Prefabricated bamboo-concrete composite beam connected by diagonally crossed steel plates and fabricating method

Abstract

A prefabricated bamboo-concrete composite beam includes a concrete slab 2, a bamboo beam 1, multiple connectors, and multiple grouting blocks 4. The concrete slab 2 is a precast reinforced concrete slab, and the concrete slab 2 is provided with multiple reserved hole slots 202 in a length direction at intervals. Each connector includes multiple steel plates 3 which are fixedly connected in a diagonal cross manner in turn, a first end of the connector is used for being implanted and fixed to the top of the bamboo beam 1, a second end of the connector is used for extending into the reserved hole slot 202, and each connector corresponds to one reserved hole slot 202.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of bamboo-concrete composite structures, and in particular to a prefabricated bamboo-concrete composite beam connected by diagonally crossed steel plates, and a fabricating method for the prefabricated bamboo-concrete composite beam. BACKGROUND

[0002] Since the 1990s, the global forest area has been decreasing, while the bamboo forest area has been increasing instead of decreasing. China is the country with the largest bamboo forest area in the world, with abundant bamboo resources. The bamboo has high tensile and compressive strength, and thus a variety of bamboo engineering materials with excellent mechanical properties have been developed one after another. Engineering bamboo members, as flexural members, still have some problems such as low section stiffness, insufficient bearing capacity and span capacity. Therefore, researchers put forward a bamboo-concrete composite beams, which is a flexural member formed by combining a bamboo beam and concrete wing plates through connectors for cooperative force bearing. The bamboo at the lower part is in tension and the concrete at the upper part is in compression, thus giving full play to the performance advantages of the two materials. The bamboo and the concrete are connected into a whole by the composite beam to work together. There are many forms of connectors, such as pin bolts, steel plates and grooves. Steel plate connectors are also called PBL (Perfobond rib) connectors. It is found that the initial stiffness and shear resistance of the PBL connectors are better than those of pin bolt connectors. At present, most common PBL connectors are made of vertical monolithic steel plates, which leads to the cracking of connection points due to stress concentration at the connection parts. Moreover, the current fabricating method is mostly cast-in-place upper concrete, which is not conducive to large-scale industrial production.

[0003] For example, a bamboo-concrete composite beam with a continuous connector is disclosed by China patent No. "201610463535.1". The bamboo beam and the concrete layer are connected to a composite beam by a perforated metal plate, which solves the defects of low bending stiffness of the bamboo structure and insufficient span capacity, as well as the application defects of insufficient anti-sliding stiffness of the common bamboo-concrete composite structure connector. However, the concrete slab at the upper part of the composite beam is cast-in-place, which is complicated in construction, uses large-area integral steel plates, and requires a large amount of steel, leading to poor economy. Developing a new reliable and economical connection mode is the basis for the application and popularization of bamboo-concrete composite structures. SUMMARY

[0004] An objective of the present disclosure is to provide a prefabricated bambooconcrete composite beam connected by diagonally crossed steel plates and a fabricating method for the prefabricated bamboo-concrete composite beam, so as to solve the problems in the prior art. A vertical connecting performance of the concrete slab and the bamboo beam is effectively improved, and the lifting trend between the concrete slab and the bamboo beam under the action of a bending moment is effectively restrained.

[0005] To achieve the objective above, the present disclosure employs the following technical solution:

[0006] A prefabricated bamboo-concrete composite beam connected by diagonally crossed steel plates provided by the present disclosure includes: a concrete slab, a bamboo beam, multiple connectors, and multiple grouting blocks. The concrete slab is a precast reinforced concrete slab, and the concrete slab is provided with multiple reserved hole slots in a length direction at intervals. The connectors include multiple steel plates which are fixedly connected in a diagonal cross manner in turn, where a first end of each connector is used for being implanted and fixed to the top of the bamboo beam, and a second end of the connector is used for extending into the reserved hole slot, and one connector corresponds to one reserved hole slot. Each grouting block is used to fix the connector extending into the reserved hole slot to the concrete slab, and is formed by grouting and pouring a grouting material into the reserved hole slot after the connector extends into the reserved hole slot.

