CN111140013A - High-rise frame column concrete replacement construction method based on active control technology - Google Patents
High-rise frame column concrete replacement construction method based on active control technology Download PDFInfo
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- CN111140013A CN111140013A CN202010083265.8A CN202010083265A CN111140013A CN 111140013 A CN111140013 A CN 111140013A CN 202010083265 A CN202010083265 A CN 202010083265A CN 111140013 A CN111140013 A CN 111140013A
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- 239000004567 concrete Substances 0.000 title claims abstract description 131
- 238000010276 construction Methods 0.000 title claims abstract description 38
- 238000005516 engineering process Methods 0.000 title claims abstract description 13
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 185
- 239000010959 steel Substances 0.000 claims abstract description 185
- 238000009434 installation Methods 0.000 claims abstract description 27
- 238000012544 monitoring process Methods 0.000 claims abstract description 22
- 210000002435 tendon Anatomy 0.000 claims abstract description 16
- 238000006073 displacement reaction Methods 0.000 claims abstract description 8
- 238000000034 method Methods 0.000 claims description 25
- 238000004364 calculation method Methods 0.000 claims description 13
- 238000013461 design Methods 0.000 claims description 13
- 230000002787 reinforcement Effects 0.000 claims description 13
- 238000006243 chemical reaction Methods 0.000 claims description 10
- 238000004458 analytical method Methods 0.000 claims description 7
- 238000004080 punching Methods 0.000 claims description 3
- 229910001220 stainless steel Inorganic materials 0.000 claims description 3
- 239000010935 stainless steel Substances 0.000 claims description 3
- 238000012423 maintenance Methods 0.000 claims description 2
- 239000010410 layer Substances 0.000 description 17
- 238000009424 underpinning Methods 0.000 description 8
- 238000010205 computational analysis Methods 0.000 description 5
- 238000003780 insertion Methods 0.000 description 4
- 230000037431 insertion Effects 0.000 description 4
- 230000003014 reinforcing effect Effects 0.000 description 4
- 241001139947 Mida Species 0.000 description 3
- 238000005553 drilling Methods 0.000 description 3
- 239000011150 reinforced concrete Substances 0.000 description 3
- 238000005096 rolling process Methods 0.000 description 3
- 238000010008 shearing Methods 0.000 description 3
- 230000007306 turnover Effects 0.000 description 3
- 238000007906 compression Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- 238000009825 accumulation Methods 0.000 description 1
- 238000004873 anchoring Methods 0.000 description 1
- 238000009435 building construction Methods 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000008092 positive effect Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04G—SCAFFOLDING; FORMS; SHUTTERING; BUILDING IMPLEMENTS OR AIDS, OR THEIR USE; HANDLING BUILDING MATERIALS ON THE SITE; REPAIRING, BREAKING-UP OR OTHER WORK ON EXISTING BUILDINGS
- E04G21/00—Preparing, conveying, or working-up building materials or building elements in situ; Other devices or measures for constructional work
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
- E04C3/00—Structural elongated elements designed for load-supporting
- E04C3/30—Columns; Pillars; Struts
- E04C3/34—Columns; Pillars; Struts of concrete other stone-like material, with or without permanent form elements, with or without internal or external reinforcement, e.g. metal coverings
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04G—SCAFFOLDING; FORMS; SHUTTERING; BUILDING IMPLEMENTS OR AIDS, OR THEIR USE; HANDLING BUILDING MATERIALS ON THE SITE; REPAIRING, BREAKING-UP OR OTHER WORK ON EXISTING BUILDINGS
- E04G21/00—Preparing, conveying, or working-up building materials or building elements in situ; Other devices or measures for constructional work
- E04G21/02—Conveying or working-up concrete or similar masses able to be heaped or cast
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04G—SCAFFOLDING; FORMS; SHUTTERING; BUILDING IMPLEMENTS OR AIDS, OR THEIR USE; HANDLING BUILDING MATERIALS ON THE SITE; REPAIRING, BREAKING-UP OR OTHER WORK ON EXISTING BUILDINGS
- E04G21/00—Preparing, conveying, or working-up building materials or building elements in situ; Other devices or measures for constructional work
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Abstract
The invention relates to a high-rise frame column concrete replacement construction method based on an active control technology, wherein a steel bolt is inserted into a hole to be replaced for a concrete frame column, one end of a steel inclined strut is fixed on the steel bolt, the other end of the steel inclined strut is installed on a beam plate and can horizontally slide, and a counter-pulling prestressed tendon is arranged at a connecting node II at two sides of the concrete frame column; installing a vertical steel support of a floor where the concrete frame column to be replaced is located, wherein the installation position corresponds to the position of the steel inclined support; installing a strain gauge and a displacement monitoring point, and monitoring stress change and structural deformation in real time; actively controlling the steel support axial force through the tension and monitoring data of the tension prestressed tendons, and realizing the unloading of the axial force of the concrete frame column; removing the concrete blocks and pouring again, and burying the concrete strain gauge; after the concrete is cured until the strength meets the requirement, the steel supports are dismantled and recycled, and the replacement of the concrete of the high-rise frame column is realized. The invention realizes the active control of the axial force unloading of the concrete frame column through the real-time monitoring of the construction.
