CN220848330U - A reinforced concrete composite beam with high shear resistance and ductility - Google Patents

Abstract

The utility model discloses a reinforced concrete composite beam with high shear bearing capacity and ductility, comprising: tension reinforcement, stirrups and compression reinforcement connected in sequence; a concrete structure arranged on the tension reinforcement, stirrups and compression reinforcement; at least two fiber-reinforced composite structures symmetrically arranged on the concrete structure and located on a side close to the compression reinforcement, and the surface of the fiber-reinforced composite structure is flush with the surface of the concrete structure. During the compression process of the composite beam close to the compression reinforcement, after the first shear crack is generated, the fiber-reinforced composite structure located close to the compression reinforcement can prevent the crack from continuing to extend, so that the failure mode of the beam is changed from brittle shear failure to ductile bending failure, while ensuring the economic benefit basis, the ductility of the composite beam is also improved, so that measures can be taken in time for components with signs of failure.

Description

A reinforced concrete composite beam with high shear resistance and ductility

Technical Field

The utility model relates to the technical field of building beams, in particular to a reinforced concrete composite beam with high shear bearing capacity and ductility.

Background technique

The shear performance of reinforced concrete beams has always been a classic but challenging problem in structural engineering. Major breakthroughs have been made in the understanding of the shear mechanism of reinforced concrete beams in the past, but the shear problem is still considered one of the most important problems in reinforced concrete. Unlike other failure modes (such as bending failure), the shear failure of reinforced concrete beams is a brittle failure with a certain degree of suddenness. Therefore, once shear failure occurs, the results are usually catastrophic, resulting in economic losses and even threatening the lives of structure users. This makes the prevention of shear failure in reinforced concrete beams a high priority.

In the existing design scheme, although the external fiber reinforced composite material method can improve the shear performance of reinforced concrete beams, the cost is relatively high and the effect of improving the brittle failure characteristics of the overall component is not good, resulting in the ductility of the overall component needs to be improved.

Therefore, the prior art still needs to be improved and developed.

Utility Model Content

In view of the above problems, an embodiment of the present application provides a reinforced concrete composite beam with high shear bearing capacity and ductility, which can improve the ductility of the composite beam so that measures can be taken in time for components showing signs of damage.

The utility model provides the following technical solutions to solve the above technical problems:

A first aspect of an embodiment of the present application provides a reinforced concrete composite beam with high shear bearing capacity and ductility, comprising:

Tensile reinforcement, stirrups and compressive reinforcement connected in sequence;

A concrete structure is arranged on the tension reinforcement, stirrups and compression reinforcement;

At least two fiber-reinforced composite structures are symmetrically arranged on the concrete structure and located on a side close to the compression reinforcement, and the surface of the fiber-reinforced composite structure is flush with the surface of the concrete structure.

In some embodiments, the fiber-reinforced composite structure is connected to the compression reinforcement;

A plurality of stirrups are provided, and each of the fiber-reinforced composite structures is connected to at least one stirrup.

In some embodiments, both ends of the fiber-reinforced composite structure extend to both sides of the concrete structure along the width direction, and at least one surface of the fiber-reinforced composite structure connected to the concrete structure is an undulating surface.

In some embodiments, two surfaces of the fiber-reinforced composite structure connected to the concrete structure are corrugated surfaces.

In some embodiments, two surfaces of the fiber-reinforced composite structure that are perpendicular to the compression reinforcement are corrugated surfaces, and one surface of the fiber-reinforced composite structure that is perpendicular to the stirrups is a corrugated surface.

In some embodiments, the fiber reinforced composite structure is a fiber reinforced cement-based composite block.

In some embodiments, it also includes:

At least two supports are provided on the concrete structure and are located on a side close to the tension reinforcement material. The two supports are respectively close to two ends of the concrete structure, and the fiber reinforced composite structure and the supports are staggered.

In some embodiments, the tensile reinforcement, the stirrups and the compressive reinforcement are all arranged in the concrete structure, the concrete structure has a plurality of grooves, at least part of the stirrups and the compressive reinforcement are present in the grooves, and the fiber reinforced composite structure is arranged in the corresponding grooves.

In some embodiments, the number of the tensile reinforcements is greater than the number of the compressive reinforcements, and a plurality of stirrups respectively connect the tensile reinforcements and the compressive reinforcements.

