CN108229006B - Method for calculating hogging moment bearing capacity of honeycomb composite beam - Google Patents

Method for calculating hogging moment bearing capacity of honeycomb composite beam Download PDF

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CN108229006B
CN108229006B CN201711480824.3A CN201711480824A CN108229006B CN 108229006 B CN108229006 B CN 108229006B CN 201711480824 A CN201711480824 A CN 201711480824A CN 108229006 B CN108229006 B CN 108229006B
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马宏伟
林朗
王自豪
程宇
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South China University of Technology SCUT
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Abstract

The invention discloses a method for calculating hogging moment bearing capacity of a honeycomb composite beam, which comprises the following steps of: firstly, the method comprises the following steps: drawing a corresponding stress sketch map; II, secondly: calculating the pure bending bearing capacity M when the cross section of the support is only acted by the negative bending momentm1(ii) a Thirdly, the method comprises the following steps: calculating the pure shear bearing capacity V when the section of the support is only under the action of the shear forcem1(ii) a Fourthly, the method comprises the following steps: when the cross section of the support bears the negative bending moment and the shearing force at the same time, calculating the first nominal bending resistance bearing capacity Mn1(ii) a Fifthly: calculating the pure bending bearing capacity M of the central section of the first holem2(ii) a Sixthly, the method comprises the following steps: calculating the pure shear bearing capacity V of the central section of the first holem2(ii) a Seventhly, the method comprises the following steps: when the central section of the first opening bears the negative bending moment and the shearing force at the same time, calculating a second nominal bending resistance bearing capacity Mn2(ii) a Eighthly: when the two sections are damaged simultaneously, the distance L between the central section of the first opening and the support is solvedc(ii) a Nine: calculating the third nominal bending resistance bearing capacity Mn. The invention comprehensively considers the checking calculation conditions of the two sections and can obtain the beam end bearing capacity when the honeycomb composite beam member is damaged.