[0007] Preferably, the connector is a diagonal cross structure formed by welding two steel plates through a welding point, and an included angle between the two steel plates is from 30 degrees to 90 degrees.

[0008] Preferably, a second end of each steel plate is provided with a U-shaped opening, multiple penetrating rebars are arranged in the reserved hole slot, both ends of the penetrating rebars are embedded and fixed into the concrete slab on both sides of the reserved hole slot, and one of the penetrating rebars corresponds to the U-shaped opening of one steel plate. After the connector extends into the reserved hole slot, one penetrating rebar is clamped into one U-shaped opening.

[0009] Preferably, the top of the bamboo beam is provided with multiple slideway groups. One slideway group includes two slideways, and first ends of the two steel plates of the connector are respectively inserted into the two slideways of one slideway group to be fixedly connected to the bamboo beam.

[0010] Preferably, the prefabricated bamboo-concrete composite beam further includes a structural adhesive layer. The structural adhesive layer is arranged in each slideway to bond and fix the first end of each steel plate to the bamboo beam.

[0011] Preferably, the slideway includes a circular arc section and a straight section, the straight section is integrally arranged at the bottom of the circular arc section, and a width of the straight section is the same as that of the steel plate.

[0012] Preferably, the slideway groups are uniformly arranged in a length direction of the bamboo beam, and two adjacent slideway groups are symmetrically arranged.

[0013] Preferably, the bamboo beam is made of one of bamboo laminated veneer lumber, bamboo plywood, bamboo laminated lumber or recombined bamboo.

[0014] Preferably, the size of the grouting block is consistent with that of the reserved hole slot, a grouting material of the grouting block is a cement-based quicksetting early-strength grouting material, and the strength of the grouting material is one grade higher than that of concrete used for the concrete slab.

[0015] Preferably, the width of the concrete slab is greater than that of the bamboo beam.

[0016] A fabricating method fora prefabricated bamboo-concrete composite beam connected by diagonally crossed steel plates above is also provided, including the following steps:

[0017] S1: processing and fabricating a concrete slab, processing and fabricating connectors and processing and fabricating a bamboo beam; providing positions of reserved hole slots when fabricating the concrete slab, where multiple steel plates are fixedly connected in a diagonal cross manner in turn to form the connectors;

[0018] S2: implanting and fixing first ends of the connectors to the top of the bamboo beam in turn, placing the concrete slab on the bamboo beam implanted with the connectors, and making second ends of the connectors extend into the reserved hole slots; and

[0019] S3: casting a grouting material in situ in each reserved hole slot of the concrete slab to form a grouting block, wherein the grouting block completely wraps a second end of each connector, and the concrete slab and the connector are connected into a whole by the grouting block, and the bamboo beam and the concrete slab are connected into a whole by the connector.

[0020] Compared with the prior art, the present disclosure has the following technical effects:

[0021] According to a prefabricated bamboo-concrete composite beam connected by diagonally crossed steel plates and a fabricating method for the prefabricated bamboo-concrete composite beam, the bamboo beam and the concrete slab are connected by connectors including multiple steel plates which are crossed diagonally in turn, and the contact area between the steel plates and the concrete slab at the upper part and the bamboo beam at the lower part can be increased by adopting diagonal cross configuration, thereby avoiding local damage caused by shear stress concentration at a connection position under a longitudinal sliding trend between the concrete slab and the bamboo beam. The diagonal cross configuration of the steel plates can effectively restrain a lifting trend between the concrete slab and the bamboo beam under the action of bending moment. The prefabrication of the composite beam can be achieved through grout anchor connection between the grouting block and the connector. Although the price of the grouting material is higher than that of ordinary concrete, the use amount of the grouting material is less. Therefore, the use of high-strength grouting material without increasing the budget can not only increase the connection strength, but also improve the local stress concentration at the connection. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] To describe the technical solutions of the embodiments of the present disclosure or in the prior art more clearly, the following briefly introduces the accompanying drawings required for describing the embodiments. Apparently, the accompanying drawings in the following description show merely some embodiments of the present disclosure, and those of ordinary skill in the art may still derive other drawings from these accompanying drawings without creative efforts.

