Device for improving bearing capacity of column embracing beam and construction method

Abstract

The invention relates to the technical field of engineering structure transformation and reinforcement, and discloses a device for improving the bearing capacity of a column embracing beam, the device comprises a column to be reinforced and the column embracing beam, a plurality of finish rolling deformed steel bars are arranged in the column embracing beam, and the outer ends of the finish rolling deformed steel bars penetrate through the extending end of a combined steel beam to be in threaded connection with high-strength nuts; a base plate is clamped between the high-strength nut and the combined steel beam; the combined steel beam is arranged outside the column embracing beam in a sleeving mode, pre-compressive stress is applied to the newly-added column embracing beam through the combined steel beam, the finish rolling deformed steel bar and the like, tensile stress caused by external loads can be counteracted, cracks can be delayed or even avoided, meanwhile, component deformation can be reduced, the overall rigidity can be improved, and therefore the shear bearing capacity of the newly-added column embracing beam is improved. And after the pre-compressive stress is applied, the combined steel beams are welded, so that the combined steel beams form a closed profile steel hoop, and the compressive strength and ductility of the newly-added column-embracing beam are improved by restraining transverse deformation of concrete, so that the shear bearing capacity of the column-embracing beam is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of engineering structure reconstruction and reinforcement, and in particular to a device and a construction method for improving the bearing capacity of a column beam. Background Art

[0002] Due to design and construction defects, daily physical, chemical and biological damage, etc., the original structural columns need to be replaced, and "column-supporting beams" are a commonly used technical means in beam-supporting column replacement projects. Figure 7 As shown, when the original structural columns 90 of the Nth floor need to be replaced, column beams 2 are added to the columns 1 to be reinforced on the N+1 and N-1 floors, and then steel supports 91 are set up on the column beams on the N-1 floor. A jack 92 and an axial force meter 93 are set between the top of the steel support 91 and the column beams on the N+1 floor, and then the jacks are loaded to remove stress from the original structural columns 90 of the Nth floor, and then the replacement work is carried out.

[0003] In the housing construction underpinning project, in order to improve the safety during construction, the commonly used methods to solve the vertical underpinning load on the column beam are: 1. Add temporary steel supports to reduce the load on the columns to be replaced. Specifically, install pre-tensioned supports with large-diameter steel pipe jacks at the mid-span of the beam, halfway outward from the intended column. If the underlying ground is backfilled with rock and soil, the bearing capacity of the foundation is limited, and a maximum of two layers of steel supports may be required. The disadvantages of this method are that it requires a large investment of manpower, materials, and machinery, and the bearing capacity of the foundation must be considered.

[0004] 2. Reduce the load on individual steel supports within the column-beam support system. Specifically, the number of large-diameter steel pipe supports within the typical column-beam support system was increased from four to eight. This method has the disadvantage of requiring a large number of steel pipes, jacks, and axial force gauges. The additional steel pipes also cramp and congest the construction space near the columns to be replaced.

[0005] 3. Increase the height of the column beam. The disadvantages of this method are: the column beam is limited by the indoor net height. Moreover, the column beam is a temporary component with a large cross-section, which increases the workload for static removal and transportation in the later stage.

[0006] 4. Add shear reinforcement. The disadvantage of this method is that, according to standard formulas, shear reinforcement can only account for about a quarter of the shear resistance of the new and old concrete, so adding more is useless. Furthermore, too much planting will damage the original structure. Summary of the Invention

[0007] The purpose of the present invention is to provide a construction method for adding steel beams to an existing frame structure. By applying pre-compressive stress to the newly added column beams through combined steel beams, precision-rolled threaded steel bars, etc., the tensile stress caused by external loads can be offset, and the generation of cracks can be delayed or even avoided. At the same time, the deformation of the components can be reduced, and the overall stiffness can be improved, thereby improving the shear bearing capacity of the newly added column beams. After the pre-compressive stress is applied, the combined steel beams are welded to form the combined steel beams into closed steel hoops. By restraining the lateral deformation of the concrete, the compressive strength and ductility of the newly added column beams are improved, thereby significantly improving the bearing capacity of the newly added column beams.

