CN112081242B - Assembled integral beam-column joint provided with shape memory alloy reinforcement and construction method - Google Patents

Abstract

The invention discloses an assembled integral beam-column joint with a shape memory alloy reinforcement and a construction method, wherein a longitudinal reinforcement of a through long beam is arranged on a prefabricated beam overlapping layer; the bottom of the U-shaped key groove at the end part of the beam and the upper overlapped layer are provided with the shape memory alloy reinforcing materials with full length, after concrete is poured, the concrete is electrified and heated, and prestress is applied to the assembled beam-column joint through deformation of the shape memory alloy reinforcing materials. The assembled beam-column joint part of the invention applies prestress by the shape memory alloy reinforcing material, can solve the defects of poor performance and easy occurrence of cracks of the assembled integral beam-column joint at the splicing part of the prefabricated part, improves the early-stage rigidity and the stress performance of the assembled integral beam-column joint, and simultaneously has simple and convenient construction and better performance of the assembled integral beam-column joint.

Description

Assembled integral beam-column joint with shape memory alloy reinforcement and construction method

technical field

The invention relates to the technical field of civil engineering, in particular to an assembled integral beam-column joint with shape memory alloy reinforcement and a construction method.

Background technique

Assembled monolithic concrete beam-column joints aim to achieve equivalent cast-in-place. When the overall performance and seismic performance of assembled monolithic beam-column joints, including strength, stiffness, bearing capacity, energy consumption, ductility and damping coefficient, are basically equivalent to the existing parameters. When pouring beam-column joints, the existing design regulations of cast-in-place reinforced concrete structures can be applied, and it is easy to popularize and apply prefabricated concrete structures. The commonly used design and construction scheme of prefabricated integral beam-column joints is: the beam-column members are prefabricated units respectively. After the prefabricated beam-column units are hoisted in place at the construction site, the prefabricated beams on both sides of the prefabricated columns are connected by connecting steel bars, and then the prefabricated beams The end and beam-column joint areas are cast-in-place concrete to complete the construction, so they are also called equivalent cast-in-place beam-column joints. In the assembled integral beam-column joint, due to the requirements of assembly construction, the lower longitudinal bars of the prefabricated beam are generally not extended or anchored in the beam-column joint area, and there are many new and old concrete contact surfaces at the end of the prefabricated beam and the beam-column joint area. The U-shaped keyway at the end of the prefabricated beam reduces the effective height and width of the beam section, and weakens the overall performance and seismic performance of the assembled integral beam-column joint.

Therefore, when the assembled integral beam-column joint is under the action of earthquake or the force is large, the end of the prefabricated beam bears a large bending moment and shear force, and at the same time, the bonding performance and shear resistance of the new and old concrete interface are poor. , the premature appearance of vertical cracks between the end of the prefabricated beam and the beam-column joint area, which leads to a certain weakening of the early strength, stiffness and bearing capacity of the assembled integral beam-column joint, and affects the assembled integral beam-column joint. The appearance and normal use make the joint performance of this type of connection method not equal to the performance of cast-in-place.

Therefore, for those skilled in the art, how to effectively improve the performance of the assembled integral beam-column joint has become an urgent technical problem to be solved in the art.

SUMMARY OF THE INVENTION

Purpose of the invention: In order to overcome the shortcomings and technical deficiencies of the above-mentioned existing assembled integral beam-column joints, improve the early seismic performance and overall performance of the assembled integral beam-column joints, and limit the development of cracks in the end of the prefabricated beam and the beam-column joint area, this The invention provides an assembled integral beam-column joint with shape memory alloy reinforcement and a construction method.

In order to realize above-mentioned technical purpose, the present invention adopts following technical scheme:

An assembled integral beam-column joint provided with shape memory alloy reinforcement,

The prefabricated column is a multi-layer column, and no concrete is poured in the beam and column joint areas; the prefabricated beam is a composite beam, and the end of the prefabricated beam is provided with a beam end U-shaped keyway;

Connecting steel bars are placed in the lower part of the U-shaped keyway of the beam end on both sides of the prefabricated column;

The prefabricated beam superimposed layer is placed with longitudinal reinforcement of the long beam;

The bottom of the beam end U-shaped keyway and the superimposed layer of the prefabricated beam are respectively placed with a long shape memory alloy bar, the shape memory alloy bar is connected with a wire, and the wire extends outside the prefabricated beam; the beam end U-shaped keyway The inner connecting reinforcement is anchored by bending or end plate;

The shape memory alloy reinforcement material is provided with an unbonded section at the interface between the beam and the column, which is anchored by end plates; the end of the prefabricated beam is encrypted with stirrups.