Description
Technical Field
The invention relates to a construction method for concrete replacement of a high-rise frame column, and belongs to the technical field of building construction.
Background
The reinforced concrete structure is the most common structural form of a high-rise building, and the strength of a concrete column directly influences the building safety. However, in actual engineering, engineering quality accidents, particularly concrete strength problems, are prone to occur due to various factors. When the concrete strength grade is greatly different from the design requirement, the generally adopted treatment mode is as follows: and (3) completely dismantling the concrete columns of the unqualified floors and buildings above the unqualified floors, and completely reworking. And the other method adopts various reinforcement measures such as a section enlarging reinforcement method, an outer-wrapping steel reinforcement method, a replacement concrete reinforcement method and the like to meet the design requirement.
The replacement concrete reinforcement method is to completely remove the unqualified frame concrete and pour the concrete meeting the design requirements again. Not only can thoroughly rework unqualified concrete to enable the building to completely meet the design requirements, but also the upper main structure can continue to be constructed during construction. The economic loss is much smaller than that of the whole building, but the difficulty is that a set of reliable structural support system is needed for unloading the load transmitted by the upper structure of the column and ensuring that the upper structure is not deformed and cracked. The existing steel support underpinning during the concrete replacement of the frame column adopts a method of arranging vertical steel supports on a plurality of floors above and below the frame column to be replaced, the method adopts the vertically arranged steel supports to replace the frame column with the original structure to transfer vertical load, generally, steel wedges are only driven into the root part of the steel support to perform vertical steel support initial tightening, and the axial force of the vertical steel supports cannot be actively controlled; in addition, the vertical steel supports are required to be supported to the bottom plate of the basement all the time, so that the phenomenon that the beam column nodes of the frame structure are subjected to large shearing force in the replacement construction stage to cause shearing damage is avoided, the required vertical support is large in using amount, and the vertical steel supports cannot be used in a rapid turnover mode.
In Sunzhong et al, a high-rise building concrete column replacement reinforcement construction method (No. 1, No. 8 p58-60 of 'China high New science and technology' 2017) adopts a reinforcement method that: (1) and arranging a support system, wherein the support system is that supports are arranged below the beams around the replacement column, and the steel pipes are used for forming combined steel pipe supports. The lower end of the combined steel pipe is provided with a screw jack, and the unloading purpose of the column is realized through the jacking of the screw jack. (2) Manually chiseling out concrete with a certain size in batches (the stirrups of the corresponding area can be cut off, but the longitudinal reinforcements are reserved); (3) placing the section steel and welding to form a lattice column; (4) installing a template and pouring concrete; and maintaining, detecting and dismantling. The construction method is a semi-replacement concrete reinforcing method provided for the framework type concrete column, the bearing capacity of the original concrete in the center part is reserved, meanwhile, profile steel is added to improve the supporting force, the reinforcing effect is quantized, and the original section size is not changed. But has higher requirements on the construction process level. Skilled personnel are required to remove the effects of concrete, welded steel plates and the like.