[0008] The above technical objectives of the present invention are achieved through the following technical solutions: A device for improving the bearing capacity of a column-embracing beam comprises a column to be reinforced and a column-embracing beam arranged on the column to be reinforced, wherein a plurality of fine-rolled threaded steel bars are arranged in the column-embracing beam, the outer ends of the plurality of fine-rolled threaded steel bars pass through the protruding ends of the composite steel beam and are screwed with high-strength nuts, and a pad is sandwiched between the high-strength nuts and the composite steel beam; The combined steel beam is sleeved outside the column beam.

[0009] Through the above technical solution, the high-strength nuts are tightened, and the high-strength nuts drive the composite steel beams inward through the pads, and pre-compression stress is applied to the column beams through the composite steel beams, so that the column beams and the columns to be reinforced are "held" tighter, and the connection between the column beams and the columns to be reinforced is tighter and more stable, which can offset the tensile stress caused by external loads, delay or even avoid the occurrence of cracks, and at the same time reduce the deformation of the column beams, improve the overall stiffness of the column beams, thereby improving the shear bearing capacity of the column beams themselves and the shear bearing capacity between the column beams and the columns to be reinforced.

[0010] The device is further configured such that a steel adhesive layer is filled between the combined steel beam and the column beam.

[0011] By setting up a steel adhesive layer, the force transmission between the composite steel beam and the column beam can be made more uniform and timely, thereby improving the loading effect of the prestressing stress.

[0012] The device is further configured as follows: the combined steel beam includes two channel steel ring beams arranged back to back, the two channel steel ring beams are fixedly connected by a plurality of connecting plates, and the arrangement of the two channel steel ring beams can enable the pre-compression stress to meet greater requirements.

[0013] A plurality of evenly distributed stiffening plates are fixed in the channel steel notches of the channel steel ring beam. The stiffening plates can increase the bearing capacity of the channel steel and reduce or avoid compression deformation of the channel steel.

[0014] The precision-rolled threaded steel bar is inserted between the two channel steel ring beams, so that the loading force of the high-strength nut and the pad on the composite steel beam can be more evenly applied.

[0015] The device is further configured as follows: the channel steel ring beam includes a pair of long side channel steels and a pair of short side channel steels, the ends of the long side channel steels and the short side channel steels are formed with connecting inclined surfaces, the pair of long side channel steels and the pair of short side channel steels are combined into a rectangular ring beam and the connecting inclined surfaces are fixed by welding.

[0016] The channel ring beam is constructed by splicing long and short channel steels, facilitating material selection and fabrication. Furthermore, the welded channel ring beam forms a closed steel hoop, further restraining the lateral deformation of the column beam concrete. This improves the compressive strength and ductility of the newly added column beam, significantly enhancing its shear capacity.

[0017] The device is further configured such that a sleeve is pre-buried between the fine-rolled threaded steel bar and the column beam, which can reduce the disturbance to the column beam itself when the fine-rolled threaded steel bar is tensioned, thereby ensuring the strength and tensile capacity of the column beam.

[0018] The device is further configured as follows: there are two sets of composite steel beams, which can further improve the shear bearing capacity of the column-holding beam itself and the shear bearing capacity between the column-holding beam and the column to be reinforced.

[0019] A construction method for improving the bearing capacity of a column beam comprises the following steps: S1: Adding column beams and pre-embedded fine-rolled threaded steel bars: Add column beam reinforcement cages around the columns to be reinforced, tie sleeves with fine-rolled threaded steel bars to the column beam reinforcement cages, and then pour special concrete to form the column beams; S2: Fabrication of composite steel beams and pre-assembly: Fabrication of long side channel steels and short side channel steels according to the actual size of the column beams, and cutting of connecting bevels at the ends of the long side channel steels and short side channel steels; Select two long side channel steels and set them back to back and weld them through multiple connecting plates to form a long side channel steel group; select two short side channel steels and set them back to back and weld them through multiple connecting plates to form a short side channel steel group; Take two long side channel steel groups and two short side channel steel groups to pre-assemble into a composite steel beam, and reserve a splicing seam at the connecting inclined surface of the long side channel steel group and the short side channel steel group; S3: Install composite steel beams and apply prestressing: S3-1: Surface treatment of column beams; S3-2: Surface treatment of composite steel beams; S3-3: Installation of composite steel beams: Apply adhesive to the bonding surfaces of the long and short side channel steel groups and place them against the surface of the column beams; socket the backing plates and high-strength nuts onto the ends of the finished rolled threaded steel bars and pre-tighten the high-strength nuts; apply pre-compression stress after the adhesive is completely cured.

