Precast column base joint and construction method therefor

Abstract

The joint has a prefabricated-reinforced-concrete column, a reinforced-concrete foundation, a column anchoring longitudinal bar, a grouting sleeve and a foundation anchoring steel bar. The foundation anchoring steel bar and the column anchoring longitudinal bar are connected by a seam filling material filling the grouting sleeve. A splicing seam between the reinforced-concrete foundation and the prefabricated-reinforced-concrete column is filled with the seam filling material. The foundation anchoring steel bar includes a vertical portion and a horizontal portion. The vertical portion includes an upper-portion anchoring section protruding out of an upper surface of the reinforced-concrete foundation, a middle-portion non-adhesive section buried within the foundation and a lower-portion anchoring section. An exterior of the middle-portion non-adhesive section is provided with an isolating sheath for isolating the middle-portion non-adhesive section and the concrete adhesion.

Claims

1. An assembled column-base connection joint, comprising a prefabricated-reinforced-concrete column (1) at an upper portion and a reinforced-concrete foundation (2) at a lower portion that are vertically correspondingly spliced, the prefabricated-reinforced-concrete column (1) being pre-buried with a column anchoring longitudinal bar (3) and a grouting sleeve (4) that are circumferentially evenly distributed along a column body, the reinforced-concrete foundation (2) being pre-buried with a foundation anchoring steel bar (6), the foundation anchoring steel bar (6) and the column anchoring longitudinal bar (3) being connected by a seam filling material (7) filling the grouting sleeve (4), and a splicing seam between the reinforced-concrete foundation (2) and the prefabricated-reinforced-concrete column (1) being filled with the seam filling material (7), wherein the foundation anchoring steel bar (6) is of an L shape, and comprises a vertical portion (8) and a horizontal portion (9), the vertical portion comprises an upper-portion anchoring section (81) protruding out of an upper surface of the reinforced-concrete foundation (2), a middle-portion non-adhesive section (82) buried within the foundation and a lower-portion anchoring section (83), the upper-portion anchoring section (81) protrudes into the grouting sleeve (4) and is connected to the column anchoring longitudinal bar (3), the middle-portion non-adhesive section (82) does not have adhesion to a foundation concrete, and the lower-portion anchoring section (83) and the horizontal portion (9) are adhesively anchored to the foundation concrete, and an exterior of the middle-portion non-adhesive section (82) is provided with an isolating sheath (10) for isolating the middle-portion non-adhesive section (82) and the concrete adhesion, and a top face of the isolating sheath (10) and an upper surface of the reinforced-concrete foundation (2) flush, wherein a length of the middle-portion non-adhesive section (82) is 3 to 20 times a diameter of the steel bar, wherein the isolating sheath (10) is a hard-material casing, and is a plastic tube or steel tube whose inner diameter is greater than a diameter of the middle-portion non-adhesive section, or the isolating sheath (10) is a plastic-cloth layer that wraps the middle-portion non-adhesive section after the middle-portion non-adhesive section has been applied a dedicated anti-corrosive lubricant grease; wherein the middle-portion non-adhesive section (82) is provided with a necking section (821), the necking section (821) has a cross-sectional area that is reduced 20 to 50%-90% of an original cross-sectional area, and the isolating sheath (10) is a hard-material casing.

2. The assembled column-base connection joint according to claim 1, wherein the necking section is a cross-section reduction that is formed by cutting, and the cross-section reduction is formed by reducing a diameter of a cross section of a steel bar of a reduction section or by cutting upper and lower sides or left and right sides of a steel bar to form a notch.

3. The assembled column-base connection joint according to claim 1, wherein the necking section (821) is left at least one non-necking elastic section (822) that is not cut, the non-necking elastic sections (822) are evenly distributed on the necking section (821), and a total length of the non-necking elastic sections (822) is not greater than a half of a total length of the necking section (821).

4. The assembled column-base connection joint according to claim 1, wherein the grouting sleeve (4) is a sleeve in a form of no independent grout-injection hole whose side wall does not have a grout-injection hole and has merely a grout exiting hole (11), the prefabricated-reinforced-concrete column (1) is provided with an internal-to-column grout flowing channel (12), the internal-to-column grout flowing channel has one end in communication with an exterior of the side wall to form a sole grout-injection hole (5), and the other end in communication with the splicing seam between the reinforced-concrete foundation (2) and the prefabricated-reinforced-concrete 21 column (1), and the splicing seam forms an external-to-column grout flowing channel of the grouting sleeve (4), wherein the seam filling material (7) is grouted from the sole grout-injection hole (13), passes through the internal-to-column grout flowing channel (12), fills the splicing seam, then fills the grouting sleeve (4), and flows out of the grout exiting hole (11).

