CN114961101A - Reinforced concrete opening beam with built-in section steel - Google Patents
Reinforced concrete opening beam with built-in section steel Download PDFInfo
- Publication number
- CN114961101A CN114961101A CN202210443658.4A CN202210443658A CN114961101A CN 114961101 A CN114961101 A CN 114961101A CN 202210443658 A CN202210443658 A CN 202210443658A CN 114961101 A CN114961101 A CN 114961101A
- Authority
- CN
- China
- Prior art keywords
- plate
- section steel
- hole
- steel
- built
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 124
- 239000010959 steel Substances 0.000 title claims abstract description 124
- 239000011150 reinforced concrete Substances 0.000 title claims abstract description 31
- 238000010008 shearing Methods 0.000 abstract description 28
- 239000007787 solid Substances 0.000 abstract description 8
- 238000012360 testing method Methods 0.000 description 45
- 239000004567 concrete Substances 0.000 description 24
- 238000013461 design Methods 0.000 description 17
- 230000003014 reinforcing effect Effects 0.000 description 12
- 238000010586 diagram Methods 0.000 description 11
- 238000005452 bending Methods 0.000 description 10
- 230000006835 compression Effects 0.000 description 9
- 238000007906 compression Methods 0.000 description 9
- 238000010276 construction Methods 0.000 description 9
- 238000000034 method Methods 0.000 description 9
- 238000004364 calculation method Methods 0.000 description 6
- 238000011161 development Methods 0.000 description 6
- 230000002787 reinforcement Effects 0.000 description 6
- 238000004458 analytical method Methods 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 4
- 229910001294 Reinforcing steel Inorganic materials 0.000 description 3
- 238000003466 welding Methods 0.000 description 3
- 210000001015 abdomen Anatomy 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000010030 laminating Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000011513 prestressed concrete Substances 0.000 description 1
Images
Classifications
-
- 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
-
- 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
Landscapes
- Engineering & Computer Science (AREA)
- Architecture (AREA)
- Civil Engineering (AREA)
- Structural Engineering (AREA)
- Rod-Shaped Construction Members (AREA)
- Reinforcement Elements For Buildings (AREA)
Abstract
The invention provides a reinforced concrete open hole beam with built-in section steel. The reinforced concrete open hole beam with the built-in profile steel comprises a sleeve and the 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 open-hole beam with the built-in section steel, the built-in section steel is optimized into a closed hexagonal structure, and the open-hole beam and the solid web beam thereof have equal strength in shearing resistance and bearing capacity.
Description
Technical Field
The invention relates to the technical field of building structural members, in particular to a reinforced concrete open hole beam with built-in section steel.
Background
When a reinforced concrete beam is provided with a large hole, in order to ensure the shearing resistance and bearing capacity of the beam, a reinforcing method is introduced in JGJ 3-2010 of technical Specification of high-rise building concrete structure, 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 of the method is complex, the reinforcing degree of the shearing-resisting bearing capacity is limited, the shearing-resisting bearing capacity at the opening of the beam is insufficient easily caused if the construction is not in place, cracks are easily caused at the opening of the beam, and the structural safety can be influenced when the cracks are serious.
A reinforced concrete open-hole beam disclosed in prior patent CN215106573U, which comprises longitudinal steel bars, stirrups and steel pipe sleeves, wherein the steel pipe sleeves penetrate through the reinforced concrete beam to form the open-hole beam, and the axial direction of the sleeves is perpendicular to the extending direction of the longitudinal steel bars.
The existing built-in steel reinforcing member is quadrilateral, and consists of upper and lower horizontal steel sections and left and right vertical batten plates, and the overhanging section of the hole opening is a straight anchor. When the hole side shear resistance bearing capacity is checked, the stress of the section steel is direct shear, the cross section shear utilization rate is less than 40%, and the material utilization rate is insufficient.
In addition, the crack at the hole side of the open-hole beam adopting the quadrilateral built-in section steel reinforcing member cannot be effectively controlled, namely, the vertical batten plate and the hole-side stirrup arranged at the hole side cannot effectively inhibit the development of the oblique crack. And when the holes are continuously drilled, the shearing resistance and the bearing capacity of the holes cannot reach the equal-strength design value.