[0020] Furthermore, the construction method also includes: S4: Welding the Composite Steel Beam into a Steel Hoop: After prestressing is complete, CO2 gas shielded welding is performed at the joints to form a closed steel hoop. This welding combines the individual channel steels into a complete steel hoop, which restrains the lateral deformation of the column beam.

[0021] Furthermore, in the above S3-3: during the installation of the composite steel beam, no steel glue is applied to the bonding surface of the long side channel steel group and the short side channel steel group within 200 to 300 mm from the connecting inclined surface, as the high temperature generated during the subsequent welding of the splicing seam may burn the glue layer; Construction methods also include: S5: Gluing the Ends of the Section Steel Hoops: After the welds have cooled, perform grouting at a depth of 200-300 mm near the joints of the section steel beams. By grouting the ends of the section steel beams, a closed ring of glue is formed between the section steel beams and the column beams. This improves the uniformity of the force applied to the column beam ends when under pressure, and also ensures a uniform restraint of the section steel beams on the column beam ends.

[0022] Furthermore, the width of the splicing seam is between 4 and 6 mm. By setting the splicing seam, firstly, the cutting accuracy of the long-side channel steel and the short-side channel steel can be reduced, and the cut size can be appropriately "borrowed" during assembly. At the same time, it can also prevent deviations when the channel steel group is spliced into a composite steel beam. Secondly, the existence of the splicing seam facilitates the subsequent welding work.

[0023] The outstanding effects of the present invention are: Compared with the existing technology, applying pre-compressive stress to the newly added column beams through combined steel beams, precision-rolled threaded steel bars, etc. can offset the tensile stress caused by external loads, delay or even avoid the occurrence of cracks, and at the same time reduce component deformation and improve overall stiffness, thereby improving the shear bearing capacity of the newly added column beams.

[0024] By setting an adhesive layer between the composite steel beam and the column beam, the transfer of prestressing stress can be made more uniform and timely.

[0025] After the pre-compression stress is applied, the composite steel beam is welded to form a closed steel hoop. By restraining the lateral deformation of the concrete, the compressive strength and ductility of the newly added column beam are improved, thereby significantly improving the bearing capacity of the newly added column beam.

[0026] The prestressed steel clamp device can greatly improve the safety reserve of the column beam during the construction of supporting beam replacement. It not only has low investment cost, but also simple and convenient construction process. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the structure of the device; Figure 2 A cross-sectional view of the device in a top-down direction; Figure 3 A cross-sectional view of the device in the front direction; Figure 4 This is a schematic diagram of the structure of the combined steel beam of the device; Figure 5 Flowchart of this construction method; Figure 6 This is a flow chart for the installation and prestressing of composite steel beams in this construction method; Figure 7 Schematic diagram of the support structure for replacing existing joists with columns.

[0028] Reference numerals: 1. Column to be reinforced; 2. Column-supporting beam; 3. Finished rolled threaded steel bar; 4. Composite steel beam; 5. High-strength nut; 6. Backing plate; 7. Steel adhesive layer; 8. Casing; 41. Channel steel ring beam; 42. Connecting plate; 43. Stiffening plate; 411, long side channel steel; 412, short side channel steel; 413, connecting bevel; 90. Original structural column; 91. Steel support; 92. Jack; 93. Axial force meter. DETAILED DESCRIPTION

[0029] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0030] The following references Figures 1 to 6 The present invention will be described: A device for improving the bearing capacity of a column beam, such as Figure 1 As shown, it includes a column to be reinforced 1 and a column-holding beam 2 arranged on the column to be reinforced 1, wherein a plurality of fine-rolled threaded steel bars 3 are arranged in the column-holding beam 2, some of which are arranged horizontally and some of which are arranged longitudinally, and the outer ends of the plurality of fine-rolled threaded steel bars 3 pass through the protruding ends of the combined steel beam 4 and are screwed with high-strength nuts 5, and a pad 6 is clamped between the high-strength nuts 5 and the combined steel beam 4; The composite steel beam 4 is provided with two sets, and the upper and lower sets are arranged outside the column beam 2.

[0031] like Figure 2 、 Figure 3 As shown, a steel adhesive layer 7 is filled between the combined steel beam 4 and the column beam 2, and a sleeve 8 is pre-buried between the finished rolled threaded steel bar 3 and the column beam 2.