[0023] FIG. 1 is a schematic diagram showing three-dimensional details of a prefabricated bamboo-concrete composite beam connected by diagonally crossed steel plates according to the present disclosure;

[0024] FIG. 2 is a three-dimensional schematic diagram of a prefabricated bambooconcrete composite beam connected by diagonally crossed steel plates according to the present disclosure;

[0025] FIG. 3 is a front view of a prefabricated bamboo-concrete composite beam connected by diagonally crossed steel plates according to the present disclosure;

[0026] FIG. 4 is a top view of FIG. 3;

[0027] FIG. 5 is a side view of FIG. 3;

[0028] FIG. 6 is a sectional view of A-A in FIG. 4;

[0029] FIG. 7 is a sectional view of B-B in FIG. 4;

[0030] FIG. 8 is a sectional view of C-C in FIG. 4;

[0031] FIG. 9 is a sectional view of D-D in FIG. 4;

[0032] FIG. 10 is a process flow chart of a fabricating method for a prefabricated bamboo-concrete composite beam connected by diagonally crossed steel plates according to Embodiment 2;

[0033] FIG. 11 is an assembly schematic diagram of a prefabricated bambooconcrete composite beam connected by diagonally crossed steel plates according to the present disclosure;

[0034] FIG. 12 is a schematic diagram of steel plates implanted into a bamboo beam in a prefabricated bamboo-concrete composite beam connected by diagonally crossed steel plates according to the present disclosure;

[0035] FIG. 13 is a schematic diagram of a steel plate in a prefabricated bambooconcrete composite beam connected by diagonally crossed steel plates according to the present disclosure.

[0036] In the drawings: 1-bamboo beam; 2-concrete slab; 3-steel plate; 4-grouting block; 101-slideway; 201-penetrating rebar; 202-reserved hole slot; 301-U-shaped opening; 302-welding point. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] The following clearly and completely describes the technical solutions in the embodiments of the present disclosure with reference to the accompanying drawings in the embodiments of the present disclosure. Apparently, the described embodiments are merely a part rather than all of the embodiments of the present disclosure. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present disclosure without creative efforts shall fall within the protection scope of the present disclosure.

[0038] An objective of the present disclosure is to provide a prefabricated bambooconcrete composite beam connected by diagonally crossed steel plates and a fabricating method for the prefabricated bamboo-concrete composite beam, so as to solve the problems in the prior art. A vertical connecting performance of the concrete slab and the bamboo beam is effectively improved, and the lifting trend between the concrete slab and the bamboo beam under the action of a bending moment is effectively restrained.

[0039] In order to make the objectives, technical solutions and advantages of the present disclosure more clearly, the present disclosure is further described in detail below with reference to the embodiments.

[0040] Embodiment 1

[0041] A prefabricated bamboo-concrete composite beam connected by diagonally crossed steel plates 3 is provided by this embodiment, as shown in FIG. 1 to FIG. 9, including a concrete slab 2, a bamboo 1, multiple connectors, and multiple grouting blocks 4. The concrete slab 2 is a precast reinforced concrete slab 2, and the concrete slab 2 is provided with multiple reserved hole slots 202 in a length direction at intervals. The connectors include multiple steel plates 3 which are fixedly connected in a diagonal cross manner in turn. A first end of each connector is used for being implanted and fixed to the top of the bamboo beam 1, a second end of the connector is used for extending into the reserved hole slot 202, and one connector corresponds to one reserved hole slot 202. The grouting block 4 is used for fixing the connector extending into the reserved hole slot 202 to the concrete slab 2, and the grouting block 4 is formed by grouting and pouring a grouting material into the reserved hole slot 202 after the connector extends into the reserved hole slot 202. The bamboo beam 1 and the concrete slab 2 are connected by the connectors including multiple steel plates 3 which are in diagonal cross in turn, and the contact area between the steel plates 3 and the concrete slab 2 at the upper part and the bamboo beam 1 at the lower part can be increased by adopting diagonal cross configuration, thereby avoiding local damage caused by shear stress concentration at a connection position under a longitudinal sliding trend between the concrete slab 2 and the bamboo beam 1. The diagonal cross configuration of the steel plates 3 can effectively restrain a lifting trend between the concrete slab 2 and the bamboo beam 1 under the action of bending moment. The prefabrication of the composite beam can be achieved through grout anchor connection between the grouting block 4 and the connector. Although the price of the grouting material is higher than that of ordinary concrete, the use amount of the grouting material is less. Therefore, the use of high-strength grouting material without increasing the budget can not only increase the connection strength, but also improve the local stress concentration at the connection.

