CN102505760B - Prefabricated combined beam and column node member - Google Patents

Abstract

A prefabricated composite beam-column node component, including intersecting beams and columns, the beams and columns are composed of ECC materials, longitudinal bars and stirrups, the transverse width of the rectangular area where the beams and columns overlap is A, and the vertical height is B; the transverse width of the beam is 2B+A. The longitudinal height is B, the longitudinal reinforcement runs through the entire length of the beam and extends 10cm to 15cm from the two beam ends; the longitudinal height of the column is 2A+B, the longitudinal reinforcement runs through the entire length of the column and extends 10cm from the two column ends ~15cm. The invention is a prefabricated component poured with reinforced ECC material, which is applied to key anti-seismic parts, especially key nodes. Compared with ordinary reinforced concrete members, the ductility and seismic performance of the structure are significantly improved. Under the requirements of seismic resistance, the use of joint stirrups is greatly reduced, and the construction problems caused by too dense stirrups in the joint area are solved.

Description

A prefabricated composite beam-column joint member

technical field

The invention relates to a fiber cement-based composite material (ECC) prefabricated beam-column node component reinforced by steel bars, which belongs to a new type of force-bearing component and is mainly used in high-seismic fortification areas to replace traditional cast-in-place reinforced concrete nodes.

Background technique

ECC (engineered cementitious composites, fiber cement-based composites for engineering) is a new type of cement-based composite material that uses cement and fine sand as fillers, and then adds synthetic fibers. A large number of research results on physical and mechanical properties show that ECC materials not only have ultra-high toughness, but also have strong energy absorption capacity. Moreover, tests have confirmed that the ultimate tensile strain value of this material is about 100 to 300 times that of ordinary concrete materials, about 5 to 10 times that of steel bars, and its value can exceed 3%, which provides a solution to the problem of concrete cracking. new ideas.

The beam-column edge joints and the surrounding areas of the frame structure have to bear a lot of internal force under the action of the earthquake. In the Wenchuan earthquake, a large number of buildings were damaged due to the plastic hinge at the beam-column end or the damage of the core area of the joint, and the general structure (frame, shear Wall structure, etc.) In order to realize the seismic design concepts and requirements of "strong column weak beam", "strong shear weak bending" and "strong joint", dense stirrups are arranged at the concrete beams, columns and their beam-column joints, To prevent the shear failure of beams and columns, but the dense stirrups bring great difficulties to the site construction, and it is easy to cause the concrete vibration of nodes or key parts to be not compacted, which brings safety hazards.

In addition, in the actual construction process, the steel bars between the prefabricated nodes and adjacent components are often connected by welding. Due to the irregular shape of the ends of the steel bars, the two joints are not easy to align, and the steel bar heads lack stable support and positioning during butt welding. As a result, the quality of welding points is often not guaranteed and becomes a weak point of the structure.

Contents of the invention

Technical problem: The present invention provides a prefabricated composite beam-column joint component that can improve the ductility and energy dissipation performance of the building structure, especially the edge joint area, so as to improve the seismic performance of the structure.

Technical solution: A prefabricated composite beam-column node component of the present invention includes intersecting beams and columns, the beams and columns are composed of engineering fiber cement-based composite materials, longitudinal bars and stirrups, and the beams and columns overlap The horizontal width of the rectangular area is A, and the vertical height is B;

The transverse width of the beam is 2B+A, and the longitudinal height is B, and the longitudinal ribs run through the entire length of the beam and protrude from the two ends of the beam by 10cm to 15cm;

The longitudinal height of the column is 2A+B, and the longitudinal reinforcement runs through the entire length of the column and extends from two column ends by 10cm to 15cm.

In the present invention, the ends of the crossbeam and the column are all fixed with angle irons, and the angle irons are welded to the steel bars. 15cm.

The present invention considers the stress characteristics of each area of the frame structure, uses ECC materials in the core area of the joint and the nearby area, designs the prefabricated beam-column joint for the frame, and finally forms the R/ECC composite member together with the steel bar.

