RU2662475C1 - Combined two-pivot system with rigid thread from rolling profiles - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention relates to construction, namely to combined two-belt system with a rigid filament from rolling profiles, and can be used in construction of buildings for various purposes: trade and warehouse buildings, land parking lots, industrial buildings. Essence of the proposed invention lies in the fact that a combined two-belt system with a rigid filament from the rolling profiles includes an upper belt in the form of a triangular arch, lower belt in the form of a rigid thread (reverse arch) of a broken outline and a lattice consisting of columns and V-shaped braces in the middle spans. Difference of claimed invention consists in that the upper belt is made gable with a slope providing the required roof slope, the arrow of the sash of the lower belt is assumed to be equal to 1/10…1/12 span, nodes of the lower belt are located along a parabolic curve. Step count is assigned to the step of the runs. Lattice and belt connections are hinged.

EFFECT: new technical solution is aimed at creating combined two-pivot system with a rigid filament from rolling profiles with a reduced material capacity with increasing bearing capacity and span of the structure, with a gable upper belt.

1 cl, 1 dwg

Description

The invention relates to the field of construction, namely to a combined two-belt system with a rigid thread from rolling profiles, and can be used in the construction of buildings for various purposes: retail and warehouse buildings, ground parking lots, industrial buildings.

Known beam-truss system, including the upper belt in the form of a rigid beam of constant cross-section, the lower belt of the broken-line truss and lattice, consisting of racks and V-braces in two middle panels (Y. Brudka, M. Lubinski / Light steel structures / Ed 2nd, additional translation from Polish Edited by S. S. Karmilov, Moscow: Stroyizdat, 1974, p. 342, Fig. 9-40, b).

The disadvantages of this technical solution is the large consumption of materials, limited bearing capacity and span of structures when using rolling profiles. The forces between the belts are distributed unevenly - the main part of the load is perceived by the upper belt, the predominant force in the belt is bending, with slight compression in the lower belt there are slight tensile forces. In addition, the rectilinear upper belt does not provide the required slope of the roof.

Also known is a combined two-belt system, including two belts curved towards each other, interconnected by vertical braces. Belts are made of cables, struts - of pipes. The upper belt is stabilizing, the lower one is bearing (Moskalev N.S. / Designs of hanging coatings. - M.: Stroyizdat, 1980, p. 231, Fig. 94).

The disadvantages of this technical solution is the need for a support circuit for the perception of the thrust force; high deformability (especially with unilateral load); curved upper belt is inconvenient for roofing.

The closest technical solution to the claimed invention is a rod-truss run, comprising an upper belt of two spaced angles, a lower parabolic belt of a round steel rod, a lattice of round steel bars and V-shaped braces located in two middle panels (Podlip A. A. / Steel bar construction of coatings. - M.: State Publishing House of Literature on Construction and Architecture, 1954, p. 146, Fig. 6).

The disadvantages of this technical solution are the small overlapping span, large deformability, low lateral stiffness, low bearing capacity.

The new technical solution is aimed at creating a non-discontinuous combined two-belt system with a rigid thread from rolling profiles with reduced material consumption while increasing the bearing capacity and span of the structure, with a gable upper belt.

The essence of the invention lies in the fact that the combined two-belt system with a rigid thread from rolling profiles, including the upper belt in the form of a triangular arch; the lower belt in the form of a rigid thread (back arch) of a broken outline and a lattice consisting of uprights and V-shaped braces in the middle spans, characterized in that the upper belt is gable with a slope providing the required roof pitch; the arrow of the sag of the lower belt is taken equal to 1/10 ... 1/12 of the span, the nodes of the lower belt are located along a parabolic curve. The step of the racks is set equal to the step of the runs. Joints of lattice and belts are hinged.

The invention is illustrated by drawings, where: 1 is a structural diagram of a combined two-belt system with a rigid thread from rolling profiles.

The combined two-belt system with a rigid thread from rolling profiles consists of an upper belt 1, a lower belt 2, racks 3, braces 4.

The constructive design solution was based on the following assumptions about static work from the load on the upper belt.

The upper belt in the form of a gently sloping arch of triangular shape on resiliently resistant struts converts part of the load into an axial compressive force, which transfers to the supports.

The other part of the load, through the struts connecting the belts, is transferred to the lower belt, where it is converted into axial tensile force.

On the supports, the belts are combined into common nodes. These nodes will be in equilibrium, since the projection of the forces in the belts on the horizontal axis "X" will be zero:

,

,

where N _in - strut in the upper zone;

N _n - strut in the lower belt.

Under the action of axial forces, the belts will deform - the upper belt will be shortened by ΔS _in , and the lower belt will be extended by ΔS _n . The magnitude of the shortening of the upper belt is:

where N _in - axial force in the upper zone;

S _in - the length of the upper belt;

And _in - the cross-sectional area of the upper belt;

E _in - the coefficient of proportionality of the material of the upper belt.

The magnitude of the elongation of the lower belt is equal to:

where N _n is the axial force in the lower zone;

S _n - the length of the lower belt;

And _n is the cross-sectional area of the lower zone;

E _n - the coefficient of proportionality of the material of the lower zone.

Since the upper belt serves as a brace for the lower belt, and the lower belt as a brace for the upper, the support nodes will move along the horizontal axis “X” until it satisfies condition (*).

For the bending state of a combined two-belt system with a rigid thread from rolled profiles, two conditions must be met:

1. Both belts should be parabolas;

2. The relationship between the arrows of the belts (f _in , f _n ) and their loads (q _in , q _n ) must satisfy the formula:

Since the first condition is not met, then in the belts there will be moments corresponding to their bending stiffnesses. Since the sizes of the belts are small in comparison with the arrows of the sag, the bending moments in them will be insignificant.

Thus, axial forces predominate in the belts of a combined two-belt system with a rigid thread from rolled profiles, therefore, the stress-strain state of the structure is more favorable than the stress-strain state of the beam-truss system with a bent upper belt. The span of the structure can be increased to 36 m with a decrease in material consumption by 20-30%. Gable top belt provides the required slope of the roof.

Claims (1)

Combined two-belt system with a rigid thread from rolling profiles, including a top belt in the form of a triangular arch, a lower belt in the form of a rigid thread (back arch) of a broken outline and a lattice consisting of racks and V-braces in the middle spans, characterized in that the upper the belt is gable with a slope that provides the required roof slope, the arrow of the sag of the lower belt is assumed to be 1/10 ... 1/12 of the span, the nodes of the lower belt are located along a parabolic curve, the step of the racks is assigned equal to the run pitch, and the joints p Echetki and belts are hinged.

Images