Parallel porous ultrathin concrete beam

Abstract

The invention relates to the field of concrete beams, and particularly discloses a parallel porous ultrathin concrete beam which comprises a beam body, a plurality of holes are formed in the beam body, and the horizontal central axis of each hole coincides with the horizontal central axis of the beam body; a hidden beam is arranged in the beam body; two groups of bent ribs are arranged in the beam body and comprise a first bent rib and a second bent rib, the first bent rib and the second bent rib are bent and crossed to form an accommodating space, and the hole is positioned in the accommodating space; the upper hidden beam and the lower hidden beam each comprise a supporting rib, dense stirrups are fixed to the outer walls of the supporting ribs, and the dense stirrups comprise two sets of full-height dense stirrups and chord member dense stirrups. The bending bearing capacity and the shearing bearing capacity of the concrete beam can be remarkably improved, so that loads can be distributed more uniformly when the concrete beam is stressed, the size of a hole which can be formed is larger, and the structural efficiency can be fully exerted.

Description

Technical Field

[0001] The invention relates to the field of concrete beams, and in particular to a parallel porous ultra-thin concrete beam. Background Art

[0002] As the requirements for the use of building construction continue to increase, construction units pay more and more attention to saving materials. At the same time, in order to improve the quality and experience, higher requirements are put forward for the net height under the beam and the electromechanical pipelines than before. In particular, most electromechanical pipelines are fixed on the installation bracket and erected later.

[0003] Due to the beam structure, it is usually necessary to further reserve the height of the beam structure when laying pipelines, which undoubtedly further compresses the indoor space. Although there are some opening structures on the beam in the prior art that allow pipelines to pass through the middle of the beam, most of them are carried out under quite strict restrictions, such as the opening height is less than 1 / 3 of the beam height, the hole width is less than 1.6 times the hole height, etc., only small-sized pipelines can pass through, and air-conditioning ducts, cable trays, etc. can only pass under the beam, which has a great impact on the clear height, indoor space quality, etc., and has a small scope of application. Summary of the invention

[0004] The invention provides a parallel porous ultra-thin concrete beam to solve the technical problems in the prior art that the opening size is small, the pipe rack can only pass under the beam, and the application range is small.

[0005] In order to solve the above problems, the present invention provides a parallel porous ultra-thin concrete beam adopting the following technical solution: comprising a beam body, a hole is opened on the beam body, and the horizontal center axis of the hole coincides with the horizontal center axis of the beam body;

[0006] A hidden beam is arranged in the beam body, and the hidden beam includes two groups, namely an upper hidden beam and a lower hidden beam, and the upper hidden beam and the lower hidden beam are respectively located at the upper and lower sides of the opening;

[0007] The beam body is provided with bent ribs, which include two groups of first bent ribs and second bent ribs. The first bent ribs and the second bent ribs are bent and crossed to form an accommodation space, and the opening is located in the accommodation space.

[0008] Both the upper hidden beam and the lower hidden beam include supporting bars, and the outer wall of the supporting bars is fixed with dense stirrups. The dense stirrups include two groups, which are full-height dense stirrups and chord dense stirrups. The full-height dense stirrups include two groups, which are located on the left and right sides of the opening, and the chord dense stirrups include two groups, which are located on the upper and lower sides of the opening;

[0009] The first bent reinforcement, the second bent reinforcement, the full-height dense stirrups, the chord dense stirrups and the supporting reinforcement are enclosed to make the accommodating space have a honeycomb structure.

[0010] Further, the first bent rib includes a first bending group, and the first bending group includes a first horizontal section, a first inclined section, a second horizontal section, a second inclined section, and a third horizontal section;

[0011] In the horizontal direction, the first inclined section is connected to the second horizontal section by inclining upward from the first horizontal section, the first inclined section and the second inclined section are symmetrically distributed on both sides of the central axis of the second horizontal section, and the second inclined section is connected to the third horizontal section by inclining downward from the second horizontal section;

[0012] The second bent ribs include a second bending group, and the second bending group and the first bending group are symmetrically distributed on upper and lower sides about the horizontal center axis of the hole.