In some embodiments, the number of the fiber reinforced cement-based composite blocks is two.

Beneficial effects: The utility model provides a reinforced concrete composite beam with high shear bearing capacity and ductility, comprising: tensile reinforcement, stirrups and compressive reinforcement connected in sequence; a concrete structure, which respectively connects the tensile reinforcement, stirrups and compressive reinforcement; at least two fiber-reinforced composite structures, which are evenly distributed on the concrete structure and located on one side close to the compressive reinforcement, and the surface of the fiber-reinforced composite structure is flush with the surface of the concrete structure. By arranging a fiber reinforced composite structure on the main beam, due to the synergistic effect of the compressive reinforcement and the stirrups, the horizontal and vertical forces in the area with the fiber reinforced composite structure can continuously meet the equilibrium conditions, and when shear failure occurs, the strength and deformation of the main beam can be improved; by changing the shape and size of the fiber reinforced composite structure, the shear bearing capacity and ductility of the entire reinforced concrete composite beam with high shear bearing capacity and ductility can be adjusted to meet different usage scenarios and usage requirements; by arranging a corrugated surface on the groove wall of the installation groove, the interface contact strength between the main beam and the fiber reinforced composite structure can be increased, making the contact between the main beam and the fiber reinforced composite structure more firm; only part of the concrete needs to be replaced with a small amount of fiber reinforced composite structure, and the cost is low; the production is simple and convenient, and can be well applied to prefabricated and assembled buildings. The utility model can improve the ductility of the composite beam while ensuring the economic benefit basis, so that measures can be taken in time for components with signs of damage.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. These drawings and text descriptions are not intended to limit the scope of the concept of the present application in any way, but to illustrate the concept of the present application for those skilled in the art by referring to specific embodiments. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

FIG1 is a three-dimensional wireframe schematic diagram of a reinforced concrete composite beam with high shear bearing capacity and ductility provided by an embodiment of the present application;

FIG2 is a schematic diagram of a planar structure of a main beam other than a fiber-reinforced composite structure provided in an embodiment of the present application;

FIG3 is a schematic diagram of a planar structure of a reinforced concrete composite beam with high shear bearing capacity and ductility provided by an embodiment of the present application;

FIG4 is a front view of a fiber-reinforced composite structure provided in an embodiment of the application;

FIG5 is a side view of a fiber-reinforced composite structure provided in an embodiment of the application;

FIG6 is a top view of a fiber-reinforced composite structure provided in an embodiment of the application;

FIG. 7 is a load-displacement curve of a reinforced concrete composite beam with high shear bearing capacity and ductility provided in an embodiment of the application as a test beam and a control beam in the prior art.

Description of reference numerals:

11. Tensile reinforcement; 12. Stirrups; 13. Compression reinforcement; 14. Support;

20. Concrete structure; 201. Groove;

30. Fiber reinforced composite structure;

301. Loading blocks.

Detailed ways

In order to make the purpose, technical scheme and effect of the utility model clearer and more specific, the technical scheme in the embodiment of the present application will be described clearly and completely in combination with the drawings in the embodiment of the present application. Obviously, the described embodiment is only a part of the embodiment of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

The inventor of the utility model found that in the existing design scheme, although the external fiber reinforced polymer (FRP) method can improve the shear performance of reinforced concrete beams, it still does not improve the brittle failure characteristics of the overall component, resulting in the ductility of the overall component to be improved.

FRP is widely used in structural reinforcement due to its corrosion resistance, light weight, high specific strength and convenient construction. The external FRP method is the earliest and most common form of FRP reinforcement technology. The disadvantage of this method is that the peeling of FRP is the most common form of damage in the external FRP reinforcement. Since the effective strain of FRP peeling is much smaller than its fracture strain, the utilization rate of FRP material is very low. In addition, although the external FRP method can improve the shear bearing capacity of reinforced concrete beams, there are almost no signs before FRP peeling, so it still has the characteristics of brittle failure. In addition, the use of fiber concrete as a whole for reinforced concrete beams can also improve the shear performance of reinforced concrete beams. The fiber concrete used is a proper amount of random fibers added to ordinary concrete. Compared with ordinary concrete, it has better splitting tensile strength, ductility and durability. Fiber concrete can delay the generation of shear cracks in the beam to a limited extent, improve the deformation capacity of concrete beams, and improve the brittle failure characteristics of concrete beams. However, the disadvantage of this method is that the price of fiber is relatively high. The use of fiber concrete for the entire beam body will greatly increase the production cost of the component.

