A double-layer reinforced precast concrete column and its joint structure

Abstract

The present invention discloses a double-layer reinforced precast concrete column and its joint structure. The inner longitudinal upper steel bars of the upper precast concrete column are cut off at the bottom surface of the joint and welded to the first end plate, while the outer longitudinal upper steel bars protrude a certain length from the bottom surface of the joint for joint anchoring. The outer longitudinal lower steel bars of the lower precast concrete column are cut off at the bottom surface of the joint and welded to the second end plate, while the inner longitudinal lower steel bars protrude a certain length from the top surface of the joint for joint anchoring. The upper precast concrete column and inner sleeve are installed together above the lower precast concrete column. The relatively enclosed space formed by the inner and outer sleeves is filled with ultra-high performance concrete slurry that compensates for shrinkage by grouting or grouting. The column is then cured at a constant temperature to the concrete's designed strength before being put into use.

Description

Technical Field

[0001] The present invention relates to the field of construction, and in particular to a precast concrete column with double reinforcement and a joint structure thereof. Background Art

[0002] With the comprehensive promotion of prefabricated and assembled concrete structures from light load and low intensity areas to medium and heavy load and high intensity areas, it is usually necessary to strengthen the reinforcement of conventional structures to adapt to higher bearing capacity and seismic ductility requirements.

[0003] Double-reinforced concrete columns, especially hollow concrete columns with double reinforcement, offer advantages such as light weight, high bearing capacity, and good ductility. They are urgently needed for widespread application in precast concrete structures. The key technology for promoting this structural form lies in precast joint technology.

[0004] Conventional wet joint connections, steel grouting sleeves or corrugated pipe grouting sleeve connections are prone to shrinkage cracks at the joints, thus affecting durability; conventional prefabricated and assembled concrete column connections are often subject to one or more loads such as tension, compression and bending moments, and the joint strength may often become a controlling factor, making it difficult to meet the high bearing capacity requirements of structures in heavy load and high-intensity areas; and some prefabricated and assembled concrete column connection forms blindly increase the size of local components or increase the structural complexity of the connection joints, resulting in poor force transmission paths between prefabricated components and excessive structural self-stress; in addition, conventional prefabricated concrete column connections (such as steel grouting sleeve connections, flange connections, etc.) require extremely high component installation accuracy. Any slight deviation will lead to failure to install smoothly, making it difficult to meet the accuracy requirements of on-site operations. Summary of the Invention

[0005] The present invention aims to solve the above-mentioned technical problems to a certain extent, and provides a double-layer reinforced precast concrete column and its joint structure to solve the technical problems such as the joints between existing prefabricated concrete support columns are easy to crack, have poor durability, have low joint strength and are difficult to meet high bearing capacity requirements, have complex joint structure and poor force transmission path, have strict joint precision requirements and are difficult to adapt to on-site operation requirements.

[0006] To solve the technical problem, the present invention provides a double-layer reinforced precast concrete column joint structure, comprising an inner sleeve fixed to an upper precast concrete column and an outer sleeve fixed to a lower precast concrete column, wherein the upper precast concrete column is provided with an inner layer of longitudinal upper steel bars and an outer layer of longitudinal upper steel bars, and the lower precast concrete column is provided with an inner layer of longitudinal lower steel bars and an outer layer of longitudinal lower steel bars;

[0007] The inner sleeve includes a first cylinder and a first annular end plate arranged in the middle of the outer side wall of the first cylinder, the first upper cylinder of the first cylinder located above the first end plate being cast in the upper precast concrete column, the first end plate being flush with the butt bottom surface of the upper precast concrete column, the diameter of the first upper cylinder being smaller than the distribution diameter of the inner layer longitudinal steel bars, the ring width of the first end plate being smaller than the spacing between the outer layer longitudinal steel bars and the outer side wall of the first cylinder, the inner layer longitudinal steel bars being cut off at the butt bottom surface and being welded to the first end plate, the outer layer longitudinal steel bars protruding out of the butt bottom surface and the protruding length being smaller than the height of the first lower cylinder of the first cylinder located below the first end plate, the interior of the first cylinder being filled with concrete of the same strength as that of the upper precast concrete column;