Disclosure of Invention
The invention aims to provide a reinforced concrete holed beam with built-in section steel, which improves the stability and shear-resistant bearing capacity of a beam body.
The technical scheme of the invention is as follows: the reinforced concrete open hole beam with the built-in profile steel comprises a sleeve and the 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 batten plates and the outward extending sections can be combined into inclined batten plates (a left inclined plate and a right inclined plate) with a certain angle, and tests and analysis show that the inclined batten plates can effectively inhibit the development of cracks on the hole side; and the section steel with the inclined batten plate can be fully utilized when being pulled so as to improve the stability of the whole structure of the open beam and realize the equal strength of the shearing-resistant bearing capacity and the 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 flanges which protrude towards both sides 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;
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 both have an included angle of 90 degrees. Including but not limited to 90 deg., and can be adjusted according to the size of the hole.
Preferably, the section steel is angle steel or T-shaped steel, and a horizontally arranged plate of the angle steel or the T-shaped steel is attached to the sleeve.
Preferably, the upper plate and the lower plate have equal length and are L, and L is 100-700 mm. Including but not limited to this range, and may be adjusted according to the desired hole size.
Preferably, the number of the sleeve and the section steel can be multiple, the sleeve and the section steel are welded by multiple section steels, and a right inclined plate of one section steel is welded with a left inclined plate of the other section steel.
Preferably, the number of sleeve pipe and shaped steel is a plurality of, and is a plurality of shaped steel welding, and one the right swash plate of shaped steel with another the left swash plate welding of shaped steel.
Compared with the related technology, the invention has the beneficial effects that:
through finite element analysis and test comparison, the hexagonal section steel has better structural stability than that of the existing patent, so that the shearing resistance and the bearing capacity of the open-hole beam are equal to those of a solid web beam;
no matter be shaped steel, angle steel or T shaped steel, it is fixed all with the laminating of level limit and sleeve pipe, further improve stability.
Compared with the existing reinforcement technology of the open-hole beam, the method has the characteristics of being good, effective in technology and reliable.
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 present invention;
FIG. 3 is a schematic view of one way of cross-section A-A of FIG. 1;
FIG. 4 is a schematic view of another mode taken along A-A of FIG. 1;
FIG. 5 is a schematic view of reinforcing steel sections of a reinforced concrete open hole beam with built-in steel sections according to a 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 reinforcing steel sections of a reinforced concrete open hole beam with built-in steel sections according to a third embodiment of the present invention;
FIG. 9 is an eccentric force member diagram;
FIG. 10 is a crack diagram of a test piece with a single round hole beam L2 (wherein, a is a crack diagram of a test piece with L2 under each level of load, and b is a fracture diagram of an opening side of the test piece with L2 under the limit load);
FIG. 11 is a crack diagram of a test piece of an L3 open three-round-hole beam (wherein, a is a crack diagram of an L3 test piece under each level of load, and b is a fracture diagram of an open hole side of an L3 test piece under a limit load);
FIG. 12 is a crack diagram of a test piece of an open square hole beam S2 (wherein, a is the crack diagram of the test piece of S2 under each stage of load, and b is the fracture diagram of the open hole side of the test piece of S2 under the limit load).
In the drawings: 1. longitudinal reinforcing steel bars; 2. hooping; 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 present invention will be described in detail below with reference to the embodiments with reference to the attached drawings. It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict. For convenience of description, the words "upper", "lower", "left" and "right" in the following description are used only to indicate the correspondence between the upper, lower, left and right directions of the drawings themselves, and do not limit the structure.