It can be understood that ductile failure refers to components that have obvious plastic deformation when exceeding the yield point. When the tensile strength is reached, it will break under great deformation. This is the plastic failure of the material, also known as ductile failure. Ductility refers to the ability to deform in the later stage without significant change in bearing capacity, that is, the ability to withstand non-elastic deformation before final failure. The failure process of components with good ductility is relatively long, and there are obvious signs of failure. Measures can be taken early to avoid casualties and the total collapse of the building. This type of failure is called ductile failure, such as the failure of a properly reinforced beam. The failure of components with poor ductility occurs suddenly, without obvious signs, and measures cannot be taken early, which is likely to cause casualties and the total collapse of the building. This type of failure is called brittle failure, such as the failure of an over-reinforced beam.

Based on this, in one embodiment of the utility model provided by the inventor, a fiber-reinforced composite structure is arranged in a concrete structure close to the compressive reinforcement side, the fiber-reinforced composite structure is evenly distributed on the concrete structure, and the surface of the concrete structure is arranged flush with the surface of the fiber-reinforced composite structure. During the compression process of the composite beam close to the compressive reinforcement side, after the first shear crack is generated, the fiber-reinforced composite structure located close to the compressive reinforcement side can prevent the crack from continuing to extend, thereby improving the ductility of the composite beam while ensuring economic benefits, so that timely measures can be taken for components with signs of damage.

The technical solution of the present application and how the technical solution of the present application solves the above-mentioned technical problems are described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The reinforced concrete composite beam with high shear bearing capacity and ductility provided by the embodiment of the present application is described in detail below in conjunction with Figures 1 and 3.

As shown in FIG. 1 and FIG. 2 , an embodiment of the present application provides a reinforced concrete composite beam with high shear bearing capacity and ductility, comprising:

The tension reinforcement 11, stirrups 12 and compression reinforcement 13 are connected in sequence;

A concrete structure 20, connecting the tension reinforcement 11, stirrups 12 and compression reinforcement 13 respectively;

At least two fiber reinforced composite structures 30 are evenly distributed on the concrete structure 20 and located on a side close to the compression reinforcement 13 . The surface of the fiber reinforced composite structure 30 is flush with the surface of the concrete structure 20 .

Specifically, the tension reinforcement 11 is located below the compression reinforcement 13, the stirrups 12 connect the compression reinforcement 13 and the tension reinforcement 11 located above and below, respectively, the concrete structure 20 covers the tension reinforcement 11 and the compression reinforcement 13 in the longitudinal direction (vertical direction), and a plurality of fiber-reinforced composite structures 30 are evenly distributed on one side of the concrete structure 20 close to the compression reinforcement 13, and the compression surface of the fiber-reinforced composite structure is flush with the compression surface (i.e., the upper surface) of the concrete structure 20, the fiber-reinforced composite structure 30 is stably connected to the concrete structure 20, and the two will not be peeled off from each other, which not only improves the shear performance of the composite beam, but also improves the ductility of the composite beam. In other words, a plurality of The fiber-reinforced composite structure is evenly arranged in the compression area of the composite beam. When the loading block 301 is located on the upper surface of the concrete structure 20 or on the compression surface of the fiber-reinforced composite structure, during the shear failure of the composite beam of the embodiment of the present application, the first shear crack first appears in the composite beam (for example, at the middle height position). The multiple fiber-reinforced composite structures 30 can block the crack extension speed, slow down the rate at which the composite beam is destroyed, and improve the ductility of the composite beam, that is, the shear brittle failure characteristics of the component in the prior art can be improved to the ductile failure characteristics of the embodiment of the present application, so that measures can be taken in time for components with signs of damage, thereby providing time for repairing the structure.

It should be noted that after the tensile reinforcement 11, the compressive reinforcement 13 and the stirrups 12 are fixedly connected, the composite beam is prepared in the following manner: concrete is poured through a specific mold, to which a fixed plate assembly is connected, and the outer wall of the fixed plate assembly forms a groove 201 of the obtained concrete structure 20; after the concrete structure 20 is cast, the fixed plate assembly is taken out of the template, and a fiber-reinforced composite material is poured in the groove 201 of the concrete structure 20 to obtain a fiber-reinforced composite structure 30.