[0008] The outer sleeve includes a second cylinder and an annular second end plate arranged in the middle of the inner side wall of the second cylinder, the second lower cylinder of the second cylinder located below the second end plate is fixedly connected to the lower precast concrete column, the second end plate is flush with the docking top surface of the lower precast concrete column, the diameter of the second lower cylinder is larger than the distribution diameter of the outer layer longitudinal lower steel bars, the ring width of the second end plate is smaller than the spacing between the inner layer longitudinal lower steel bars and the inner side wall of the second cylinder, the outer layer longitudinal lower steel bars are cut off at the docking bottom surface and welded to the second end plate, the inner layer longitudinal lower steel bars protrude from the docking top surface and the protruding length is smaller than the height of the second upper cylinder of the second cylinder located above the second end plate, and the interior of the second lower cylinder is filled with concrete with the same strength as the lower precast concrete column;

[0009] The outer diameter of the first lower cylinder is smaller than the distributed inner diameter of the inner layer longitudinal lower steel bars, the inner diameter of the second upper cylinder is larger than the distributed outer diameter of the outer layer longitudinal upper steel bars, the heights of the first lower cylinder and the second upper cylinder are matched, and an annular grouting joint groove is formed between the first lower cylinder, the second upper cylinder, the joint bottom surface and the joint top surface; a grouting outlet is provided at the top of the annular grouting joint groove, and a grouting port is provided at the bottom of the annular grouting joint groove; ultra-high performance concrete is filled in the annular grouting joint groove to form a grouting layer.

[0010] Preferably, the bottom surface of the concrete filled in the first cylinder and the top surface of the concrete filled in the second lower cylinder are respectively provided with positioning protrusions and positioning grooves that match each other.

[0011] Preferably, an adjustment pad is provided between the bottom surface of the concrete filled in the first cylinder and the top surface of the concrete filled in the second lower cylinder, and the shape of the adjustment pad matches the shape and distribution of the paired positioning protrusions and positioning grooves.

[0012] Preferably, the inner side surface and the outer side surface of the first cylinder and the inner side surface of the second cylinder are all provided with horizontal annular shear keys and vertical shear keys.

[0013] Preferably, the first cylinder and the first end plate are fixed by welding or integrally cast; the second cylinder and the second end plate are fixed by welding or integrally cast.

[0014] Preferably, a buttress shear key or a shear key is provided at the connection between the outer side wall of the first cylinder body of the inner sleeve and the first end plate; a buttress shear key or a shear key is provided at the connection between the inner side wall of the second cylinder body of the outer sleeve and the second end plate.

[0015] Preferably, the size of the butt joint top surface of the lower precast concrete column is greater than or equal to the size of the butt joint bottom surface of the upper precast concrete column.

[0016] Preferably, an adjustment groove is carved on the outer side wall of the lower end of the upper precast concrete column near the docking bottom surface, and the size of the adjustment groove matches the size of the second upper cylinder.

[0017] Preferably, the inner diameter of the second upper cylinder is greater than or equal to the size of the upper precast concrete column.

[0018] Preferably, it further comprises a slurry discharge pipe, wherein the slurry discharge pipe is connected to the slurry discharge port and the horizontal height of the slurry discharge hole at the free end of the slurry discharge pipe is higher than the horizontal height of the upper end of the adjustment tank.

[0019] The present invention also provides a double-layer reinforced precast concrete column, comprising an upper precast concrete column and a lower precast concrete column, wherein the connection between the upper precast concrete column and the lower precast concrete column adopts the double-layer reinforced precast concrete column joint structure as described in any one of the above items.