[0032] like Figure 4 As shown, the composite steel beam 4 includes two back-to-back channel steel ring beams 41, the two channel steel ring beams 41 are fixedly connected by a plurality of connecting plates 42, and a plurality of uniformly distributed stiffening plates 43 are fixed in the channel steel notches of the channel steel ring beams 41; The finished rolled threaded steel bar 3 is inserted between the two channel steel ring beams 41 .

[0033] The channel steel ring beam 41 includes a pair of long side channel steels 411 and a pair of short side channel steels 412. The ends of the long side channel steels 411 and the short side channel steels 412 are formed with connecting inclined surfaces 413. The pair of long side channel steels 411 and the pair of short side channel steels 412 are combined into a rectangular ring beam and the connecting inclined surfaces 413 are fixed by welding.

[0034] A construction method for improving the bearing capacity of a column beam comprises the following steps: S1: Add column beams and pre-embedded fine-rolled threaded steel bars: According to the specifications and design requirements, first add a column beam reinforcement cage around the column 1 to be reinforced, tie the sleeve 8 with the fine-rolled threaded steel bar 3 on the column beam reinforcement cage, and then pour special concrete to form the column beam 2.

[0035] S2: Fabrication and Pre-assembly of Composite Steel Beams 4: After the column beams are cast and formed, the actual planar dimensions of the beams are measured on site. Using a laser level, tape measure, and ink fountain, a sample is placed on a nearby floor surface. Next, No. 16 channel steel is cut according to the design requirements for long channel steel 411 and short channel steel 412. Connecting bevels 413 are cut at the ends of the long channel steel 411 and short channel steel 412. Once the cutting is complete, 10mm thick steel plates are welded into the channel steel notches as stiffeners 43. Stiffeners 43 are spaced 200 mm apart.

[0036] After the processing is completed, select two processed equal-length long-side channel steels 411 back to back, and use several 160㎜*100㎜*10㎜ connecting plates 42 to weld them into a long-side channel steel group. In the same way, select two processed equal-length short-side channel steels 412 back to back, and use several 160㎜*100㎜*10㎜ connecting plates 42 to weld them into a short-side channel steel group.

[0037] Then, take two long-side channel steel groups and two short-side channel steel groups and pre-assemble them according to the ink lines on the floor surface, and leave a 4-6mm splicing seam at the splicing bevel.

[0038] S3: Install the composite steel beam and apply prestressing, specifically S3-1: Surface treatment of the column beam; according to the requirements of the design drawings and combined with on-site measurement and positioning, the surface of the column beam where the composite steel beam is required is laid out and polished to expose the solid concrete stone and form a flat rough surface. Finally, wipe the surface with absorbent cotton dipped in acetone or blow with oil-free high-pressure air to clean the dust and oil on the concrete surface.

[0039] S3-2: Surface treatment of composite steel beams; remove rust and roughen the adhesive surface of the composite steel beams with a grinding wheel machine or a wire brush grinder. The grinding lines should be perpendicular to the force direction of the composite steel beams; wipe the adhesive surface clean with absorbent cotton dipped in acetone.

[0040] S3-3: Installation of Composite Steel Beams: First, place the long and short channel groups on the finished rebar. Apply adhesive to the bonding surfaces of the long and short channel groups. However, avoid applying adhesive within 200-300 mm of the bonding surface of the long and short channel groups from the connecting bevel. This is because welding at the bevel joint generates high temperatures, which can burn the adhesive. Ensure a gap of approximately 3 mm between the bonding surface of the channel steel and the concrete surface to ensure the thickness required for subsequent joint sealing and grouting. Next, use a manual forklift to lift the long and short channel groups into place. Place a backing plate 6 on the end of the finished rebar. The backing plate is preferably a double plate (200 mm x 200 mm x 20 mm + 100 mm x 100 mm x 20 mm). Finally, tighten with high-strength nuts 6. After the adhesive has fully cured, use a torque wrench to quantitatively apply prestressing stress.

[0041] S4: Welding of composite steel beams into steel hoop: After the pre-stress loading is completed, use carbon dioxide gas shielded welding to perform welding operations at the joints to weld the steel beams into closed steel hoop.

[0042] S5: Glue filling at the end of the steel hoop: After the weld has cooled down, perform the sealing and gluing operation at 200 to 300 mm near the joint of the steel beam.

[0043] S6: Construct another composite steel beam according to the above steps S2, S3, S4 and S5.

[0044] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications of the above assumptions should also be regarded as the scope of protection of the present invention.