Zhengyuexin, etc., a construction method for reinforcing and reinforcing the integral replacement concrete of a concrete column of a high-rise building (construction technology, No. 40, No. 352, p91-100) on 11 months in 2011, aiming at more upper floors (8 floors or more than 10 floors), and when the load born by an unqualified concrete column is larger, the whole column replaces the processing and construction of the concrete. The load which can be relieved by steel pipe support is calculated according to the support capacity of a single steel pipe, the support capacity of a screw jack and the inclined-compression shear-resistant bearing capacity of the concrete at the beam end. However, the method is required to be carried out strictly according to the design sequence of the supporting system, when concrete is removed in each stage, the removed section is required to be as small as possible and is not required to exceed 1/4 of the section, and the section of the residual concrete is required to be larger as possible. But also requires the use of specialized personnel to operate jacks and the like.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to solve the technical problem of providing the high-rise frame column concrete replacement construction method based on the active control technology, and the method has the characteristics of less steel support consumption, light weight, convenience for manual transportation and installation, short turnover service cycle, real-time monitoring in the whole process and active control.
In order to solve the technical problem, the invention is realized as follows:
the high-rise frame column concrete replacement construction method based on the active control technology comprises the following steps:
Step 3, installation of a connecting node II: the connecting node II is arranged on the upper layer of beam slab and the lower layer of beam slab, is 800-1000 mm away from the concrete frame column, is filled with a stainless steel sheet between the connecting node II and the beam slab to reduce friction force, and is provided with tension prestressed tendons between the connecting node II on the left side and the right side of the concrete frame column, and the prestressed tendons are tightened initially to ensure the stress of the inclined strut.
That is, the connection nodes I, II are connected to the two ends of the same steel sprag, respectively, to facilitate its connection to both the concrete frame column and the beam slab.
And 4, installing the vertical steel supports of the floor where the concrete frame column to be replaced is located, wherein the installation positions correspond to the steel inclined struts located on the upper layer and the lower layer and the concrete beam plate connecting nodes, and after the installation is completed and the verticality is adjusted, prestress is applied to the adjustable column feet of the vertical steel supports to realize the initial tightening of the vertical steel supports.
After the steel support is installed, the formed integral pattern is as follows: a vertical steel support is arranged between an upper beam plate and a lower beam plate of a floor where a to-be-replaced concrete frame column is located, steel inclined struts are arranged on the upper floor and the lower floor of the floor where the to-be-replaced frame column is located, one end of each steel inclined strut is fixed to the upper (lower) beam plate of the floor where the to-be-replaced frame column is located through one end of a connecting joint II, and the steel inclined struts can horizontally slide; the other end is fixed on a steel bolt of the concrete frame column by means of a connecting node I. In order to balance stress, the steel inclined struts and the vertical steel struts are symmetrically arranged on the concrete frame column, and opposite-pulling prestressed tendons are further mounted at the roots of the two symmetrical steel inclined struts.
Step 5, installing strain gauges on the inclined steel supports and the vertical steel supports, and monitoring stress changes in the construction process; mounting a displacement monitoring point at the connecting node I, and monitoring the vertical deformation of the structure in the construction process; and a real-time monitoring system is adopted for strain and deformation monitoring.
And 6, controlling the axial force of the vertical steel support through the tension and monitoring data of the steel diagonal bracing connecting node II on the tension prestressed tendon, realizing the active control of the axial force unloading of the to-be-replaced concrete frame column, and determining the prestress tension force according to the calculation analysis and construction monitoring result so as to ensure that the design and safety control requirements are met.
Step 7, replacing the concrete of the concrete frame column to be replaced: and (4) removing the concrete blocks and pouring again according to the design scheme, and burying the concrete strain gauge.
And 8, unloading the vertical steel support after the strength maintenance of the newly poured concrete meets the requirements, realizing stress conversion by loosening the counter-pulling prestressed tendons, and judging whether the unloading is finished through strain monitoring data arranged on the steel inclined strut and the vertical steel support.