[0013] Furthermore, the diameters of the first bent rib and the second bent rib are both set to d, a tension zone is formed on the first horizontal section and the third horizontal section of the first bent rib, and the anchorage length of the tension zone is 20d, a compression zone is formed on the first horizontal section and the third horizontal section of the second bent rib, and the anchorage length of the compression zone is 10d, and the anchorage length of the second horizontal section of both the first bent rib and the second bent rib is ≥20d.

[0014] Furthermore, the bending angle of the first inclined section in the first bent rib and the second bent rib relative to the first horizontal section is 45°.

[0015] Furthermore, the beam height is set to H, the opening height is set to h, h≤0.4H, and the opening width is set to W, W≤2.5h.

[0016] Furthermore, n openings are provided, n is allowed to be 2 or more, the beam length is set to L, the cumulative opening width is nW, nW≤0.4L, and the spacing between two adjacent openings is l, l≥0.8W.

[0017] Furthermore, a frame column edge is arranged on one side of the beam body, and the minimum distance between the opening and the frame column edge is L1, 1.5H≥L1≥1.2H.

[0018] Furthermore, the hole is arranged in a rectangular shape, and armpit corners are arranged at the four corners of the hole.

[0019] Furthermore, the number of supporting ribs in the lower hidden beam is greater than the number of supporting ribs in the upper hidden beam, and the number of supporting ribs in the upper hidden beam and the lower hidden beam respectively include at least two groups, the supporting ribs are arranged horizontally, and the two groups of supporting ribs are evenly distributed in the vertical direction.

[0020] Furthermore, the dense stirrups include a plurality of dense stirrups, and the spacing between two adjacent dense stirrups is 40mm-60mm.

[0021] The beneficial effects of the parallel porous ultra-thin concrete beam provided by the present invention are:

[0022] 1. By setting the upper and lower hidden beams in the beam body, and the honeycomb structure formed by the bent ribs, the bending and shearing bearing capacity of the concrete beam can be significantly improved, so that the concrete beam can distribute the load more evenly when subjected to force, thereby improving the stability of the overall structure, and thus making the cross-sectional aspect ratio of the beam body higher, which can greatly reduce the deadweight of the beam body, and make the size of the opening that can be opened larger, so that the structural efficiency can be fully utilized, and there is no need to configure bent ribs at the corners of the openings, which can effectively reduce the building height, reduce the demand for construction materials and energy consumption, and help achieve the goals of energy conservation, emission reduction and sustainable development;

[0023] 2. Raise the opening from the bottom of the beam to the middle of the beam. While increasing the indoor net height, it can also promote natural ventilation and improve ventilation effects, making the house a product of architectural-structural-mechanical-electrical synergy integration, which is more practical. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] By reading the following detailed description with reference to the accompanying drawings, the above and other objects, features and advantages of the exemplary embodiments of the present invention will become readily understood. In the accompanying drawings, several embodiments of the present invention are shown in an exemplary and non-limiting manner, and the same or corresponding reference numerals represent the same or corresponding parts, wherein:

[0025] Figure 1 It is a structural schematic diagram of a parallel porous ultra-thin concrete beam of the present invention;

[0026] Figure 2 It is a structural schematic diagram of a first bending group and a second bending group of a parallel porous ultra-thin concrete beam of the present invention;

[0027] Figure 3 It is a schematic cross-sectional structure diagram of a parallel porous ultra-thin concrete beam of the present invention;

[0028] Figure 4 This is the comparison diagram of stirrup strain at typical locations;

[0029] Figure 5 This is a comparison diagram of the mid-span displacement of the beam;

[0030] Figure 6 This is the comparison diagram of the compressive strain of the longitudinal reinforcement in the upper part of the beam span;

[0031] Figure 7 This is the comparison diagram of the tensile strain of the longitudinal reinforcement in the lower part of the beam span;

[0032] Figure 8 is the hysteresis curve of specimen 2-1;

[0033] Fig. 9 is the hysteresis curve of specimen 2-2;

[0034] Fig.10is the hysteresis curve of specimen 2-3;

[0035] Fig.11 It is the load-displacement skeleton curve of the node specimen.