[0042] In a preferred embodiment, the connector is a diagonal cross structure formed by welding two steel plates 3 through a welding point 302, and an included angle between the two steel plates 3 is from 30 degrees to 90 degrees. The connector is simple in structure, and capable of increasing the contact area between the steel plate 3 and the concrete slab 2 at the upper part and the bamboo beam 1 at the lower part.

[0043] In a preferred embodiment, a second end of each steel plate 3 is provided with a U-shaped opening 301, multiple penetrating rebars 201 are arranged in the reserved hole slot 202, both ends of the penetrating rebars 201 are embedded and fixed into the concrete slab 2 on both sides of the reserved hole slot 202. During the fabrication of the concrete slab 2, the penetrating rebars 201 are embedded into the concrete slab 2, and one penetrating rebar 201 corresponds to the U-shaped opening 301 of one steel plate 3. After the connector extends into the reserved hole slot 202, one penetrating rebar 201 is clamped into one U-shaped opening 301. The width of the U-shaped opening 301 at the upper part of the steel plate 3 is slightly greater than a diameter of the penetrating rebar 201, and a depth of the U-shaped opening 301 is greater than a distance from an upper surface of the concrete slab 2 to the bottom of the penetrating rebar 201. The U-shaped opening 301 at the upper part of the steel plate 3 can penetrate through the pre-embedded penetrating rebar 201 in the concrete slab 2 to achieve prefabricated production.

[0044] In a preferred embodiment, the top of the bamboo beam 1 is provided with multiple slideway groups, one slideway group includes two slideways 101, and first ends of the two steel plates 3 of the connector are respectively inserted into the two slideways 101 of one slideway group to be fixedly connected to the bamboo beam 1.

[0045] In a preferred embodiment, the prefabricated bamboo-concrete composite beam further includes a structural adhesive layer. The structural adhesive layer is arranged in each slideway 101 to bond and fix the first end of the steel plate 3 to the bamboo beam 1. The firmness degree of the steel plate 3 in the bamboo beam 1 can further be improved by injecting a structural adhesive into the slideway 101.

[0046] In a preferred embodiment, the slideway 101 includes a circular arc section and a straight section, the straight section is integrally arranged at the bottom of the circular arc section, and a width of the straight section is the same as that of the steel plate 3. The slideway 101 in the bamboo beam 1 is provided with the circular arc section, such that the steel plate 3 can be rapidly implanted into the bamboo beam 1.

[0047] In a preferred embodiment, the slideway groups are uniformly arranged in a length direction of the bamboo beam 1, and two adjacent slideway groups are symmetrically arranged to make circular arc directions of corresponding slideways 101 of the adjacent slideway groups opposite, the opposite circular arc directions of the adjacent slideways 101 can achieve opposite implantation directions of the steel plates 3, thus facilitating the steel plate 3 to resist the relative sliding between the bamboo beam 1 and the concrete slab 2 in different directions. Moreover, the slideway groups are uniformly and discretely arranged in the length direction of the bamboo beam 1, and the connectors in fit with the slideway groups are also discretely and uniformly arranged. The discretely arranged connectors can avoid local stress concentration and decompose the whole structural system into a few components, thus making the construction convenient.

[0048] In a preferred embodiment, the bamboo beam 1 is made of one of bamboo laminated veneer lumber, bamboo plywood, bamboo laminated lumber or recombined bamboo.