And step 10, standing the concrete column to be newly poured, and dismantling and transferring the steel support after the strain and the crack of the frame column after replacement are stable, so that the replacement of the concrete of the high-rise frame column is realized.
The invention has the following positive effects:
① the unloading steel support for the concrete frame column has less usage amount and light weight, and is convenient for manual transportation and installation;
②, the tension of the prestressed tendons and the construction of the steel support axial force are monitored in real time through the connecting joint II, the steel support axial force is actively controlled, and the active control of the concrete frame column axial force unloading is realized;
③ adjustable column feet are arranged at the bottom of the vertical steel support of the floor where the concrete frame column is to be replaced, so that the initial tightening of the vertical steel support and the unloading of the vertical steel support in the stress system conversion stage after the concrete replacement can be carried out in the installation stage;
④ in actual construction, the connecting nodes I, II are all dry connections, which is convenient for quick installation and turnover use in construction;
⑤, determining the tension of the prestressed tendon through calculation analysis and real-time construction monitoring;
⑥ the steel support is removed after standing for 6h after the stress system is converted, so as to prevent sudden safety accidents.
Drawings
FIG. 1 is a schematic illustration of a concrete coring position; in fig. 1, the hatched area is the concrete frame column 12 to be replaced;
fig. 2 is a schematic view illustrating the installation of a shear steel plate and a connection node I (a connection node of a steel stay and a concrete frame column); wherein, 31-steel bolt; 32-connecting steel plates; 33-shear steel plates; 34-a shear bolt;
FIG. 3 is a perspective view of the completed installation of the steel support; wherein: 1 concrete frame column; 2-concrete beam slab; 3-a connecting node (connecting node I) of the steel inclined strut and the concrete frame column; 4-steel diagonal bracing; 5-connecting nodes (connecting nodes II) of the steel inclined struts and the concrete beam plates; 6-vertical steel support; 7-adjustable column base; 11-steel pin insertion holes on the concrete frame column; 51-oppositely pulling the prestressed tendons; 71-adjusting screw;
FIG. 4 is a plan view of the completed installation of the steel support;
FIG. 5 is a block diagram of an overall model of computational analysis of the overall process of displacement using Midas/gen;
FIG. 6 is a steel support model for computational analysis of the overall process of displacement using Midas/gen;
fig. 7 is a steel support unit number.
Detailed Description
The present invention will be described in further detail with reference to specific embodiments.
Example 1
Drilling and coring step for concrete column
Fig. 1 is a schematic diagram of a core taking position of a concrete frame column, wherein the actual core taking position is determined according to the current situation of a field structure in order to facilitate the operation of the core taking machine, and the vertical distance from the center position of core taking to the beam bottom or the plate top is 200mm basically.
Before core position lofting of the concrete frame column, the positions of the main reinforcements and the stirrups are determined by a reinforcement scanner, so that the stressed main reinforcements of the concrete frame column are prevented from being damaged in the construction process as much as possible.
A core is taken by adopting a water-taking hole to obtain a steel pin insertion hole 11 on the concrete frame column, a 40Cr steel bolt 31 with the diameter of 44mm is inserted into the steel pin insertion hole, a connection node I for stress system conversion is installed, the disturbance of electric drill punching on the original frame column is avoided, a water drill bit with the diameter of 46 ＊ 450mm is matched with the core taking machine, and the effective depth of the core taking is ensured to reach 350mm (the effective insertion depth of the steel pin is ensured to reach 350 mm).
During coring, the deviation of the coring position should be controlled not to exceed +/-15 mm, and the coring positions on the left side and the right side of the concrete column should be symmetrical.
Mounting of connecting joint of steel inclined strut and concrete frame column
Fig. 2 is a schematic view illustrating the installation of a shear steel plate and a connection node I (a connection node of a steel stay and a concrete frame column);
the ear plate has one end with a hole for fixing the steel diagonal brace 4 and the other end welded on the connecting steel plate 32 with the hole to form a connecting node I, and is used for fixing the steel diagonal brace and the concrete frame column in the subsequent steps.
The whole weight of the connecting joint I is about 200kg, manual transportation can be achieved, however, a chain block of 1t is needed to assist in installation, a hole is formed in an upper floor, and the connecting joint is integrally hoisted through the chain block.