Claims

1. A device for improving the bearing capacity of a column-embracing beam, comprising a column to be reinforced (1) and a column-embracing beam (2) arranged on the column to be reinforced (1), characterized in that: A plurality of fine-rolled threaded steel bars (3) are provided in the column beam (2); the outer ends of the fine-rolled threaded steel bars (3) pass through the protruding ends of the combined steel beam (4) and are screwed with high-strength nuts (5); a pad (6) is clamped between the high-strength nuts (5) and the combined steel beam (4); The combined steel beam (4) is sleeved outside the column-embracing beam (2).

2. The device for improving the bearing capacity of a column beam according to claim 1, characterized in that: A steel adhesive layer (7) is filled between the combined steel beam (4) and the column beam (2).

3. The device for improving the bearing capacity of a column beam according to claim 1, characterized in that: The combined steel beam (4) comprises two channel steel ring beams (41) arranged back to back, the two channel steel ring beams (41) being fixedly connected via a plurality of connecting plates (42), and a plurality of uniformly distributed stiffening plates (43) being fixed in the channel steel notches of the channel steel ring beams (41); The finished rolled threaded steel bar (3) is inserted between the two channel steel ring beams (41).

4. The device for improving the bearing capacity of a column beam according to claim 3, characterized in that: The channel steel ring beam (41) comprises a pair of long-side channel steels (411) and a pair of short-side channel steels (412), and ends of the long-side channel steels (411) and the short-side channel steels (412) are formed with connecting inclined surfaces (413). The pair of long-side channel steels (411) and the pair of short-side channel steels (412) are combined into a rectangular ring beam, and the connecting inclined surfaces (413) are fixed by welding.

5. The device for improving the bearing capacity of a column beam according to claim 1, characterized in that: A sleeve (8) is pre-buried between the finished rolled threaded steel bar (3) and the column beam (2).

6. The device for improving the bearing capacity of a column beam according to claim 1, characterized in that: There are two sets of combined steel beams (4).

7. A construction method for improving the bearing capacity of a column beam, characterized by: The following steps are involved: S1: Adding a column beam and pre-embedded fine-rolled threaded steel bars: Adding a column beam reinforcement cage around the column to be reinforced (1), tying the sleeve (8) with the fine-rolled threaded steel bars (3) on the column beam reinforcement cage, and then pouring special concrete to form the column beam (2); S2: Manufacturing the combined steel beam (4) and pre-assembling: manufacturing the long side channel steel (411) and the short side channel steel (412) according to the actual size of the column beam (2), and cutting the connecting bevel (413) at the ends of the long side channel steel (411) and the short side channel steel (412); Two long side channel steels (411) are selected and arranged back to back and welded through a plurality of connecting plates (42) to form a long side channel steel group; two short side channel steels (412) are selected and arranged back to back and welded through a plurality of connecting plates (42) to form a short side channel steel group; Two long side channel steel groups and two short side channel steel groups are pre-assembled into a composite steel beam (4), and a splicing seam is reserved at the connecting inclined surface (413) of the long side channel steel group and the short side channel steel group; S3: Install composite steel beams and apply prestressing: S3-1: Surface treatment of column beams; S3-2: Surface treatment of composite steel beams; S3-3: Installation of composite steel beams: Apply adhesive glue to the bonding surfaces of the long side channel steel group and the short side channel steel group and place them on the surface of the column beam; pre-tighten the high-strength nuts (5) after fitting the pads (6) and high-strength nuts (5) at the ends of the finished rolled threaded steel (3); apply pre-compression stress after the adhesive glue is completely cured.

8. The construction method for improving the bearing capacity of a column beam according to claim 7, characterized in that: Also includes: S4: Welding of composite steel beams into steel hoop: After the pre-stress loading is completed, use carbon dioxide gas shielded welding to perform welding operations at the joints to weld the steel beams into closed steel hoop.

9. The construction method for improving the bearing capacity of a column beam according to claim 7, characterized in that: S3-3: When installing the composite steel beam, do not apply steel glue on the bonding surface of the long side channel steel group and the short side channel steel group within 200 to 300 mm from the connecting slope; Also includes: S5: Glue filling at the end of the steel hoop: After the weld has cooled down, perform the sealing and gluing operation at 200 to 300 mm near the joint of the steel beam.

10. The construction method for improving the bearing capacity of a column beam according to claim 7, characterized in that: The width of the splicing seam is 4 to 6 mm.

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