CN114961101B - Reinforced concrete hole beam with built-in section steel - Google Patents
Reinforced concrete hole beam with built-in section steel Download PDFInfo
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- CN114961101B CN114961101B CN202210443658.4A CN202210443658A CN114961101B CN 114961101 B CN114961101 B CN 114961101B CN 202210443658 A CN202210443658 A CN 202210443658A CN 114961101 B CN114961101 B CN 114961101B
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 128
- 239000010959 steel Substances 0.000 title claims abstract description 128
- 239000011150 reinforced concrete Substances 0.000 title claims abstract description 29
- 239000007787 solid Substances 0.000 abstract description 7
- 238000010008 shearing Methods 0.000 description 42
- 238000012360 testing method Methods 0.000 description 41
- 239000004567 concrete Substances 0.000 description 24
- 238000013461 design Methods 0.000 description 18
- 230000002787 reinforcement Effects 0.000 description 11
- 238000005452 bending Methods 0.000 description 10
- 238000000034 method Methods 0.000 description 10
- 238000004364 calculation method Methods 0.000 description 9
- 238000011161 development Methods 0.000 description 9
- 230000006835 compression Effects 0.000 description 7
- 238000007906 compression Methods 0.000 description 7
- 238000010276 construction Methods 0.000 description 7
- 238000004458 analytical method Methods 0.000 description 6
- 230000003014 reinforcing effect Effects 0.000 description 6
- 210000001015 abdomen Anatomy 0.000 description 4
- 238000002474 experimental method Methods 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 3
- 239000011148 porous material Substances 0.000 description 3
- 101100127288 Mus musculus Kif1a gene Proteins 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000010030 laminating Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 239000011513 prestressed concrete Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Classifications
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
- E04C3/00—Structural elongated elements designed for load-supporting
- E04C3/02—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces
- E04C3/20—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces of concrete or other stone-like material, e.g. with reinforcements or tensioning members
- E04C3/205—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces of concrete or other stone-like material, e.g. with reinforcements or tensioning members with apertured web, e.g. frameworks, trusses
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
- E04C5/00—Reinforcing elements, e.g. for concrete; Auxiliary elements therefor
- E04C5/01—Reinforcing elements of metal, e.g. with non-structural coatings
- E04C5/02—Reinforcing elements of metal, e.g. with non-structural coatings of low bending resistance
- E04C5/03—Reinforcing elements of metal, e.g. with non-structural coatings of low bending resistance with indentations, projections, ribs, or the like, for augmenting the adherence to the concrete
Abstract
The invention provides a reinforced concrete hole beam with built-in section steel. The reinforced concrete hole beam with the built-in profile steel comprises a sleeve and profile steel arranged on the periphery of the sleeve, wherein the profile steel is hexagonal and comprises an upper plate, a lower plate, a left inclined plate and a right inclined plate, and the left inclined plate and the right inclined plate are symmetrically connected to two ends of the upper plate and the lower plate so that the profile steel is enclosed into a closed shape. According to the reinforced concrete hole-forming beam with the built-in section steel, the built-in section steel is optimized into a closed hexagonal structure, so that the hole-forming beam and the solid web beam realize equal strength of shear bearing capacity.
Description
Technical Field
The invention relates to the technical field of building structural members, in particular to a reinforced concrete hole-forming beam with built-in section steel.
Background
When a reinforced concrete beam is provided with a large hole, in order to ensure the shearing bearing capacity of the beam, a reinforcing method is introduced in the technical Specification of high-rise building concrete structure JGJ 3-2010, and additional longitudinal steel bars and stirrups are required to be arranged at the periphery of the hole of the beam. However, the construction process is complex, the reinforcement degree of the shearing resistance bearing capacity is limited, the shearing resistance bearing capacity at the beam opening is easy to be insufficient when the construction is not in place, cracks are easy to appear at the beam opening, and the structural safety can be influenced when the construction is serious.
The reinforced concrete hole-forming beam disclosed in the prior patent CN215106573U comprises longitudinal steel bars, stirrups and a steel tube sleeve, wherein the steel tube sleeve penetrates through the reinforced concrete beam to form the hole-forming beam, and the axial direction of the sleeve is perpendicular to the extending direction of the longitudinal steel bars.
The existing built-in steel reinforcement is quadrilateral, and consists of upper and lower horizontal steel sections and left and right vertical lacing plates, and the outer extension section of the hole is a straight anchor. When the checking calculation of the shearing bearing capacity of the hole side is carried out, the stress of the section steel is direct shearing, the shearing utilization rate of the section is less than 40%, and the material utilization is insufficient.