Example one
As shown in fig. 1, the reinforced concrete open hole beam with built-in section steel provided by the embodiment comprises longitudinal steel bars 1, stirrups 2, sleeves 3 and section steel 4. The connecting structure among the longitudinal steel bars 1, the stirrups 2 and the sleeves 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 inclined plate 43 and a right inclined plate 44, and the left inclined plate 43 and the right inclined plate 44 are symmetrically connected to both ends of the upper plate 41 and the lower plate 42 so that the section steel 4 is enclosed into a closed shape. The ends of the upper plate 41, the lower plate 42, the left sloping plate 43 and the right sloping plate 44 adjacent to the sleeve 3 are provided with flanges 45 protruding towards the same direction, 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 location of the upper and lower plates 41, 42 abut the outer wall of the sleeve 3 (as shown in figure 1). The left inclined plate 43 and the right inclined plate 44 both have an included angle of 90 degrees
In the embodiment, the number of the sleeve 3 and the number of the section steel 4 are both one, and the sleeve 3 is a single round 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 is 150mm (including but not limited to).
As shown in FIG. 3, the section steel 4 is an angle steel, and the horizontal side of the section steel 4 can be arranged forward or backward. In other embodiments, the upper plate 41, the lower plate 42, the left sloping plate 43 and the right sloping plate 44 are provided with flanges 45 protruding towards both sides adjacent to the end of the sleeve 3, 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 included angles can serve as inclined ribs to inhibit the development of lateral inclined cracks at the hole and improve the stress performance of the open beam.
The shear failure resistance bearing capacity of the open-round 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 it is a square hole or a round hole), and the lower chord 6 is located below the beam hole. As shown in fig. 3 and 4, longitudinal steel bars 1 and stirrups 2 are arranged in the upper chord 5 and the lower chord 6. Meanwhile, the upper plate 41 of the section steel 4 is located in the upper chord 5, and the lower plate 42 is located in the lower chord 6. The reinforcing member of the section steel 4 is hexagonal and is formed by welding equal-edge angle steel or T-shaped steel. The flange 45 of the section steel 4 is tightly attached to the hole; the left and right sloping plates are positioned at the hole side. The shear-resistant bearing capacity of the hole side shear failure is assumed to be formed by hole side concrete, a left inclined plate A and a right inclined plate A st And vertical stirrup A v The shear bearing capacity of the upper and lower chords for shearing failure is assumed to be formed by concrete in the upper and lower chords and upper and lower plates A of the section steel cw 、A tw And the opening stirrups are provided with vertical opening stirrups Ac sv and At sv, the opening stirrups are welded with the upper plate and the lower plate of the section steel, and C is the effective stress range of the hole side stirrups. A. the s1 Is an upper chord top longitudinal bar A cy And A s2 Respectively an upper chord bottom section steel flange and a frame stud; a. the s3 And A ty Lower plate flange and frame stud, A, of section steel respectively s4 The lower chord bottom longitudinal bar.
If the built-in section steel is used for reinforcing the reinforced concrete beam with the round hole, the hole side shear damage is caused, the shearing resistance bearing capacity of the beam is supposed to be composed of three parts, namely hole side concrete, vertical stirrups and inclined section steel:
V u ＝V c +V sv +V st (1)
the following description is briefly made of the items of the formula (1)。V u For the hole side to resist shear bearing force, V c For shear-bearing capacity of concrete, V sv The stirrup resists shear bearing forces.
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 Respectively the section width, the section effective height and the diameter of the round hole of the holed beam; f. of t The design value of the axial tensile strength of the concrete is obtained; alpha is alpha cv Is a shear-to-span ratio impact parameter; λ is the open-cell beam shear span ratio, λ ═ l p /h 0 ，l p When lambda is less than 1.5, the lambda is 1.5, and when lambda is more than 3.0, the lambda is 3.0; k is a radical of c For the parameters of the hole influence, referring to article 3.12.4 of handbook of concrete structure construction and document RC open-cell beam bearing capacity experimental study and theoretical analysis, beta is 1.61, and beta is 2 when multiple round holes are opened.
V sv ＝2A v f yv (5)
In the formula: a. the v The cross section area of all stirrups intersected with the inclined crack in the range of C on one side of the circular hole is configured, C is the effective stress range of the hole-side stirrups, and C is usually equal to hc 0+ d 0 H 0 is the effective height of the hole upper chord pressure lever; f. of yv Design values for tensile strength of the hole-side stirrup are obtained.
