A prefabricated building concrete frame column dry type grouting-free rapid connecting structure and connecting method

Abstract

The application discloses a dry grouting-free quick connecting structure and method for a fabricated building concrete frame column. A lower prefabricated column head extends a round-head bolt-shaped vertical steel bar, and a shear key with an anchor steel bar is pre-buried in the center of the column head; a trapezoidal key head is arranged at the end of the shear key; a column head sleeve is arranged on the upper prefabricated column head, a bottom end head anchoring plate is fixedly connected, bolt holes matched with the vertical steel bar and offset communication through bolt holes are formed in the anchoring plate, and the two are extended upwards to form a closed vertical steel bar protection cylinder; a shear key hole is formed in the center of the protection cylinder and is extended upwards to form a shear key protection cylinder; an inclined tongue plate is welded to the inner side wall of the protection cylinder; an anchor steel bar and a stiffening rib plate are welded to the anchoring plate; and tie steel bars are welded to the inner side of the sleeve. During installation, the upper column hole position is aligned with the lower column bolt head and the shear key, and then the bolt head is moved to the left, the bolt head is inserted into the through bolt hole, the shear key is pushed into the protection cylinder and is automatically clamped by the tongue plate to realize self-bearing fixation. The application is dry assembled, grouting-free welded and installed quickly, is reliable in stress, and does not need complex support.

Description

Technical Field

[0001] This invention belongs to the field of prefabricated concrete building structure engineering, specifically relating to a vertical connection node structure and connection method for prefabricated concrete frame columns, and in particular a rapid connection structure that enables dry assembly of upper and lower precast columns without grouting or welding. Background Technology

[0002] With the rapid advancement of my country's construction industrialization, prefabricated concrete buildings have been widely used. In prefabricated concrete frame structures, the frame columns, as the main vertical load-bearing components, are crucial for structural safety through their vertical connection. Currently, the following technical solutions are commonly used for the vertical connection of prefabricated concrete frame columns: 1. Rebar sleeve grouting connection: The longitudinal reinforcement of the upper and lower columns is inserted into pre-embedded sleeves, and high-strength grout is injected under high pressure to bond and transfer force. This technology is currently the most widely used connection method in engineering. However, sleeve grouting is a concealed project, and incomplete grouting, voids, and leaks are difficult to detect, easily leaving structural safety hazards. In addition, the on-site mixing and injection of grout are greatly affected by weather and temperature, and normal construction cannot be carried out under low-temperature conditions in winter, making it difficult to guarantee the construction period. 2. Rebar grout anchor lap connection: Holes are reserved at the ends of the prefabricated columns, and the upper and lower column reinforcements are lapped in the holes, with grout injected later for anchoring and force transfer. This method also suffers from problems such as a large amount of on-site wet work, difficulty in inspecting grouting quality, and frequent occurrences of dense reinforcement within the holes and incomplete concrete pouring. 3. Dry connection with steel flange bolts: Steel plate flanges are pre-embedded at the column ends and spliced ​​by locking with high-strength bolts. This method achieves a dry connection, but the joint stiffness of purely bolted connections is insufficient, resulting in poor seismic ductility and susceptibility to brittle failure under seismic loads. 4. On-site reinforcement lap splicing + post-cast concrete: On-site lap splicing of reinforcement bars, formwork, and in-situ pouring of joint concrete result in a large amount of on-site wet work, long curing time, and a long construction period. Low temperatures in winter prevent normal construction, which does not conform to the core concept of rapid construction in prefabricated buildings. 5. On-site welding butt connection of longitudinal reinforcement: High temperatures during on-site welding can easily damage the base material of the reinforcement bars, resulting in unstable weld quality and high safety risks associated with high-altitude welding. There is an urgent need for a new type of prefabricated frame column connection structure that is rationally stressed, easy to install, has controllable quality, and excellent seismic performance. Summary of the Invention

[0003] To address the aforementioned problems in existing technologies, this invention provides a dry, grout-free, rapid connection structure and method for prefabricated building concrete frame columns.

