SU1761897A1 - Prestressed metal-wood girder and method of prestressing it - Google Patents

Abstract

Usage: reinforcement beamed floors of buildings during their reconstruction. SUMMARY OF THE INVENTION: A pre-stressed metal-beam includes a glued package of planks, a metal reinforcing element and end stops. The beam is equipped with metal anchors and connections placed symmetrically over the span of the beam with the same pitch, and each stop is made in the form of paired plates installed vertically and parallel to each other, connected to the anchors and covering the reinforcing element fixed to them with their ends. The connections are fixed by one ends to the reinforcing element, and the other ends are embedded in a glued package of boards. The method of prestressing a metal beam includes setting the reinforcing element, fixing it to the end stops, and stressing the reinforcing element to remove the bending of the beam. Simultaneously with the bending of the beam, the reinforcing element is additionally strained. 2 sec. f-ly, 4 ill. cl

Description

The invention relates to the field of construction and is intended to strengthen the ceiling slabs of buildings during their reconstruction.

A prestressed wooden beam is known, including a glued package of planks, stops and prestressed reinforcement.

The disadvantages of this design are the stops, which are metal-intensive and heavy, and increase the risk of the beam breaking from spalling.

The closest technical solution to the invention is a prestressed wooden beam, including a wooden element, a metal reinforcing element, stops at both ends of the beam.

The disadvantage of this design is the method of sealing the pair of lugs in the package. The location of the latter, perpendicular to the longitudinal axis of the beam, assumes to be treated as ordinary dowels, and, therefore, possessing significant for statically

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uncertain system of compliance, leading to a redistribution of forces in the system and negating the effect of prestressing. The disadvantage is also that the reinforcing element is located in the stretched zone of the beam, which creates difficulties in the production of the floor structure and worsens the interior of the room.

There is a known method of prestressing a beam, including setting the tightening, its stress and bending of the beam against the tightening stress.

The disadvantage of the known method is the great laboriousness of pulling the tension, which requires complicated additional devices.

The closest to the invention to the technical essence is a method that includes pre-bending the beam, setting the tie, fixing it on the compressed face of the beam and pre-stressing by removing the pre-bending force from the beam.

The disadvantage of this method is the great complexity and low efficiency.

The aim of the invention is to increase the carrying capacity during the reconstruction of the beam and reduce the labor intensity of the prestress during the reconstruction of the beam with a deflection higher than allowed.

FIG. 1 shows a prestressed metal-beam, a little reconstruction, general view; in fig. 2 is a view A-A in FIG. one; in fig. 3 - metal-beam with mounting accessories before reconstruction; in fig. 4 - metal-wooden beam with mounting accessories after elimination of the beam deflection.

The prestressed metal beam includes wood element 1, reinforcing element 2, stops 3, metal anchors 4, links 5. Reinforcing element, stops and links are placed on the compressed edge of the beam. The stops are made in the form of pair-parallel vertical plates connected to the anchors 4. The distance between the ends of the plates of the stops 3 that are extreme to the beam supports 1 must be less than or equal to the length of the reinforcing element 1 before the prestress without the absolute value of the deformations of the wood 1 and metal - chesky reinforcing 2 prestressing elements. The reinforcing element 2 is placed between the plates of the stops 3 and fixed to them in welding, and secured to the wooden element 1 by links 5.

In the manufacture of the beam, the stops 3 are placed on the compressed face of the wood element 1 and fixed to the anchors 4. Then the reinforcing element 2 is placed between the plates of each stop 3 and fixed with one link 5 in the middle of the beam span. The mounting traverse b is installed at both ends of the wood of element 1 on its upper face with an emphasis on the ends of element 2. The mounting spire gel is installed with one stand 7 and flexible spans 8. The stand has a screw jack 9. The top end of the stand 7 is abutted to the bottom face of the tree of the element 1, the extensions 8 are fastened to the lower end of the stand 7. The other end of each stretch 8 is fixed on the crossbar 6. The stand 7 is moved apart by means of the screw jack 9, and the crossbars 6 move the extensions 8, while the cross bars 6 compress reinforcing element t 2, prednapr hectares of its compression. After prestressing, the reinforcing element 2 is fastened by welding to the stops 3 and connections 5 in the span of the beam to the wooden element 2.

Claims (2)

The effect of this technical solution is manifested in the practice of reconstruction of buildings and structures, when reinforcement of wood bending elements is required in order to increase their strength and rigidity, but access to which from the bottom is difficult or unacceptable to reinforce the lower edge from a technological or aesthetic point of view. In such cases, the amplification of the top of the compressed zone, having a reinforcing element on the upper face of the element. When reinforcing the ceiling beams, this solution allows covering the reinforcing element in the thickness of the ceiling (by the height of the lag). It is known that when reinforcing bending elements, two basic tasks have to be solved from a constructive point of view: ensuring that the connection between the reinforcing and reinforcing elements is small enough to allow them to work together, to make the reinforcing element as fully as possible when loading the operational load. The first task is solved by using V-glued anchors as reinforcements for the reinforcing element, which, as confirmed experimentally, have high shear stiffness. The solution of the second problem is achieved by prestressing the reinforcing element, the prestressing method being a combination of two main known prestressing methods; preloading in the opposite direction and mechanical prestressing of the reinforcement, but performed simultaneously by a single process using a special sprengel. Claim 1. Pre-stressed metal girder, including a glued package of planks, a metal reinforcing element and end stops, characterized in that, in order to increase the bearing capacity during the reconstruction of the beam, it is equipped with metal anchors and connections placed symmetrically span of the beam with the same pitch, each stop is made in the form of paired plates installed vertically and parallel to each other, connected to the anchors and covering the reinforcing 0 five the element attached to it with its ends, the connection is fixed with one ends to the reinforcing element, and with the other ends embedded in a glued package of boards. 2. A method of preliminary, stressing a metal beam, including setting up a reinforcing element, fixing it to the end stops, and stressing the reinforcing element by removing the bend of the beam, characterized in that, in order to reduce the labor intensity of the prestress when reconstructing the beam with a deflection higher than allowed , simultaneously with the bending of the beam, the reinforcing element is additionally strained. FIG. one . 2 J PL - 5 five J