The width of the U-shaped keyway at the beam end is not less than 1/3 of the width of the prefabricated beam, and not less than 150mm, and the precast concrete wall thickness of the U-shaped keyway at the beam end is not less than the sum of the diameter of the stirrup and 2 times the concrete protective layer. Less than 60mm, and not more than 1/3 of the width of the prefabricated beam.

The length of the U-shaped keyway at the beam end is the length of the connecting steel bar +50mm extending into the keyway, and can be adjusted according to the building modulus, and the length of the shape memory alloy steel bar is less than the length of the connecting steel bar.

The lower longitudinal bars of the prefabricated beam do not extend into the beam-column joint area, but are pre-buried in the prefabricated concrete or bent in the U-shaped keyway at the beam end.

The selection of the connecting steel bars and shape memory alloy steel bars follows the principle of small diameter and multiple numbers, and the diameters of the connecting steel bars and shape memory alloy steel bars are not less than 14mm and not greater than 28mm; the outer surface of the shape memory alloy steel bars is provided with ribs or the concave-convex surface, the bonding performance with concrete is not lower than that of the connecting steel bars in the U-shaped keyway at the beam end; it is arranged in the same layer or the upper and lower layers are arranged in the U-shaped keyway at the beam end;

When the bonding performance between the shape memory alloy steel bar and the concrete is not lower than that of the steel bar with the same diameter, its length is the same as the anchorage length of the steel bar with the same diameter.

When the width of the U-shaped keyway at the beam end is less than 1/2 of the beam width, the shape memory alloy reinforcement is provided with an unbonded section, and the unbonded section of the shape memory alloy reinforcement is arranged at the interface between the beam and the column. The length of the unbonded section in the column and at the beam end shall not be less than 5 times the diameter of the shape memory alloy reinforcement.

The shape memory alloy bars are iron-based-shape memory alloy bars.

The invention further discloses a construction method for an assembled integral beam-column joint based on setting shape memory alloy reinforcement, comprising the following steps:

Step 1: First, carry out the hoisting construction of multi-layer prefabricated columns. The upper and lower prefabricated columns are connected by column longitudinal bars. The prefabricated columns and the foundation or lower components are connected by grouting sleeves or bellows. After the prefabricated columns are constructed, temporary supports are set up. ;

Step 2: After the prefabricated column is installed and constructed, the prefabricated beam is hoisted. There is a gap of 20mm-40mm between the prefabricated beam and the prefabricated column to facilitate construction. After the prefabricated beam is hoisted in place, check whether the position of the prefabricated beam in three directions is accurate;

Step 3: After the prefabricated beam is installed in place, place connecting steel bars and shape memory alloy bars at the bottom of the U-shaped keyway at the beam end, and fix them, and then place the long longitudinal bars and shape memory alloy bars on the prefabricated beam superimposed layer The length of the upper and lower shape memory alloy bars is less than the length of the connecting bars, pay attention to the thickness of the protective layer of the connecting bars and the shape memory alloy bars meeting the requirements of the current regulations, and not less than 20 mm, and the shape memory alloy bars are not less than 20 mm. There is no direct contact between the connecting bars; finally, the closed part of the prefabricated beam opening stirrups and the stirrups in the prefabricated column node area are arranged;

Step 4: After the steel reinforcement construction of the assembled integral beam-column joint is completed, set the formwork at the end of the prefabricated beam, the beam-column joint area and the three parts of the prefabricated beam superimposed layer, and then pour concrete. Fine stone concrete with one grade higher strength, and the poured concrete adopts non-shrinking or micro-expansion concrete, and the end of the prefabricated beam is reinforced with stirrups. 100mm.