[0004] The object of this invention is achieved in the following manner: A dry, grout-free, quick-connect structure for prefabricated concrete frame columns includes an upper prefabricated column and a lower prefabricated column. Vertical reinforcing bars are installed inside the lower prefabricated column. The ends of the vertical reinforcing bars extending out of the column head are vertical reinforcing bar connecting bolts, which are round-headed bolts. A shear key is pre-embedded in the center of the column head of the lower prefabricated column. Anchor reinforcing bars are welded to the pre-embedded end of the shear key. The anchor reinforcing bars are set along the length of the shear key to firmly anchor the shear key in the lower prefabricated column. A trapezoidal shear key head is provided at the end of the shear key. The upper precast column is fitted with a column head sleeve. The outer diameter of the column head sleeve is the same as the outer diameter of the lower precast column, and the inner diameter is the same as the outer diameter of the column head of the lower precast column. An end anchor plate is fixedly installed at the bottom of the column head sleeve. The end anchor plate is provided with rebar connection bolt holes that match the position, quantity and size of the vertical rebar. A through bolt hole is provided next to each rebar connection bolt hole. The through bolt hole and the rebar connection bolt hole are interconnected and offset by 30-60°. The diameter of the through bolt hole is the same as the diameter of the vertical rebar connection bolt head. The through bolt hole and the rebar connection bolt hole extend upward towards the precast column to form a vertical rebar sleeve. The upper surface of the vertical rebar sleeve is closed. The length of the vertical rebar sleeve is the same as the height of the vertical rebar connection bolt head. The end anchor plate is also provided with a shear key hole in the center. The shear key hole extends upward towards the precast column to form a shear key sleeve. The upper surface of the shear key sleeve is closed. The size of the shear key sleeve matches the size of the shear key. A tongue plate is welded to the inner wall of the shear key sleeve. The tongue plate is used to clamp the shear key. Anchor bars are welded to the upper surface of the end anchor plate to firmly anchor the end anchor plate into the upper precast column. Stiffening ribs are also welded to the upper surface of the end anchor plate. The stiffening ribs include transverse ribs and vertical ribs, which intersect in a cross shape. The transverse ribs and vertical ribs are disconnected at the shear key sleeve. Tie bars are welded to the middle position of the upper part of the column head sleeve and fixed to the steel bars in the upper precast column.

[0005] The diameter of the bolt head for connecting vertical reinforcing bars is 1.5 times the diameter of the vertical reinforcing bar.

[0006] The bolt hole is offset by 45° from the bolt hole connecting to the reinforcing bar.

[0007] The ends of the horizontal and vertical stiffening ribs are bent and welded to the inner wall of the column head sleeve.

[0008] The end plate anchor bars are L-shaped, with four bars evenly distributed within the upper precast column.

[0009] The shear key casing is made of thick-walled steel pipe with a rectangular cross-section.

[0010] A method for dry, grout-free, rapid connection of concrete frame columns in prefabricated buildings includes the following steps. (1) Fabrication of lower precast columns Multiple vertical steel bars with round-headed bolt-like ends extend evenly around the column head of the lower precast column, and a shear key is pre-embedded in the center of the column head of the lower precast column; (2) Fabricate column head sleeves and end anchor plates Rebar connection bolt holes matching the position, quantity, and size of the vertical rebars are made on the end anchor plate. A through bolt hole, which is connected to each rebar connection bolt hole and offset by 30-60°, is made next to it. The diameter of the through bolt hole is the same as the diameter of the vertical rebar connection bolt head. A vertical rebar sleeve with a closed upper surface is welded upward at the through bolt hole and the rebar connection bolt hole. A shear key hole is made in the center of the end anchor plate. A shear key sleeve with a closed upper surface is welded upward at the shear key hole. An inwardly inclined tongue plate is welded to the inner side wall of the shear key sleeve. The column head sleeve is fixedly connected along the edge of the end anchor plate. End plate anchor bars and stiffening ribs are welded to the upper surface of the end anchor plate to form a sleeve assembly. (3) Fabrication of precast columns The sleeve assembly is fitted onto the top of the upper precast column. Tie bars are welded to the middle position inside the sleeve of the column head and fixedly connected to the steel bars inside the upper precast column. Concrete is poured to anchor the sleeve assembly to the top of the upper precast column. (4) Lift the upper precast column and align the bolt holes and shear key holes at the ends of the upper precast column with the steel bar connection bolts and shear keys at the head of the lower precast column, respectively. (5) Move the upper precast column to the lower right so that the steel bar connector head and the shear key are completely inserted into the bolt hole and the shear key hole respectively. The tongue plate of the shear key sleeve on the long side wall automatically clamps the shear key to achieve self-supporting temporary fixation. (6) Check the connection and positioning of the upper and lower precast columns. Once it is confirmed that there are no abnormalities, the installation is complete.