Right side of formula (1) item 3V st And (4) calculating the contribution of the hole side inclined plate to the shearing bearing capacity of the reinforced concrete simply-supported open hole beam according to the formula (6).
V st ＝2f at n 1 A st sinα (6)
In the formula: f. of at The design value is the tensile strength of the inclined section steel; n is 1 The number of steel limbs inclined at one side of the hole, A st The cross section area of the single-limb inclined plate is the cross section area 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 bar, typically 45.
[ handbook of concrete Structure construction ] item 3.12.6, Specification A d f yd ＝2A v f yv Wherein A is d And A v The cross sections of all the oblique ribs and all the hooping ribs which are intersected with the oblique cracks in the range of C at one side of the circular hole are respectively the cross sections of all the oblique ribs and the cross sections of all the hooping ribs; f. of yd And f yv The design values of the tensile strength of the hole-side diagonal rib and the tensile strength of the stirrup are respectively. Referring to this item, the report similarly specifies the hole-side inclined section steel and the stirrup, see formula (7).
n 1 A st f at ＝2A v f yv (7)
When n is true 1 A st f at >2A v f yv When, take n 1 A st f at ＝2A v f yv 。
In order to prevent the hole side from generating oblique pressure damage, the control condition of the hole side section of the RC beam is shown as the formula (8):
V u ≤0.25β c f t b(h 0 -d 0 ) (8)
β c the concrete strength influence coefficient is obtained according to GB 50010-2010 concrete structure design Specification.
If the open beam is subjected to chord member shearing damage, the shearing bearing capacity of the open section of the test piece can be regarded as the superposition of the shearing bearing capacity 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 a concrete structure construction manual and a composite structure design specification item 5.2.5-2, and the shearing bearing capacity V is resistant u Comprises the following steps:
V u ＝V s +V x (9)
in the formula: v s For the shear-carrying capacity of the compression chord member, V x In order to bear the shear force of the tension chord, the document "stress performance of a beam with a round hole in the web and design method thereof" indicates that when the web of the beam is provided with a round hole, V is formed s :V x The stress performance of the prestressed concrete and reinforced concrete open-hole beam and the design method thereof can be taken as 7:3, and the document indicates that the length L of the open-hole beam is equal to the length of the open-hole beam when the web part of the beam is provided with the square open-hole>0.6 hole height, V s :V x It may be 8: 2. Lambda [ alpha ] c And λ t Shear-span ratios of stressed and tensioned chords, respectively, λ assuming chord inflection points at 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 circular hole; f. of t The design value of the axial tensile strength of the concrete is obtained; h is c0 And h t0 The effective heights of the sections of the pressed chord and the pulled chord are respectively; eta 1 And η 2 For the stress reduction coefficient of the hooping and the profile steel web in the compression chord member, the document 'calculation of the shearing bearing capacity of the reinforced concrete simply-supported beam with the open holes at the abdomen' finds out after the test: when the RC open-pore beam is subjected to chord shearing failure, the internal cracks of the stressed chord are fewer, and the critical cracks are formed and developed before the RC open-pore beam is broken, so that the stress development of stirrups in the stressed chord is insufficient, the strain of the stirrups is 30% -60% of the yield strain, the reduction coefficient 1 is 0.4, 0.8 is taken as 2 when a round hole is opened, and 0.75 is taken as 2 when a square hole is opened; a. the sv,c 、A sv,t All the cross-sectional areas of the hooping limbs are respectively arranged in the same cross section of the compression chord member and the tension chord member; s c And s t The distance between stirrups in the length direction of the chord in the compression chord and the tension chord is respectively; vcsp and Vt sp provide shear resistance for the web of the inner steel of the upper and lower chords, respectivelyThe combined structure design specification 5.2.5-2 provides the calculation of the shear-resisting bearing capacity of the inclined section of the steel reinforced concrete beam under the action of concentrated load, the shear-resisting bearing capacity provided by the steel web and the section calculation shear span ratio are in inverse proportion, and the V is calculated by referring to the item c sp And V t sp Calculated according to equations (12) and (13), respectively.