And after the connecting joint I is integrally hoisted to the position, the connecting joint I is temporarily fixed, the relative position of the steel bolt 31 and the ear plate is accurately measured, and pin holes in the shear-resistant steel plate 33 (the thickness of the steel plate is 30mm) are machined according to actual measurement data. After the pin holes of the shear steel plates are processed, the shear steel plates 33 are installed on the connecting nodes I through 6 8.8-grade M20 high-strength shear bolts 34, so that the steel bolts 31 are ensured to effectively transfer shear force, and finally the steel diagonal bracing and concrete frame column connecting nodes 3 are formed.
The shear steel plate 33 is added on the connecting steel plate, so that the dimensional deviation of the core drilling on the concrete column is larger, which is about 10mm conventionally, so that in order to ensure that each steel bolt can bear the shear force, a large hole is formed on the connecting steel plate 32, the hole opening of the pin hole on the shear steel plate 33 is carried out on site according to the actual core drilling position on the concrete column (namely, the steel pin jack 11 on the concrete frame column), and then the shear steel plate and the connecting steel plate 32 are connected into a whole through the shear bolt 34.
Thirdly, mounting of connecting joint of steel inclined strut and concrete beam plate
Fig. 3 and 4 are a perspective view and a plan view of the steel support after installation, and as shown in fig. 3 and 4, a connection node II is installed on the upper layer and the lower layer of beam slab, and is 800 mm-1000 mm away from the concrete frame column, and a stainless steel sheet with the thickness of 1mm is padded between the connection node II and the beam slab to reduce friction force, so that left and right position adjustment is facilitated (for example, the concrete structure surface is rough, and high-strength grouting material can be adopted for leveling first). The weight of the steel chain hoist is about 200kg, the steel chain hoist can be transported manually, 1t of the steel chain hoist is also needed for auxiliary installation, holes can be formed in the upper floor slab or temporary steel supports can be arranged, and the chain hoist is used for integrally hoisting the connecting joint II.
The length of the steel diagonal brace is determined according to the size of the installation position of the connecting node II, and if the length of the steel diagonal brace is adjusted on site, the length of the steel diagonal brace is adjusted in time.
After the installation of the steel diagonal brace and the concrete beam plate connecting node 5 is completed, the steel diagonal brace 4 and the steel diagonal brace root between the left and right sides of the concrete frame column 1 are installed on the tension prestressed rib 51, the finish rolling deformed steel bar is adopted, the finish rolling deformed steel bar is tightened for the first time, and the stress of the steel diagonal brace is ensured.
Four, installation of vertical steel support of replacement layer
And (3) installing the vertical steel support 6 to be used for replacing the floor of the concrete frame column according to the installation position of the steel diagonal support and the concrete beam plate connecting node 5, ensuring that the steel diagonal support corresponds to the vertical steel support 6 in the vertical position, and avoiding the concrete beam from bearing shearing force.
The weight of a single vertical steel support 6 is about 350kg, the vertical steel support can be transported manually, a chain block of 1t is also needed for auxiliary installation, a hole can be formed in an upper floor, and the chain block is used for integrally hoisting the vertical steel support.
And after the vertical steel support is installed, performing initial tightening on the finish-rolled deformed steel bar at the root part of the column base to ensure that the vertical steel support is in a stressed state. The column base of the vertical steel support adopts an adjustable column base 7, and an adjusting screw rod 71 is additionally arranged on the adjustable column base 7, so that the vertical steel column can be pre-tightened, and the steel column is ensured to be in a stressed state before active control.
Fifthly, the underpinning steel support is integrally installed
The underpinning steel supports (namely the steel inclined struts arranged between the concrete frame column 1 and the concrete beam slab 2 and the vertical steel supports arranged between the concrete beam slab 2 at the position of the concrete frame column 12 to be replaced) are arranged according to the design positions, the positions of the supporting points of the upper layer and the lower layer are ensured to correspond, the tension prestressed tendons are subjected to stress conversion through the connection nodes of the tension steel inclined struts and the concrete beam slab, and each underpinning steel support is required to be in a stress state before tension.