[0011] Compared with existing technologies, this invention achieves dry assembly of upper and lower precast columns, eliminating the need for on-site welding and grouting, resulting in fast installation and high precision; it integrates vertical bearing capacity, bending resistance, shear resistance, and seismic energy dissipation, ensuring reliable stress at the nodes; it features self-positioning and leveling, and self-supporting temporary fixation, eliminating the need for complex supports. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the structure of the present invention.

[0013] Figure 2 This is a top view of the precast column according to the present invention.

[0014] Figure 3 This is a perspective view of the precast column according to the present invention.

[0015] Figure 4 This is a top-view perspective view of the precast column of the present invention.

[0016] Figure 5This is a bottom view of the precast column of the present invention.

[0017] Schematic diagram of the shear key structure.

[0018] In the diagram: 1-Upper precast column, 2-End anchor plate, 3-Column head sleeve, 4-Shear key sleeve, 5-Tilting plate, 6-Stiffening rib, 7-End plate anchor bar, 8-Tie bar; 9-Pulley hole, 10-Rebar connection bolt hole, 11-Shear key, 12-Shear key head, 13-Vertical reinforcement, 14-Vertical reinforcement connection bolt head, 15-Anchored reinforcement, 16-Rebar connection bolt head sleeve, 18-Lower precast column. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. After reading the contents of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by this invention.

[0020] like Figure 1-3 As shown, this invention discloses a dry, grout-free, quick-connect structure for prefabricated concrete frame columns, including an upper prefabricated column 1 and a lower prefabricated column 18. Vertical reinforcing bars 13 are installed inside the lower prefabricated column 18. The ends of the vertical reinforcing bars 13 extending out of the column head are vertical reinforcing bar connecting bolt heads 14, which are round-headed bolts. A shear key 11 is pre-embedded in the center of the column head of the lower prefabricated column 18. Anchor reinforcing bars 15 are welded to the pre-embedded end of the shear key 11. The anchor reinforcing bars 15 are arranged along the length direction of the shear key 11 to firmly anchor the shear key 11 into the lower prefabricated column 18. A trapezoidal shear key head 12 is provided at the end of the shear key.

[0021] like Figure 1 , Figure 4 and Figure 5 As shown, a column head sleeve 3 is fitted onto the column head of the upper precast column 1. The outer diameter of the column head sleeve 3 is the same as the outer diameter of the lower precast column 18, and the inner diameter is the same as the outer diameter of the column head of the lower precast column 1. The bottom of the column head sleeve 3 is fixedly connected to the end anchor plate 2. The end anchor plate 2 is provided with steel bar connection bolt holes 10 that match the position, quantity, and size of the vertical steel bars 13. A bolt hole 9 is provided next to each steel bar connection bolt hole 10. The bolt hole 9 and the steel bar connection bolt hole 10 are interconnected and offset by 30-60°. The diameter of the bolt hole 9 is the same as the diameter of the vertical steel bar connection bolt head 14. The bolt hole 9 and the steel bar connection bolt hole 10 extend upwards towards the precast column to form a vertical steel bar sleeve 16. The upper surface of the vertical steel bar sleeve 16 is closed, and the length of the vertical steel bar sleeve 16 is the same as the height of the vertical steel bar connection bolt head 14. The end anchor plate 2 is also provided with a shear key hole in the center. The shear key hole extends upward towards the precast column to form a shear key sleeve 4. The upper surface of the shear key sleeve 4 is closed. The size of the shear key sleeve 4 matches the size of the shear key. The shear key sleeve 4 is welded to the inner wall of the long side. The shear key sleeve 4 is provided on both sides of the shear key sleeve 4. The shear key sleeve 5 is inclined towards the inside of the shear key sleeve 4. The shear key sleeve 5 is used to clamp the shear key 11. End plate anchor bars 7 are welded to the upper surface of the end anchor plate 2 to firmly anchor the end anchor plate 2 into the upper precast column 1. Stiffening ribs 6 are also welded to the upper surface of the end anchor plate 2. The stiffening ribs 6 include transverse ribs and vertical ribs, which intersect in a cross shape. The transverse ribs and vertical ribs are disconnected at the shear key sleeve 4. Tie bars 8 are welded to the middle position of the upper part of the column head sleeve 3 and are fixed to the steel bars in the upper precast column.