[0036] Description of reference numerals:

[0037] 1. Beam body;

[0038] 11. Hidden beam; 111. Upper hidden beam; 112. Lower hidden beam; 113. Support ribs; 114. Increased stirrups;

[0039] 12, bent ribs; 121, first bent ribs; 1211, first bending group; 101, first horizontal section; 102, first inclined section; 103, second horizontal section; 104, second inclined section; 105, third horizontal section; 106, tension zone; 122, second bent ribs; 1221, second bending group; 107, compression zone;

[0040] 2. Hole opening; 21. Armpit angle. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Those skilled in the art should know that the embodiments described below are part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0042] Any number of elements in the drawings is for illustration and not limitation, and any naming is for distinction only and does not have any limiting meaning.

[0043] The principle and spirit of the present invention are explained in detail below with reference to several representative embodiments of the present invention.

[0044] The present invention provides a parallel porous ultra-thin concrete beam, such as Figure 1 to Figure 2 As shown, it comprises a beam body 1, a hole 2 is opened on the beam body 1, and the horizontal center axis of the hole 2 coincides with the horizontal center axis of the beam body 1;

[0045] A hidden beam 11 is arranged in the beam body 1. The hidden beam 11 includes two groups, namely an upper hidden beam 111 and a lower hidden beam 112. The upper hidden beam 111 and the lower hidden beam 112 are respectively located at the upper and lower sides of the opening 2;

[0046] The beam body 1 is provided with bent ribs 12, which include two groups of first bent ribs 121 and second bent ribs 122. The first bent ribs 121 and the second bent ribs 122 are bent and crossed to form an accommodation space, and the opening 2 is located in the accommodation space;

[0047] The upper hidden beam 111 and the lower hidden beam 112 both include support bars 113, and the outer wall of the support bars is fixed with dense stirrups 114. The dense stirrups 114 include two groups, which are full-height dense stirrups and chord dense stirrups. The full-height dense stirrups include two groups, which are respectively located on the left and right sides of the opening, and the chord dense stirrups include two groups, which are respectively located on the upper and lower sides of the opening.

[0048] The first bent ribs 121, the second bent ribs 122, the full-height dense stirrups, the chord dense stirrups, and the supporting ribs 113 are enclosed so that the accommodating space has a honeycomb structure.

[0049] In this embodiment, when the beam body 1 is subjected to a load, the load is first transferred to the lower surface through the upper surface of the beam body 1. During the transfer process, due to the existence of the upper hidden beam 111 and the lower hidden beam 112, the load will be more evenly distributed in the entire beam body 1. At the same time, the honeycomb structure formed by the bent ribs 12 can also play a role in dispersing the load, making the concrete beam more stable when subjected to force. The beam body 1 can absorb and dissipate energy more coordinately when deformed, which helps to reduce the stress concentration phenomenon of the structure, thereby improving the bearing capacity of the structure. In addition, through the close connection and coordinated work between the various components, the beam body 1 can maintain good overall performance when subjected to a large load or emergency situation, and is not easily damaged.

[0050] In this embodiment, the first bent rib 121 includes a first bending group 1211, and the first bending group 1211 includes a first horizontal section 101, a first inclined section 102, a second horizontal section 103, a second inclined section 104, and a third horizontal section 105;

[0051] In the horizontal direction, the first inclined section 102 is connected to the second horizontal section 103 by being inclined upward from the first horizontal section 101. The first inclined section 102 and the second inclined section 104 are symmetrically distributed on both sides of the central axis of the second horizontal section 103. The second inclined section 104 is connected to the third horizontal section 105 by being inclined downward from the second horizontal section 103.

[0052] The second bent rib 122 includes a second bending group 1221 , and the second bending group 1221 and the first bending group 1211 are symmetrically distributed on upper and lower sides about the horizontal center axis of the opening 2 .

[0053] In this embodiment, the first bent rib 121 and the second bent rib 122 both include multiple bending sections, forming a complex spatial structure, which can not only increase the bonding area between the steel bar and the concrete, but also improve the tensile and shear resistance of the steel bar. In addition, the first bending group 1211 and the second bending group 1221 are symmetrically distributed on both sides of the horizontal center axis of the opening 2, so that the beam body 1 can distribute the load more evenly when subjected to force, and can effectively avoid the occurrence of stress concentration. In this embodiment, the first bent rib 121 and the second bent rib 122 cross to form a honeycomb structure, and the accommodating space is a hexagonal structure. The vertical center axis and the horizontal center axis of the opening 2 and the accommodating space coincide with each other, so that the stress distribution in the beam body 1 is more uniform, avoiding the occurrence of stress concentration.

