced beams causes significant difficulties in the manufacture of the corresponding corrugated sheets and is therefore considered undesirable. The shape of reinforced beams can be different: rectangular, trapezoidal, polygonal, segmented, etc. The most technologically advanced reinforcement according to the proposed method of beams with a rectangular outline.

The invention is illustrated by drawings, on which:

figure 1 - reinforced on the supporting sections of the beam. Reinforcement is made using corrugated sheets, clamps and waist elements;

figure 2 is a cross section of a reinforced section of the beam in figure 1 along a transverse clamp;

figure 3 is a longitudinal section of the beam in figure 1 (for clarity, one of the two symmetrical halves of the beam is shown);

figure 4 - reinforced on the supporting sections of the beam. Reinforcement is performed using sheets with “deaf” (stamped) corrugations;

figure 5 is a cross section of a reinforced section of the beam in figure 4;

figure 6 - beam I-beam cross-section, reinforced in the supporting sections of the variable-corrugated sheets;

Fig.7 is a fragment of a beam monolithic reinforced concrete floor with a beam reinforced at the supporting sections (for clarity, one of the two symmetrical halves is shown). Reinforcement is made using variable-corrugated sheets and waist elements;

Fig.8 is a side view of the structure of Fig.7.

The proposed method is as follows:

- prepare the surface of the reinforced beam 1 for the repair and restoration work: mechanically cleaned from the products of corrosion and decay, washed with water under pressure;

- the surface of the reinforced section of the beam 1 is treated with an adhesive composition (primers, primers);

- if it is necessary to carry out repairs on the existing section of the reinforced beam 1, non-through holes (sockets) are drilled in it in a staggered manner, injection pipes are installed and the repair composition is pumped;

- mount (if necessary, their device) internal additional reinforcing elements 2. Previously, in the beam 1, it is possible to arrange the corresponding grooves;

- in the beam 1 and in the corresponding sections of the reinforcing corrugated sheets 3, drill holes for anchors 4 or through tie-bolts 5;

- using anchors 4 or through coupling bolts 5, metal corrugated sheets 3, previously coated with an anti-corrosion compound, are attached to the beam 1;

- arrange reinforcing elements 6 of the upper and lower zones, as well as end elements 7, if they are provided for by the amplification project;

- carry out the fastening of the corrugated sheets 3 to the elements 6 of the belts and the end elements 7, for example, using electric welding;

- in the cavity between the corrugated sheets 3 and the beam 1 is injected defect-removing solution 8, for example, through holes 9;

- if necessary, arrange additional external reinforcing elements;

- after hardening (a set of design strength, if provided) of the defect removal solution 8, a reinforced beam 1 is tested for the design load.

The listed sequence of stages of the invention may be changed based on specific conditions of use. As an option: first arrange the elements 6 of the upper and lower zones, then arrange the internal additional reinforcing elements 2, and only after that - reinforcing corrugated sheets 3 and end elements 7.

Features of the proposed method:

reinforcing corrugated sheets 3 in addition to the supporting function play the role of a fixed formwork for defect removal solution 8, which may have a bearing capacity, working in cramped conditions and, thereby, additionally strengthening the beam 1;

the viscosity of the defect removal solution 8 is prescribed taking into account the convenience of its injection, the characteristics of shrinkage and hardening, the set of required strength, penetration into the defective sections of the beam 1, and minimization of possible leaks through the leakage of adjacency of the elements. The listed circumstances can be mutually contradictory (such as viscosity from the condition of penetration into defective areas and from the condition of minimizing leaks), therefore, the optimal properties of solution 8 (as a compromise solution) are assigned according to the specific conditions of amplification and subsequent operation of beam 1, taking into account the known elimination techniques defects and reconstruction of dependencies;

residual welding forces from welding of the corrugated sheets 3 to the reinforcing elements of the belts 6 are compensated by the flexibility of the corrugated sheets 3 in the direction perpendicular to the corrugations and do not significantly affect the stress-strain state of the structure;

the temperature of the reinforced beam 1 should not be lower than + 5 ° C, because at lower temperatures, the appearance of additional internal forces, closing cracks, and difficult penetration of the defect removal solution 8. The temperature of beam 1 above + 40 ° C is undesirable, because in addition to the appearance of additional internal efforts, the conditions for the use of most known from the prior art flaw removal solutions 8 based on resins are violated.

Recommendations on loading modes of the reinforced beam 1 when implementing the proposed method:

- repair work, i.e. elimination of defects by injection into the channels of the repair composition previously drilled in the beam is recommended when the structure is loaded, because structural cracks are most revealed. Reinforcing elements (including elements 2, 3, 6, 7) are recommended to be mounted with unloaded beam 1, which is justified by their subsequent joint deformation and compression when an external load is applied. The injection of defect eliminating solution 8 into the cavities formed by corrugated sheets 3 and beam 1 is recommended to be carried out with a loaded structure, with the exception of defect eliminating solutions 8, which have a bearing capacity after hardening;

- injection of the defect eliminating solution 8 is carried out, as a rule, under a pressure of not more than 4 atm (0.4 MPa), while the places of the possible leakage of solution 8 to the outer parts of the structure can be treated with sealing compounds to prevent leaks.

The result of using the proposed method is a beam 1 reinforced at the supporting sections, capable of absorbing large loads compared to the initial state, having increased torsional rigidity, more stable, durable and protected from aggressive influences of a predominantly corrosive nature.

Claims (4)

1. A method of strengthening the supporting sections of the beams, including preparing the surface, treating it with an adhesive composition, carrying out repair work if necessary, characterized in that the reinforcement is carried out by attaching to the supporting sections of the beam at least on one side relative to the cross section of the corrugated beam metal sheets with constant parameters of corrugations or alternately corrugated metal sheets, the location of the corrugations can be transverse or inclined, in all or only some cavities, about razovannye between the corrugated sheets and the beam is injected or not injected defektoustranyayuschy solution. 2. The method of reinforcing the supporting sections of the beams according to claim 1, characterized in that on the supporting sections of the beams arrange additional internal and / or external reinforcing elements, the step and direction of which are coordinated with the step and direction of the corrugations of the metal sheets. 3. The method of strengthening the supporting sections of the beams according to claim 1 or 2, characterized in that a cement-sand mixture having bearing capacity after hardening is used as the injected defect eliminating solution. 4. The method of strengthening the supporting sections of the beams according to claim 1 or 2, characterized in that the beam is reinforced with waist and / or end elements.

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