[0020] In the double-layer reinforced precast concrete column and its joint structure in the technical solution of the present invention, the upper precast concrete column is provided with an inner layer of longitudinal upper steel bars and an outer layer of longitudinal upper steel bars, and the lower precast concrete column is provided with an inner layer of longitudinal lower steel bars and an outer layer of longitudinal lower steel bars. The upper precast concrete column is butt-jointed with the lower precast concrete column, and the double-layer longitudinal reinforcement includes an outer layer of longitudinal reinforcement and an inner layer of longitudinal reinforcement; the inner layer of longitudinal upper reinforcement of the upper precast concrete column is cut off at the butt bottom surface and welded to the first end plate, and the outer layer of longitudinal upper reinforcement protrudes out of the butt bottom surface for a certain length for joint anchoring; the outer layer of longitudinal lower reinforcement of the lower precast concrete column is cut off at the butt bottom surface and welded to the second end plate, and the inner layer of longitudinal lower reinforcement protrudes out of the butt top surface for a certain length for joint anchoring; after the lower precast concrete column and the outer sleeve are prefabricated in place together, the upper precast concrete column and the inner sleeve are installed together above the lower precast concrete column, and the relatively closed space formed by the inner and outer sleeves is filled with ultra-high performance concrete slurry that compensates for shrinkage by grouting or seating, and can be put into use after constant temperature curing to the design strength of the concrete. The double-layer reinforced precast concrete column and its joint structure in the technical solution of the present invention have the advantages of strong nodes, continuous reinforcement, adjustable height, and automatic centering. The core filling can transfer the axial force in the first phase load and reduce the axial compression ratio of the joint. It can be applied to column-to-column connection, base-to-column connection, column-to-cap beam connection, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0023] In the attached figure:

[0024] Figure 1 A longitudinal cross-sectional view of a precast concrete column joint structure with double reinforcement in a split state according to an embodiment of the present invention;

[0025] Figure 2 A longitudinal cross-sectional view of a precast concrete column joint structure with double reinforcement in an embodiment of the present invention in a assembled state;

[0026] Figure 3 Schematic diagram of the partial assembly structure of the outer sleeve with shear keys and the outer longitudinal lower reinforcement;

[0027] Figure 4 This is a schematic diagram of the partial assembly structure of the inner sleeve and the inner longitudinal reinforcement;

[0028] Figure 5 This is an enlarged view of the specific structure of a double-layer reinforced precast concrete column joint structure in one embodiment of the present invention;

[0029] Figure 6 It is a longitudinal cross-sectional view of a precast concrete column joint structure with variable diameter and double-layer reinforcement in another specific embodiment in a assembled state. DETAILED DESCRIPTION

[0030] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific embodiments of the present invention are now described in detail with reference to the accompanying drawings. In the following description, it should be understood that the directions or positional relationships indicated by "front", "back", "up", "down", "left", "right", "longitudinal", "horizontal", "vertical", "horizontal", "top", "bottom", "inside", "outside", "head", "tail", etc. are based on the directions or positional relationships shown in the accompanying drawings and are constructed and operated in specific directions. They are only for the convenience of describing the technical solution and do not indicate that the devices or components referred to must have specific directions. Therefore, they should not be understood as limiting the present invention.

[0031] It should also be noted that, unless otherwise clearly specified and limited, terms such as "installed", "connected", "connected", "fixed", and "set" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. When an element is referred to as being "on" or "under" another element, the element can be "directly" or "indirectly" located on the other element, or there may be one or more intervening elements. The terms "first", "second", "third", etc. are only for the convenience of describing the present technical solution, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second", "third", etc. may explicitly or implicitly include one or more of such features. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0032] In the following description, specific details such as particular system structures and techniques are provided for purposes of illustration, not limitation, to facilitate a thorough understanding of the embodiments of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.

[0033] like Figure 1-5 Figure 1 shows a double-reinforced precast concrete column 100 provided in one embodiment of the present invention. The column comprises an upper precast concrete column 10, a lower precast concrete column 20, an inner sleeve (not numbered), and an outer sleeve (not numbered). The inner sleeve is secured to the upper precast concrete column 10, and the outer sleeve is secured to the lower precast concrete column 20.

[0034] The upper precast concrete column 10 and the lower precast concrete column 20 are both double-layer reinforced. The upper precast concrete column 10 is provided with an inner layer of longitudinal upper steel bars 101 and an outer layer of longitudinal upper steel bars 102, and the lower precast concrete column 20 is provided with an inner layer of longitudinal lower steel bars 201 and an outer layer of longitudinal lower steel bars 202.