5. The assembled column-base connection joint according to claim 4, wherein the internal-to-column grout flowing channel (12) is of a reverse L shape, and comprises a horizontal channel (121) and a vertical channel (122), the horizontal channel (121) is in communication with the exterior of the side wall, the vertical channel (122) is in communication with the splicing seam, and the vertical channel (122) is located in a vertical axis of the prefabricated-reinforced-concrete column (1).

6. A method for constructing the assembled column-base connection joint according to claim 4, wherein steps of the constructing are as follows: Step 1: binding a foundation steel reinforcement cage and providing a template; Step 2: processing the foundation anchoring steel bar; Step 3: placing the foundation anchoring steel bar (6) into a predetermined position in the template, installing the isolating sheath (10), and then pouring concrete to form the reinforced-concrete foundation (2); Step 4: binding the column steel reinforcement cage, the column anchoring longitudinal bar (3) and the grouting sleeve (4), providing an external-to-column template and an internal template of the internal-to-column grout flowing channel (12), and pouring concrete to form the prefabricated-reinforced-concrete column (1) and the internal-to-column grout flowing channel (12); Step 5: transporting the prefabricated-reinforced-concrete column (1) to a site, temporarily placing in place, inserting the foundation anchoring steel bar (6) into the grouting sleeve (4), providing a temporary support, and fixing to ensure a width of the splicing seam; Step 6: grouting the seam filling material (7) from the sole grout-injection hole (5), and the seam filling material (7) passing through the internal-to-column grout flowing channel (1), filling the splicing seam, then filling the grouting sleeve (4), and flowing out of the grout exiting hole (11), to pour the steel-bar connecting sleeves to be full; and Step 7: after the seam filling material within the grouting sleeve has reached a required strength, dismantling the temporary support of the prefabricated-reinforced-concrete column (1), to complete the constructing of the column base joint.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present disclosure will be described below in further details by referring to the drawings.

(2) FIG. 1 is a schematic diagram of the column base joint of an embodiment of the present disclosure.

(3) FIG. 2 is a schematic diagram of the A-A section of FIG. 1,

(4) FIG. 3 is a schematic diagram of the energy consuming steel-bar necking section of the foundation anchoring steel bar of an embodiment of the present disclosure.

(5) FIG. 4 is a schematic diagram of the energy consuming steel-bar necking section and the non-necking elastic section of the foundation anchoring steel bar of an embodiment of the present disclosure,

(6) FIG. 5 is a schematic diagram of the B-B section of FIG. 3, which is the mode of cross-section reduction by reducing the diameter of the cross section of the steel bar of the reduction section.

(7) FIG. 6 is a schematic diagram of the C-C section of FIG. 4, which is the mode of cross-section reduction by cutting the upper and lower sides of the steel bar to form a notch.

(8) FIG. 7 is a schematic diagram of the present disclosure wherein the isolating sheath is a hard-material casing.

(9) FIG. 8 is a schematic diagram of the D-D section of FIG. 7.

(10) Reference numbers: 1—prefabricated-reinforced-concrete column, 2—reinforced-concrete foundation, 3—column anchoring longitudinal bar, 4—grouting sleeve, 5—sole grout-injection hole, 6—foundation anchoring steel bar, 7—seam filling material, 8—vertical portion, 81—upper-portion anchoring section, 82—middle-portion non-adhesive section, 821—necking section, 822—non-necking elastic section, 83—lower-portion anchoring section, 9—horizontal portion, 10—isolating sheath, 11—grout exiting hole, 12—internal-to-column grout flowing channel, 121—horizontal channel, 122—vertical channel, and 13—contour line of original cross section.

DETAILED DESCRIPTION

(11) The embodiment is shown in FIGS. 1-2. An assembled column-base connection joint comprises a prefabricated-reinforced-concrete column 1 at the upper portion and a reinforced-concrete foundation 2 at the lower portion that are vertically correspondingly spliced. The prefabricated-reinforced-concrete column 1 is pre-buried with a column anchoring longitudinal bar 3 and a grouting sleeve 4 that are circumferentially evenly distributed along the column body. The reinforced-concrete foundation 2 is pre-buried with a foundation anchoring steel bar 6. The foundation anchoring steel bar 6 and the column anchoring longitudinal bar 3 are connected by a seam filling material 7 filling the grouting sleeve 4. A splicing seam between the reinforced-concrete foundation 2 and the prefabricated-reinforced-concrete column 1 is filled with the seam filling material 7. The grouting sleeve 4 is a conventional grouting sleeve.