Sixthly, calculation and analysis of prestress control
In the embodiment, the axial force conversion of the replaced concrete frame column is realized through an active control technology, namely, the prestressed tendons are subjected to partial axial force unloading through active tensioning, so that the core column stress of the steel support and the concrete frame layer column in the actual replacement process is ensured to meet the design requirement. According to the calculation, under the condition that only the core column is reserved after the surface layer of the concrete frame layer is chiseled, the stress of the vertical steel support shaft force is about 2000 kN.
Computational analysis the displacement overall process computational analysis was performed using Midas/gen, the computational analysis steps including:
step (1): the concrete frame column 12 to be replaced (800mm x 900mm) is not replaced;
step (2): underpinning steel support installation (installation of a steel inclined support and a vertical steel support) and tensioning of a tension prestressed tendon;
and (3): the concrete frame column 12 to be replaced (800mm x 900mm) was replaced with a reinforced concrete column (400mm x 450 mm).
6.1 tensing prestressing to 50kN
According to the construction steps, calculation analysis is carried out according to an accumulation model of the whole construction process, and prestress is applied (replaced) according to external force. The unit numbers of the underpinning steel supports are shown in figure 7, wherein the prestressed tensioning force units are numbered 6544 and 6547; the concrete displacement layer supports steel column unit numbers 6548, 6549.
And (1) the steel support (comprising the steel inclined support and the vertical steel support) is not installed, so that the internal force of the steel support is 0.
And (2) mounting a steel support and tensioning the prestress by 50 kN.
And (3) replacing the frame column 12 to be replaced with the concrete.
And extracting the axial force of each construction steel support according to the calculation result, and showing in a table 1.
TABLE 1 axial force variation of steel bracing at each construction step
| Unit cell | Load(s) | Phases | Step (ii) of | Internal force-I (kN) | Internal force-J (kN) |
| 6544 | Total up to | step1 | 001(Final) | 0 | 0 |
| 6544 | Total up to | step2 | 001 (last) | 49.999999 | 49.999999 |
| 6544 | Total up to | step3 | 001 (last) | 106.797482 | 106.797482 |
| 6547 | Total up to | step1 | 001 (last) | 0 | 0 |
| 6547 | Total up to | step2 | 001 (last) | 49.999999 | 49.999999 |
| 6547 | Total up to | step3 | 001 (last) | 103.381348 | 103.381348 |
| 6548 | Total up to | step1 | 001 (last) | 0 | 0 |
| 6548 | Total up to | step2 | 001 (last) | -74.794746 | -79.549868 |
| 6548 | Total up to | step3 | 001 (last) | -517.058738 | -521.81386 |
| 6549 | Total up to | step1 | 001 (last) | 0 | 0 |
| 6549 | Total up to | step2 | 001 (last) | -74.794015 | -79.549137 |
| 6549 | Total up to | step3 | 001 (last) | -516.385998 | -521.14112 |
| 6550 | Total up to | step1 | 001 (last) | 0 | 0 |
| 6550 | Total up to | step2 | 001 (last) | -148.116243 | -151.560658 |
| 6550 | Total up to | step3 | 001 (last) | -318.325185 | -321.7696 |
| 6551 | Total up to | step1 | 001 (last) | 0 | 0 |
| 6551 | Total up to | step2 | 001 (last) | -148.116243 | -151.560658 |
| 6551 | Total up to | step3 | 001 (last) | -318.325185 | -321.7696 |
| 6552 | Total up to | step1 | 001 (last) | 0 | 0 |
| 6552 | Total up to | step2 | 001 (last) | -148.116243 | -151.560658 |
| 6552 | Total up to | step3 | 001 (last) | -308.08782 | -311.532235 |
| 6553 | Total up to | step1 | 001 (last) | 0 | 0 |
| 6553 | Total up to | step2 | 001 (last) | -148.116243 | -151.560658 |
| 6553 | Total up to | step3 | 001 (last) | -308.08782 | -311.532235 |
The calculation result of the table 1 shows that the prestress is only 50kN in tension, and the vertical steel support underpinning pretightening force is 75 kN; after the concrete frame column to be replaced is stripped to the core column, the vertical steel support axial force is changed to 516kN, the floor vertical maximum deformation is minus 0.95mm, and the design control target is not reached.