When pouring concrete and vibrating, ensure that the steel bars are not disturbed, and the wires connected to the shape memory alloy bars are not damaged. The wires can be covered with rubber hoses for protection, and the concrete at the joints is densely filled;

Step 5: After the construction of the prefabricated beams is completed and the strength of the post-cast concrete reaches more than 60% of the design strength, connect the wires on the shape memory alloy bars to the AC power supply, and energize the shape memory alloy bars to heat the shape memory alloy bars. Driven by its shape memory effect, the concrete in the area of the fabricated beam-column joint will be prestressed.

Connecting steel bars and shape memory alloy steel bars are placed at the lower part of the U-shaped keyway at the beam end. The reinforcement area of the shape memory alloy steel bars is determined by calculating the prestress level, and some steel bars are replaced by the principle of equal strength to reduce the reinforcement area of the connecting steel bars. .

The inner wall of the U-shaped keyway at the beam end is chiseled, and the roughness of the concrete surface meets the requirements of the current regulations;

When the length of the connecting steel bars in the U-shaped keyway at the beam end is linear, it shall meet the requirements of the current regulations of "Code for Design of Concrete Structures" GB50010-2010 and "Plane Overall Representation Method of Construction Drawings of Concrete Structures Drawing Rules and Structural Details 16G101-1" , use bending anchorage and end plate anchorage; when the diameter of the connecting steel bar is greater than 22 mm, use bending anchorage or end plate anchorage.

Beneficial effects:

An assembled integral beam-column joint and construction method provided with shape memory alloy bars of the present invention have the following beneficial effects:

The invention applies prestress to the post-cast concrete in the assembled integral beam-column joint area through shape memory alloy reinforcement, which can improve the connection performance of the prefabricated beam end and the cast-in-place beam-column joint, improve the shear resistance of the contact surface between the new and the old concrete, and limit the The development of concrete cracks in the contact surface between the prefabricated beam and the beam-column joint area improves the early stiffness and overall performance of the prefabricated beam-column joint, and reduces the contact surface between the old and new concrete and the beam longitudinal reinforcement in the prefabricated beam-column joint area. The performance of column joints is weakened to achieve performance targets equal to or exceeding those of cast-in-place joints.

Description of drawings

Figure 1 Setting up the beam-column joint of shape memory alloy reinforcement.

Figure 2 Part of the unbonded shape memory alloy reinforced beam-column joint.

Fig. 3 Partially unbonded shape memory alloy reinforced beam-column joints anchored at the ends.

Figure 4 Fabricated beam-column connection type A with short keyway.

Figure 5 Fabricated beam-column connection type B with short keyway.

Figure 6. Structure diagram of shape memory alloy reinforcement in fabricated beam-column joints.

Figure 7. Section of the end of the prefabricated beam when the keyway width is small.

Figure 8. Section of the end of the prefabricated beam when the keyway width is large.

Figure 9. The middle section of the prefabricated beam.

Among them: 1- prefabricated beam, 2- prefabricated beam laminated layer, 3- beam end U-shaped keyway, 4- prefabricated beam laminated layer through-length longitudinal reinforcement, 5- upper shape memory alloy reinforcement, 6- prefabricated beam stirrup , 7- The longitudinal reinforcement of the lower part of the prefabricated beam, 8- The inner connecting reinforcement of the U-shaped keyway at the beam end, 9- The lower shape memory alloy reinforcement, 10- The shape memory alloy reinforcement unbonded section, 11- Precast concrete, 12- Cast-in-place Concrete, 13-prefabricated column, 14-prefabricated column longitudinal reinforcement, 15-prefabricated column stirrup, 16-shape memory alloy reinforcement end anchorage, 17-prefabricated beam lower longitudinal reinforcement bending anchorage, 18-keyway inner connecting reinforcement bending Folding anchor, 19-shape memory alloy bar connecting wire, 20-AC power supply, 21-nut, 22-anchoring steel plate, 23-shape memory alloy bar thread, 24-rubber hose, 25-filling foam.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings.

As shown in FIGS. 2 to 5 , an assembled integral beam-column joint provided with shape memory alloy bars of the present invention includes a prefabricated beam 1 and a prefabricated column 13 ; the end of the prefabricated beam 1 is provided with a beam end U-shaped keyway 3 , the upper part of the prefabricated beam 1 is the post-cast laminated layer 2, the prefabricated beam stirrups are open stirrups 6, the lower longitudinal bars 7 of the prefabricated beams are located in the prefabricated concrete 12, and the lower longitudinal bars 7 of the prefabricated beams can also be anchored 17 in the beam by bending In the end U-shaped keyway 3; the width of the beam-end U-shaped keyway 3 reserved at the end of the prefabricated beam should not be less than 1/3 of the beam width, and should not be less than 150mm.