[0049] In a preferred embodiment, the size of the grouting block 4 is consistent with that of the reserved hole slot 202, a grouting material of the grouting block 4 is a cementbased quick-setting early-strength grouting material, and the strength of the grouting material is one grade higher than that of concrete used for the concrete slab 2. The grouting block 4 and the connector are in grout anchorage connection using quick-setting early-strength grouting material, so as to achieve the prefabrication of the composite beam. Although the price of the grouting material is higher than that of ordinary concrete, the use amount of the grouting material is less. Therefore, the use of high-strength grouting material without increasing the budget can not only increase the connection strength, but also improve the local stress concentration at the connection.

[0050] In a preferred embodiment, the width of the concrete slab 2 is greater than that of the bamboo beam 1.

[0051] Embodiment 2

[0052] A fabricating method fora prefabricated bamboo-concrete composite beam connected by diagonally crossed steel plates according to any one of Embodiment 1, as shown in FIG. 10 to FIG. 13, includes the following steps:

[0053] A. Precasting concrete slab. Penetrating rebars 201 are placed in a formwork and positions of reserved hole slots 202 are provided. Concrete is cast in situ in the formwork, and then is cured to form a precast concrete slab 2. After the curing is finished, the penetrating rebars 201, the reserved hole slots 202 and the surface of the concrete slab 2 are cleaned and kept at a dry and clean state.

[0054] B. Processing connector. A U-shaped opening 301 is cut at an upper part of each steel plate by a numerical control laser cutting machine, and two steel plates are welded at a middle welding point 302 with a set included angle to form a whole steel plate 3 with a diagonal cross structure, where an included angle between the two steel plates is 30 degrees to 90 degrees. A width of the U-shaped opening 301 on the upper part of the steel plate 3 is slightly greater than a diameter of the penetrating rebar 201, and a depth of the U-shaped opening 301 is greater than a distance from an upper surface of the concrete slab 2 to the bottom of the penetrating rebar 201.

[0055] C. Processing bamboo beam. Slideways 101 are provided at an upper part of the bamboo beam 1 using cutting equipment, where each slideway 101 includes a circular arc section and a horizontal section, the number of the slideways 101 is twice that of connectors, a width of the bottom horizontal section of the circular arc slideway 101 is equal to that of the bottom of the steel plate 3, and the circular arc sections of two adjacent circular arc slideways 101 are in opposite directions.

[0056] D. Implanting steel plate into bamboo beam. The lower parts of the connectors are implanted into the bamboo beam 1 along the slideway 101 in turn, and the structural adhesive is injected into the slideway 101 to cover the whole slideway 101. The surface of the bamboo beam is cleaned after the structural adhesive reaches the bonding strength, and the bamboo beam 1 and the connector are connected into a whole by the structural adhesive.

[0057] E. Assembling concrete slab. The precast concrete slab 2 is placed on the bamboo beam 1 implanted with the steel plates 3, the bottom of the concrete slab 2 is attached to an upper surface of the bamboo beam 1, the upper part of the steel plate 3 is completely located in the reserved hole slot 202, and the U-shaped opening 301 at the upper part of the steel plate 3 penetrates through the penetrating rebar 201 in the reserved hole slot 202.

[0058] F. Cast grouting block in situ. A cement-based grouting material is cast in situ in the reserved hole slot 202 of the concrete slab 2 to form a rectangular grouting block 4, the grouting block 4 completely wraps the upper part of the steel plate 3, and thus the concrete slab 2 and the steel plate 3 are connected into a whole by the grouting block, and the bamboo beam 1 and the concrete slab 2 are connected into a whole by the steel plate 3.

[0059] Specific examples are used herein for illustration of the principles and implementation methods of the present disclosure. The description of the embodiments is merely used to help illustrate the method and its core principles of the present disclosure. In addition, a person of ordinary skill in the art can make various modifications in terms of specific embodiments and scope of application in accordance with the teachings of the present disclosure. In conclusion, the content of this specification shall not be construed as a limitation to the present disclosure.