In some embodiments, the fiber reinforced composite structure 30 is a fiber reinforced cement-based composite block.

Specifically, the fiber reinforced composite structure 30 is a fiber reinforced composite layer (ie, an ECC block).

It is worth noting that the embodiment of the present application uses fiber-reinforced cementitious composite material (Engineered Cementitious Composite, abbreviated as ECC) to replace the concrete in the shear span compression zone of the reinforced concrete beam (i.e., the groove 201 part of the concrete structure 20 of the present application), thereby simultaneously improving the shear bearing capacity and ductility of the component and changing the brittle characteristics of shear failure.

It is understandable that the total shear force of the reinforced concrete beam is borne by the concrete and the stirrups 12. The shear contribution of the concrete is mainly composed of the pinning effect of the longitudinal reinforcement, the aggregate bite effect of the oblique crack interface, and the shear contribution of the uncracked concrete in the compression zone; the first two mechanisms are related to shear slip, so the shear contribution that can be provided is extremely limited. The uncracked compression zone concrete is the top priority to ensure the shear strength of the reinforced concrete beam. The inventor of the present application found that the compression zone concrete is the key to controlling the limit state of the reinforced concrete beam. The embodiment of the present application uses high-performance materials (i.e., fiber-reinforced composite structure 30) in the compression zone, so that the horizontal and vertical forces in the region can continue to meet the equilibrium conditions. When shear failure occurs, this method can improve the strength and deformation capacity of the composite beam, that is, it can significantly improve the shear bearing capacity and ductility of the reinforced concrete beam, so that the failure mode of the composite beam transitions from shear brittle failure to bending ductile failure. During the failure process of the composite beam, its side cracks can serve as a warning to the construction or observation personnel, so that the composite beam with signs of failure can be prevented, reinforced, and other series of measures can be taken.

It should also be noted that the fiber-reinforced cement-based composite structure (ECC block) is a randomly distributed fiber-reinforced cement-based composite material with good physical and mechanical properties, and has excellent performance in terms of safety, durability, and applicability. It has the following characteristics: ECC blocks have high toughness, large deformation, multi-point cracking, can effectively absorb seismic wave energy, and have a good effect on resisting impact and vibration; ECC blocks have good durability, due to the perfect combination of its randomly distributed fiber-reinforced structure and cement matrix, so that ECC blocks can resist chemical corrosion and physical damage in various natural environments; ECC blocks have good applicability and strong plasticity, and can be made into various shapes and sizes, which has great flexibility for building design and construction; ECC blocks also have good heat insulation, sound insulation, moisture resistance and other properties

In other embodiments, the fiber-reinforced composite structure 30 may also be configured as a reinforced fiber concrete block (mixed with random fibers), or other high-strength and high-ductility materials that can be connected to concrete.

In some embodiments, as shown in FIG. 1 , both ends of the fiber reinforced composite structure 30 extend to both sides of the concrete structure 20 along the width direction, and at least one surface of the fiber reinforced composite structure 30 connected to the concrete structure 20 is an undulating surface.

Specifically, the width direction is the front-to-back extension direction. In this embodiment, the front and rear surfaces of the fiber-reinforced composite structure 30 are flush with the front and rear surfaces of the concrete structure 20, that is, the three surfaces of the fiber-reinforced composite structure 30 are respectively connected to the bottom surface and the two side surfaces of the groove 201 of the concrete structure 20, at least one of the three surfaces is an undulating surface, and the corresponding concrete structure 20 has at least one undulating surface. The interface contact is increased by matching the undulating surfaces, the interface strength is improved, and the purpose of more stable connection between the concrete structure 20 and the fiber-reinforced composite structure 30 is achieved, thereby improving the ductility of the composite beam; the other three surfaces of the fiber-reinforced composite structure 30, namely the pressure surface (upper surface) and the front and back surfaces are all planes, ensuring that the overall structural surface of the composite beam is flat for subsequent installation.

It should be noted that the undulating surface includes a corrugated surface and a serrated surface.

In some embodiments, two surfaces of the fiber-reinforced composite structure 30 connected to the concrete structure 20 are corrugated surfaces.