The prefabricated column 13 is a multi-layer prefabricated column, the upper and lower prefabricated columns are connected by the prefabricated column longitudinal bars 14, and the prefabricated column stirrups 15 are not provided in the beam-column node area.

The connecting steel bar 8 and the shape memory alloy steel bar 9 are placed in the U-shaped keyway 3 of the beam end, and the long longitudinal bar 4 and the shape memory alloy steel bar 5 are placed on the upper part of the prefabricated beam. Concrete 12 is poured in the U-shaped keyway 3 at the beam end, the prefabricated beam superimposed layer 2 and the beam-column joint area. The length of the shape memory alloy reinforcement 9 in the U-shaped keyway 3 at the beam end should not be greater than the length of the connecting reinforcement 8 in the keyway 3;

As shown in Figure 2, Figure 3, Figure 5 and Figure 6, when the width of the U-shaped keyway 3 at the end of the prefabricated beam is less than 1/2 of the beam width, the U-shaped keyway 3 at the beam end overlaps with the prefabricated beam The shape memory alloy reinforcement in layer 2 should be provided with an unbonded section 10. The length L1 of the unbonded section 10 for the shape memory alloy reinforcement should not be less than 5 times the diameter of the shape memory alloy reinforcement. The non-bonded section 10 is realized by arranging rubber hoses 24 and filling foam 25 on the surface of the reinforced material, and the shape memory alloy reinforced material is connected with the AC power source 20 through the wire 19. After the construction is completed, the electric heating is applied to the assembled integral beam-column joint. prestressed.

As shown in Figure 3-6, in order to reduce the length and amount of shape memory alloy bars and save material costs, the shape memory alloy bars can be anchored at the ends of the shape memory alloy bars 16. At this time, it is necessary to Threads 23 are pre-processed at the ends of the bars, and the anchoring steel plates 22 are fixed by the matching nuts 21 before construction. The net area of the anchoring steel plates 22 should not be less than 4 times the area of the shape memory alloy bars.

As shown in Figures 4 and 5, in order to reduce the length of the U-shaped keyway 3 reserved at the end of the prefabricated beam, the lower longitudinal bars 7 of the prefabricated beam can be bent and anchored 17 at the U-shaped end of the beam through the lower longitudinal bars of the prefabricated beam. In the keyway, at this time, the shape memory alloy steel bar can be anchored 16 by the end of the shape memory alloy steel bar, and the connecting steel bar 8 in the keyway is bent and anchored 18 by the connecting steel bar in the keyway.

As shown in Figure 7-9, the connecting steel bars 8 and shape memory alloy bars 9 in the U-shaped keyway 3 at the beam end can be arranged in double layers, and when the width of the U-shaped keyway 3 at the beam end is large, a single-layer arrangement can also be used; The thickness of the protective layer and the spacing between the reinforcing bars 8 and the shape memory alloy bars 9 should meet the requirements of the current regulations.

The present invention also provides a construction method for an assembled integral beam-column joint for setting shape memory alloy bars. Taking FIG. 2 and FIG. 6 as examples, the method includes the following steps:

Step 1: First, carry out the hoisting construction of the multi-layer prefabricated columns 13. The upper and lower prefabricated columns 13 are connected by the column longitudinal bars 14, and the prefabricated columns and the foundation or lower components are connected by grouting sleeves or corrugated pipes. After the construction of the prefabricated columns is completed Set up temporary support;

Step 2: After the prefabricated column 13 is installed and constructed, the prefabricated beam 1 is hoisted. There is a gap of 20mm-40mm between the prefabricated beam and the prefabricated column to facilitate construction. After the prefabricated beam is hoisted in place, check whether the position of the prefabricated beam in three directions is correct. precise;