[0054] In this embodiment, when there are multiple openings 2, multiple first bending groups 1211 and second bending groups 1221 on the bent ribs 12 are also correspondingly arranged. The multiple first bending groups 1211 and second bending groups 1221 are respectively connected in sequence along the first bent ribs 121 and the second bent ribs 122, so that multiple accommodating spaces are formed in the beam body 1, ensuring that the layout of the steel bars around each opening 2 is sufficiently tight and reasonable, thereby providing sufficient supporting force.

[0055] In this embodiment, the diameters of the first bent rib 121 and the second bent rib 122 are both set to d, a tension zone 106 is formed on the first horizontal section 101 and the third horizontal section 105 of the first bent rib 121, and the anchorage length of the tension zone 106 is 20d, a compression zone 107 is formed on the first horizontal section 101 and the third horizontal section 105 of the second bent rib 122, and the anchorage length of the compression zone 107 is 10d, and the anchorage lengths of the second horizontal section 103 of both the first bent rib 121 and the second bent rib 122 are ≥20d. By precisely controlling the anchorage lengths of different parts, the layout of the steel bars in the beam body 1 can be made more reasonable and efficient, which helps to reduce the use of steel bars and reduce construction costs, while maintaining or improving the bearing capacity of the structure.

[0056] In this embodiment, the anchorage length of the tension zone 106 is greater than the anchorage length of the compression zone 107, which ensures that the steel bars have sufficient length to transmit the tension under tension and prevent the steel bars from being pulled out or broken under the action of the tension, thereby improving the safety of the structure. Although the anchorage length of the compression zone 107 is shorter than that of the tension zone 106, considering that the steel bars in the compression zone 107 mainly bear pressure and have a relatively low risk of being pulled out, an anchorage length of 10d is usually sufficient to meet safety requirements. The anchorage length of the second horizontal section 103 is greater than the anchorage length of the tension zone 106, which makes the connection of the steel bars in the beam body 1 more secure, and can effectively enhance the overall stability of the structure. Especially when the beam body 1 is subjected to complex loads, this secure connection can ensure that the various parts of the beam body 1 work together to resist external loads.

[0057] In this embodiment, the first inclined section 102 of the first bent rib 121 and the second bent rib 122 has a bending angle of 45° with respect to the first horizontal section 101, which can enable the steel bar to better exert its tensile or compressive properties when subjected to force. In the tension zone 106, the steel bar is bent at an angle of 45° to more effectively resist the tensile force and prevent the steel bar from being pulled out or broken under the action of the tensile force; in the compression zone 107, although the steel bar mainly bears pressure, the 45° bending angle also helps to improve the bonding force between the steel bar and the concrete, thereby enhancing the overall stability of the structure.

[0058] In this embodiment, the beam height is set to H, the height of the opening 2 is set to h, h≤0.4H, the width of the opening 2 is set to W, W≤2.5h, there are n openings 2, n is allowed to be 2 or more, and multiple openings are evenly distributed in the horizontal direction. The beam length is set to L, the cumulative width of the opening 2 is nW, nW≤0.4L, the spacing between two adjacent openings 2 is l, l≥0.8W, a frame column edge is set on one side of the beam body 1, and the minimum distance between the opening 2 and the frame column edge is L1, 1.5H≥L1≥1.2H. In this embodiment, by ensuring the reasonable layout and coordination between the beam and the opening 2 to maintain the overall performance, bearing capacity and safety of the structure, and by precisely controlling these parameters, the force performance of the beam body 1 can be optimized, the stability and durability of the structure can be improved, and the needs of construction and use can be met at the same time.

[0059] In this embodiment, the opening 2 is configured to be rectangular, and armpit corners 21 are provided at the four corners of the opening 2. The provision of the armpit corners 21 can increase the rigidity around the opening 2, and help resist the local stress concentration caused by the existence of the opening 2. By dispersing the stress to a larger area, the armpit corners 21 can strengthen the connection between the beam body 1 and the opening 2, thereby improving the stability of the overall structure, and when subjected to horizontal loads or shear forces, the armpit corners 21 can absorb and disperse these forces, thereby protecting the beam body 1 from damage.