Specifically, the two surfaces where the fiber reinforced composite structure 30 and the concrete structure 20 are connected are corrugated surfaces.

In some embodiments, two surfaces of the fiber-reinforced composite structure 30 that are perpendicular to the compression reinforcement are corrugated surfaces; and one surface of the fiber-reinforced composite structure 30 that is perpendicular to the stirrups is a corrugated surface.

Specifically, as shown in FIG. 1 , in this embodiment, the two end faces of the fiber reinforced composite structure 30 along the length direction (i.e., the left and right extension direction) are corrugated surfaces, but not limited to this. It can also be set that one of the end faces and the bottom surface are corrugated surfaces, or all three surfaces are corrugated surfaces.

In the embodiment of the present application, by evenly disposing at least two fiber-reinforced composite structures 30 in the groove 201 in the compression area of the concrete structure 20 , the shear bearing capacity and ductility of the reinforced concrete beam can be improved at the same time.

In some embodiments, as shown in FIG1 , the fiber-reinforced composite structure 30 is connected to the compression reinforcement 13 ;

A plurality of stirrups 12 are provided, and each of the fiber reinforced composite structures 30 is connected to at least one stirrup 12 .

Specifically, the fiber reinforced composite structure 30 has a certain thickness (i.e., height), is connected to part of the compressive reinforcement 13 and part of the stirrups 12, and is in contact with the concrete structure through the corrugated surface of the fiber reinforced composite structure 30. In this way, the fiber reinforced composite structure 30 can be stably connected to the concrete structure 20, so that the beam can be balanced in the force process, and based on the characteristics of the fiber reinforced composite structure 30, the ductility of the composite beam is improved.

In some embodiments, as shown in Figure 1, the tensile reinforcement 11, the stirrups 12 and the compressive reinforcement 13 are all arranged in the concrete structure 20, the concrete structure 20 has a plurality of grooves 201, at least part of the stirrups 12 and the compressive reinforcement 13 are present in the grooves 201, and the fiber reinforced composite structure 30 is arranged in the corresponding grooves 201.

Specifically, after the concrete structure 20 is poured, part of the stirrups 12 and the compressive reinforcement 13 are exposed, so that the fiber reinforced composite structure 30 formed by pouring can be stably connected to the stirrups 12 and the compressive reinforcement 13 .

In some embodiments, as shown in FIG. 1 , the number of the tension reinforcements 11 is greater than the number of the compression reinforcements 13 , and a plurality of stirrups 12 respectively connect each of the tension reinforcements 11 and each of the compression reinforcements 13 .

In some embodiments, the spacing between the reinforcements at the two ends of the concrete structure 20 is smaller than the spacing between the reinforcements at the middle portion of the concrete structure 20 .

Specifically, the compression reinforcement 13 and the tension reinforcement 11 extend in the transverse direction of the length (i.e., the length direction, left and right); there are two compression reinforcements 13 and six tension reinforcements 11, three of which form a layer, and two layers are stacked, and multiple stirrups 12 are distributed in the length direction, each stirrup 12 connects two compression reinforcements 13 and at least four tension reinforcements 11, and the stirrups 12 are distributed at the ends of the composite beam (i.e., the left and right sides of the concrete structure 20) with a higher density, and at the middle with a lower density, so as to ensure the shear resistance of the composite beam, and the compression area is generally the middle of the concrete structure 20 and the upper surface of the fiber reinforced composite structure 30. It can be understood that the arrangement of the steel bars and stirrups meets the requirements of the specification.

Furthermore, the compressive reinforcement 13 is a compressive longitudinal reinforcement, and the tensile reinforcement 11 is a tensile longitudinal reinforcement; the tensile longitudinal reinforcement uses 6 HPB400 ribbed steel bars with a diameter of 20 mm, the compressive longitudinal reinforcement uses 2 HPB400 ribbed steel bars with a diameter of 14 mm, and the stirrups 12 use HPB400 ribbed steel bars with a diameter of 12 mm to ensure that the member undergoes shear failure. The width of the ECC block is 360 mm, the length is 200 mm, and the height is 150 mm.