Beneficial effects: Compared with the existing cast-in-place concrete beam-column joints, the present invention has the following advantages:

1. The core area of the joint and its surrounding areas are the main parts of the force under the earthquake, which mainly bear the role of absorbing and dissipating the seismic energy. After using ECC materials, the components show high ductility and good energy dissipation performance. In the experimental comparison between traditional reinforced concrete beam-column joints and R/ECC composite beam-column joints with exactly the same reinforcement ratio, each seismic index of the present invention shows obvious advantages, and what Fig. 2 shows is the R/ECC composite joint Compared with the skeleton curve of ordinary RC joints under low cycle load, the ultimate bearing capacity of R/ECC composite joints is 20% higher than that of ordinary RC joints, and the displacement during failure is increased by 15%. It can be seen from the skeleton curves that R/ECC composite joints After reaching the ultimate load, the bearing capacity does not drop rapidly, but has a longer and more stable decline section. This is due to the high toughness of the ECC material, which can inhibit the development of cracks and ensure that the joints still have a large bearing capacity after yielding. force and deformability.

2. Nodes are the main parts of absorbing seismic energy in earthquakes, so the energy dissipation performance of nodes will directly affect the seismic performance of structures. The curve in Figure 3 shows the comparison of the cumulative energy consumption of the two nodes when subjected to seismic cyclic loads. The seismic energy absorbed by the R/ECC composite node under earthquake action is several times that of the ordinary RC node, which fully illustrates the R/ECC ECC composite nodes have the characteristics of high ductility and high energy consumption.

3. As shown in Figure 4, the stiffness curves of the ring lines of the two combined nodes under the action of earthquakes, the stiffness degradation of the experimental structure can be represented by the stiffness of the ring lines under the same deformation. Ordinary concrete joints, and the decline in the curve in the late stage of cyclic loading is relatively gentle, which shows that the ECC material can delay the strength degradation of the joints in the later period by limiting the joint cracks and delaying the stiffness decay, so that the joints can maintain their proper strength under greater deformation. Bearing capacity, thereby improving the ductility of the joint.

4. Experimental research shows that the reinforced concrete joints finally achieve joint failure under the action of low-cycle cyclic loads, while the R/ECC joints with the same reinforcement ratio finally show beam end failure, reaching the "strength" required by the seismic code. Node" and beam end failure mode. In the core area of the node, the R/ECC composite node can meet the requirements of the seismic code by using fewer stirrups than the reinforced concrete node. The function of stirrups has been replaced, and the use of fewer stirrups can effectively solve the construction problem of too dense stirrups in the node area.

5. During the construction process, the quality of the welding points between the steel bars is often not guaranteed, which becomes the weak point of the structure. In the present invention, a triangle iron is welded at the steel bar joint at the end of the beam and column, and the steel bar can be regarded as resting on the triangle iron, which improves the stability and firmness of butt welding with adjacent steel bars, and ensures the rigidity and welding quality here.

6. The corrugated shape formed by the section of the beam and the end of the column increases the contact area, which will help the combination with the adjacent components during the construction process, and avoid this area from becoming a weak area for stress.

7. Prefabricated ECC joints are the key parts of the frame structure. Compared with cast-in-place reinforced concrete joints, the quality is easier to control and guarantee during the production process, which solves the problem of dense reinforcement mesh and unrealistic concrete pouring during construction at cast-in-place joints. Difficult problem, the integrity of the node part is good. During installation, it can be well connected with the surrounding cast-in-place concrete and bear the force together. In addition, the use of such prefabricated components can save steel bars and templates, meeting the development trend of energy conservation and environmental protection.

8. Due to the bridging effect of the fibers in the ECC material, when the structure is under the action of a lower load level, many cracks develop, and the width of the cracks is extremely small. The nodes show a fine network, and no main cracks appear. It is applied in After the actual project, when the R/ECC composite joint is subjected to a low-intensity earthquake, the crack width in the core area and its surrounding area is significantly smaller than that of ordinary reinforced concrete joints, which is almost invisible to the naked eye, so there is no need to repair it after the earthquake You can continue to use it.

9. The present invention also extends the application of ECC material to the plastic hinge area at the beam end and column end near the core area. Under the action of an earthquake, these areas are subjected to a large bending moment, and cracks first appear and develop here , and finally when a main crack expands to a certain width, the bearing capacity decreases rapidly, and the component fails. In this area, the micro-crack development characteristics of ECC materials will be brought into play, which will delay the appearance of main cracks, prolong the working time of components under higher bearing capacity, and improve the overall ductility and energy dissipation performance of the structure.