[0022] In a further preferred embodiment, the vertical rebar connecting bolt head 14 is rough-machined from the vertical rebar 13 using an upsetting machine with electric heating, and the diameter of the vertical rebar connecting bolt head 14 is 1.5 times the diameter of the vertical rebar 13.

[0023] In a further preferred embodiment, the shear key 11 is made of thick-walled square steel, and the shear key head 12 is located on one side of the end of the shear key 11 and is machined into a trapezoidal shape to facilitate guidance and insertion during installation.

[0024] In a further preferred embodiment, the end anchor plate 2 is made of Q460 high-strength low-alloy steel plate, and its size is adapted to the cross-sectional size of the upper precast column 1.

[0025] In a further preferred embodiment, the shear key casing 4 is made of a thick-walled rectangular steel pipe. Its cross-sectional width is the sum of the width of the shear key 11 and the wall thickness of the shear key casing, and its cross-sectional length is the sum of 4 / 3 of the longitudinal dimension of the end of the shear key 11 and the wall thickness of the casing.

[0026] The ends of both the transverse and vertical ribs of the stiffening rib 6 are bent to increase the contact area with the inner wall of the column head sleeve 3, facilitating welding and fixing to the inner wall of the column head sleeve 3. The thickness of the stiffening rib 6 is the same as the thickness of the side plate 3, and the stiffening rib 6 and the side plate 3 are connected by a bevel weld 16.

[0027] In a further preferred embodiment, the column head sleeve 3 is made of Q460 high-strength low-alloy steel plate and welded together. The column head sleeve 3 is set along the edge of the end anchor plate 2 and is processed with a V-shaped double-sided bevel. It is then welded and fixed to the end anchor plate 2 by gas metal arc welding.

[0028] A method for dry, grout-free, rapid connection of concrete frame columns in prefabricated buildings, specifically including the following steps: (1) Fabrication of lower precast columns Multiple vertical steel bars 13 with round-headed bolt-shaped ends are evenly extended around the column head of the lower precast column 18, and a shear key 11 is pre-embedded in the center of the column head of the lower precast column. (2) Fabricate column head sleeves and end anchor plates On the end anchor plate 2, rebar connection bolt holes 10 are opened to match the position, quantity and size of the vertical rebar 13. A through bolt hole 9 is opened next to each rebar connection bolt hole 10, which is connected to it and offset by 30-60°. The diameter of the through bolt hole 9 is the same as the diameter of the vertical rebar connection bolt head 14. A vertical rebar sleeve 16 with its upper surface closed is welded upward at the through bolt hole 9 and the rebar connection bolt hole 10. A shear key hole is opened in the center of the end anchor plate 2. A shear key sleeve 4 with its upper surface closed is welded upward at the shear key hole. An inwardly inclined tongue plate 5 is welded to the inner side wall of the shear key sleeve 4. The column head sleeve 3 is fixedly connected along the edge of the end anchor plate 2. The end plate anchor bar 7 and stiffening rib plate 6 are welded to the upper surface of the end anchor plate 2 to form a sleeve assembly. (3) Fabrication of precast columns The sleeve assembly is fitted onto the column head of the upper precast column 1. A tie bar 8 is welded to the middle position inside the column head sleeve 3 and the tie bar 8 is fixedly connected to the steel bar inside the upper precast column 1. Concrete is poured to anchor the sleeve assembly to the column head of the upper precast column 1. (4) Lift the upper precast column 1 and align the bolt hole 9 and shear key hole at the end of the upper precast column 1 with the steel bar connecting bolt head 14 and shear key 11 at the head of the lower precast column 18 respectively; (5) Move the upper precast column 1 to the lower right so that the steel bar connecting bolt head 14 and the shear key 11 are completely inserted into the bolt hole 9 and the shear key hole respectively. The tongue plate 5 on the long side wall of the shear key sleeve 4 automatically clamps the shear key 11 to achieve self-supporting temporary fixation. (6) Check the connection and positioning of the upper precast column 1 and the lower precast column 18. Once it is confirmed that there are no abnormalities, the installation is completed.