6.2 tensioning prestressing to 500kN
And secondly, mounting and tensioning the steel support with a prestress of 500 kN.
And thirdly, replacing the concrete columns of the replacement layer.
And extracting the axial force of each construction steel support according to the calculation result, and showing in a table 2.
TABLE 2 axial force variation of steel bracing at each construction step
| Unit cell | Load(s) | Phases | Step (ii) of | Internal force-I (kN) | Internal force-J (kN) |
| 6544 | Total up to | step1 | 001 (last) | 0 | 0 |
| 6544 | Total up to | step2 | 001 (last) | 499.999986 | 499.999986 |
| 6544 | Total up to | step3 | 001 (last) | 537.771256 | 537.771256 |
| 6547 | Total up to | step1 | 001 (last) | 0 | 0 |
| 6547 | Total up to | step2 | 001 (last) | 499.999986 | 499.999986 |
| 6547 | Total up to | step3 | 001 (last) | 535.371368 | 535.371368 |
| 6548 | Total up to | step1 | 001 (last) | 0 | 0 |
| 6548 | Total up to | step2 | 001 (last) | -764.18393 | -768.93905 |
| 6548 | Total up to | step3 | 001 (Final)) | -1058.5867 | -1063.3418 |
| 6549 | Total up to | step1 | 001 (last) | 0 | 0 |
| 6549 | Total up to | step2 | 001 (last) | -764.17507 | -768.93019 |
| 6549 | Total up to | step3 | 001 (last) | -1057.9082 | -1062.6633 |
| 6550 | Total up to | step1 | 001 (last) | 0 | 0 |
| 6550 | Total up to | step2 | 001 (last) | -1496.6623 | -1500.1067 |
| 6550 | Total up to | step3 | 001 (last) | -1609.8541 | -1613.2985 |
| 6551 | Total up to | step1 | 001 (last) | 0 | 0 |
| 6551 | Total up to | step2 | 001 (last) | -1496.6623 | -1500.1067 |
| 6551 | Total up to | step3 | 001 (last) | -1609.8541 | -1613.2985 |
| 6552 | Total up to | step1 | 001 (last) | 0 | 0 |
| 6552 | Total up to | step2 | 001 (last) | -1496.6623 | -1500.1067 |
| 6552 | Total up to | step3 | 001 (last) | -1602.6622 | -1606.1066 |
| 6553 | Total up to | step1 | 001 (last) | 0 | 0 |
| 6553 | Total up to | step2 | 001 (last) | -1496.6623 | -1500.1067 |
| 6553 | Total up to | step3 | 001 (last) | -1602.6622 | -1606.1066 |
The calculation results in the table 2 show that the prestress is only 500kN for tensioning, the underpinning pretightening force of the vertical steel support is 750kN, and the maximum deformation of the corresponding floor surface reaches 0.93 mm; after the concrete is stripped to the core column, the vertical steel support axial force is changed to 1050kN, and the floor vertical maximum deformation is-0.57 mm. Therefore, in the actual construction process, the active unloading control is realized by tensioning the finish rolling twisted steel, and the stress of the core column in the concrete replacement process is ensured to meet the design requirement.
Seven, calculation and analysis of concrete column steel pin
The diameter of a single steel bolt is 44mm, the effective anchoring length is 350mm, and the local compression area is 25mm multiplied by 350 mm; the calculation according to the local bearing of the reinforced concrete can obtain:
F＝1.35×1.0×1.732×14.3×25×350＝290kN
the overall bearing capacity of the 8 steel bolts (and correspondingly the number of steel pin receptacles 11 on the concrete frame column is 8) is 2340 kN.
The vertical shear force value of the unilateral connecting node is 1500kN, and the safety factor is 1.56.
The cross-sectional area of a single steel pin is 1520mm2And the shear strength is 190MPa, the shear bearing capacity of a single steel bolt is 289kN, and is equal to the local bearing capacity of concrete, so that the bearing requirement is met.