[0060] In this embodiment, the number of supporting ribs 113 in the lower hidden beam 112 is greater than the number of supporting ribs 113 in the upper hidden beam 111, and the number of supporting ribs 113 in the upper hidden beam 111 and the lower hidden beam 112 respectively include at least two groups, the supporting ribs 113 are horizontally arranged, and the two groups of supporting ribs 113 are evenly distributed in the vertical direction.

[0061] In this embodiment, in the upper concealed beam 111, the support ribs 113 include two groups, the two groups of support ribs 113 are distributed along the vertical direction, and the two groups of support ribs 113 are fixed in the dense hoop 114;

[0062] In the lower hidden beam 112 , the support ribs 113 include four groups, the four groups of support ribs 113 are evenly distributed along the vertical direction, and the four groups of support ribs 113 are all fixed in the dense hoop reinforcement 114 .

[0063] In this embodiment, located above the opening 2, the supporting ribs 113 in the upper hidden beam 111 are fixed in one group of chord rod dense stirrups located above the opening; located below the opening 2, the supporting ribs 113 in the lower hidden beam 112 are fixed in another group of chord rod dense stirrups located below the opening 2; located on the left side of the opening 2, the supporting ribs 113 in the upper hidden beam 111 and the supporting ribs 113 in the lower hidden beam 112 are both fixed in one group of full-height dense stirrups on the left side of the opening 2; located on the right side of the opening 2, the supporting ribs 113 in the upper hidden beam 111 and the supporting ribs 113 in the lower hidden beam 112 are both fixed in another group of full-height dense stirrups on the right side of the opening 2.

[0064] In this embodiment, in the upper hidden beam 111 and the lower hidden beam 112, multiple groups of support ribs 113 are evenly distributed in the vertical direction, which can effectively enhance the vertical bearing capacity of the upper hidden beam 111 and the lower hidden beam 112, and the lower hidden beam 112 has a stronger bearing capacity in the vertical direction, and can better resist the load from below or the side. Each group of support ribs 113 is firmly fixed inside the stirrups 114 to ensure that they can work together to resist external forces.

[0065] In other embodiments, the number of support ribs 113 in the upper hidden beam 111 and the lower hidden beam 112 can be adjusted according to actual usage requirements.

[0066] In this embodiment, the dense stirrups include a plurality of stirrups, and the spacing between two adjacent stirrups 114 is 40 mm to 60 mm. In this embodiment, the spacing between two adjacent stirrups 114 is 50 mm.

[0067] The parallel porous ultra-thin concrete beam provided by the present invention is mainly based on the considerations of load transfer and distribution, deformation coordination and energy consumption, and overall stability. By arranging the upper hidden beam 111 and the lower hidden beam 112 in the beam body 1, and the honeycomb structure formed by the bent ribs 12, the bending bearing capacity and the shear bearing capacity of the concrete beam can be significantly improved, so that the concrete beam can distribute the load more evenly when subjected to force, thereby improving the stability of the overall structure, and further making the cross-sectional aspect ratio of the beam body 1 higher, which can greatly reduce the deadweight of the beam body 1, and making the size of the opening 2 that can be opened larger, which can give full play to the structural efficiency, and there is no need to configure the bent ribs 12 at the corners of the opening 2, which can effectively reduce the building storey height, reduce the demand for construction materials and energy consumption, and help achieve the goals of energy conservation, emission reduction and sustainable development;

[0068] In addition, raising the opening 2 from the bottom of the beam to the middle of the beam can not only increase the indoor net height, but also promote natural ventilation and improve ventilation effects, making the house a product of architectural-structural-mechanical-electrical synergy integration and more practical.

[0069] In order to verify this embodiment, a static ultimate bearing capacity test and a low-cycle repeated test of the beam-column joint were carried out.

[0070] Static ultimate bearing capacity test study:

[0071] Five beam specimens were designed for four-point bending performance tests, including comparative tests with and without openings. In the loading frame, a jack was used to perform two-point symmetrical loading through the distribution beam. The load was graded, with each level of load being 20kN. Loading started from zero until the specimen was destroyed or the bearing capacity dropped below 85%. The experiment studied the bending bearing capacity of the cross-section of the beam specimens, deflection changes, crack appearance and development process, and failure mode. The vertical load of the test is displayed by a compression load sensor. The test measurements mainly include vertical loads, strain values ​​of the longitudinal steel bars in the control section of the pure bending section of the beam under each level of load, steel bar strain at the corresponding position of the beam opening, shear deformation in the plastic hinge zone, beam support and mid-span deflections, and specimen failure process and phenomena.