In some embodiments, as shown in FIG1 , the composite beam further comprises:

At least two supports 14 are provided on the concrete structure 20 and are located on a side close to the tension reinforcement 11. The two supports 14 are respectively close to two ends of the concrete structure 20. The fiber reinforced composite structure 30 and the supports 14 are staggered in the transverse direction.

Specifically, two supports 14 are provided, which are respectively located on the lower surface of the concrete structure 20 near the left and right ends, and the supports 14 and the fiber reinforced composite structure 30 are not in the same vertical direction.

In some embodiments, the number of the fiber reinforced cement-based composite blocks is two.

In this embodiment, there are two ECC blocks, which are arranged above the concrete structure 20. The two ECC blocks divide the upper part of the concrete structure 20 into three equal parts. The left and right sides of each ECC block are both corrugated surfaces. The concrete structure 20 has two grooves 201, and the left and right sides of each groove 201 are corrugated surfaces facing the corresponding ECC block. The ECC block is completely arranged in the groove 201, so that the pressure surface (upper surface), front side surface, and rear side surface of the ECC block are respectively aligned with the upper surface, front side surface, and rear side surface of the concrete structure 20. In other embodiments, the number of ECC blocks can be set to 3, 4, or 5, which can be modified according to actual needs.

It should be noted that during the shear failure of the composite beam, after the first shear crack was generated, as the load level increased, due to the characteristics of the ECC block, the shear crack was blocked by the ECC block, and the material in the compression zone could continue to maintain the horizontal and vertical force balance conditions, and the component could continue to bear and deform. After the load reached the peak, multiple cracks appeared in the web of the component, extending to the surrounding of the ECC block. Before the load dropped significantly, the test beam had a large deformation, and there were certain signs before the failure, and the failure mode transitioned from brittle shear failure to ductile bending failure.

The composite beam of the embodiment of the present application is used as a test beam, and a comparative test is performed with a beam of the prior art as a control beam, so as to explain in detail the effect of the composite beam of the embodiment of the present application on improving the ductility of the composite beam:

The concrete structure of the composite beam used as the test beam is provided with two evenly distributed ECC blocks on the side close to the compressive reinforcement, and the control beam is an ordinary reinforced concrete beam; during the test, the concrete structure of the composite beam is provided with a support at both ends close to the tensile reinforcement, and the control beam is provided with the same support; the position of the ECC block on the composite beam is used as the compressive loading point, that is, the loading block 301 is set, and the loading block is set at the corresponding position of the control beam where the ECC block is not set.

In order to ensure that the beam undergoes shear failure, the tensile reinforcement 11 uses 6 HPB400 ribbed steel bars with a diameter of 20 mm, the compressive reinforcement 13 uses 2 HPB400 ribbed steel bars with a diameter of 14 mm, and the stirrup 110 uses HPB400 ribbed steel bars with a diameter of 12 mm. The control beam is set in the same way; the spacing between multiple stirrups of the test beam and the control beam is also the same, set to 200 mm respectively.

The mechanical properties of the steel bars of the composite beam are shown in Table 1. The actual strength of the concrete is 35 MPa. The mix ratio and mechanical properties of the ECC blocks are shown in Tables 2 and 3, respectively. ECC pouring was carried out 24 hours after the concrete pouring was completed, and the shear test was carried out after curing at room temperature for 28 days.

Table 1: Mechanical properties of steel bars

Table 2: ECC mix ratio

Table 3: ECC mechanical properties

Through the shear test, the failure mode of the control beam is a typical shear failure mode. The first shear crack first appears at the middle height of the beam, and gradually extends to the support and loading point as the load increases. Finally, the shear crack extends to the concrete in the compression zone, and the concrete in the compression zone is crushed, and the entire control beam undergoes brittle shear failure. However, due to the effect of the ECC block, the failure mode of the test beam is significantly different. After the first shear crack occurs, as the load level increases, due to the characteristics of the ECC material, the shear crack is blocked by the ECC block, and the material in the compression zone can continue to maintain horizontal and vertical force balance conditions (the ECC block is connected to the compression reinforcement and stirrups respectively), and the component can continue to bear and deform. After the load reaches the peak, multiple cracks appear in the web of the test beam, extending to the surrounding of the ECC block. Before the load drops significantly, the test beam undergoes a large deformation, and there are certain signs before failure. The failure mode transitions from brittle shear failure to ductile bending failure.