λ c And λ t Calculating the shear-span ratio for the stressed chord and the tensioned chord, respectively, and assuming that the inflection point of the chord occurs at the midpoint of the chord, lambda c ＝0.5l 0 /h c0 ，λ t ＝0.5l 0 /h t0 When λ is less than 1.5, it is 1.5, and when λ is more than 3.0, it is 3.0; l. the 0 The diameter of the round hole or the length of the square hole; a. the cw And A tw The areas of the upper plate and the lower plate of a single limb in the tension chord are respectively under pressure and the area of the upper plate and the lower plate of the single limb in the tension chord; f. of a The design value of the tensile strength of the section steel is obtained; n is c And n t The number of the steel limbs in the compression chord member and the tension chord member is respectively.
Suppose N c And N t The axial forces of the compression chord member and the tension chord member respectively have the following effects on the simply supported holed beam under the action of concentrated load:
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 concrete compressive strength.
In order to prevent the oblique pressure damage of the compression chord member and the tension chord member, the section control conditions are shown as (16) and (17), and the section control conditions are known from the existing concrete structure design specification GB 50010-2010 and the existing composite structure design specification JGJ 138-2016: the gamma values for the RC beam and the steel reinforced concrete beam are 0.25 and 0.45 respectively.
V c ≤γf t bh c0 (16)
V t ≤γf t bh t0 (17)
The upper chord and the lower chord of the patent are between the two, so the 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 three section steels 4 are welded, specifically: and the right inclined plate 44 of one section steel 4 is jointed and welded with the left inclined plate 43 of the other section steel 4. When the right sloping plate 44 and the left sloping plate 43 are welded, the horizontal side of the section steel 4 needs to be avoided in a notched manner.
Example three, the first example is repeated, except that the sleeve 3 is square, so that the size of L of the upper plate 41 and the lower plate 42 can be designed to be longer, and in this example, L is 600mm (including but not limited to). In practical use, the T-section steel is most suitable for the L-size lengthening of the section steel 4.
Calculating shearing resistance bearing capacity of the side shearing damage of the square-hole RC beam hole; if the built-in section steel is used for reinforcing the RC beam with the square hole to generate hole side shearing damage, when the size of the square hole formed in the web part of the RC beam is large (the height of the square hole is larger than 0.4 times of the height of the beam, and the length of the square hole is larger than 0.6 times of the height of the hole), for safety consideration, the method refers to the items 3.11.3 and 3.11.4 of concrete structure construction handbook, supposing that the shearing resistance bearing capacity is provided by hole side stirrups and hole side hoop inclined section steel, and can be calculated according to the formula (18).
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 describes each item of the formula (18) briefly. V b For the hole side to resist shear bearing force, V sv For the hole-side stirrups resisting the shear-bearing capacity, V st The hole side inclined plate resists shearing bearing capacity. As can be seen from the handbook of concrete Structure construction, items 3.11.3 and 3.11.4, the angle of the inclined plate is generally 45 degrees, so V st ：V sv It may be 2: 1.
Calculating shearing damage shearing bearing capacity of the square hole RC beam chord; if the built-in section steel is used for reinforcing the RC beam with the open square hole and chord shearing damage occurs, according to the calculation of the first embodiment, when the length L of the hole is greater than 0.6h, the open square hole beam is similar to a hollow truss, the shearing force borne by the upper plate 41 is (0.8-0.9) V, the shearing force borne 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 the bending resistance bearing capacity of the upper chord and the lower chord of the RC beam with the square hole; longitudinal reinforcement A in the upper chord 5 s2 And A cy Can be calculated according to the symmetric reinforcement eccentric compression member, the diagram of the eccentric compression member is shown in figure 9, firstly, the N is obtained according to the formulas (14) and (15) c Zeta is obtained from the formula (21) and is compared with b And (5) comparing and judging the size of the eccentric pressed component.
When ζ is less than or equal to ζ b The upper chord 5 can be calculated according to the large bias, and the upper chord frame stud is generally 10mm and 12mm, A s2 Provides bending resistance bearing capacity M s2 Can be calculated according to the formula (22), A cy Can be calculated as in equation (23).
