RU2569524C1 - Perforated beam - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: perforated beam is made of rolled double-tee shape, cut along the axis of the wall with certain contour for each half of the beam and welded by protruding parts of the produced halves so that holes in the form of an ellipse are produced. Elliptical holes have different angle of inclination of the main axis of the ellipse to the axis of the beam. The central elliptical hole with its main axis is arranged perpendicular to the longitudinal axis of the beam, and others - at the angle of 45 degrees symmetrically relative to the centre of the beam. Elliptical openings may have the angle of inclination smoothly changing from 90 degrees in the centre of the beam to 45 degrees in support sections symmetrically to the centre of the beam.

EFFECT: reduced concentration of stresses in a wall of perforated beams, which results in increased reliability and durability of structures.

3 cl, 9 dwg, 1 tbl

Description

The invention relates to the field of construction and can be used to cover large spans.

Known designs of beams with hexagonal wall perforation, obtained by cutting the wall of a rolling I-beam along a zigzag broken line with a regular step and then welding both halves in combined wall protrusions (patent RU 16176, IPC E04C 3/08, 3/10, published 10.12. 2000; patent RU 2154717, IPC E04C 3/08, published on 08.20.2000; SNiP II-2-81. Steel structures. Beams with perforated wall, p. 54). At the same time, the height of the beam increases, the material of the section is redistributed, the relative area of the belts increases. The disadvantage of this solution is a complex stress-strain state due to stress concentration in the corners of the holes closer to the belts.

A technical solution is also known (patent EP 0324206 A1, IPC E04C 3/08, author Walker, Peter Allan. UK Patent Application GB 2492176 A), in which perforated beams are made from a rolled beam cut along the wall and welded from the halves obtained. The first continuous section is made along the beam wall, the second section is along the beam wall along a path different from the path of the first section. Sections outline rectilinear sections lying on opposite sides of the center line of the wall, and curved sections connecting the nearest ends of adjacent rectilinear sections. The centers of all straight sections are evenly distributed along the length of the beam at a given distance. Curved sections can be in the form of a semicircle or semi-ellipse. The cut halves of the beam are welded to each other in the areas formed by comparing the straight sections of the two halves. Perforated beams can be made with curved holes, round, elliptical.

This technical solution was made as a prototype as the closest both in essence and in the composition of the elements.

The disadvantage of this solution is the complex stress-strain state of the wall with holes in the form of a circle and an ellipse (with a vertical and horizontal main axis), expressed in an increased concentration of stresses in the wall at the boundaries of the holes, which can lead to fluidity of the material or premature destruction of the beam.

The technical result consists in reducing the stress concentration in the wall of perforated beams, which leads to increased reliability and durability of structures.

The technical result is achieved in that in a known perforated beam made of a rolled I-beam profile, cut along the axis of the wall with a certain outline for each half of the beam and welded by the protruding parts of the formed halves so as to obtain holes in the form of an ellipse. A distinctive feature is that the elliptical holes have different angles of inclination of the main axis of the ellipse to the axis of the beam. The central elliptical hole with the main axis is perpendicular to the longitudinal axis of the beam, and the rest are at an angle of 45 degrees symmetrical relative to the center of the beam, or the elliptical holes have an angle of inclination that varies smoothly from 90 degrees in the center of the beam to 45 degrees in the supporting sections symmetrically relative to the center of the beam. At the same time, stress concentrations are reduced, which leads to an increase in the operational reliability and durability of the structure.

The proposed technical solution is illustrated by drawings. In FIG. 1 shows the wall of a beam with elliptical perforation with the inclination of the main axes of the elliptical holes at an angle of 45 degrees to the axis of the wall, the main axis of the hole located in the middle of the length of the beam being oriented vertically. Here a is the upper part of the beam wall, b is the lower part of the beam wall, c is an elliptical hole, d is the welding section.

In FIG. 2 shows the cut lines of the rolling I-beam profile necessary for the manufacture of a perforated beam, where a is the upper part of the wall of the beam, b is the lower part of the wall of the beam.

In FIG. Figure 3 shows a beam with elliptical perforation with a variable inclination of the main axes of the elliptical holes to the axis of the wall, where a is the upper part of the wall of the beam, b is the lower part of the wall of the beam, c is an elliptical hole, d is the welding section. The inclination of the holes varies from 45 degrees near the beam support with a gradual increase to 90 degrees in the middle of the beam.

In FIG. 4 shows a sectional diagram of a rolling I-beam profile, which makes it possible to obtain holes with a variable inclination of the main axes to the longitudinal axis of the beam, where a is the upper part of the wall of the beam, b is the lower part of the wall of the beam.

The stress-strain state of the beam wall with round and elliptical holes of various orientations was calculated using the LIRA-9.6 software package. The calculation results in the form of voltage isopoles are presented in FIG. 5-9.

Here:

In FIG. 5 shows an isopole of reduced stresses in a wall with round holes;

in FIG. 6 - isopole of reduced stresses in the wall with holes in the form of an ellipse with a vertically oriented main axis;

in FIG. 7 - isopole of reduced stresses in the wall with holes in the form of an ellipse with a horizontally oriented main axis;

in FIG. 8 - isopole of reduced stresses in the wall with holes in the form of an ellipse with the main axes oriented at an angle of 45 degrees to the axis of the beam;

in FIG. 9 - isopole of reduced stresses in the wall with holes in the form of an ellipse with the main axes having a variable inclination of the main axes, varying from 90 degrees to the longitudinal axis of the beam to 45 degrees in the reference zone.

On all diagrams, compression is indicated in blue, and extension in brown. The color intensity corresponds to the magnitude of the voltage. The numbers indicate the points at which the voltages are determined. The stress values at these points are shown in table 1.

A detailed analysis of the stress-strain state of the wall of the perforated beam shows a decrease in the magnitude and concentration of stresses when using perforation holes in the form of ellipses with an inclination of their main axis.

As can be seen from the above table, the proposed shape of the holes in the wall in the form of ellipses with an inclination of the main axis to the axis of the beam equal to 45 degrees symmetrically located relative to the center, as well as with a variable inclination of the main axes of the elliptical holes shown in Figs. 8 and 9, they reduce stress at these points by an average of 10 percent.

The proposed perforated beam, made in the described manner, allows to reduce the weight of the finished structure and reduce stress concentration in the wall. This leads to increased reliability and durability of the structure.

Claims (3)

1. A perforated beam made of a rolled I-profile, cut along the axis of the wall with a certain shape for each half of the beam and welded by the protruding parts of the formed halves so as to obtain holes in the form of an ellipse, characterized in that the elliptical holes have different angles of inclination of the main axis of the ellipse to the axis of the beam. 2. The perforated beam according to claim 1, characterized in that the central elliptical hole with the main axis is perpendicular to the longitudinal axis of the beam, and the others are symmetrically relative to the center of the beam at an angle of 45 degrees. 3. The perforated beam according to claim 1, characterized in that the elliptical holes have an angle of inclination that varies smoothly from 90 degrees in the center of the beam to 45 degrees in the supporting sections symmetrically relative to the center of the beam.

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