As shown in Figure 7, at the beginning of loading, the curves of both beams increased linearly, and the two curves almost overlapped before the control beam reached its peak value. After the control beam suffered brittle failure, the load of the test beam continued to increase. After reaching the peak load, the test beam showed a platform end and did not fail immediately. The load decreased slightly, but the deflection increased significantly.

Table 4 shows the comparison of the peak load and deflection of the two beams. Compared with the control beam, the load of the test beam increased by 13.4% and the deflection increased by 50.6%.

Table 4: Test results of ductile reinforced concrete beams in compression zone

The embodiment of the present application replaces part of the concrete in the compression zone in the prior art with a small amount of ECC blocks, thereby improving the shear resistance and ductility while reducing the cost. In addition, the composite beam is simple and convenient to manufacture and can be well applied to prefabricated and assembled buildings.

The composite beam preparation method adopts a mold that uses a corrugated template and is placed on both sides of the ECC block to ensure the interface bonding performance between the ECC block and the concrete, and the concrete and the ECC are poured separately; according to the "Standard for Test Methods for Physical and Mechanical Properties of Concrete" GB/T 50081-2019, "Pebbles and Crushed Stones for Construction" GB/T 14685-2011 and "Sand for Construction" GB/T14684-2011, the concrete is mixed; the mixed concrete is poured into the mold, and vibrated with an inserted vibrator, and the vibrator is continuously inserted until the concrete is uniform, ensuring that there are no large bubbles on the surface of the component, and demolding after curing for 24 hours, the templates on both sides of the two internal ECC blocks are removed, and the templates around the ECC blocks are installed; ECC is made, the ECC is fully stirred until there is no agglomeration, poured and cured, and demolded after 24 hours.

In the description of this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

In the description of the present application, it should be understood that the terms "longitudinal", "lateral", "length", "width", "height", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

The terms "first", "second", "third", "fourth", etc. (if any) in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present application described herein can, for example, be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims (10)

1. A reinforced concrete composite beam of high shear load capacity and ductility comprising:

The tension bar, the stirrup and the compression bar are sequentially connected;

The concrete structure is arranged on the tension bar material, the stirrup and the pressed bar material;

At least two fiber reinforced composite structures are symmetrically arranged on the concrete structure and are positioned on one side close to the pressed reinforcement, and the surfaces of the fiber reinforced composite structures are flush with the surfaces of the concrete structure.

2. The high shear load bearing and ductile reinforced concrete composite beam according to claim 1 wherein said fiber reinforced composite structure is coupled to said pressed tendons;

The stirrups are provided with a plurality of stirrups, and each fiber reinforced composite structure is connected with at least one stirrup.

3. The reinforced concrete composite beam of claim 1, wherein the fiber reinforced composite structure has two ends extending in a width direction to two sides of the concrete structure, and at least one surface of the fiber reinforced composite structure connected to the concrete structure is a relief surface.

4. A reinforced concrete composite beam of high shear capacity and ductility according to claim 3, wherein the two faces of the fiber reinforced composite structure to which the concrete structure is attached are corrugated faces.

5. The reinforced concrete composite beam of claim 4, wherein two faces of the fiber reinforced composite structure perpendicular to the pressed tendons are corrugated faces, and one face of the fiber reinforced composite structure perpendicular to the stirrups is corrugated face.

6. The reinforced concrete composite beam of claim 1, wherein the fiber reinforced composite structure is a fiber cement-based composite block.

7. The high shear load bearing and ductile reinforced concrete composite beam according to claim 3 further comprising:

The two supports are arranged on the concrete structure and are positioned on one side close to the tension rib material, the two supports are respectively close to two ends of the concrete structure, and the fiber reinforced composite structure and the supports are arranged in a staggered mode.

8. The reinforced concrete composite beam of claim 1, wherein the tension bar, the stirrup, and the compression bar are all disposed within the concrete structure, the concrete structure having a plurality of grooves, at least a portion of the stirrup and compression bar being present within the grooves, the fiber reinforced composite structure being disposed within the corresponding groove.

9. The reinforced concrete composite beam of claim 8, wherein the number of tension bars is greater than the number of compression bars, and a plurality of the stirrups connect the tension bars and the compression bars, respectively.

10. The reinforced concrete composite beam of claim 6, wherein the number of fiber cement-based composite blocks is two.