Claims

1. A prefabricated bamboo-concrete composite beam connected by diagonally crossed steel plates, comprising:a concrete slab, wherein the concrete slab is a precast reinforced concrete slab, and the concrete slab is provided with a plurality of reserved hole slots in a length direction at intervals;a bamboo beam;a plurality of connectors, comprising a plurality of steel plates which are fixedly connected in a diagonal cross manner in turn, wherein a first end of each connector is used for being implanted and fixed to the top of the bamboo beam, and a second end of the connector is used for extending into the reserved hole slot, and one connector corresponds to one reserved hole slot; anda plurality of grouting blocks, wherein each grouting block is used to fix the connector extending into the reserved hole slot to the concrete slab, and is formed by grouting and pouring a grouting material into the reserved hole slot after the connector extends into the reserved hole slot.

2. The prefabricated bamboo-concrete composite beam connected by diagonally crossed steel plates according to claim 1, wherein the connector is a diagonal cross structure formed by welding two steel plates through a welding point, and an included angle between the two steel plates is from 30 degrees to 90 degrees.

3. The prefabricated bamboo-concrete composite beam connected by diagonally crossed steel plates according to claim 2, wherein a second end of each steel plate is provided with a U-shaped opening, a plurality of penetrating rebars are arranged in the reserved hole slot, both ends of the penetrating rebars are embedded and fixed into the concrete slab on both sides of the reserved hole slot, one of the penetrating rebars corresponds to the U-shaped opening of one steel plate, and after the connector extends into the reserved hole slot, one penetrating rebar is clamped into one U-shaped opening.

4. The prefabricated bamboo-concrete composite beam connected by diagonally crossed steel plates according to claim 2, wherein the top of the bamboo beam is provided with a plurality of slideway groups, one slideway group comprises two slideways, and first ends of the two steel plates of the connector are respectively inserted into the two slideways of one slideway group to be fixedly connected to the bamboo beam.

5. The prefabricated bamboo-concrete composite beam connected by diagonally crossed steel plates according to claim 4, further comprising a structural adhesive layer, wherein the structural adhesive layer is arranged in each slideway to bond and fix the first end of each steel plate to the bamboo beam.

6. The prefabricated bamboo-concrete composite beam connected by diagonally crossed steel plates according to claim 5, wherein the slideway comprises a circular arc section and a straight section, and the straight section is integrally arranged at the bottom of the circular arc section, and a width of the straight section is the same as that of the steel plate.

7. The prefabricated bamboo-concrete composite beam connected by diagonally crossed steel plates according to claim 6, wherein the slideway groups are uniformly arranged in a length direction of the bamboo beam, and two adjacent slideway groups are symmetrically arranged.

8. The prefabricated bamboo-concrete composite beam connected by diagonally crossed steel plates according to claim 1, wherein the bamboo beam is made of one of bamboo laminated veneer lumber, bamboo plywood, bamboo laminated lumber or recombined bamboo.

9. The prefabricated bamboo-concrete composite beam connected by diagonally crossed steel plates according to claim 1, wherein the size of the grouting block is consistent with that of the reserved hole slot, a grouting material of the grouting block is a cement-based quick-setting early-strength grouting material, and the strength of the grouting material is one grade higher than that of concrete used for the concrete slab.

10. fabricating method for a prefabricated bamboo-concrete composite beam connected by diagonally crossed steel plates according to any one of claims 1 to 9, comprising the following steps:S1: processing and fabricating a concrete slab, processing and fabricating connectors and processing and fabricating a bamboo beam; providing positions of reserved hole slots when fabricating the concrete slab, wherein a plurality of steel plates are fixedly connected in a diagonal cross manner in turn to form the connectors;S2: implanting and fixing first ends of the connectors to the top of the bamboo beam in turn, placing the concrete slab on the bamboo beam implanted with the connectors, and making second ends of the connectors extend into the reserved hole slots; andS3: casting a grouting material in situ in each reserved hole slot of the concrete slab to form a grouting block, wherein the grouting block completely wraps a second endof each connector, and the concrete slab and the connector are connected into a whole by the grouting block, and the bamboo beam and the concrete slab are connected into a whole by the connector.

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