[0029] In step (2), the column head sleeve and end anchor plate are fabricated according to the following steps: (1) Based on the relative position of the vertical reinforcement 13 of the corresponding precast column, lay out the coordinates of the vertical reinforcement on the end anchor plate 2; (2) Process the bolt holes 10 for the steel bars, with the hole diameter being the same as the diameter of the vertical steel bar 13; (3) Lay out the coordinates of the bolt hole 9 at an angle of 30-60° to the bolt hole 10 corresponding to each vertical steel bar, preferably at 45° to the upper left; (4) Machining the bolt hole 9, the diameter of the bolt hole 9 is 1.5 times the diameter of the rebar connection bolt hole 10 (consistent with the upsetting diameter of the rebar connection bolt head 14). (5) Process the vertical steel reinforcement sleeve 16. The length of the vertical steel reinforcement sleeve 16 is equal to the thickness of the steel reinforcement connector head 14. The upper end of the vertical steel reinforcement sleeve is closed with a steel plate to prevent concrete from entering when the upper precast column is poured. (6) Weld and fix the vertical steel reinforcement sleeve 16 to the end anchor plate 2 at the positions of the bolt hole 9 and the steel reinforcement connection bolt hole 10; (7) Lay out the coordinates of the shear key hole at the center of the end anchor plate 2. The size of the shear key hole is compatible with the cross-sectional size of the shear key 11. Its position is located at the center of the end anchor plate 2 at a certain angle. The inclination direction and angle are consistent with the vertical steel reinforcement casing 16. (8) Weld four end plate anchor bars 7 onto the end anchor plate 2, using double-sided welds.

[0030] The present invention has the following significant technical effects: (1) Efficient and convenient construction. The upper and lower precast columns are dry-assembled, eliminating the need for welding and grouting on site. The connection can be completed with only one displacement after hoisting and alignment, resulting in fast installation. The bolt head of the bolt hole and the rebar connection is designed with an offset of 30-60°. Combined with the guiding effect of the trapezoidal shear key head, the alignment tolerance is good and the installation accuracy is high.

[0031] (2) The joint has reliable stress performance. Vertical force is transmitted through the mechanical engagement of the vertical steel bar connecting bolt head and the steel bar connecting bolt hole. The shear key and the tongue plate clamp the structure to transmit horizontal shear force. The stiffening rib plate and cross structure enhance the joint stiffness, realizing the integrated and coordinated work of vertical bearing, bending resistance, shear resistance and seismic energy dissipation. The joint has high bearing capacity and clear force transmission path.

[0032] (3) Self-stabilizing during construction. The tilted tongue plate inside the shear key casing automatically and elastically clamps the shear key when it is installed, forming a self-supporting temporary fixing system. This eliminates the need for complex temporary supports, reduces costs, and improves construction safety and convenience.

[0033] (4) Excellent durability. The upper surfaces of the vertical reinforcement casing and the shear key casing are sealed, effectively preventing concrete slurry or debris from entering the duct after the precast column is poured and installed, ensuring the cleanliness and long-term durability of the connection parts. The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several changes and improvements without departing from the overall concept of the present invention, and these should also be considered within the scope of protection of the present invention.

Claims

1. A dry-type, grout-free, quick-connect structure for prefabricated concrete frame columns, comprising an upper prefabricated column (1) and a lower prefabricated column (18), wherein vertical reinforcing bars (13) are provided inside the lower prefabricated column (18), characterized in that: The end of the vertical reinforcing bar (13) extending out of the column head is the vertical reinforcing bar connecting bolt head (14). The vertical reinforcing bar connecting bolt head (14) is in the shape of a round head bolt. The shear key (11) is pre-embedded in the center of the column head of the lower precast column (18). The pre-embedded end of the shear key (11) is welded with anchor bars (15). The anchor bars (15) are set along the length direction of the shear key (11) to firmly anchor the shear key (11) in the lower precast column (18). The end of the shear key is provided with a trapezoidal shear key head (12). The column head of the upper precast column (1) is fitted with a column head sleeve (3). The outer diameter of the column head sleeve (3) is the same as the outer diameter of the lower precast column (18), and the inner diameter is the same as the outer diameter of the column head of the lower precast column (1). The bottom of the column head sleeve (3) is fixedly provided with an end anchor plate (2). The end anchor plate (2) is provided with steel bar connection bolt holes (10) that match the position, quantity and size of the vertical steel bar (13). Each steel bar connection bolt hole (10) is provided with a through bolt hole (9). The through bolt hole (9) and the steel bar connection bolt hole (10) are connected to each other and offset by 30-60°. The diameter of the through bolt hole (9) is the same as the diameter of the vertical steel bar connection bolt head (14). The through bolt hole (9) and the steel bar connection bolt hole (10) extend upwards in the direction of the precast column to form a vertical steel bar sleeve (16). The upper surface of the vertical steel bar sleeve (16) is closed. The length of the vertical steel bar sleeve (16) is the same as the height of the vertical steel bar connection bolt head (14). The end anchor plate (2) is also provided with a shear key hole in the center. The shear key hole extends upward in the direction of the precast column to form a shear key sleeve (4). The upper surface of the shear key sleeve (4) is closed. The size of the shear key sleeve (4) matches the size of the shear key. The shear key sleeve (4) is welded with a tongue plate (5) on the inner side wall. The tongue plate (5) is used to clamp the shear key (11). The end anchor plate (2) is welded with end plate anchor bars (7) on the upper surface to firmly anchor the end anchor plate (2) into the upper precast column (1). The end anchor plate (2) is also welded with stiffening ribs (6) on the upper surface. The stiffening ribs (6) include horizontal ribs and vertical ribs, which intersect in a cross shape. The horizontal ribs and vertical ribs are disconnected at the shear key sleeve (4). Tie bars (8) are welded to the middle position of the upper part of the column head sleeve (3). The tie bars (8) are fixed to the steel bars in the upper precast column.