Step 3: After the prefabricated beam is installed in place, place the connecting steel bar 8 and the shape memory alloy steel bar 9 at the bottom of the U-shaped keyway 3 at the beam end, and fix them. The end of the shape memory alloy steel bar 9 is connected to the wire 19, and the wire extends out of the prefabricated beam; then place the long longitudinal bar 4 and the shape memory alloy bar 5 in the prefabricated beam superimposed layer. The length of the shape memory alloy bar is less than the connecting bar 8, and attention should be paid to the connecting bar and the upper shape memory alloy bar 5 and the thickness of the protective layer of the lower shape memory alloy reinforcement material 9 and the shape memory alloy reinforcement material has no direct contact with the reinforcement; finally arrange the closed part of the prefabricated beam opening stirrup 6 and the stirrup in the prefabricated column node area;

Step 4: After the steel reinforcement construction of the assembled integral beam-column joint is completed, set the template at the end of the prefabricated beam, the beam-column joint area and the prefabricated beam superimposed layer 2, and then pour the concrete 12, and the poured concrete 12 adopts the grade ratio. The precast concrete 11 is fine stone concrete with one grade higher in strength, and the poured concrete 12 is made of non-shrinking or micro-expansion concrete. When the concrete is poured and vibrated, it is ensured that the steel bars will not be disturbed, and the upper shape memory alloy bars 5 and the lower shape memory will not be damaged. The wires 19 connected to the alloy bars 9 are filled with concrete at the joints;

Step 5: After the construction of the prefabricated beam is completed, after the strength of the post-cast concrete 12 reaches more than 60% of the design strength, connect the wire 19 on the shape memory alloy reinforcement to the AC power supply 20, and connect the upper shape memory alloy reinforcement 5 and the lower The shape memory alloy reinforcement 9 is heated by electricity, and the upper shape memory alloy reinforcement 5 and the lower shape memory alloy reinforcement 9 will apply prestress to the concrete in the area of the prefabricated beam-column joint driven by the shape memory effect.

The above is only the preferred embodiment of the present invention, it should be pointed out that: for those skilled in the art, without departing from the principle of the present invention, several improvements and modifications can also be made, and these improvements and modifications are also It should be regarded as the protection scope of the present invention.

Claims (6)