In addition, the crack of the perforated Liang Kongce adopting the quadrangular built-in steel reinforcement can not be effectively controlled by finite element analysis and experiments, namely, the inclined crack development can not be effectively restrained by arranging the vertical lacing plate and the hole-side stirrup on the hole side. And when holes are continuously opened, the shearing bearing capacity of the steel plate cannot reach an equal-strength design value.
Disclosure of Invention
The invention aims to provide a reinforced concrete open-hole beam with built-in section steel, which improves the stability and the shearing bearing capacity of a beam body.
The technical scheme of the invention is as follows: the reinforced concrete hole beam with the built-in profile steel comprises a sleeve and profile steel arranged on the periphery of the sleeve, wherein the profile steel is hexagonal and comprises an upper plate, a lower plate, a left inclined plate and a right inclined plate, and the left inclined plate and the right inclined plate are symmetrically connected to two ends of the upper plate and the lower plate so that the profile steel is enclosed into a closed shape.
In the scheme, the section steel is optimized into a closed hexagonal structure, the hole side vertical lacing plates and the outer extending sections can be combined into inclined lacing plates (a left inclined plate and a right inclined plate) with a certain angle, and experiments and analysis show that the inclined lacing plates can effectively inhibit the crack development at the hole side; and the profile steel with the inclined batten plates can be fully utilized when being pulled, so that the stability of the whole structure of the hole beam is improved, and the shearing bearing capacity is equal to that of a solid web beam.
Preferably, flanges protruding towards the same direction are arranged at the tail ends of the upper plate, the lower plate, the left inclined plate and the right inclined plate, which are close to the sleeve, and the flanges are welded in sequence; or the tail ends of the upper plate, the lower plate, the left inclined plate and the right inclined plate, which are close to the sleeve, are provided with flanges protruding towards two sides;
flanges at the positions of the upper plate and the lower plate are attached to the outer wall of the sleeve.
Preferably, the left inclined plate and the right inclined plate have an included angle of 90 degrees. Including but not limited to 90 deg., and may be specifically adjusted according to the desired hole size.
Preferably, the steel section is angle steel or T-shaped steel, and a horizontally arranged plate of the angle steel or T-shaped steel is attached to the sleeve.
Preferably, the upper plate and the lower plate have equal lengths and are L, and l=100 to 700mm. Including but not limited to this range, may be specifically adjusted according to the desired hole size.
Preferably, the number of the sleeve and the section steel may be plural, the sleeve and the section steel are welded by plural section steels, and the right sloping plate of one section steel is welded with the left sloping plate of the other section steel.
Preferably, the number of the sleeve and the section steel is plural, plural section steels are welded, and the right sloping plate of one section steel is welded with the left sloping plate of the other section steel.
Compared with the related art, the invention has the beneficial effects that:
1. through finite element analysis and experimental comparison, the hexagonal section steel has better structural stability than the prior patent, so that the shearing bearing capacity of the hole beam is equal to that of the solid web beam;
2. whether for shaped steel, angle steel or T shaped steel, all with horizontal limit and sleeve pipe laminating fixed, further improve stability.
3. Compared with the prior reinforcement technology of the hole beam, the method has the characteristics of better method, effective technology and reliability.
Drawings
Fig. 1 is a schematic structural view of a reinforced concrete open-hole beam with built-in section steel according to a first embodiment of the present invention;
FIG. 2 is a schematic structural view of the section steel provided by the invention;
FIG. 3 is a schematic view of one manner of cross-section along A-A of FIG. 1;
FIG. 4 is a schematic view of another manner of cross section along A-A of FIG. 1;
FIG. 5 is a schematic view of a section steel reinforcement of a reinforced concrete open-hole beam with built-in section steel according to the first embodiment of the present invention;
fig. 6 is a schematic structural view of a reinforced concrete open-hole beam with built-in section steel according to a second embodiment of the present invention;
fig. 7 is a schematic structural view of a reinforced concrete open-hole beam with built-in section steel according to a third embodiment of the present invention;
FIG. 8 is a schematic view of a section steel reinforcement of a reinforced concrete open-hole beam with built-in section steel according to a third embodiment of the present invention;
FIG. 9 is a force diagram of an eccentric force member;
FIG. 10 is a graph of a crack of an L2 test piece with a single round hole beam (wherein a is a graph of the crack of the L2 test piece under each stage of load; b is a graph of damage on the open hole side of the L2 test piece under limit load);
FIG. 11 is a graph of a crack of an L3 test piece with a triple round hole beam (wherein a is a graph of the crack of the L3 test piece under each stage of load; b is a broken graph of the open hole side of the L3 test piece under limit load);
fig. 12 is a graph of a crack of the test piece of the open hole beam S2 (where a is a graph of a crack of the test piece S2 under each stage of load; and b is a graph of a broken hole side of the test piece S2 under a limit load).
In the accompanying drawings: 1. longitudinal steel bars; 2. stirrups; 3. a sleeve; 4. section steel; 41. an upper plate; 42. a lower plate; 43. a left sloping plate; 44. a right sloping plate; 45. a flange; 5. an upper chord; 6. a lower chord.
Detailed Description
The invention will be described in detail below with reference to the drawings in connection with embodiments. It should be noted that, without conflict, the embodiments of the present invention and features of the embodiments may be combined with each other. For convenience of description, the words "upper", "lower", "left" and "right" are used hereinafter to denote only the directions corresponding to the upper, lower, left, and right directions of the drawings, and do not limit the structure.
Example 1
As shown in fig. 1, the reinforced concrete hole beam with built-in section steel provided in this embodiment includes a longitudinal steel bar 1, a stirrup 2, a sleeve 3 and section steel 4. The connecting structure among the longitudinal steel bars 1, the stirrups 2 and the sleeve 3 is the same as that of the prior patent.
As shown in fig. 2, the section steel 4 is hexagonal and includes an upper plate 41, a lower plate 42, a left sloping plate 43 and a right sloping plate 44, and the left sloping plate 43 and the right sloping plate 44 are symmetrically connected to two ends of the upper plate 41 and the lower plate 42, so that the section steel 4 is enclosed into a closed shape. The upper plate 41, the lower plate 42, the left inclined plate 43 and the right inclined plate 44 are provided with flanges 45 protruding towards the same direction at the tail end of the sleeve 3, so that the section of the section steel 4 forms an angle steel structure, and the flanges 45 are connected in sequence. The flanges 45 at the positions of the upper plate 41 and the lower plate 42 are attached to the outer wall of the sleeve 3 (as shown in fig. 1). The left inclined plate 43 and the right inclined plate 44 have an included angle of 90 degrees
In this embodiment, the number of the sleeve 3 and the section steel 4 is one, and the sleeve 3 is a single circular hole. The upper plate 41 and the lower plate 42 are equal in length and are both L. L is designed according to the diameter of a single circular hole, in this embodiment l=150 mm (including but not limited to).
As shown in fig. 3, the section steel 4 is angle steel, and the horizontal edge of the section steel 4 can be arranged forward or backward. In other embodiments, the ends of the upper plate 41, the lower plate 42, the left inclined plate 43 and the right inclined plate 44 adjacent to the sleeve 3 are provided with flanges 45 protruding toward both sides, as shown in fig. 4, and the section steel 4 is a T-section steel.
The left inclined plate and the right inclined plate which are bent to form an included angle are designed to act as inclined ribs, inhibit the development of inclined cracks at the side of the opening and improve the stress performance of the opening beam.
The shear failure resistance bearing capacity of the circular hole RC beam is calculated as follows: as shown in fig. 5, after the concrete beam is bored, the upper chord 5 is located above the beam hole (whether square or round), and the lower chord 6 is located below the beam hole. As shown in fig. 3 and 4, the upper chord 5 and the lower chord 6 are respectively provided with a longitudinal steel bar 1 and a stirrup 2.Meanwhile, the upper plate 41 of the section steel 4 is positioned in the upper chord 5, and the lower plate 42 is positioned in the lower chord 6. The steel section 4 reinforcing member is hexagonal and is formed by welding equilateral angle steel or T-shaped steel. The flange 45 of the section steel 4 is tightly clung to the hole; the left and right sloping plates are positioned at the hole side. Kong Cejian shear failure resistance is assumed to be determined by the hole side concrete, left and right sloping plates A st Vertical stirrup A v Providing the shearing bearing capacity of the shearing damage of the upper chord member and the lower chord member, and supposing that the upper plate A and the lower plate A of the concrete and the section steel in the upper chord member and the lower chord member cw 、A tw And C is the effective stress range of the hole side stirrup, wherein the hole side stirrup is provided with vertical opening stirrups Ac sv and Atsv, and the opening stirrups are welded with an upper plate and a lower plate of the section steel. A is that s1 Is an upper chord top longitudinal rib A cy And A is a s2 The upper chord bottom section steel flange and the standing rib are respectively arranged; a is that s3 And A is a ty Lower plate flange and stand bar of section steel respectively, A s4 The lower chord bottom longitudinal rib is formed.
If the built-in steel reinforced concrete beam with the round hole is cut and destroyed Kong Cejian, the shear bearing capacity is supposed to be composed of three parts of hole side concrete, vertical stirrups and inclined steel, namely:
V u ＝V c +V sv +V st (1)
the following will briefly explain each item of the formula (1). V (V) u For the hole side shear bearing capacity, V c Is the shear bearing capacity of concrete, V sv Is the shearing bearing capacity of the stirrup.
Right side of item 1V c The proposal of 3.12.4 of the manual of concrete structure construction can be calculated according to the formula (2) for the contribution of the hole side concrete to the shearing bearing capacity of the simply supported and perforated beam of the perforated reinforced concrete.
V c ＝α cv k c f t bh 0 (2)
a cv ＝1.75/(λ+1) (3)
k c ＝1-βd 0 /h (4)
b、h 0 And d 0 The width of the cross section, the effective height of the cross section and the diameter of the circular hole of the hole beam are respectively; f (f) t The design value of the tensile strength of the concrete axle center is designed; alpha cv The shear span ratio influence parameter is; lambda is the shear-span ratio of the open-cell beam, lambda=l p /h 0 ，l p To concentrate the force to the support distance, λ=1.5 is taken when λ < 1.5, and λ=3.0 is taken when λ > 3.0; k (k) c For the hole influence parameters, refer to 3.12.4 of the handbook of concrete structure and RC open-pore beam bearing capacity test research and theoretical analysis of the literature, beta is 1.61, and beta is 2 when multiple round holes are formed.
Right side of item 2V sv The contribution of stirrups to the shearing bearing capacity of the reinforced concrete simply-supported circular hole beam is suggested by the manual of concrete structure construction and can be calculated according to the formula (5).
V sv ＝2A v f yv (5)
Wherein: a is that v In order to configure all stirrup sectional areas intersecting the oblique slits in the range of C on one side of the circular hole, C is the effective stress range of the stirrup on the hole side, and C=hc 0+d is usually taken 0 2, hc 0 is the effective height of the hole upper chord compression bar; f (f) yv The design value of the tensile strength of the hole side stirrup is designed.
Right side of item 3V st The contribution of the inclined plate to the shearing bearing capacity of the reinforced concrete simply supported open-pore beam is Kong Ceqing, and the calculation is carried out according to the formula (6).
V st ＝2f at n 1 A st sinα (6)
Wherein: f (f) at The tensile strength design value of the inclined section steel is set; n is n 1 The number of the inclined steel limbs at one side of the hole A st The cross section of the single-limb inclined plate is the cross section of one side of the circular hole and the inclined crack; a is the angle between the inclined plate and the longitudinal axis of the rod, typically 45 °.
Concrete Structure Manual 3.12.6 Provisions A d f yd ＝2A v f yv Wherein A is d And A is a v The cross sections of all inclined ribs and all stirrup cross sections which are intersected with the inclined cracks in the range of one side C of the circular hole are respectively; f (f) yd And f yv Respectively the tensile strength design values of the hole side inclined bars and the stirrups. With reference to the item, the report pairKong Ceqing the inclined steel and stirrup are defined in a similar way, and the formula (7) is shown.
n 1 A st f at ＝2A v f yv (7)
When actually n 1 A st f at >2A v f yv When taking n 1 A st f at ＝2A v f yv 。
In order to prevent the hole side from being broken by oblique pressure, the RC Liang Kongce section control condition is as shown in the formula (8):
V u ≤0.25β c f t b(h 0 -d 0 ) (8)
β c the concrete strength influence coefficient is taken according to GB 50010-2010 'concrete structure design Specification'.
If the chord member is sheared and damaged by the hole beam, the shearing bearing capacity of the perforated section of the test piece can be regarded as the superposition of the shearing bearing capacities of the upper chord member and the lower chord member, the shearing bearing capacity of the upper chord member and the lower chord member can be calculated by referring to the items 5.2.5-2 of the manual of concrete structure construction and the combined structural design specification, and the shearing bearing capacity V of the combined structural design specification u The method comprises the following steps:
V u ＝V s +V x (9)
wherein: v (V) s For bearing force of the pressed chord member under shear, V x For the shear bearing capacity of the tension chord member, the literature 'the bearing performance of a beam with a round hole at the belly and a design method thereof' indicates V when the round hole is formed at the belly of the beam s :V x The method can be taken as 7:3, and the literature on the stress performance of prestressed concrete and reinforced concrete open-cell beams and the design method thereof indicates that the length L of the hole is equal to that of the open-cell hole at the web part of the beam>At 0.6 hole height, V s :V x May be taken as 8:2. Lambda (lambda) c And lambda (lambda) t The shear-to-span ratios of the pressed and pulled chords, respectively, lambda assuming that the chord recurve occurs at the chord midpoint c ＝0.5l b /h c0 ，λ t ＝0.5l h /h t0 ，l h The length of the rectangular hole or the diameter of the round hole; f (f) t The design value of the axial tensile strength of the concrete is designed; h is a c0 And h t0 The effective heights of the sections of the pressed string rod and the tension string rod are respectively; η (eta) 1 And eta 2 For the stress reduction coefficient of the stirrups and the steel web plates in the pressed chord, the literature 'calculation of the shearing bearing capacity of the belly open-pore reinforced concrete simply supported beam' finds after experiments: when the RC perforated beam is subjected to chord shearing damage, the internal cracks of the pressed chord are fewer, critical cracks of the RC perforated beam are formed and developed before the RC perforated beam is damaged, so that the stress development of stirrups in the pressed chord is insufficient, the stirrups are strained to be 30% -60% of yield strain, the reduction coefficient 1 is 0.4, the number of the holes is 0.8 when the holes are formed, and the number of the holes is 0.75 when the holes are formed; a is that sv,c 、A sv,t All the cross-sectional areas of the stirrups arranged in the same cross section of the compression chord member and the tension chord member respectively; s is(s) c Sum s t The gaps of stirrups in the pressed and tension chords along the length direction of the chords are respectively; vc sp and Vt sp are respectively the shearing bearing capacity provided by steel webs in upper and lower chords, the combined structural design Specification item 5.2.5-2 proposes the calculation of the shearing bearing capacity of the inclined section of the section steel concrete beam under the concentrated load, the shearing bearing capacity provided by the steel webs is inversely related to the calculated shearing span ratio of the section, and the V is calculated by referring to the calculation c sp And V is equal to t sp Calculated according to the formula (12) and the formula (13), respectively.
λ c And lambda (lambda) t Calculated shear-span ratio for compression and tension chords, respectivelyAssuming that the chord recurve point occurs at the chord midpoint, λ c ＝0.5l 0 /h c0 ，λ t ＝0.5l 0 /h t0 When λ < 1.5, λ=1.5, and when λ > 3.0, λ=3.0; l (L) 0 Is the diameter of a round hole or the length of a square hole; a is that cw And A is a tw The areas of the upper and lower plates of the single limb in the pressed and tension chord members are respectively; f (f) a The tensile strength design value of the section steel is set; n is n c And n t The number of the steel limbs in the pressed chord and the tension chord is respectively.
Let N be c And N t The axial forces of the compression and tension chords are respectively that the simple supporting hole beam under the concentrated load is:
N c ＝0.3f c bh c N c ≥0.3f c bh c (15)
wherein a is the distance from the center of the hole to the support, f c The design value is the compressive strength of the concrete.
In order to prevent the pressed chord member and the tension chord member from being damaged by oblique pressing, the section control conditions are shown in (16) and (17), and the section control conditions are known from the existing concrete structural design specifications of GB 50010-2010 and the combined structural design specifications of JGJ 138-2016: for RC beams and steel reinforced concrete beams, the gamma values are 0.25 and 0.45, respectively.
V c ≤γf t bh c0 (16)
V t ≤γf t bh t0 (17)
The upper chord member and the lower chord member are arranged between the two chord members, so gamma is 0.35.
Example two
As shown in fig. 3, the first embodiment is repeated, except that the number of the sleeve 3 and the section steel 4 is three, and the three section steels 4 are welded, specifically: the right sloping plate 44 of one section steel 4 is bonded and welded with the left sloping plate 43 of the other section steel 4. When the right swash plate 44 and the left swash plate 43 are welded, the horizontal edge of the steel section 4 needs to be avoided, and the steel section can be avoided in a notched manner.
Embodiment three, embodiment one, is repeated except that the sleeve 3 is square, whereby the dimension of L designing the upper and lower plates 41, 42 can be lengthened, in this embodiment l=600 mm (including but not limited to). In practical use, the section steel 4 is optimally T-shaped steel aiming at lengthening of L size.
Calculating the shearing damage bearing capacity of the open square hole RC beam hole side shearing; if the built-in section steel is reinforced and the square hole RC beam is subjected to Kong Cejian cutting and breakage, when the square hole formed in the web part of the RC beam is large in size (the square hole is greater than 0.4 times of the beam height, and the square hole is greater than 0.6 times of the hole height), the shear bearing capacity of the RC beam can be calculated according to the formula (18) by referring to the terms 3.11.3 and 3.11.4 of the handbook of concrete structure construction under the assumption that the shear bearing capacity is provided by hole side stirrups and hole side stirrups.
V b ＝V sv +V st (18)
V sv ＝n 1 A sv f yv (h o -h h )/2s 2 (19)
V st ＝n 2 f at A st sinα (20)
The following will briefly explain each item of the formula (18). V (V) b For the hole side shear bearing capacity, V sv Is the shearing bearing capacity of the hole side stirrup, V st And Kong Ceqing the shear bearing capacity of the sloping plate. As can be seen from items 3.11.3 and 3.11.4 of the handbook of concrete Structure, the inclined plate angle is 45℃so that V st ：V sv Can be taken as 2:1.
Calculating the shearing damage shearing bearing capacity of the RC beam chord member of the square hole; if chord shear failure occurs in the built-in section steel reinforced open-square RC beam, according to the first embodiment, for the open-square beam, when the length L of the opening is greater than 0.6h, the open-square beam is similar to a hollow truss, the shearing force born by the upper plate 41 is (0.8-0.9) V, the shearing force born by the lower plate 42 is (0.1-0.2) V, wherein h is the height of the square hole, and V is the total shearing force of the section.
Calculating bending resistance bearing capacity of upper and lower chords of the RC beam of the square hole; longitudinal reinforcement a in upper chord 5 s2 And A cy The calculation can be performed according to the symmetrical reinforcement eccentric compression component, the eccentric compression component is shown in figure 9, N is calculated according to the first step of (14) and (15) c Zeta is obtained according to the formula (21) and is equal to ζ b And comparing and judging the eccentric compression members.
When ζ is less than or equal to ζ b When the upper chord member 5 is in use, the upper chord member is calculated according to the large bias voltage, the upper chord member stud is generally 10mm and 12mm, A s2 Providing bending load bearing capacity M s2 Can be calculated according to formula (22), A cy Can be calculated according to formula (23).
When ζ > ζ b When the upper chord member is used, the upper chord member can be calculated according to small bias voltage, the upper chord member stud is generally 10mm and 12mm, A s2 Providing bending load bearing capacity M s2 Can be calculated according to equation (24).
Zeta is taken into formula (23) and calculated to obtain A cy A is obtained according to the principle of symmetrical reinforcement s1 The calculation method is similar to that described above, and will not be described again here.
The lower chord member 6 is a tension chord member, and longitudinal ribs A therein s3 、A s4 With section steel flange A ty The eccentric tension member may be calculated approximately according to the formula (25).
M t1 ＝0.25V t l h M t2 ＝0.75V t l h (25)
When the axial force N t Acting on A s3 、A ty And A is a S4 When in between, the steel bar A is erected s3 The bending resistance is calculated according to the formula (26), A ty Calculated by the equation (27) for the small eccentric tension of the 1-1 section, the internal force acting on the section takes N t And M t1 ：
A s4 Calculated from the small eccentric tension of 2-2 sections, but the internal force acting on the section takes N t And M t2 。
When the axial force N t Not acting on A s3 、A ty And A is a S4 When in between, the steel bar A is erected s3 The bending resistance provided is calculated according to the formula (26), and A is calculated according to the formulas (29) and (30) ty And A is a S4 。
The section steel and the corresponding solid web beam of the above three embodiments were tested, wherein the section steel test pieces of the first embodiment are numbered L2, L3 and S2, respectively. In order to realize the equal strength of the L2, L3 and S2 test pieces and the shearing bearing capacity of the corresponding solid web beams, the round hole test piece is reinforced by adopting built-in profile steel with the strength of Q235B, and the actually measured yield strength is about 305MPa; the square hole test piece is reinforced by adopting built-in profile steel with the strength of Q355B, and the measured yield strength is about 415MPa. The common side vertical reinforcement stirrup of three hole test pieces adopts HRB400, the diameter is 6mm and 8mm, and the actual measurement yield strength is 420Mpa.
The L2 and L3 test pieces have the same shearing bearing capacity as the solid web girder, and the concrete V u The S2 test piece with 129kN is equal to the real web girder in shear bearing capacity, and the specific V is u =234 kN. Calculating L2 and L3 side inclined plate A st With vertical stirrup A v Calculating the sectional area of the inclined plate A on the S2 side st With vertical stirrup A v A cross section. Calculating L2, L3 and S2 upper and lower plates A cw 、A tw With vertical stirrup A sv,c 、A sv,t Calculating the sectional area of the S2 test piece upper chord member inner A s1 、A cy 、A s2 Cross-sectional area and inner bottom chord A s3 、A ty 、A s4 The sectional areas, wherein 3 circular holes of the L3 test piece are subjected to independent calculation and reinforcement arrangement according to each hole, and the calculation results are shown in tables 1, 2 and 3.
TABLE 1 inclined section steel at one side of hole and stirrup sectional area
Note that: effective stress range C=hc 0+d of side stirrups of holes of each hole-formed test piece 0 2=200mm, the L2 and L3 test piece inclined profile steel a are 45 degrees and 57 degrees respectively. S2 the inclined profile steel a of the test piece is 45 degrees.
TABLE 2 chord inner Steel web and stirrup Cross section
Note that: only one row of double-limb hoops are considered in the upper chord member and the lower chord member of each circular hole test piece to resist shearing.
Table 3 S2 cross section of chord member inner longitudinal bars and section steel flanges
Referring to the data in tables 1-3, the steel reinforcing members of the L2 and L3 test pieces are welded by using equilateral angle steel, and the S2 test piece is welded by using T-shaped steel. The reinforcing design of the L2 and L3 test pieces is shown in fig. 1 and 6; s2, the reinforcing design of the test piece is shown in fig. 7.
Analysis of test results:
the crack development of the L2 test piece is shown in fig. 10, and as can be seen from fig. 10a, when the midspan load P=88 kN, a plurality of positive cracks are first formed at the bottom of the midspan beam, and when the load P is gradually increased to 161kN, oblique cracks are respectively formed at the left upper corner and the right lower corner of the round hole; as the load P increases further, a large number of cracks appear below the round hole and at the bottom of the reinforcing side, and the cracks are gradually changed from bending cracks to bending-shearing oblique cracks, and gradually extend to the loading point, the oblique crack at the upper right corner of the round hole side gradually develops to the loading point, and the oblique crack at the lower left corner develops to the support; when the load P reaches 195kN, a long oblique crack suddenly appears at the beam web part, and the left side of the round hole extends to the left side support; when the load P is increased to 275kN, an inclined crack suddenly appears on the upper chord member of the round hole, and when the load reaches 285kN, the crack rapidly develops to a loading point and runs horizontally. As can be seen from fig. 10b, the crack forms a critical crack with the oblique crack at the lower left corner of the round hole, and the top concrete of the left side beam at the loading point is crushed. The chord member shear failure of the open side of the L2 test piece occurs under the load p=285, and the shear bearing capacity of the L2 test piece is 142.5kN.
The crack development of the L3 test piece is shown in FIG. 11, and as can be seen from FIG. 11, the crack development of the L3 test piece is approximately the same as that of the L2 test piece, a Liang Dingzheng crack is generated firstly, and a positive crack gradually becomes a bending shear crack along with the increase of the load P and gradually develops towards a loading point; as the load P gradually increases to 116kN, three round holes are all provided with hole angle oblique cracks, the horizontal included angle of the oblique cracks is about 45 degrees, and the oblique cracks gradually extend to the loading point and the left support; when the load P=195, inter-hole oblique cracks appear among the holes of the round holes, and the inward bending shear cracks of the lower chord member of the round holes are gradually increased; when the load P=245 kN, an elongated oblique crack suddenly appears at the upper chord member of the No. 1 hole, and when the load P continues to increase to 295kN, the elongated oblique crack rapidly extends to the vicinity of the loading point and forms a critical oblique crack together with the oblique crack at the left lower corner of the No. 1 hole. And the chord member on the open side of the L3 test piece is subjected to shearing damage when the load P=295, and the shearing bearing capacity of the L3 test piece is 147.5kN.
S2, the crack development of the test piece is shown in FIG. 12, and as can be seen from FIG. 12: when the load P=165 kN in the midspan, oblique cracks appear at the left upper corner and the right lower corner of the square hole, when the load P is gradually increased to 192kN, a plurality of positive cracks appear at the bottom of the beam at the midspan, and when the load P is further increased, a large number of positive cracks appear on the lower chord member of the square hole, and the oblique cracks at the hole angle gradually extend to the loading point and the support from the bending cracks to the bending shear oblique cracks; when the load P reaches 383kN, a long oblique crack suddenly appears on the belly of the upper chord member, and the trend is horizontal; when the load P is further increased to 420kN, the oblique crack rapidly develops to a loading point, and when the load is further increased to 462kN, the roof beam concrete is crushed, the S2 test piece is subjected to shearing damage, and the shearing bearing capacity of the test piece is about 231kN.
From the analysis, the development of the oblique crack at the hole side of the L2, L3 and S2 test pieces is more sufficient than that at the encryption side; when chord shear failure occurs at the open side, the number of lower chord splits is greater than the number of upper chords, and the upper chord splits are typically only one and typically occur abruptly near the failure load. Experiments prove that the reinforced concrete hole-forming beam with the built-in section steel can achieve equal strength of the shear bearing capacity and the solid web beam, and the method is good and the technology is reliable.
The foregoing description is only illustrative of the present invention and is not intended to limit the scope of the invention, and all equivalent structures or equivalent processes or direct or indirect application in other related technical fields are included in the scope of the present invention.