When ζ > ζ b When, the upper chord member canThe upper chord is generally 10mm and 12mm, A, calculated according to the small bias s2 Provides bending resistance bearing capacity M s2 Can be calculated as shown in equation (24).
Zeta is brought into formula (23), and A is calculated cy Calculating A according to the principle of symmetrical reinforcement s1 The calculation method is similar to that described above, and is not described herein again.
The lower chord 6 is a tension chord, and a longitudinal rib A therein s3 、A s4 With the flange A of the section steel ty It can be approximately calculated according to the asymmetric eccentric tension member as equation (25).
M t1 ＝0.25V t l h M t2 ＝0.75V t l h (25)
When axial force N t Act on A s3 、A ty And A S4 In between, the steel bar A is erected s3 The bending resistance provided is calculated according to the formula (26), A ty Calculated from the 1-1 section according to the small eccentric tension formula (27), the internal force acting on the section is N t And M t1 ：
A s4 Calculated from the small eccentric tension of 2-2 cross-sections, but taking the internal force acting on the cross-section as N t And M t2 。
When axial force N t Do not act on A s3 、A ty And A S4 While in the middle, the frameVertical steel bar A s3 The bending resistance provided is calculated according to formula (26), and A is calculated according to formulas (29) and (30) ty And A S4 。
The steel sections and corresponding solid web beams of the above three examples were tested, wherein the test pieces of the steel sections of the first example were numbered as L2, L3 and S2, respectively. In order to realize the equal strength of the L2, L3 and S2 test pieces and the shear bearing capacity of the corresponding solid web beam, the open-round hole test piece is reinforced by adopting built-in section steel with the strength of Q235B, and the actually measured yield strength is about 305 MPa; the open square hole test piece is reinforced by using built-in steel with the strength of Q355B, and the actually measured yield strength is about 415 MPa. The common side vertical reinforcing stirrups of the three holed test pieces adopt HRB400, the diameters of the three side vertical reinforcing stirrups are 6mm and 8mm, and the actually measured yield strength is 420 Mpa.
The shear bearing capacity of the L2 and L3 test pieces is equal to that of the solid web girder, and the concrete V is u 129kN makes the shear-resisting bearing capacity of the S2 test piece equal to that of a solid web beam, and the concrete V is u 234 kN. Calculating the L2 and L3 side inclined plate A st With vertical stirrup A v Cross sectional area, calculating S2 side inclined plate A st With vertical stirrup A v Cross section. Calculate the upper and lower plates A of L2, L3, and S2 cw 、A tw With vertical stirrup A sv,c 、A sv,t Cross section area, calculating the inside A of the upper chord of the test piece of S2 s1 、A cy 、A s2 Cross sectional area, and lower chord inner A s3 、A ty 、A s4 Cross-sectional area, wherein the 3 round holes of the L3 test specimen were individually reinforced for each hole, and the calculation results are shown in tables 1, 2, and 3.
TABLE 1 hole side inclined section and stirrup sectional area
Note: the effective stress range C of the stirrup at the hole side of each holed test piece is hc 0+ d 0 The inclined section steel a of the test pieces L2 and L3 is 45 degrees and 57 degrees respectively when the angle is 200 mm/2. The test piece of S2 had the inclined section steel a of 45.
TABLE 2 chord member internal section steel web and stirrup sectional area
Note: only one row of double-limb hoops are considered to shear in the upper chord member and the lower chord member of each test piece with the circular holes.
Referring to the data in tables 1-3, the steel reinforcing members of the L2 and L3 test pieces are welded by equal angle steel, and the S2 test piece is welded by T-shaped steel. The L2 and L3 test piece reinforcement design is shown in figures 1 and 6; the reinforcement design of the test piece of S2 is shown in FIG. 7.