[0072] The comparison diagram of stirrup strain at typical locations is attached. Figure 4 , see the attached comparison diagram of beam mid-span displacement Figure 5 , the comparison diagram of the compressive strain of the longitudinal reinforcement in the upper part of the beam span is shown in the attached Figure 6 , the comparison diagram of longitudinal reinforcement tensile strain in the middle and lower part of the beam span is shown in the attached Figure 7 .

[0073] From the comparison diagram of mid-span displacement of beams, it can be seen that the displacement changes of the five beams have the same trend as the stress changes of the stirrups at the opening edge: although specimens 1-1, 1-3, 1-4 and 1-5 have openings, their stiffness is significantly greater than that of specimen 1-2. Under the same load conditions, specimen 1-2 has the largest displacement, indicating that the reinforcement bars at the upper and lower edges and corners of the opening have improved the stiffness of the beam to a certain extent; before loading to 250kN, the displacements of specimens 1-1, 1-3, 1-4 and 1-5 are very close. In the middle and late stages of the bending load, the stiffness of specimen 1-4 decreases significantly compared with the other three specimens, and its displacement develops faster, but its stiffness is larger than that of specimen 1-2.

[0074] From the upper longitudinal reinforcement compressive strain comparison diagram and the lower longitudinal reinforcement tensile strain comparison diagram in the middle of the beam span, it can be seen that the strains of the upper and lower longitudinal reinforcements of the five beams show a trend of increasing under compression and tension, respectively. According to the general principle of concrete beam stress, the upper longitudinal reinforcement and concrete are subjected to stress together, and its strain is basically consistent with the compressive concrete: at the initial loading stage, the compressive strain change trend of the longitudinal reinforcement of each beam is basically the same; after the load exceeds 250kN, the upper compressive concrete area of ​​specimen 1-3 is much smaller than that of other specimens due to the lack of flange plates, and the upper steel bar compressive strain is significantly greater than that of other beams; the upper compressive steel bar ultimate strains of the open hole beam specimens 1-1, 1-3 and 1-4 are similar, and the final failure mode is also the crushing of the upper concrete; while the steel bar compressive strain of specimen 1-5 is slightly larger because the strain change position is close to the concrete failure position. For the stress of the lower tensile reinforcement, specimens 1-1, 1-3, and 1-5 are similar. The lower longitudinal reinforcement did not begin to yield until the specimens were completely destroyed, indicating that the reinforced steel bars near the opening played the role of longitudinal reinforcement, resulting in excessive reinforcement at the bottom of the beam, which requires further optimization. Specimen 1-2 is an ordinary concrete beam. Its strain increased steadily in the early stage. As the load increased until the bottom longitudinal reinforcement entered the yield stage, the compressive strain began to shake and become abnormal. Finally, the upper concrete was destroyed in compression, which was basically consistent with the failure characteristics of the properly reinforced beam. Specimen 1-4, which did not have the bent reinforcement at the corner of the opening, had a longitudinal reinforcement strain change trend that was basically consistent with specimen 1-2. The final failure forms of the two were also similar: the upper concrete was crushed after the lower reinforcement yielded, and the ultimate bearing capacity was basically the same. This shows that in terms of bending resistance alone, concrete beams with openings do not need to be over-reinforced.

[0075] Study on low cycle repeated tests of beam-column joints:

[0076] A total of three specimens were made. Specimen 2-1 was a beam-column joint with a rectangular opening in the floor slab, and specimens 2-2 and 2-3 were beam-column joints with no opening in the floor slab.

[0077] Low-cycle repeated load seismic tests were carried out on three beam-column edge node specimens. An electro-hydraulic servo actuator was used to apply horizontal reciprocating load on the top of the node specimen column to simulate the horizontal seismic load. Four jacks and high-strength steel rods were used to apply constant vertical pressure to the node specimen column to simulate the vertical load on the column during the service of the node. At the same time, the failure modes of beam-column node specimens with rectangular openings in floor slabs and beam-column node specimens with no openings in floor slabs under seismic action and the change laws of various seismic performance indicators were studied.

[0078] From the crack distribution and failure morphology during the test, it can be seen that the failure morphology of the three specimens is that the concrete on the surface of the beam near the column end is peeled off in large quantities, the longitudinal reinforcement at the bottom is buckled and damaged, the stress on the node is greatly reduced, and the bearing capacity is completely lost in the end. The failure morphology is very similar. Specimen 2-1 with a hole in the beam failed until it finally failed. The crack width near the rectangular hole is still much smaller than the end near the column at the root of the beam, and there is no obvious peeling of the concrete around the hole. If specimen 2-2 is used as the benchmark, when the inter-story displacement angle is 2%, the positive horizontal load and negative horizontal load differ by no more than 6% from the other two specimens.

[0079] The hysteresis curve is the load-displacement curve obtained when the specimen is subjected to low-cycle reciprocating loads. It is the main basis for determining the structural restoring force model and conducting nonlinear seismic response analysis. The hysteresis curve can very intuitively reflect the energy dissipation capacity, deformation performance, ductility characteristics, stiffness degradation and strength attenuation of the component. The hysteresis curve of specimen 2-1 is shown in the attached figure. Figure 8 , the hysteresis curve of specimen 2-2 is shown in the attached Fig. 9 , the hysteresis curve of specimen 2-3 is shown in the attached Fig.10 .

[0080] At the initial stage of loading, the load-displacement curves of each specimen basically change linearly, indicating that the specimen is in the elastic stage; with the increase of cyclic displacement, after the node reaches the maximum bearing capacity, the loads at each level remain basically unchanged, but the slope of the curve decreases faster and the node stiffness degrades, indicating that the node has good ductility.

[0081] The skeleton curve reflects the strength, stiffness and other characteristics of the structure and components at each stage of stress and deformation. The load-displacement skeleton curve of each node specimen is shown in the attached Fig.10 .

[0082] It can be seen from the skeleton curves of each specimen that the skeleton curves of the three specimens basically coincide, the elastic stage remains a straight line, the inflection point and peak load of the curve are basically the same, and the extension length of the horizontal section is also very close.

[0083] The ductility coefficient is an indicator that reflects the plastic deformation capacity of structural components.

[0084] Ductility coefficient of each specimen:

[0085] Test piece Limit deformation(mm) Yield deformation(mm) Ductility coefficient 2-1 95.9 27.4 3.5 2-2 95.9 27.4 3.5 2-3 95.9 27.4 3.5

[0086] As can be seen from the above table, the ductility coefficients of the three specimens are all 3.5, which shows that the different beam openings and beam height-to-thickness ratios of the specimens have no obvious effect on the ductility of the nodes.

[0087] The following conclusions can be drawn from the test results:

[0088] 1. The maximum vertical ultimate bearing capacities of beam specimens 1-1, 1-4, 1-5 with floor openings, beam specimen 1-2 with floor openings but without openings, and beam specimen 1-3 without floor openings are 718 kN, 534 kN, 550 kN, 500 kN, and 550 kN, respectively. The bearing capacity of beam specimen 1-1 with floor openings is about 33% higher than that of beam specimen 1-2 with floor openings but without openings, while beam specimens 1-4 and 1-5 with floor openings are basically equivalent to the bearing capacity of ordinary concrete specimen 1-2 without openings. The ultimate bearing capacity data show that the reasonable design of beam web openings on the parallel porous ultra-thin concrete beam provided by the present invention does not significantly reduce the bending bearing capacity of the concrete beam.

[0089] 2. For beam web opening components that are mainly used for bending resistance, the parallel porous ultra-thin concrete beam provided by the present invention can achieve the bending resistance effect of an ordinary beam without openings under the same conditions even if only normal opening reinforcement horizontal steel bars and vertical stirrups are arranged. Therefore, when the width of the beam section is limited, it is not necessary to arrange bent reinforcement at the corners of the openings.

[0090] According to the above description of this specification, those skilled in the art may also understand that the terms used below, such as "up", "down", "front", "back", "left", "right", "width", "horizontal", "top", "bottom", "inside", "outside" and the like, which indicate orientation or positional relationships, are based on the orientation or positional relationships shown in the drawings of this specification, and are only for the purpose of facilitating the explanation of the scheme of the present invention and simplifying the description, rather than explicitly or implicitly indicating that the devices or elements involved must have the specific orientation, be constructed and operated in a specific orientation. Therefore, the above-mentioned orientation or positional relationship terms cannot be understood or interpreted as limitations on the scheme of the present invention.

