SU964087A1 - Ferroconcrete column - Google Patents

Description

(54) CONCRETE COLUMN

one

The invention relates to the construction, in particular to prefabricated frame construction of multi-storey buildings of public and industrial use.

Reinforced concrete columns with stretched concrete are known, containing precompressed longitudinal reinforcement bars of high strength steel 1.

In this case, the carrying capacity of the known columns is increased to 10-12 / o in comparison with similar columns with conventional non-stressed reinforcement. However, in this case, the crack resistance and stability of the column is reduced.

Closest to the present invention is a reinforced concrete column comprising a concrete body, compressed and expanded reinforcing elements of high-strength steel, in which the expanded reinforcing elements are connected to the compressed reinforcing elements by means of loops 2.

In this case, part of the reinforcing elements are pre-compressed, after the concrete is hardened, the other part is stretched. In this case, the strength increases, however, the stability of the column decreases as compared to the column with conventional non-stressed reinforcement, and the crack resistance of the multi-level jointless columns in the transport stage is insufficient.

The concrete body is thus stretched.

The purpose of the invention is to increase the strength, crack resistance and stability of the columns.

The goal is achieved by the fact that in a reinforced concrete column comprising a concrete body, squeezed and stretched reinforcing elements of high-strength steel, the force in the stretched reinforcing elements exceeds the force of the in-compressed reinforcing elements, while the concrete body is compressed.

Stretch and compression reinforcements in the reinforcement are created, respectively, by pre-compression and tension before the concrete begins to harden.

FIG. 1 shows a reinforced concrete column; in fig. 2 - the same section.

Claims (2)

The reinforced concrete column is a concrete body 1 reinforced with high-strength steel elements, with the elements 2 being compressed and the elements 3 stretched. Elements 2 and 3 are attached by wire twists 4 from in the filling wire to the frame 5, which consists of longitudinal elements 2 and transverse rods 6. The latter are made with releases so that they rest against the walls and bottom of the formwork 7 and the thrust plates 8, which fixed to the side walls of the mold. This ensures the stability of the frame during its preliminary compression. Steel plates 9 are fastened to both ends of the framework, in which holes are provided for the passage of longitudinal elements. The rods 2 are secured in the plates 9 with screws 10. The fastening of the carcass to the plates 9 with screws 10 allows pre-compression of the rods 2 even in case of deviations of the rod lengths from the designed dimensions. Longitudinal pre-stretched reinforcement 3 of high-strength rod steel or ropes may be located symmetrically or asymmetrically across the column section (if uneven compression of the concrete body is necessary). The pre-compression of the rods 2 by the force of the NOC is carried out using a hydraulic jack. The reactive force after the end of the compression and removal of the jack is transmitted to the supports of the stand or to the force formwork. The prestretching of the reinforcement 3 is also performed by a jack with the transfer of the reactive force Nop to the stops. After the concrete has been concreted and reinforced with concrete of sufficient strength, prestretched reinforcement 3 is first released, which leads to compression of the concrete and additional compression of the longitudinal rods 2. Then the rods 2 are released from the retaining devices, and the stress will cause tensile stresses in the concrete compressive stresses from force Nop. The total stresses in the concrete are compressive stresses. Consider a column with a section of 30x30 cm. Armature 2 consists of four rods with a diameter of 22 mm of steel of class АV (area of rods RAS 15), valve 3 is of two rods with a diameter of 25 mm of steel of class АV. The preliminary compression of reinforcement was 246 MPa, the preliminary stretching of the op was 760 MPa. The precompression force NOC is 373.9 kN, and the prestress force Nop is 746.3 kN. The grade of concrete is M 300, the transfer strength is equal to the grade. The total compressive stress, eg, after tempering the entire reinforcement, is 3.5 MPw in concrete, in reinforcement 2 — Ra.o + b + n 400 + 24b + 6, .55-3; 5,669 MPa, in reinforcement 3 (taking into account losses prestressing boron 736.7 MPa. Critical force at t fo / h 0, l and at non-stressed reinforcement () NKP 58211.6 A, where A is 6.4Eg- / 1a. If there is only pre-compressed reinforcement in the column, the value There is no reduction because concrete is stretched (Cc) If there are precompressed and pre-stretched reinforcement in the column, Nopos (as in the invention), Kn 1.82 (with uniform reduction of concrete) and NKP 67784.7 A. Thus, the ultimate compressive stress in reinforcement 2 is increased by 67%, which makes it possible to increase the strength of the column. Compressing concrete with stretched reinforcement 3 increases the stability of the column. Compared with a column having a conventional non-compressible reinforcement, the critical force has increased by more than by 16%, Compared with a column that has only pre-compressed reinforcement, this difference is even greater. The column crack resistance also increases. The solution proposed for the columns of medium flexibility (C / h 10-20) most frequently encountered in construction practice leads to a simultaneous increase in bearing capacity, crack resistance and stability. The invention includes a reinforced concrete column comprising a concrete body, compressed and stretched reinforcing elements made of high strength steel, characterized in that, in order to increase strength, crack resistance and stability, the force in the stretched reinforcing elements exceeds the force in the compressed reinforcing elements, while the concrete body is compressed. Sources of information taken into account in the examination 1. Mailn R.L., Medynsky V.L. Resistance to compression of reinforced concrete elements with pre-stretched concrete. - “Izv. Higher studies, institutions. Building and Architecture, 1980, № 6, p. 26-30. 2. USSR author's certificate in application number 2800703 / 29-33, cl. E 04 C 3/34 06.24.1979 (prototype).