And (3) analyzing 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 is 88kN, a plurality of positive cracks first appear at the bottom of the midspan beam, and as the load P gradually increases to 161kN, oblique cracks respectively appear at the upper left corner and the lower right corner of the round hole; along with further increase of the load P, a large number of cracks appear below the round hole and at the bottom of the reinforcing side, the cracks are gradually changed from bending cracks to bent shear inclined cracks and gradually extend to the loading point, the inclined crack at the upper right corner on the side of the round hole gradually develops to the loading point, and the inclined crack at the lower left corner develops to the support; when the load P reaches 195kN, a long oblique crack suddenly appears at the web part of the beam, and the long oblique crack extends from the left side of the circular hole to the left side of the base; when the load P is increased to 275kN, an inclined crack suddenly appears on the upper chord of the round hole, and when the load reaches 285kN, the crack rapidly develops to a loading point and moves horizontally. As can be seen from fig. 10b, the crack and the oblique crack at the lower left corner of the circular hole form a critical crack, and the concrete at the top of the beam at the left side of the loading point is crushed. When the load P of the L2 test piece was 285, the chord shear failure on the open hole side occurred, and the shear bearing capacity of the L2 test piece was 142.5 kN.
The L3 test piece crack develops as shown in FIG. 11, and as can be seen from FIG. 11, the L3 test piece crack develops approximately the same as the L2 test piece, a beam top normal crack firstly appears, and the normal crack gradually becomes a bending shear crack along with the increase of the load P and gradually develops towards a loading point; with the load P gradually increasing to 116kN, hole angle inclined cracks appear in all the three round holes, the horizontal included angle of the inclined cracks is about 45 degrees, and the inclined cracks gradually extend to the loading point and the left support; when the load P is 195, oblique cracks among the holes of the circular hole occur, and the bending shear cracks in the lower chord of the circular hole gradually increase; when the load P is 245kN, a narrow inclined crack suddenly appears at the upper chord of the No. 1 hole, the load P quickly extends to the vicinity of a loading point when the load P is continuously increased to 295kN, and the load P and the inclined crack at the lower left corner of the No. 1 hole form a critical inclined crack together. The shear failure of the open-hole side chord member occurred in the L3 test piece when the load P was 295, and the shear bearing capacity of the L3 test piece was 147.5 kN.
The crack development of the test piece of S2 is shown in FIG. 12, and it can be seen from FIG. 12 that: when midspan load P is 165kN, oblique cracks respectively appear at the upper left corner and the lower right corner of the square hole, a plurality of normal cracks appear at the bottom of the beam at the midspan part as the load P is gradually increased to 192kN, a large number of normal cracks appear on the lower chord member of the square hole as the load P is further increased, the normal cracks are gradually changed from bending cracks to bending shear oblique cracks, and the hole corner oblique cracks gradually extend towards the loading point and the support; when the load P reaches 383kN, a long inclined crack appears suddenly at the abdomen of the upper chord and the trend is relatively horizontal; when the load P is increased to 420kN, the inclined crack rapidly develops to a loading point, when the load is further increased to 462kN, the concrete on the top of the beam is crushed, and the S2 test piece is subjected to shear failure, and the shear bearing capacity is about 231 kN.
From the above analysis, the oblique cracks of the test pieces L2, L3 and S2 are more fully developed than the oblique cracks of the open side of the test piece; when the chord shearing failure occurs on the opening side, the number of the lower chord cracks is more than that of the upper chord, and the upper chord cracks are usually only one and usually appear suddenly when the load is broken. Tests prove that the reinforced concrete open-hole beam with the built-in section steel can achieve equal strength of shear bearing capacity and a solid web beam, and is good in method and reliable in technology.
The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by using the contents of the present specification and the accompanying drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (5)
1. The reinforced concrete open-hole beam with the built-in section steel comprises a sleeve (3) and is characterized by further comprising the section steel (4) arranged on the periphery of the sleeve (3), wherein the section 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 both provided with included angles; the left inclined plate (43) and the right inclined 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.
2. The reinforced concrete holed beam with built-in section steel as claimed in claim 1, wherein the upper plate (41), the lower plate (42), the left sloping plate (43) and the right sloping plate (44) are provided with flanges (45) protruding towards the same direction near the ends of the sleeve (3), and the flanges (45) are connected in sequence; or flanges (45) which protrude towards both sides are arranged at the tail ends of the upper plate (41), the lower plate (42), the left inclined plate (43) and the right inclined plate (44) which are close to the sleeve (3);
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).