[0035] The upper precast concrete column 10 and the lower precast concrete column 20 are butt-jointed and installed via the butt-jointed structure designed in this embodiment.

[0036] Please combine Figure 1-2 as well as Figure 4 The inner sleeve includes a first cylinder 111 and an annular first end plate 112 arranged in the middle of the outer wall of the first cylinder 111. The first upper cylinder 1111 of the first cylinder 111 located above the first end plate 112 is cast in the upper precast concrete column 10. The first end plate 112 is flush with the docking bottom surface 31 of the upper precast concrete column 10. The diameter of the first upper cylinder 1111 is smaller than the distribution diameter of the inner longitudinal steel bars 101. The ring width of the first end plate 112 is The outer longitudinal steel bars 102 are smaller than the distance between the outer side wall of the first cylinder 111, the inner longitudinal steel bars 101 are cut off at the docking bottom surface 31 and welded to the first end plate 112, the outer longitudinal steel bars 102 protrude from the docking bottom surface 31 and the protruding length is smaller than the height of the first lower cylinder 1112 of the first cylinder 111 located below the first end plate 112, and the interior of the first cylinder 111 is filled with concrete with the same strength as that of the upper precast concrete column 10.

[0037] The distribution diameter of the inner longitudinal steel bars 101 refers to the size of the inner longitudinal steel bars 101 distributed circumferentially along the upper precast concrete column 10. Generally speaking, if the upper precast concrete column 10 is cylindrical, the inner longitudinal steel bars 101 are also distributed in a ring shape, and the distribution diameter refers to the diameter of the ring formed by the inner longitudinal steel bars 101. If the upper precast concrete column 10 is a square column, the distribution diameter refers to the side length of the square formed by the inner longitudinal steel bars 101. Similarly, the distribution diameters of the outer longitudinal steel bars 102, the inner longitudinal lower steel bars 201, and the outer longitudinal lower steel bars 202 described below in this embodiment have the same meanings as above and will not be repeated hereafter.

[0038] The outer sleeve includes a second cylinder 211 and an annular second end plate 212 arranged in the middle of the inner wall of the second cylinder 211. The second lower cylinder 2111 of the second cylinder 211 located below the second end plate 212 is fixedly connected to the lower precast concrete column 20. The second end plate 212 is flush with the docking top surface 32 of the lower precast concrete column 20. The diameter of the second lower cylinder 2111 is larger than the distribution diameter of the outer layer longitudinal lower steel bars 202, and the ring width of the second end plate 212 is smaller than The distance between the inner layer longitudinal lower steel bar 201 and the inner side wall of the second cylinder 211, the outer layer longitudinal lower steel bar 202 is cut off at the docking bottom surface 32 and welded to the second end plate 212, the inner layer longitudinal lower steel bar 201 protrudes out of the docking top surface 32 and the protruding length is less than the height of the second upper cylinder 2112 of the second cylinder 211 located above the second end plate 212, and the interior of the second lower cylinder 2111 is filled with concrete with the same strength as the lower precast concrete column 20.

[0039] The second lower cylinder 2111 and the lower precast concrete column 20 may be fixedly connected by pouring the second lower cylinder 2111 on the end of the lower precast concrete column 20, or by welding, bolting, riveting, or the like.

[0040] The first cylinder 111 is filled with concrete of the same strength as the upper precast concrete column 10, and the second lower cylinder 2111 is filled with concrete of the same strength as the lower precast concrete column 20. The core filling can transfer the axial force in the primary load and reduce the axial compression ratio of the joint.

[0041] The outer diameter of the first lower cylinder 1112 is smaller than the distributed inner diameter of the inner layer longitudinal lower steel bar 201, the inner diameter of the second upper cylinder 2112 is larger than the distributed outer diameter of the outer layer longitudinal upper steel bar 102, the height of the first lower cylinder 1112 and the second upper cylinder 2112 are matched, and an annular grouting docking groove is formed between the first lower cylinder 1112, the second upper cylinder 2112, the docking bottom surface 31 and the docking top surface 32.

[0042] A grouting port 41 is provided at the top of the annular grouting butt joint groove 40 , and a grouting port 42 is provided at the bottom of the annular grouting butt joint groove; ultra-high performance concrete is filled in the annular grouting butt joint groove to form a grouting layer.