The above embodiments do not limit the technical solutions of the present invention in any way, and all technical solutions obtained by means of equivalent replacement or equivalent transformation fall within the protection scope of the present invention.
Claims (5)
1. The high-rise frame column concrete replacement construction method based on the active control technology is characterized by comprising the following steps of:
step 1, coring and punching: horizontally coring the frame columns of the upper layer and the lower layer of the concrete frame column to be replaced to obtain steel pin jacks, wherein the verticality of coring is ensured during coring, and main reinforcements and stirrups of the columns are avoided;
step 2, installation of the connecting node I: inserting a steel bolt into the obtained steel bolt jack, and installing a connecting node I for stress system conversion;
step 3, installation of a connection node II: the connecting nodes II are arranged on the upper layer of beam slab and the lower layer of beam slab and are 800 mm-1000 mm away from the concrete frame column, and counter-tension prestressed tendons are arranged between the connecting nodes II on the left side and the right side of the concrete frame column and are tightened for the first time, so that the stress of the steel diagonal brace is ensured;
step 4, installing vertical steel supports of the floor where the concrete frame column to be replaced is located, wherein the installation positions correspond to the connection nodes of the steel inclined struts located on the upper layer and the lower layer and the concrete beam slab, and after the installation is completed and the verticality is adjusted, prestress is applied to adjustable column feet of the vertical steel supports to achieve initial tightening of the vertical steel supports;
step 5, installing strain gauges on the inclined steel supports and the vertical steel supports, and monitoring stress changes in the construction process; mounting a displacement monitoring point at the connecting node I, and monitoring the vertical deformation of the structure in the construction process; a real-time monitoring system is adopted for strain and deformation monitoring;
step 6, controlling the axial force of the vertical steel support through the tension of the steel diagonal bracing connecting node II, realizing the active control of the axial force unloading of the to-be-replaced concrete frame column, and determining the prestress tension force according to the calculation analysis and construction monitoring results so as to ensure that the design and safety control requirements are met;
step 7, replacing the concrete of the concrete frame column to be replaced: according to the design scheme, the concrete is dismantled in blocks and poured again, and the concrete strain gauge is buried;
step 8, unloading the vertical steel support after the strength maintenance of the newly poured concrete meets the requirements, realizing stress conversion by loosening the counter-pulling prestressed tendons, and judging whether the unloading is finished through strain monitoring data arranged on the steel inclined strut and the vertical steel support;
step 9, after the conversion of the stress system is completed, the steel support is not dismantled temporarily; observing the change of an appearance crack of newly poured concrete and the data change of the embedded concrete strain gauge;
and step 10, standing until the newly-poured concrete column meets the stress requirement, dismantling and transferring the steel support for use, and realizing the replacement of the concrete of the high-rise frame column.
2. The concrete replacement construction method for the high-rise frame column based on the active control technology as claimed in claim 1, wherein one end of the ear plate is provided with a hole for fixing the steel diagonal brace, and the other end of the ear plate is welded on the connecting steel plate with the hole to form an upper connecting node I, and the connecting nodes I and II are respectively connected to two ends of the same steel diagonal brace and used for fixing the steel diagonal brace to the concrete frame column and the beam plate.
3. The high-rise frame column concrete displacement construction method based on the active control technology as claimed in claim 1, wherein step 3, stainless steel sheets are padded between the connecting joint II and the beam plate to reduce friction.
4. The active control technology-based concrete replacement construction method for the high-rise frame column according to claim 1, wherein in the step 1, the number and the diameter of the holes are determined according to the axial force of the concrete frame column to be unloaded, and the safety factor is required to be not lower than 1.5.
5. The high-rise frame column concrete replacement construction method based on the active control technology according to claim 1, wherein in step 6, the prestress applied to the tension prestressed tendon by the steel diagonal bracing connecting node II is comprehensively determined according to the calculation analysis result and the field monitoring data.
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| CN113281184A (en) * | 2021-06-15 | 2021-08-20 | 王永泉 | Reliability test method for reinforced concrete frame column active unloading scheme |
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