2. The dry, grout-free, rapid connection structure for prefabricated concrete frame columns according to claim 1, characterized in that: The diameter of the vertical reinforcing bar connector (14) is 1.5 times the diameter of the vertical reinforcing bar (13).

3. The dry, grout-free, quick-connect structure for prefabricated concrete frame columns according to claim 1, characterized in that: The bolt hole (9) is offset by 45° from the rebar connection bolt hole (10).

4. The dry, grout-free, quick-connect structure for prefabricated concrete frame columns according to claim 1, characterized in that: The ends of the horizontal and vertical ribs of the stiffening rib (6) are bent and welded to the inner wall of the column head sleeve (3).

5. The dry, grout-free, quick-connect structure for prefabricated concrete frame columns according to claim 1, characterized in that: The end plate anchor bars (7) are L-shaped, with four bars evenly distributed inside the upper precast column (1).

6. The dry, grout-free, quick-connect structure for prefabricated concrete frame columns according to claim 1, characterized in that: The shear key casing (4) is made of thick-walled steel pipe with a rectangular cross section.

7. A method for dry, grout-free, rapid connection of prefabricated concrete frame columns, characterized in that: Includes the following steps, (1) Fabrication of lower precast columns Multiple vertical steel bars (13) with round-headed bolts extend evenly around the column head of the lower precast column (18), and a shear key (11) is pre-embedded in the center of the column head of the lower precast column. (2) Fabricate column head sleeves and end anchor plates On the end anchor plate (2), a rebar connection bolt hole (10) matching the position, quantity and size of the vertical rebar (13) is opened, and a through bolt hole (9) connected to and offset by 30-60° is opened on the side of each rebar connection bolt hole (10). The diameter of the through bolt hole (9) is the same as the diameter of the vertical rebar connection bolt head (14). A vertical rebar sleeve (16) with a closed upper surface is welded upward at the through bolt hole (9) and the rebar connection bolt hole (10). A shear key hole is opened in the center of the end anchor plate (2), and a shear key sleeve (4) with a closed upper surface is welded upward at the shear key hole. An inwardly inclined tongue plate (5) is welded on the inner side wall of the shear key sleeve (4). The column head sleeve (3) is fixedly connected along the edge of the end anchor plate (2). An end plate anchor bar (7) and stiffening rib plate (6) are welded on the upper surface of the end anchor plate (2) to form a sleeve assembly. (3) Fabrication of precast columns The sleeve assembly is placed on the column head of the upper precast column (1), and the tie bar (8) is welded in the middle of the inner side of the column head sleeve (3). The tie bar (8) is fixedly connected to the steel bar in the upper precast column (1), and concrete is poured to anchor the sleeve assembly to the column head of the upper precast column (1). (4) Lift the upper precast column (1) and align the bolt hole (9) and shear key hole at the end of the upper precast column (1) with the steel bar connecting bolt head (14) and shear key (11) of the lower precast column (18). (5) Move the upper precast column (1) to the lower right so that the steel bar connecting bolt head (14) and the shear key (11) are completely inserted into the bolt hole (9) and the shear key hole respectively. The tongue plate (5) of the shear key sleeve (4) along the long side wall automatically clamps the shear key (11) to achieve self-supporting temporary fixation. (6) Check the connection and positioning of the upper precast column (1) and the lower precast column (18). Once it is confirmed that there are no abnormalities, the installation is completed.

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