[0043] In this embodiment, the inner layer of longitudinal upper steel bars 101 of the upper precast concrete column 10 is cut off at the butt bottom surface 31 and welded to the first end plate 112, and the outer layer of longitudinal upper steel bars 102 protrudes from the butt bottom surface 31 for a certain length for joint anchoring; the outer layer of longitudinal lower steel bars 202 of the lower precast concrete column 20 is cut off at the butt bottom surface 32 and welded to the second end plate 212, and the inner layer of longitudinal lower steel bars 201 protrudes from the butt top surface 32 for a certain length for joint anchoring; after the lower precast concrete column 10 and the outer sleeve are prefabricated in place together, the precast body consisting of the upper precast concrete column 10 and the inner sleeve is installed together above the lower precast concrete column 20, and the relatively closed space formed by the inner and outer sleeves is filled with ultra-high performance concrete slurry that compensates for shrinkage by grouting or seating grouting, and can be put into use after constant temperature curing to the design strength of the concrete.

[0044] Furthermore, in an optional embodiment, the bottom surface of the concrete filled in the first cylinder 111 and the top surface of the concrete filled in the second lower cylinder 2111 are respectively provided with matching positioning protrusions 61 and positioning grooves 62. Specifically, the matching positioning protrusions 61 and positioning grooves 62 can facilitate the positioning of the upper precast concrete column 10 and the lower precast concrete column 20 during docking, making positioning simpler and more accurate.

[0045] Furthermore, in an optional embodiment, an adjustment pad 50 is provided between the bottom surface of the concrete filled in the first cylinder 111 and the top surface of the concrete filled in the second lower cylinder 2111. The shape of the adjustment pad 50 matches the shape and distribution of the paired positioning protrusions and positioning grooves. The height of the joint structure can be adjusted by the arrangement of the adjustment pad 50.

[0046] Furthermore, in an optional embodiment, the outer layer longitudinal upper steel bars 102, the inner layer longitudinal upper steel bars 101, the outer layer longitudinal lower steel bars 202, and the inner layer longitudinal lower steel bars 201 are all bundled with stirrups.

[0047] Please combine Figure 3 and Figure 5 Furthermore, in an optional embodiment, the inner and outer sides of the first and second cylinders 111 and 211 are both provided with horizontal circumferential shear keys 71 and vertical shear keys 72. The shear keys can increase the bond strength between the concrete and the sleeve in all directions, providing tensile, compressive, and torsional bearing capacity.

[0048] Furthermore, in an optional embodiment, the first cylinder 111 and the first end plate 112 are fixed by welding or integrally cast; the second cylinder 211 and the second end plate 212 are fixed by welding or integrally cast.

[0049] Furthermore, please combine the diagram Figure 2 and Figure 5 In an optional embodiment, an adjustment groove 90 is carved on the outer wall of the lower end of the upper precast concrete column 10 near the docking bottom surface 31, and the size of the adjustment groove matches the size of the second upper cylinder 2112.

[0050] In this embodiment, slurry is discharged by providing a slurry discharge pipe 400. The slurry discharge pipe 400 is connected to the slurry discharge port 41, and the slurry discharge hole at the free end of the slurry discharge pipe 400 is higher than the level of the upper end of the adjustment tank 90. It is understood that the grouting port 42 is also connected to a slurry inlet pipe (not numbered in the figure).

[0051] Please combine Figure 6 Furthermore, in an optional embodiment, the size of the docking top surface 32 of the lower precast concrete column 20 is greater than or equal to the size of the docking bottom surface 31 of the upper precast concrete column 10 .

[0052] Furthermore, in an optional embodiment, the size of the second upper cylinder 2112 is larger than the size of the upper precast concrete column 10 .

[0053] Specifically, the end structural dimensions and forms of the upper and lower precast concrete columns can be the same or different, and can be of any equal shape, any same shape with a large-enclosed small shape, or any different shape with a large-enclosed small shape (including round-enclosed square, square-enclosed round, etc.).