10. More than 70% of the ECC material is fly ash, which mainly comes from the waste residue after coal combustion in thermal power plants. Therefore, ECC material is an environmentally friendly material, and the prefabricated parts cast by it are also resistant to fly ash. The waste utilization can achieve the reusable use of natural resources while ensuring the superior performance of components.

Description of drawings

Fig. 1 is a sectional view of the present invention;

Fig. 2 is a side sectional view of the present invention, among the figure a is the length that the angle iron stretches into the beam, b is the length that the longitudinal reinforcement runs through the beam and stretches out from the column end, and c is the length that the angle iron exceeds the longitudinal reinforcement portion;

Fig. 3 is the end section view of beam and column of the present invention;

Fig. 4 is the skeleton curve comparative figure of the present invention and common reinforced concrete joint;

Fig. 5 is the cumulative energy consumption curve comparative figure of the present invention and common reinforced concrete joint;

Fig. 6 is a comparative diagram of the loop stiffness curves of the present invention and ordinary reinforced concrete nodes.

In the figure, there are: beam 1, column 2, longitudinal reinforcement 3, stirrup 4, and angle iron 5.

Detailed ways

The prefabricated composite beam-column node component of the present invention includes intersecting beams 1 and columns 2, the beams 1 and columns 2 are composed of ECC materials, longitudinal bars 3 and stirrups 4, and the cross beams 1 and columns 2 overlap each other in a rectangular shape The transverse width of the area is A, and the longitudinal height is B; the transverse width of the beam 1 is 2B+A, and the longitudinal height is B, and the longitudinal rib 3 runs through the entire length of the beam 1 and protrudes from the two beam ends by 10cm to 15cm; the column 2 The vertical height is 2A+B, and the longitudinal rib 3 runs through the entire length of the column 2 and protrudes from the two column ends by 10cm to 15cm.

In the present invention, the ends of the crossbeam 1 and the column 2 are all fixed with angle irons 5, and the angle irons 5 are welded with the steel bar 3, and the lengths of the angle irons 5 extending into the crossbeam 1 and the columns 2 are 10-15 cm, exceeding the longitudinal The length of the ends of the ribs 3 is 10-15 cm.

The preparation process of the prefabricated composite beam-column node member of the present invention is:

1. Determine the values of A and B according to the design requirements, make a mold, bind the steel bars so that the steel bars protrude from the end of the mold to a length of b, and then weld a triangle iron at the end of the steel bar. The length of the triangle iron deep into the mold is a, which must exceed the steel bar The head length is c.

2. Insert the corrugated plate at the end of the beam and column in the mold, and make the triangle iron pass through the corrugated plate to a length of b+c, then pour in ECC material and vibrate carefully, remove the corrugated plate after final setting, and maintain it for 28 days A prefab can be formed.

In the actual installation project of building construction, two prefabricated composite beam-column joint members of the present invention are connected and installed with steel bars, and at the ends of the two prefabricated composite beam-column joint members, the ends of the longitudinal bars 3 are tightly welded to the steel bars , the protruding steel bars are also tightly welded with the angle irons, and then ordinary concrete is poured in-situ at the connecting section of the two prefabricated composite beam-column joint members until it is formed.

Claims (1)

1. a Prefabricated composite beam column node component, it is characterized in that, comprise the crossbeam (1) and the column (2) that intersect, described crossbeam (1) and column (2) are built composition by fiber cement based composites, vertical muscle (3) and stirrup (4) for engineering, crossbeam (1) is A with the transverse width of the rectangular area of column (2) cross-coincidence, is vertically highly B; The end cross-sectional of crossbeam (1) and column (2) is bellows-shaped;

The transverse width of described crossbeam (1) is 2B+A, is vertically highly B, and described vertical muscle (3) runs through crossbeam (1) total length and stretches out two beam-ends 10cm～15cm;

Vertical height of described column (2) is 2A+B, and vertical muscle (3) runs through column (2) total length and stretches out two styletable length 10cm～15cm;

The end of crossbeam (1) and column (2) all is fixed with angle bar (5), described angle bar (5) and reinforcing bar (3) welding, the length that angle bar (5) puts in crossbeam (1) and column (2) is 10～15cm, and the length that exceeds vertical muscle (3) end is 10～15cm.

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