Claims (4)
1. The reinforced concrete hole beam with the built-in profile steel comprises a sleeve (3) and is characterized by further comprising profile steel (4) arranged on the periphery of the sleeve (3), wherein the profile steel (4) is hexagonal and comprises an upper plate (41), a lower plate (42), a left inclined plate (43) and a right inclined plate (44), and the left inclined plate (43) and the right inclined plate (44) are provided with included angles; the left inclined plate (43) and the right inclined plate (44) are symmetrically connected to the two ends of the upper plate (41) and the lower plate (42) so that the section steel (4) is enclosed into a closed shape;
the tail ends of the upper plate (41), the lower plate (42), the left inclined plate (43) and the right inclined plate (44) close to the sleeve (3) are provided with flanges (45) protruding towards the same direction, and the flanges (45) are sequentially connected; or, the tail ends of the upper plate (41), the lower plate (42), the left inclined plate (43) and the right inclined plate (44) close to the sleeve (3) are provided with flanges (45) protruding towards two sides;
the flange (45) at the positions of the upper plate (41) and the lower plate (42) is attached to the outer wall of the sleeve (3), a gap is formed between the left inclined plate (43) and the outer wall of the sleeve (3), and a gap is formed between the right inclined plate (44) and the outer wall of the sleeve (3).
2. The reinforced concrete open-cell beam of built-in section steel according to claim 1, wherein the left sloping plate (43) and the right sloping plate (44) each have an angle of 90 °.
3. The reinforced concrete hole beam with built-in section steel according to claim 1, wherein the upper plate (41) and the lower plate (42) are equal in length and are L, l=100 to 700mm.
4. The reinforced concrete open-cell beam of built-in section steel according to claim 1, characterized in that the number of the bushings (3) and section steel (4) is plural, plural section steel (4) are welded, and the right sloping plate (44) of one section steel (4) is welded with the left sloping plate (43) of another section steel (4).
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Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001317159A (en) * | 2000-05-08 | 2001-11-16 | Toshiro Suzuki | Reinforced structure of opening part of steel beam |
| JP2003147901A (en) * | 2001-11-08 | 2003-05-21 | Toshiro Suzuki | Reinforcing structure of opening part of steel beam and reinforcing fitting |
| JP2011017123A (en) * | 2009-07-07 | 2011-01-27 | Hazama Corp | Opening periphery reinforcing member in reinforced concrete beam with opening, and reinforcing structure and method using the same |
| JP2012197661A (en) * | 2011-03-09 | 2012-10-18 | Koryo Kaihatsu Kk | Reinforcement metal plate and reinforcement structure for steel frame beam using the same |
| KR101691546B1 (en) * | 2016-06-15 | 2016-12-30 | 주식회사 아이에스중공업 | Steel built up box beam for the hollow type concrete composite girder |
| JP2018016953A (en) * | 2016-07-25 | 2018-02-01 | 旭化成建材株式会社 | Beam reinforcement metal fitting |
| CN113719031A (en) * | 2021-08-06 | 2021-11-30 | 中国建筑第八工程局有限公司 | Reinforcing structure of open beam and construction method thereof |
| CN215106573U (en) * | 2021-01-29 | 2021-12-10 | 中机国际工程设计研究院有限责任公司 | Reinforced concrete beam with holes |
| JP2022046170A (en) * | 2020-09-10 | 2022-03-23 | 大成建設株式会社 | Beam member |
-
2022
- 2022-04-26 CN CN202210443658.4A patent/CN114961101B/en active Active
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001317159A (en) * | 2000-05-08 | 2001-11-16 | Toshiro Suzuki | Reinforced structure of opening part of steel beam |
| JP2003147901A (en) * | 2001-11-08 | 2003-05-21 | Toshiro Suzuki | Reinforcing structure of opening part of steel beam and reinforcing fitting |
| JP2011017123A (en) * | 2009-07-07 | 2011-01-27 | Hazama Corp | Opening periphery reinforcing member in reinforced concrete beam with opening, and reinforcing structure and method using the same |
| JP2012197661A (en) * | 2011-03-09 | 2012-10-18 | Koryo Kaihatsu Kk | Reinforcement metal plate and reinforcement structure for steel frame beam using the same |
| KR101691546B1 (en) * | 2016-06-15 | 2016-12-30 | 주식회사 아이에스중공업 | Steel built up box beam for the hollow type concrete composite girder |
| JP2018016953A (en) * | 2016-07-25 | 2018-02-01 | 旭化成建材株式会社 | Beam reinforcement metal fitting |
| JP2022046170A (en) * | 2020-09-10 | 2022-03-23 | 大成建設株式会社 | Beam member |
| CN215106573U (en) * | 2021-01-29 | 2021-12-10 | 中机国际工程设计研究院有限责任公司 | Reinforced concrete beam with holes |
| CN113719031A (en) * | 2021-08-06 | 2021-11-30 | 中国建筑第八工程局有限公司 | Reinforcing structure of open beam and construction method thereof |
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