1. an assembled integral beam-column joint for setting shape memory alloy reinforcement, characterized in that: The prefabricated column is a multi-layer column, and no concrete is poured in the beam and column joint areas; the prefabricated beam is a composite beam, and the end of the prefabricated beam is provided with a beam end U-shaped keyway; Connecting steel bars (8) are placed at the lower part of the U-shaped keyway at the beam end on both sides of the prefabricated column; The prefabricated beam superimposed layer is placed with longitudinal reinforcement of the long beam; The bottom of the beam end U-shaped keyway and the superimposed layer of the prefabricated beam are respectively placed with a long shape memory alloy bar, the shape memory alloy bar is connected with a wire, and the wire extends outside the prefabricated beam; the beam end U-shaped keyway The inner connecting reinforcement is anchored by bending or end plate; When the width of the U-shaped keyway at the beam end is less than 1/2 of the beam width, the shape memory alloy reinforcement is provided with a non-bonded section at the interface between the beam and the column, and the end plate is used for anchoring. The length of the knot section is not less than 5 times the diameter of the shape memory alloy bar; the end of the prefabricated beam is encrypted with stirrups; the unbonded section of the shape memory alloy bar is realized by setting a rubber hose and filling foam on the surface of the bar; The width of the U-shaped keyway at the beam end is not less than 1/3 of the width of the prefabricated beam, and not less than 150mm, and the precast concrete wall thickness of the U-shaped keyway at the beam end is not less than the sum of the diameter of the stirrup and 2 times the concrete protective layer. Less than 60mm, and not more than 1/3 of the width of the prefabricated beam; The longitudinal reinforcement at the lower part of the prefabricated beam does not extend into the beam-column joint area, but is pre-buried in the prefabricated concrete or bent in the U-shaped keyway at the beam end; The selection of the connecting steel bars and shape memory alloy steel bars follows the principle of small diameter and multiple numbers, and the diameters of the connecting steel bars and shape memory alloy steel bars are not less than 14mm and not greater than 28mm; the outer surface of the shape memory alloy steel bars is provided with ribs or the concave-convex surface, the bonding performance with concrete is not lower than that of the connecting steel bars in the U-shaped keyway at the beam end; it is arranged in the same layer or the upper and lower layers are arranged in the U-shaped keyway at the beam end; When the bonding performance between the shape memory alloy steel bar and the concrete is not lower than that of the steel bar with the same diameter, its length is the same as the anchorage length of the steel bar with the same diameter. 2. The assembled integral beam-column joint with shape memory alloy reinforcement according to claim 1, characterized in that: the length of the U-shaped keyway at the beam end is taken to extend into the keyway to connect the steel bar length+50mm, and can be pressed The building modulus is adjusted, and the length of the shape memory alloy bars is less than the length of the connecting bars. 3 . The assembled integral beam-column joint provided with shape memory alloy bars according to claim 1 , wherein the shape memory alloy bars are iron-based-shape memory alloy bars. 4 . 4. A construction method based on the assembly of the integral beam-column joint of the shape memory alloy reinforcement material set according to any one of claims 1 to 3, characterized in that, comprising the following steps: Step 1: First, carry out the hoisting construction of multi-layer prefabricated columns. The upper and lower prefabricated columns are connected by column longitudinal bars. The prefabricated columns and the foundation or lower components are connected by grouting sleeves or bellows. After the prefabricated columns are constructed, temporary supports are set up. ; Step 2: After the prefabricated column is installed and constructed, the prefabricated beam is hoisted. There is a gap of 20mm-40mm between the prefabricated beam and the prefabricated column to facilitate construction. After the prefabricated beam is hoisted in place, check whether the position of the prefabricated beam in three directions is accurate; Step 3: After the prefabricated beam is installed in place, place connecting steel bars and shape memory alloy bars at the bottom of the U-shaped keyway at the beam end, and fix them, and then place the long longitudinal bars and shape memory alloy bars on the prefabricated beam superimposed layer The length of the upper and lower shape memory alloy bars is less than the length of the connecting bars, pay attention to the thickness of the protective layer of the connecting bars and the shape memory alloy bars meeting the requirements of the current regulations, and not less than 20 mm, and the shape memory alloy bars are not less than 20 mm. There is no direct contact between the connecting bars; finally, the closed part of the prefabricated beam opening stirrups and the stirrups in the prefabricated column node area are arranged; Step 4: After the steel reinforcement construction of the assembled integral beam-column joint is completed, set the formwork at the end of the prefabricated beam, the beam-column joint area and the three parts of the prefabricated beam superimposed layer, and then pour concrete. Fine stone concrete with one grade higher strength, and the poured concrete adopts non-shrinking or micro-expansion concrete, and the end of the prefabricated beam is reinforced with stirrups. 100mm; When pouring concrete and vibrating, ensure that the steel bars are not disturbed, and the wires connected to the shape memory alloy bars are not damaged. The wires can be covered with rubber hoses for protection, and the concrete at the joints is densely filled; Step 5: After the construction of the prefabricated beams is completed and the strength of the post-cast concrete reaches more than 60% of the design strength, connect the wires on the shape memory alloy bars to the AC power supply, and energize the shape memory alloy bars to heat the shape memory alloy bars. Driven by its shape memory effect, the concrete in the area of the fabricated beam-column joint will be prestressed. 5. The construction method of the assembled integral beam-column joint for setting shape memory alloy bars according to claim 4, characterized in that: connecting steel bars and shape memory alloy bars are placed in the lower part of the U-shaped keyway at the beam end, and the shape memory alloy bars The reinforcement area of the material is determined by the calculation of its prestress level, and the reinforcement area of the connecting reinforcement is reduced by replacing part of the reinforcement by the principle of equal strength. 6. The construction method of the assembled integral beam-column joint with shape memory alloy reinforcement according to claim 4, wherein the inner wall of the U-shaped keyway at the beam end is chiseled, and the roughness of the concrete surface meets the current requirements of the regulations; When the length of the connecting steel bars in the U-shaped keyway at the beam end is linear, it shall meet the requirements of the current regulations of "Code for Design of Concrete Structures" GB50010-2010 and "Plane Overall Representation Method of Construction Drawings of Concrete Structures Drawing Rules and Structural Details 16G101-1" , use bending anchorage and end plate anchorage; when the diameter of the connecting steel bar is greater than 22 mm, use bending anchorage or end plate anchorage.

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