[0054] This embodiment also provides a computer verification method for various design parameters of a double-layer reinforced precast concrete column joint structure to assist in illustrating the technical effects of this embodiment.

[0055] (1) Equivalent shear thickness of sleeve:

[0056]

[0057] ——Equivalent shear thickness of sleeve (unit: mm);

[0058] t——sleeve wall thickness (unit: mm);

[0059] A r ——Horizontal shear key cross-sectional area (unit: mm 2 );

[0060] l r ——The length of the horizontal shear key within a single standard horizontal shear key spacing (unit: mm) 2 );

[0061] A ex ——The sleeve expansion area within a single standard horizontal shear key spacing (unit: mm 2 );

[0062] (2) Equivalent tensile and compressive thickness of sleeve:

[0063]

[0064] ——Equivalent tensile and compressive thickness of sleeve (unit: mm);

[0065] t——sleeve wall thickness (unit: mm);

[0066] A se ——Cross-sectional area of sleeve wall (unit: mm 2 );

[0067] A a ——Vertical shear key cross-sectional area (unit: mm 2 );

[0068] n——number of vertical shear keys in the section;

[0069] The calculation method of the inner and outer sleeve thickness is:

[0070] (1) Method 1: Equivalent stirrup method:

[0071] 1) Stirrup ratio of standard section area:

[0072]

[0073] P sv ——Standard section area stirrup ratio (%);

[0074] A su ——Total cross-sectional area of stirrups arranged within a single standard stirrup spacing (unit: mm 2 );

[0075] S v ——Standard stirrup spacing (unit: mm);

[0076] b——section width (unit: mm);

[0077] According to the equivalent stirrup method, the restraint capacity of the steel sleeve and stirrups within a single standard stirrup spacing is equal, that is, the sleeve wall converted thickness is:

[0078]

[0079] ——Equivalent shear thickness of sleeve (unit: mm);

[0080] P sv ——Stirrup ratio of standard section area (%);

[0081] b——section width (unit: mm);

[0082] f sd ——Design tensile and compressive strength of stirrups (unit: MPa);

[0083] f ttd ——Design tensile and compressive strength of sleeve wall (unit: MPa);

[0084] 2) Standard section volume stirrup ratio:

[0085]

[0086] p v ——Standard section volume stirrup ratio (%);

[0087] A sv ——Total cross-sectional area of stirrups arranged within a single standard stirrup spacing (unit: mm 2 );

[0088] A cor ——Cross-sectional area of core area concrete (unit: mm 2 );

[0089] l sv ——the length of stirrups within a single standard spacing (unit: mm);

[0090] s v ——Standard stirrup spacing (unit: mm);

[0091] According to the equivalent stirrup method, the volume of the steel sleeve and stirrups is equal within a single standard stirrup spacing, that is, the sleeve wall converted thickness is:

[0092]

[0093] ——Equivalent shear thickness of sleeve (unit: mm);

[0094] P v ——Standard section volume stirrup ratio (%);

[0095] A cor ——Cross-sectional area of core area concrete (unit: mm 2 );

[0096] In summary, the equivalent sleeve thickness calculated by the equivalent hoop method can be taken as:

[0097]

[0098] (2) Method 2: Determination by equivalent longitudinal reinforcement method

[0099] Standard segment longitudinal reinforcement ratio:

[0100]

[0101] P s ——Standard segment longitudinal reinforcement ratio (%);

[0102] A s ——Total cross-sectional area of longitudinal reinforcement in the section (unit: mm 2 );

[0103] A0——Effective cross-sectional area (unit: mm 2 );

[0104] According to the equivalent longitudinal reinforcement method, the tensile and compressive capacity of the steel sleeve and the longitudinal reinforcement are equal, that is, the sleeve wall converted thickness is:

[0105]

[0106] ——Equivalent tensile and compressive thickness of sleeve (unit: mm);

[0107] P s ——Longitudinal reinforcement ratio of standard section (%);

[0108] L a ——sleeve circumference (unit: mm);

[0109] f sd ——Design tensile and compressive strength of longitudinal reinforcement (unit: MPa);

[0110] f ttd ——Design tensile and compressive strength of sleeve wall (unit: MPa);

[0111] (3) Design and calculation method of sleeve wall thickness and horizontal and vertical shear keys

[0112] From the above content, it can be seen that due to the existence of horizontal and vertical shear keys, the sleeve wall thickness has different equivalent thicknesses in the shear and tensile and compressive directions respectively. Considering economy, a suitable basic wall thickness can be set, and then different horizontal and vertical shear keys can be set to match different wall thickness requirements.

[0113] In actual application, t (unit: mm) can be rounded up and shall not be less than 2 mm.

[0114] The calculation method of the vertical length of the inner and outer sleeves is:

[0115] Once the pull-out resistance of the sleeve and steel bar is determined, the structural dimensions and arrangement spacing of the horizontal and vertical shear keys can be adjusted accordingly.

[0116] Calculation method for the minimum length of the end reinforcement extending from the upper (lower) surface of the concrete column:

[0117] 1) The minimum length of the inner ring steel bars extending from the upper surface of the lower concrete column is:

[0118]

[0119] L i min ——The minimum length of the inner ring steel bars extending from the upper surface of the lower concrete column (mm);

[0120] L ia ——The minimum anchorage length of the inner ring steel bar in the grouting material, the upsetting steel bar is 15d is , straight steel bar takes 20 d is (mm);

[0121] ——Adjustable value of the joint, see the diagram for details (unit: mm);

[0122] d is ——Diameter of inner ring steel bar (unit: mm).

[0123] 2) The minimum length of the outer ring steel bars extending from the lower surface of the upper concrete column is:

[0124]

[0125] L o min ——The minimum length of the outer ring steel bars extending from the lower surface of the upper concrete column (mm);

[0126] L oa——The minimum anchorage length of the outer ring steel bar in the grouting material, the upsetting steel bar is 15d os , straight steel bar takes 20 d os (mm);

[0127] d os ——Diameter of outer ring steel bar (unit: mm).

[0128] The calculation method for the minimum exposed height above the end plate of the outer sleeve (of the lower concrete column) is:

[0129]

[0130] L s min ——Minimum exposed height above the end plate of the outer sleeve of the lower concrete column (mm);

[0131] L i min ——The minimum length of the inner ring steel bars extending from the upper surface of the lower concrete column (mm);

[0132] L o min ——The minimum length of the outer ring steel bars extending from the lower surface of the upper concrete column (mm);

[0133] ——Adjustable value of the connector.

[0134] The calculation method for the minimum exposed height below the inner sleeve end plate (of the upper concrete column) is:

[0135]

[0136] L i min ——Minimum exposed height below the inner sleeve end plate of the upper concrete column (mm);

[0137] L i min ——The minimum length of the inner ring steel bars extending from the upper surface of the lower concrete column (mm);

[0138] L o min ——The minimum length of the outer ring steel bars extending from the lower surface of the upper concrete column (mm).

[0139] All longitudinal reinforcements extending into the confined space of the grouting are swaged steel bars, which can significantly reduce the anchorage length of the steel bars.

[0140] It is understandable that the above embodiments only express the preferred implementation modes of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the patent scope of the present invention. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present invention, the above technical features can be freely combined, and several deformations and improvements can be made, all of which fall within the scope of protection of the present invention. Therefore, all equivalent changes and modifications made to the scope of the claims of the present invention should fall within the scope of coverage of the claims of the present invention.

Claims

1. A double-layer reinforced precast concrete column joint structure, comprising an inner sleeve fixed to an upper precast concrete column and an outer sleeve fixed to a lower precast concrete column, wherein: The upper precast concrete column is provided with an inner layer of longitudinal upper steel bars and an outer layer of longitudinal upper steel bars, and the lower precast concrete column is provided with an inner layer of longitudinal lower steel bars and an outer layer of longitudinal lower steel bars; it is characterized in that: The inner sleeve includes a first cylinder and a first annular end plate arranged in the middle of the outer side wall of the first cylinder, the first upper cylinder of the first cylinder located above the first end plate being cast in the upper precast concrete column, the first end plate being flush with the butt bottom surface of the upper precast concrete column, the diameter of the first upper cylinder being smaller than the distribution diameter of the inner layer longitudinal steel bars, the ring width of the first end plate being smaller than the spacing between the outer layer longitudinal steel bars and the outer side wall of the first cylinder, the inner layer longitudinal steel bars being cut off at the butt bottom surface and being welded to the first end plate, the outer layer longitudinal steel bars protruding out of the butt bottom surface and the protruding length being smaller than the height of the first lower cylinder of the first cylinder located below the first end plate, the interior of the first cylinder being filled with concrete of the same strength as that of the upper precast concrete column; The outer sleeve includes a second cylinder and an annular second end plate arranged in the middle of the inner side wall of the second cylinder, the second lower cylinder of the second cylinder located below the second end plate is fixedly connected to the lower precast concrete column, the second end plate is flush with the docking top surface of the lower precast concrete column, the diameter of the second lower cylinder is larger than the distribution diameter of the outer layer longitudinal lower steel bars, the ring width of the second end plate is smaller than the spacing between the inner layer longitudinal lower steel bars and the inner side wall of the second cylinder, the outer layer longitudinal lower steel bars are cut off at the docking bottom surface and welded to the second end plate, the inner layer longitudinal lower steel bars protrude from the docking top surface and the protruding length is smaller than the height of the second upper cylinder of the second cylinder located above the second end plate; The outer diameter of the first lower cylinder is smaller than the distributed inner diameter of the inner layer longitudinal lower steel bars, the inner diameter of the second upper cylinder is larger than the distributed outer diameter of the outer layer longitudinal upper steel bars, the heights of the first lower cylinder and the second upper cylinder are matched, and an annular grouting joint groove is formed between the first lower cylinder, the second upper cylinder, the joint bottom surface and the joint top surface; a grouting outlet is provided at the top of the annular grouting joint groove, and a grouting port is provided at the bottom of the annular grouting joint groove; ultra-high performance concrete is filled in the annular grouting joint groove to form a grouting layer.

2. The double-layer reinforced precast concrete column joint structure according to claim 1, characterized in that: The bottom surface of the concrete filled in the first cylinder and the top surface of the concrete filled in the second lower cylinder are respectively provided with positioning protrusions and positioning grooves that match each other.

3. The double-layer reinforced precast concrete column joint structure according to claim 2, characterized in that: An adjustment pad is provided between the bottom surface of the concrete filled in the first cylinder and the top surface of the concrete filled in the second lower cylinder. The shape of the adjustment pad matches the shape and distribution of the paired positioning protrusions and positioning grooves.

4. The double-layer reinforced precast concrete column joint structure according to claim 1, characterized in that: The inner side surface and the outer side surface of the first cylinder and the inner side surface of the second cylinder are all provided with horizontal annular shear keys and vertical shear keys.

5. The double-layer reinforced precast concrete column joint structure according to claim 1, characterized in that: The first cylinder and the first end plate are fixed by welding or integrally cast; the second cylinder and the second end plate are fixed by welding or integrally cast.

6. The double-layer reinforced precast concrete column joint structure according to claim 1, characterized in that: The size of the butt joint top surface of the lower precast concrete column is greater than or equal to the size of the butt joint bottom surface of the upper precast concrete column.

7. The double-layer reinforced precast concrete column joint structure according to claim 6, characterized in that: An adjustment groove is carved on the outer side wall of the lower end of the upper precast concrete column near the docking bottom surface, and the size of the adjustment groove matches the size of the second upper cylinder.

8. The double-layer reinforced precast concrete column joint structure according to claim 7, characterized in that: The inner diameter of the second upper cylinder is greater than or equal to the size of the upper precast concrete column.

9. The double-layer reinforced precast concrete column joint structure according to claim 7, characterized in that: It also includes a slurry discharge pipe, which is connected to the slurry discharge port and the horizontal height of the slurry discharge hole at the free end of the slurry discharge pipe is higher than the horizontal height of the upper end of the adjustment tank.

10. A double-layer reinforced precast concrete column, comprising an upper precast concrete column and a lower precast concrete column, characterized in that: The connection between the upper precast concrete column and the lower precast concrete column adopts the double-layer reinforced precast concrete column joint structure according to any one of claims 1 to 9.

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