[0091] In addition, in the description of this specification, “plurality” means at least two, for example, two, three or more, etc., unless otherwise clearly and specifically defined.

Claims

1. A parallel porous ultra-thin concrete beam, comprising a beam body, a hole is opened on the beam body, characterized in that: The horizontal center axis of the opening coincides with the horizontal center axis of the beam body; A hidden beam is arranged in the beam body, and the hidden beam includes two groups, namely an upper hidden beam and a lower hidden beam, and the upper hidden beam and the lower hidden beam are respectively located at the upper and lower sides of the opening; The beam body is provided with bent ribs, which include two groups of first bent ribs and second bent ribs. The first bent ribs and the second bent ribs are bent and crossed to form an accommodation space, and the opening is located in the accommodation space. Both the upper hidden beam and the lower hidden beam include supporting bars, and the outer wall of the supporting bars is fixed with dense stirrups. The dense stirrups include two groups, which are full-height dense stirrups and chord dense stirrups. The full-height dense stirrups include two groups, which are located on the left and right sides of the opening, and the chord dense stirrups include two groups, which are located on the upper and lower sides of the opening; The first bent reinforcement, the second bent reinforcement, the full-height dense stirrups, the chord dense stirrups and the supporting reinforcement are enclosed to make the accommodating space have a honeycomb structure.

2. The parallel porous ultra-thin concrete beam according to claim 1, characterized in that: The first bent rib includes a first bending group, and the first bending group includes a first horizontal section, a first inclined section, a second horizontal section, a second inclined section, and a third horizontal section; In the horizontal direction, the first inclined section is connected to the second horizontal section by inclining upward from the first horizontal section, the first inclined section and the second inclined section are symmetrically distributed on both sides of the central axis of the second horizontal section, and the second inclined section is connected to the third horizontal section by inclining downward from the second horizontal section; The second bent ribs include a second bending group, and the second bending group and the first bending group are symmetrically distributed on upper and lower sides about the horizontal center axis of the hole.

3. The parallel porous ultra-thin concrete beam according to claim 2, characterized in that: The diameters of the first bent rib and the second bent rib are both set to d, a tension zone is formed on the first horizontal section and the third horizontal section of the first bent rib, and the anchorage length of the tension zone is 20d, a compression zone is formed on the first horizontal section and the third horizontal section of the second bent rib, and the anchorage length of the compression zone is 10d, and the anchorage length of the second horizontal section of the first bent rib and the second bent rib is both ≥20d.

4. The parallel porous ultra-thin concrete beam according to claim 2, characterized in that: The bending angle of the first inclined section in the first bent rib and the second bent rib relative to the first horizontal section is 45°.

5. The parallel porous ultra-thin concrete beam according to any one of claims 1 to 4, characterized in that: The beam height is set to H, the opening height is set to h, h≤0.4H, and the opening width is set to W, W≤2.5h.

6. The parallel porous ultra-thin concrete beam according to claim 5, characterized in that: There are n openings, n is allowed to be 2 or above, the beam length is set to L, the cumulative opening width is nW, nW≤0.4L, and the spacing between two adjacent openings is l, l≥0.8W.

7. The parallel porous ultra-thin concrete beam according to claim 5, characterized in that: A frame column edge is set on one side of the beam body, and the minimum distance between the opening and the frame column edge is L1, 1.5H ≥ L1 ≥ 1.2H.

8. The parallel porous ultra-thin concrete beam according to any one of claims 1 to 7, characterized in that: The opening is set in a rectangular shape, and armpit corners are set at the four corners of the opening.

9. The parallel porous ultra-thin concrete beam according to any one of claims 1 to 7, characterized in that: The number of supporting ribs in the lower hidden beam is greater than that in the upper hidden beam. The number of supporting ribs in the upper hidden beam and the lower hidden beam respectively include at least two groups. The supporting ribs are arranged horizontally, and the two groups of supporting ribs are evenly distributed along the vertical direction.

10. The parallel porous ultra-thin concrete beam according to claim 9, characterized in that: The encrypted stirrups include several stirrups, and the spacing between two adjacent stirrups is 40mm-60mm.

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