3. The reinforced concrete holed beam with built-in section steel according to claim 1, characterized in that the left sloping plate (43) and the right sloping plate (44) have an included angle of 90 °.
4. The reinforced concrete open-hole beam with the built-in section steel as claimed in claim 1, wherein the upper plate (41) and the lower plate (42) are equal in length and are L, and L is 100-700 mm.
5. A reinforced concrete holed beam with built-in section steel according to claim 1, characterized in that the number of said sleeves (3) and section steel (4) is plural, a plurality of said section steel (4) are welded, and the right sloping plate (44) of one said section steel (4) is welded with the left sloping plate (43) of another said section steel (4).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210443658.4A CN114961101B (en) | 2022-04-26 | 2022-04-26 | Reinforced concrete hole beam with built-in section steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210443658.4A CN114961101B (en) | 2022-04-26 | 2022-04-26 | Reinforced concrete hole beam with built-in section steel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN114961101A true CN114961101A (en) | 2022-08-30 |
| CN114961101B CN114961101B (en) | 2024-03-12 |
Family
ID=82978859
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210443658.4A Active CN114961101B (en) | 2022-04-26 | 2022-04-26 | Reinforced concrete hole beam with built-in section steel |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114961101B (en) |
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 |
Also Published As
| Publication number | Publication date |
|---|---|
| CN114961101B (en) | 2024-03-12 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US9765521B1 (en) | Precast reinforced concrete construction elements with pre-stressing connectors | |
| US6012256A (en) | Moment-resistant structure, sustainer and method of resisting episodic loads | |
| Nie et al. | Seismic behavior of connections composed of CFSSTCs and steel–concrete composite beams—experimental study | |
| Panchacharam et al. | Torsional behavior of reinforced concrete beams strengthened with FRP composites | |
| Gourley et al. | A synopsis of studies of the monotonic and cyclic behaviour of concrete-filled steel tube beam-columns | |
| CN111287335A (en) | Connecting joint of outer frame steel beam and core tube inner steel column and construction method thereof | |
| US11352790B2 (en) | Method of introducing prestress to beam-column joint of PC structure in triaxial compression | |
| Zhang et al. | Investigation of side plate connections in an S-CFST column frame under a column-loss scenario | |
| Rajagopal et al. | Seismic behavior of exterior beam-column joint using mechanical anchorage under reversal loading: An experimental study | |
| CN207974266U (en) | A kind of anti-buckling support coupling beam of assembled X-shaped | |
| CN211774633U (en) | Outer frame roof beam and concrete core section of thick bamboo inner steel bone post connected node in super high-rise structure | |
| CN114961101A (en) | Reinforced concrete opening beam with built-in section steel | |
| CN107605064A (en) | A kind of anti-buckling support coupling beam of assembled X-shaped | |
| Kamimura et al. | Influence of joint reinforcement on strength and deformation of interior beam-column subassemblages | |
| Pidgurskyi et al. | Investigation of the stress-strain state of beams with different types of web perforation | |
| Kawaguchi et al. | Experimental study on structural characteristics of portal frames consisting of square CFT columns | |
| Yan et al. | Cyclic tests on concrete-filled composite plate shear walls with enhanced C-channels | |
| Patrick | Experimental investigation and design of longitudinal shear reinforcement in composite edge beams | |
| CN201343782Y (en) | Combined coupling beam for inclined steel bracing strut concrete shear wall | |
| Suzuki et al. | Structural performance of mixed member composed of steel reinforced concrete and reinforced concrete | |
| Shah et al. | Effects of Steel Bracings in the Progressive Collapse Resistance of Reinforced Concrete Building | |
| Tremblay et al. | Flexural demand on partially-encased composite columns in multi-storey concentrically braced steel frames | |
| Hyashi et al. | Experimental studies on retrofit by partially encased concrete to the steel I-girder subjected to buckling deformation | |
| Kamimura et al. | Mechanical behavior of reinforced concrete beam-column assemblages with eccentricity | |
| CN215802674U (en) | Section steel part parcel concrete combination beam |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |