EA010214B1 - A butt joint of composite reinforced concrete columns and a method of forming thereof - Google Patents

Abstract

The present invention relates to building and can be used in reinforced concrete frames of multistory buildings and constructions.A butt-joint of the composite columns (fig. 1) comprises the end parts of the columns 1 with main longitudinal reinforcement which rods 2 are torn at the ends. Transversal steel sheets are fixed at the flat butts of the joined columns. These sheets can be solid 3 along the whole butt of every column or as angular cast-in details or as double cast-in details. The anchor rods 9 overlapped the rods 2 of torn main reinforcement of the column are fixed to the end cast-in details in the conical apertures in the weld. Indirect reinforcement in the form of netting 10 is located in the zone of the anchoring of the rods 2 and 9. Angle niches 7 formed by corners 6 are made at the corners of the columns butts. Joined columns are connected at the corners in the niches 7 by the pins 14 with a screw thread by means of the fixing nuts 15, 16 and by the elevating nuts 17. Indirect reinforcement in the form of the one or several nets 18 and solid concrete are placed in a gap 8 between the butts.The method of the butt-joint forming includes fixing the pins 14 on the upper end of the lower column, screwing the elevating nuts 17 on the pins, placing the welded nets 18 above the lower column, leaning the upper column on the elevating nuts 17, placing the upper column to a designed position by the nuts 17 and subsequent fixing the position of the said column by means of the fixing nuts 16. After that falsework of the joint is built and reception and output bins are formed. Concreting the joint is made by one-way supplying the concrete mix to the reception bin under the influence of vibration until the gap between the butts, the angle niches and the output bin are filled by said mix. The concrete mix remained in the bins is detached from the joint and the trunks of the columns by the flat steel gate valve sheets dipped with vibration into the mix along the sides of the column. When concrete becomes solid enough, falsework is disassembled. Concreting the butt-joints is made for the group of the joints from the one batch of the concrete mix. The invention provides increasing reliability of the butt-joint of the composite columns, decreasing steel intensity and working hours for forming said butt-joints.

Description

The invention relates to the construction and can be used in the reinforced concrete frames of high-rise buildings and structures.

Known butt connection of columns with longitudinal working reinforcement torn off at the joint and flat ends, equipped with steel front plates, reinforcing rods, short rods placed in channels along broken working reinforcement, and including an interfacial gap filled with steel centering and peripheral liners, as well as high-strength mortar [1] .

The known joint provides an even distribution of the contact stresses in the joint and is distinguished by a rather high bearing capacity. However, it is difficult and time-consuming in production, it is metal-intensive, does not have sufficient technological reliability.

A butt joint is known, including end sections of columns with transverse steel sheets attached to the welding to the rods of the longitudinal reinforcement torn off at the ends of the columns, and a centering gasket. [2, p. 89; FIG. 3.10]. The joint is relatively simple in execution. The disadvantage of the joint is thermal welding deformations and stresses that occur in the joint elements when mounting the end plates to the reinforcement cage and reduce the reliability of the butt joint.

Closest to the proposed is a butt joint of columns [3], including steel sheets at the ends of the columns, secured by anchor rods arranged overlap parallel to the torn ends of the working reinforcement, niches at the ends of the columns, as well as studs with screw thread, fixed in the holes of steel sheets at the ends joined columns at the ends in the niches of both columns with nuts, in the gap between the end steel sheets there is a centering gasket and adjusting nuts, and the niches are cast with concrete.

Known joint has a high bearing capacity. The disadvantage of it is the high metal consumption, as well as the relatively small size of the interfacing gap, which causes difficulties in placing adjustment nuts in it and filling it with a cement-sand mortar.

A known method of performing a butt joint, including alternately installing on the same axis of abutting columns made with transverse steel sheets, attaching thereto a steel border along the contour and then filling the gap between the end steel sheets of abutting columns with a solution [4, FIG. 12, p. 27-29].

The known method is relatively simple in execution. However, the resulting joint is not sufficiently reliable, it is also not able to perceive the bending moments that occur under the load at the joint.

The closest to the present invention is a method for performing a joint [3], including alternately installing the lower and upper joined columns with flat ends on one axis, fixing the upper column in the design position with its attachment to the lower column with studs, fixing and adjusting nuts, as well as with a preliminary placement in the friction gap of the centering strip and the solution.

The known method provides a high rate of installation of columns. However, it is quite time-consuming and allows you to get reliable and high-strength joints on the screw connections, but at a sufficiently high metal content.

The main task, the solution of which the proposed technical solutions of the butt joint of precast concrete columns and the method of its implementation are directed, is to increase the reliability of the butt joints of the columns, to reduce the metal intensity of the joints and labor costs for their implementation.

The solution of this problem is achieved by the fact that the butt joint of precast reinforced concrete columns, including the end sections of the joined columns with transverse end steel sheets, provided with anchor rods rigidly connected with them, located at the ends parallel to the rods of the working reinforcement, the friction gap filled with concrete, and studs with screw cutting attached fastening and adjustment nuts to the front sheets of abutting columns in their corner niches formed by steel corners and caulked concrete m In concrete of the butt joint interfacing gap, indirect reinforcement is placed in the form of at least one reinforcing mesh with the formation of a monolithic reinforced concrete insert, transverse end sheets from the side of the interfacing gap are provided with rigidly attached to them along the contour with discrete bordering. Anchor rods are attached to the end sheets in the conical razsenkovanny holes from the side of the interfacing gap on the welding and placed along the perimeter of the cross-section of the columns in the alignments with the rods of their longitudinal reinforcement.

In the butt joint of prefabricated columns, the discrete bordering of the transverse end sheets from the side of the interfacing gap can be made in the form of steel prismatic or cylindrical rods welded to the end sheets in part of the length of their sides.

In the butt joint of prefabricated columns, at least one end steel sheet is made in the form of a solid plate.

In the butt joint of prefabricated columns, the transverse steel sheets at the ends of the joined columns can be made in the form of discrete embedded parts placed at the corners of the columns and rigidly interconnected in the plane of each end for welding with rebars.

- 1 010214

This technical result is achieved by the fact that the method of performing butt joints of columns includes alternately installing the lower and upper joined columns on the same vertical axis, fixing the upward-pointing studs with adjustment nuts on the end of the lower column, supporting the upper column on the quote nuts, installing these nuts into the design the position of the upper column, the fixing of its position by fastening nuts in the corner niches, and staking concrete with all the corner niches. At the same time, after placing the indirect reinforcement above the end of the lower column, they rest on the adjusting nuts to form an interfacing gap provided with indirect reinforcement, and fixing the upper column with fastening nuts in the lower corner niches is carried out immediately after it is installed in the design position with adjusting nuts. Then, on the two opposite side faces of the columns, shuttering shields are secured closely at the level of the inter-joint gap and corner niches, and on the other two faces of the columns, inclined boards are fixed at an angle to them, which together with the two previously installed shields, form receiving and output bins. After that, the supply bin begins to flow with the vibration of the concrete mixture until the interfacing gap, all corner niches and the output bin are completely filled, and then, in the receiving and output bins, vibrant metal sheets are shuttered under the influence of vibration, cutting off the concrete mix in both bunkers , and after the concrete has been installed with the required strength, the joint formwork is dismantled, and the cut-off remains of concrete are removed.

Comparison of the proposed technical solution with the prototype makes it possible to notice that it differs from the well-known new features: (I) indirect reinforcement in the form of at least one welded reinforcing mesh with the formation of a monolithic reinforced concrete insert is placed in the interfacing concrete; (2) the transverse face sheets on the side of the interfacing gap are provided with a discrete border rigidly attached to them along the contour; (3) anchor rods are rigidly attached to the end sheets in the conical razsenkovanny holes on the side of the firing gap on the welding; and (4) placed along the perimeter of the cross-section of the columns in the sections with dangling rods of their longitudinal reinforcement. At the same time (5) the discrete bordering of the transverse end sheets from the side of the interfacing gap is made in the form of steel cylindrical or prismatic rods welded to the end sheets in part of the length of their sides; (6) at least one end sheet in the butt joint is made in the form of a solid plate; (7) the transverse steel sheets at the ends of joined columns are made composite in the form of discrete embedded parts rigidly interconnected in the plane of each end face in welding with rebar.

The method for performing a butt joint includes the following sequence of operations: (9) the upper column, after placing the indirect reinforcement above the end of the lower column, is supported on the adjusting nuts; (10) after the upper column is installed by means of adjusting nuts in the design position, its position is immediately fixed by fastening nuts in the lower corner niches of the upper column with the formation of an interfacing gap provided with indirect reinforcement; then (11) on the two opposite side faces of the columns, shuttering shields are fastened closely at the level of the inter-joint gap and corner niches, and on the other two faces of the columns, inclined boards are fixed at an angle to them, which together with the two previously installed shields form receiving and output bunkers; after that (12), the flow into the receiving bunker starts the flow with the vibration of the concrete mixture until the interfacing gap, all corner niches and the output bin are completely filled; then (13) under the influence of vibration, metal plates slide into the receiving and output bunkers closely along the side faces of the columns, cutting off the concrete mix in both bunkers; and (14) after the concrete has reached the required strength, the joint formwork is dismantled and the cut-off residues of concrete are removed.

All of these features allow you to provide welded columns of increased reliability with high-precision placement of columns in the design position without the use of welding, traditional bulky mounting jigs and tooling, while reducing metal consumption and labor costs for its device.

All the listed features of the proposed technical solution in the above amount are unknown, and the achieved technical results on the proposed solution are superior to those known, allow you to completely solve the task and create a super-total result due to the mutual amplification of the effects of each of the listed features on each other.

The essence of the proposed technical solution is illustrated by drawings.

FIG. 1 shows the proposed joint connection of columns on the same vertical axis, side view;

in fig. 2 is the same, the cross-section A-A of the column in FIG. one;

in fig. 3 is the same cross section bb of the column in FIG. 1, the case of a solid face plate;

in fig. 4 is the same cross section bb of the column in FIG. 1, the case of composite plates in the form of discrete corner inserts at the ends of the columns;

in fig. 5 is the same section bb in FIG. 1 at the junction between the ends of the columns;

in fig. 6 - the design of discrete corner inserts of the column face is presented, isometric view;

in fig. 7 is a fragment of the construction of solid end sheets of columns placed at the junction in the

- 2,010,214 ect position, isometric view;

in fig. 8 - the case of composite plates in the form of paired embedded parts of the ends of joined columns, placed in the joint in the design position, isometric view;

in fig. 9 - the joint formwork is represented;

in fig. 10 is the same; the section G-D in FIG. 9, with the scheme of concrete supply to the joint.

The proposed joint connection of prefabricated columns (Fig. 1-10) includes end sections of columns 1 with longitudinal reinforcement, the rods 2 of which are anchored in concrete at the ends. At the ends of the joined columns 1 transverse steel sheets are placed. These sheets can be solid 3 around the end of the column 1, or composite in the form of discrete corner inserts 4, or in the form of paired embedded parts 5. In the corners to the end sheets 3, 4, 5 on the welding are attached vertical steel corners 6, forming the ends of the columns 1 are angular niches 7. To the same sheets in the tapered holes on the side of the interfacing gap 8, anchor rods are fixed on the welding: 9, located on the end sections of the columns parallel and overlapping to the rods 2 of the broken working armature of the columns. The rods 9 and 2 are located in the same alignment along the entire perimeter of the cross-section of the columns. In the area of their anchoring is placed indirect reinforcement in the form of welded meshes 10.

On the end sheets 3 along the perimeter from the side of the interfacing gap 8, a discrete bordering in the form of rods 11 is attached to the welding. Discrete angular end parts 4 in the plane of the end face of each column 1 are rigidly interconnected by perimeter bordering rods 11, as well as short rods 12. Paired mechanical embedded parts 5 are also joined by welding with the rods 11 of the border at the side faces of the ends of the column and rods 12. In addition, paired mechanical embedded parts 5 on the joined columns to ensure uniformity of stressed the features in the concrete of the joint are rotated relative to each other by 90 ° (see Fig. 8).

In the corner niches 7, the end sheets 3, 4, 5 contain through holes 13 for passing and fixing the ends of the studs 14 with a screw thread. The studs 14 are fixed on the end sheet in the niches 7 of the lower column with fastening nuts 15, and in the upper column they are fixed in its niches 7 with fastening nuts 16 and below with adjusting nuts 17. When assembling the butt joint, the upper column rests on the corners on these adjusting nuts 17 placed on the studs 14 in the interfacing gap 8. Between the ends of the columns 1 in the concrete interfacing gap 8, laid with strength control, indirect reinforcement is placed in the form of one or several welded meshes 18, forming a monolithic reinforced concrete insert, but adjacent to the ends of the two columns. The end steel sheets 3, 4 or 5 of both columns 1, provided with anchor rods 9, are joined in the joint 8 by vertical studs 14, passed through the holes 13 and fixed at the ends on these sheets 3, 4 or 5 by fastening nuts 15 and 16 in the corner niches of the columns . The required cross-sectional area of the anchor rods 9 is determined by calculation from the condition of exceeding the strength of the cross sections of the end sections of the columns above the strength of the sections of the stem of the column with the specified security parameters. Therefore, in any case, the calculation of the cross-sectional area of the anchor rods 9 should be at least 0.4 of the cross-sectional area of the rods 2 of the working reinforcement of the barrel string.

Thus, along the junction of 8 columns 1, the continuity of the longitudinal reinforcement is preserved, which ensures the perception not only of the longitudinal forces, but also together with the longitudinal forces of the bending moments by all sections of both the trunk of the columns and the joint.

The presence of indirect reinforcement in the form of welded meshes 10 and 18, as well as end plates 3, 4 and 5 with rods 11 bordering them allows to realize in the concrete end sections of columns 1 at the junction 8 and at the junction 8 a volumetric stress state and significantly increase the strength of the concrete sections in specified places. The presence of adjusting nuts 17 allows not only to ensure precise installation of columns 1 during installation, but also to eliminate the need for a centering gasket in the butt gap 8. As a result, a stress concentrator, which contributes to the longitudinal compression of the column loads, is eliminated at the joint. Moreover, the use of monolithic concrete in the butt gap 8 with indirect reinforcement with nets 18 significantly increased the operational reliability of the joint, because at the contacts of the monolithic concrete joint 8 with the ends of the joined prefabricated columns 1, there is inevitably tight junction without any local leaks, regardless of the possible distortions of the ends arising in the manufacture of precast concrete columns 1. This means that the danger of local collapse of concrete in the joint is eliminated and the full use of strength with properties of the materials of the column and the joint.

Thus, compared with the analogues [1, 2] and the prototype [3], in the specified joint of the columns, in the presence of the above signs, a new quality is obtained, which ensures an increase in the carrying capacity and reliability of the butt joint by creating a uniform stress state and eliminating probability of local damage to concrete on the contact surfaces. The design of the end sheets 4 and 5 provide with their use a significant reduction in metal consumption of the butt joint.

The proposed joint connection of prefabricated columns 1 is performed in the following sequence. First install and fix in the design position of the lower column. On its upper face sheet 3, 4 or 5 fastening nuts 15 fix the studs 14 pointing upwards. Above

- 3 010214 lower columns install welded meshes 18 of indirect reinforcement, adjusting nuts 17 are screwed onto studs 14 from the required mark. 17 Adjustment nuts 17 support lower end sheets 3, 4 or 5 of the upper column by passing studs 14 through openings 13 of these sheets. After installing the upper column in the desired design position by means of adjusting nuts 17, the upper column in the design position is fixed on the studs 14 with fastening nuts 16 in the corner niches 7. Then, on two side faces of the column butt 1, vertical formwork shields 20 are fastened with two screws On the other sides of the columns opposite to the junction, inclined boards of formwork 21 are fastened so that a receiving 22 and an output 23 bunkers are formed. The supply of concrete mix 24 is carried out under the influence of vibration generated by a deep vibrator 25, only on one side of the junction through the receiving bin 22 to completely fill the interfacing gap 8, all corner niches 7 and the output bin 23. Immediately after completing the concrete mix in the joint, along the side the faces of the columns in the bunkers 22 and 23 under the influence of vibration immerse metal sheets 26, cutting off the excess concrete mix from the joint 8 and the corner niches 7. After the concrete has been set in the firing gap 8 and the corner niches 7 required Ruggedness, formwork joint 20, the sheets 21 and 26 is dismantled, and the concrete residues excised from hoppers 22 and 23 are removed. Concreting of butt joints is performed for a group of joints from one batch of concrete mix.

Thus, in the present method, the proposed joint connection of columns is carried out without additional operations and rearrangements, as in the prototype [3], in one step at the minimum labor and energy costs. Completely eliminated the need for mounting jigs, in complex control and technological equipment. In general, the above method of making butt joints of columns complements the advantages of a constructive solution, ensures obtaining reliable, durable and high-precision butt joints of columns, technological reliability and high rate of construction with its use. Butt joint does not require welding work at the construction site, practically does not depend on weather conditions, since local heating of the end sections of the columns at the joint and thermally insulated formwork provide, as shown by experimental use, high-quality laying of concrete mix and at negative air temperature. In addition, non-heating technologies based on the use of polymer concretes can also be applied at negative temperatures.

The proposed technical solution represents a new developing direction in the design of multi-storey frame buildings for mass use, in which, along with increased safety and reliability, a high rate of construction is ensured.

Information sources

1. RF patent №2233368, Cl. E 04B 1/38, BI No. 21, 07.27.04

2. Dykhovichny Yu.A., Maksimenko V.A. Precast reinforced concrete unified frame. Experience of Moscow construction. Design, manufacture, installation, development prospects. M .: stroiizdat, 1985, 296, ill.

3. RF patent number 2244789, Cl. E 04C 3/34, E 04B 1/38, BI No. 2, 01.20.05

4. VNIIIS Gosstroy USSR. Series 8. Building structures. Survey information. Joints of reinforced concrete elements of frames of multi-storey buildings. Matkov N.G. Overview. M .: VNIIIS, 1982, 95 s, ill. (Fig. 12, p. 27-29)

Claims (5)

1. The butt joint of precast concrete columns, including the end sections of the joined columns with transverse end steel sheets equipped with anchor rods rigidly connected to them, located at the ends of the columns parallel to the longitudinal reinforcement rods, the end-to-end gap filled with concrete, and screw threaded rods attached with fasteners and adjusting nuts to the transverse end sheets of the joined columns in their corner niches, formed by steel corners rigidly attached to the end sheets for welding and embossed with concrete, characterized in that indirect reinforcement is placed in the concrete of the end-to-end gap in the form of at least one welded reinforcing mesh with the formation of a monolithic reinforced concrete insert, the transverse end sheets from the side of the end-to-end gap are provided with discrete bordering rigidly attached to them along the contour, anchor rods rigidly attached to the end sheets in conical countersink holes from the side of the inter-face gap in welding and placed along the perimeter of the cross-section of the columns ah with the rods of the longitudinal reinforcement. 2. The butt joint of prefabricated columns according to claim 1, characterized in that the discrete bordering of the transverse end sheets is made in the form of steel cylindrical or prismatic rods welded from the end to end faces to the end sheets on a part of the length of their sides. 3. The butt joint of prefabricated columns according to any one of claims 1 or 2, characterized in that at least one end steel sheet is made in the form of a solid plate. 4. The butt joint of prefabricated columns according to any one of claims 1 or 2, characterized in that the transverse steel sheets at the ends of the joined columns are made composite in the form of discrete embedded - 4 010214 parts rigidly interconnected in the plane of each end face for welding by reinforcing bordering beams. 5. A method of making a butt connection of columns according to any one of claims 1 to 4, including alternately installing the lower and upper abutting columns on the same vertical axis, securing the studs with adjustment nuts directed upward on the end of the lower column, supporting the upper column on the adjustment nuts and installing it by means of these nuts in the design position, fixing the position of the upper column with fixing nuts in the corner niches and caulking with concrete all the corner niches, characterized in that the upper column after placing the lower The indirect fittings are supported on alignment nuts with the formation of an end-to-end gap provided with indirect reinforcement, and the upper column is fixed with fixing nuts in the lower corner niches immediately after its installation in the design position by the adjustment nuts, then on the two opposite side faces of the columns closely at the level of the inter-gap and vertical formwork panels are fixed to the corner niches, and on two other faces of the columns at an angle to them, inclined panels are fixed, forming together with two wounds with installed shields, the receiving and output bunkers, after which they start feeding concrete with vibration until the end gap is completely filled, all corner niches and the output bunker are completely filled, then metal sheets are immersed in the receiving and output bunkers along the side faces of the columns under the influence of vibration - the gates that cut off the concrete mixture in both hoppers, and after the concrete has set the required strength, the joint formwork is removed, and the cut off concrete remains are removed.