(12) The seam filling material is a high-strength quick-hardening-cement-based grouting material or a steel fiber, carbon fiber or other fiber quick-hardening-cement-based grouting material or a polymer mortar material that have a compressive strength above 45 MPa.

(13) The foundation anchoring steel bar 6 is of an L shape, and comprises a vertical portion 8 and a horizontal portion 9. The vertical portion comprises an upper-portion anchoring section 81 protruding out of the upper surface of the reinforced-concrete foundation 2, a middle-portion non-adhesive section 82 buried within the foundation and a lower-portion anchoring section 83. The upper-portion anchoring section 81 protrudes into the grouting sleeve 4 and is connected to the column anchoring longitudinal bar 3. The middle-portion non-adhesive section 82 does not have adhesion to the foundation concrete. The lower-portion anchoring section 83 and the horizontal portion 9 are adhesively anchored to the foundation concrete.

(14) The exterior of the middle-portion non-adhesive section 82 is provided with an isolating sheath 10 for isolating the middle-portion non-adhesive section 82 and the concrete adhesion. The top face of the isolating sheath 10 and the upper surface of the reinforced-concrete foundation 2 flush.

(15) The length of the middle-portion non-adhesive section 82 is required to be determined by calculation. Checking calculation on flexure stability should be performed to ensure that it is not flexurally damaged, to the extent that can ensure that the steel bar of the structure does not have an excessively large plastic deformation at the design ultimate load to result in structure damage. Generally the length is 3 to 20 times the diameter of the steel bar.

(16) The isolating sheath 10 is a hard-material casing, and is a plastic tube or steel tube whose inner diameter is greater than the diameter of the middle-portion non-adhesive section, or the isolating sheath 10 is a plastic-cloth layer that wraps the middle-portion non-adhesive section after the middle-portion non-adhesive section has been applied a dedicated anti-corrosive lubricant grease. As shown in FIGS. 7-8, in the present embodiment it is a hard-material casing.

(17) As shown in FIG. 3, further in another embodiment, the middle-portion non-adhesive section 82 may also be provided with a necking section 821, and the necking section 821 has a cross-sectional area that is reduced to 50%-90% of the original cross-sectional area, in which case the isolating sheath 10 must be a hard-material casing. The necking section is a cross-section reduction that is formed by cutting, and the cross-section reduction is formed by reducing the diameter of the cross section of the steel bar of a reduction section or by cutting upper and lower sides or left and right sides of the steel bar to form a notch. As shown in FIGS. 5 and 6, the contour line 13 of the original cross section is also shown in the figures.

(18) As shown in FIG. 4, further in another embodiment, the necking section 821 may also be treated by sectional cutting, to leave at least one non-necking elastic section 822 that is not cut, which is generally 1-5 sections. The non-necking elastic sections can provide elastic support to the necking section in yielding and in turn improve the energy consumption performance of the necking section and the mechanical property of the column base joint. The non-necking elastic sections 822 are evenly distributed on the necking section 821. The non-necking elastic sections 822 divide the necking section into a plurality of subsections of similar lengths. The total length of the non-necking elastic sections 822 is not greater than a half of the total length of the necking section 821.

(19) In the present embodiment, as shown in FIG. 1, the grouting sleeve 4 is a sleeve in the form of no independent grout-injection hole whose side wall does not have a grout-injection hole and has merely a grout exiting hole 11. The prefabricated-reinforced-concrete column 1 is provided with an internal-to-column grout flowing channel 12. The internal-to-column grout flowing channel has one end in communication with the exterior of the side wall to form a sole grout-injection hole 5, and the other end in communication with the splicing seam between the reinforced-concrete foundation 2 and the prefabricated-reinforced-concrete column 1. The seam filling material 7 is grouted from the sole grout-injection hole 13, passes through the internal-to-column grout flowing channel 12, fills the splicing seam, then fills the grouting sleeve 4, and flows out of the grout exiting hole 11.

(20) At the moment, the splicing seam serves as a measure for eliminating the set-up error in the installation process, and also serves as the external-to-column grout flowing channel of the sleeve in the form of no independent grout-injection hole. The width of the splicing seam is 20-30 mm. The edge of the seam filling material that is at the splicing seam exceeds the edge of the prefabricated-reinforced-concrete column.

(21) As shown in FIG. 1, the internal-to-column grout flowing channel 12 is of a reverse L shape, and comprises a horizontal channel 121 and a vertical channel 122. The horizontal channel 121 is in communication with the exterior of the side wall. The vertical channel 122 is in communication with the splicing seam. The vertical channel 122 is located in the vertical axis of the prefabricated-reinforced-concrete column 1.

(22) A method for constructing the assembled column-base connection joint comprises the steps of the constructing as follows:

(23) Step 1: binding a foundation steel reinforcement cage and providing a template;

(24) Step 2: processing the foundation anchoring steel bar;

(25) Step 3: placing the foundation anchoring, steel bar 6 into a predetermined position in the template, installing the isolating sheath, and then pouring, concrete to form the reinforced-concrete foundation 2;

(26) Step 4: binding the column steel reinforcement cage, the column anchoring longitudinal bar 3 and the grouting sleeve 4, providing a template, and pouring concrete to form the prefabricated-reinforced-concrete column 1;

(27) Step 5: transporting the prefabricated-reinforced-concrete column 1 to a site, temporarily placing in place, inserting the foundation anchoring steel bar 6 into the grouting sleeve 4, providing a temporary support, and fixing to ensure a width of the splicing seam; wherein the position of the surface of the foundation where the prefabricated column is installed and the bottom face of the prefabricated column should be treated to be a coarse surface or be provided with a shear key slot to ensure the reliability of the shear resistance of the joint, and in performing the coarse surface treatment, the position of the template is coated a retarder, stripped, and washed by using high-pressure water, to form the coarse surface;

(28) Step 6: filling the splicing seam by using the seam filling material 7, and then grouting the seam filling material 7 into the grouting sleeve; and

(29) Step 7: after the seam filling material within the grouting sleeve has reached a required strength, dismantling the temporary support of the prefabricated-reinforced-concrete column 1, to complete the constructing of the column base joint.

(30) A method for constructing the assembled column-base connection joint comprises the steps of the constructing as follows:

(31) Step 1: binding a foundation steel reinforcement cage and providing a template;

(32) Step 2: processing the foundation anchoring steel bar;

(33) Step 3: placing the foundation anchoring steel bar 6 into a predetermined position in the template, installing the isolating sheath 10, and then pouring concrete to form the reinforced-concrete foundation 2;

(34) Step 4: binding the column steel reinforcement cage, the column anchoring longitudinal bar 3 and the grouting sleeve 4, providing an external-to-column template and an internal template of the internal-to-column grout flowing channel 12, and pouring concrete to form the prefabricated-reinforced-concrete column 1 and the internal-to-column grout flowing channel 12;

(35) Step 5: transporting the prefabricated-reinforced-concrete column 1 to a site, temporarily placing in place, inserting the foundation anchoring steel bar 6 into the grouting sleeve 4, providing a temporary support, and fixing to ensure a width of the splicing seam; wherein the position of the surface of the foundation where the prefabricated column is installed and the bottom face of the prefabricated column should be treated to be a coarse surface or be provided with a shear key slot to ensure the reliability of the shear resistance of the joint, and in performing the coarse surface treatment, the position of the template is coated a retarder, stripped, and washed by using high-pressure water, to form the coarse surface;

(36) Step 6: grouting the seam filling material 7 from the sole grout-injection hole 5, and the seam filling material 7 passing through the internal-to-column grout flowing channel 1, filling the splicing seam, then filling the grouting sleeve 4, and flowing out of the grout exiting hole 11, to pour the steel-bar connecting sleeves to be full; and

(37) Step 7: after the seam filling material within the grouting sleeve has reached a required strength, dismantling the temporary support of the prefabricated-reinforced-concrete column 1, to complete the constructing of the column base joint.

(38) In practical constructing, the foundation may be prefabricated in a plant and may also be site-poured in the construction site. Moreover, in order to monitor the strain state of the anchoring steel bar, the middle-portion non-adhesive section on the four foundation anchoring steel bars at the corners of the connection joint may be provided with strain gauges, and in practical engineering the key stressed column base joints can be spot tested to perform strain monitoring of the middle-portion non-adhesive section.

(39) The area of the column bottom of the prefabricated-reinforced-concrete column may be enclosed by a coating steel plate, which further improves the ductility of the column-base concrete, and alleviates the degree of the damage to the column base of the prefabricated column under the action of earthquakes. When the column base is treated by using the coating steel plate, the coating steel plate of the column base is poured together with the prefabricated column by using a bolt. Its thickness should be determined by calculation, to the extent that can satisfy the requirements on the constriction on the column-base concrete and ensure that the column-base concrete is not pressed to failure at the design ultimate pad. The height of the coating steel plate should be determined by calculation, to ensure that the column cross section that is adjacent to the upper end of the coating steel plate of the prefabricated column is not damaged under the load of earthquakes that rarely happen.