Description

Method for calculating hogging moment bearing capacity of honeycomb composite beam
Technical Field
The invention relates to the field of structural engineering in civil engineering, in particular to a method for calculating hogging moment bearing capacity of a honeycomb composite beam.
Background
The steel and concrete composite beam can fully exert the advantages of steel and concrete materials, and has the characteristics of high strength and steel saving. The holes are formed in the web plates of the combined beam, the steel beams are made into honeycomb beams, and the equipment pipelines are moved through the holes, so that the height of the building layer can be effectively reduced, and the engineering cost is reduced. When the honeycomb composite beam is applied to a frame, a large negative bending moment is applied to the support. Foreign specifications give a calculation formula of the bending resistance bearing capacity of the honeycomb composite beam component layer, but the specifications are not uniform and are mostly concentrated on the bearing capacity calculation of the positive bending moment area. The research on the components in China mostly focuses on the research on the mechanical properties of the honeycomb composite beam when the honeycomb composite beam bears the positive bending moment. The blank of the bearing capacity research of the hogging moment section of the honeycomb composite beam greatly limits the application of the honeycomb composite beam.
Disclosure of Invention
The invention aims to solve the current engineering requirement, and provides a calculation formula of the bending resistance bearing capacity of a member aiming at the stress characteristic of a honeycomb composite beam in the application of a frame structure and having a larger negative bending moment at a support.
The invention is realized by adopting the following technical scheme:
a method for calculating hogging moment bearing capacity of a honeycomb composite beam comprises the following steps:
the method comprises the following steps: given expansion ratio K, determining the calculated length L of the beam in the hogging moment area0And on the assumption that the distance between the central section of the first opening and the support is L, drawing a corresponding stress sketch map, and obtaining M according to the stress sketch map1And M2Relation of (1), M1And M2Bending moments borne by the cross section of the support and the central cross section of the first hole are respectively;
step two: calculating the pure bending bearing capacity M when the cross section of the support is only acted by the negative bending momentm1；
Step three: calculating the pure shear bearing capacity V when the section of the support is only under the action of the shear forcem1；
Step four: when the cross section of the support bears the negative bending moment and the shearing force simultaneously, the bending resistance bearing capacity of the cross section of the support is weakened by considering the shearing force, and the nominal bending resistance bearing capacity of the cross section of the support at the moment is defined as a first nominal bending resistance bearing capacity Mn1Calculate Mn1The calculation formula is as follows:
Figure GDA0002970020060000021
step five: calculating the pure bending bearing capacity M of the central section of the first holem2；
Step six: calculating the pure shear bearing capacity V of the central section of the first holem2；
Step seven: when the central cross section of the first opening simultaneously bears the negative bending moment and the shearing force, the nominal bending bearing capacity of the central cross section of the first opening is defined as a second nominal bending bearing capacity Mn2Calculating the second nominal bending-resistant bearing capacity Mn2The calculation formula is as follows:
Figure GDA0002970020060000022
step eight: when the cross section of the support and the central cross section of the first hole are simultaneously damaged, the distance between the central cross section of the first hole and the support is defined as a critical distance LcLet M stand for1＝Mn1，M2＝Mn2Solving for Lc；
Step nine: considering the strength failure of the cross section of the support and the central cross section of the first opening, the nominal bending resistance of the cross section of the support is defined as a third nominal bending resistance MnCalculate MnThe calculation method is as follows:
when L is equal to LcAt this time M2＝Mn2Showing that the cross section of the support and the central cross section of the first hole are simultaneously damaged, and at the moment, MnComprises the following steps:
Mn＝Mn1；
when L is<LcAt this time M2>Mn2Indicating that the central section of the first opening is firstly damaged, and M is at the momentnComprises the following steps:
Figure GDA0002970020060000023
when L is>LcAt this time M2<Mn2Indicating that the cross-section of the support is broken first, at which time MnComprises the following steps: mn＝Mn1。
Further, the second step specifically includes:
the hogging moment bearing capacity of the support section is composed of two parts of moment of internal force of the tension steel bar to the neutral axis of the combined beam and moment of steel beam stress to the neutral axis of the combined beam:
Mm1＝T(as+y1)+Pyc(y2-y1)
T＝Astfst
Pyc＝Asf
wherein T is the resultant force of the steel bars when the concrete and the steel beam work together, AstCross-sectional area of longitudinal reinforcement in the area of the slab in the hogging moment region, fstIs the design value of the tensile strength of the steel bar, f is the design value of the tensile strength of the steel material, asIs the distance from the centroid of the section of the longitudinal steel bar to the surface of the upper flange of the steel beam, y1The distance from the tensile force action line of the steel beam tension area to the surface of the upper flange of the steel beam, y2The distance from the steel beam plastic neutralization shaft to the steel beam upper flange surface, PycFor compressive bearing capacity of the section of the steel beam, AsIs the cross-sectional area of the steel beam.
Further, the third step specifically includes:
pure shear bearing capacity V when the cross section of the support is only acted by shear forcem1Provided by its steel beam web:
Vm1＝0.6fAw
in the formula AwThe area of the section of the steel beam web plate of the non-opening section of the honeycomb composite beam is shown, and f is the design value of the tensile strength of steel.
Further, the fifth step specifically includes:
when the plastic neutralizing shaft is arranged in the steel beam and positioned in the upper flange, the pure bending bearing capacity of the central section of the first hole is as follows:
Figure GDA0002970020060000031
Figure GDA0002970020060000041
in the formula asThe distance from the center of gravity of the steel bar to the bottom surface of the concrete slab, x is the distance from the plastic neutralization shaft of the composite beam to the top surface of the upper flange of the steel beam, H is the beam height of the honeycomb beam, bf、tfRespectively upper flange width and thickness, twIs the web thickness, stWeb height for a T-section; a. thesnThe cross-sectional area of the honeycomb steel beam representing the central cross section of the first opening, AstCross-sectional area of longitudinal reinforcement in the area of the slab in the hogging moment region, fstF is the design value of the tensile strength of the steel bar, and f is the design value of the tensile strength of the steel;
when the plastic neutralizing shaft is positioned in the T-shaped section on the honeycomb steel beam, the pure bending bearing capacity of the central section of the first hole is as follows:
Figure GDA0002970020060000042
Figure GDA0002970020060000043
wherein S represents the area moment from the T-shaped section to the neutral axis of the honeycomb steel beam;
when the plastic neutralizing shaft is not arranged in the steel beam, the pure bending bearing capacity of the central section of the first hole is as follows:
Figure GDA0002970020060000044
further, the sixth step specifically includes: pure shear bearing capacity V of central section of first holem2The sum of the shear-resisting bearing capacity of the upper T-shaped section and the lower T-shaped section of the steel beam is as follows:
Vm2＝∑Vt
in the formula VtThe shear-resistant bearing capacity of the T-shaped section can be obtained by the following steps:
when in use
Figure GDA0002970020060000045
And then the shearing-resistant bearing capacity of the central section of the first hole is as follows:
Figure GDA0002970020060000046
when in use
Figure GDA0002970020060000047
And then the shearing-resistant bearing capacity of the central section of the first hole is as follows:
Vm2＝∑Vpt
wherein λ ═ a0/st，a0Indicating the length of the opening or of the T-section in the direction of the beam axis, VptShowing the plastic shear-bearing capacity of the T-section web,
Figure GDA0002970020060000051
f is the design value of tensile strength of steel material, twIs the web thickness, stWeb height of T-shaped cross-section, ∑ VptRepresenting the sum of the plastic shear-bearing capacity of the two T-section webs.
Compared with the prior art, the invention has the following advantages and effects:
unlike a general composite beam, the expansion ratio and the first hole spacing can affect the stress characteristics of the honeycomb composite beam together, and the honeycomb composite beam under the action of the negative bending moment can be damaged not only at the section with the largest bending moment and shearing force (namely, the section close to the support), but also at the first hole close to the support. Therefore, for the honeycomb composite beam, besides the bearing capacity of the support cross section, the bearing capacity at the center cross section of the first hole needs to be checked. The calculation method of the bearing capacity of the hogging moment area honeycomb composite beam comprehensively considers the checking calculation conditions of the two sections, and can obtain the bearing capacity of the beam end when the honeycomb composite beam member is damaged. Meanwhile, a concept and a calculation method capable of predicting the critical distance of the damage occurrence position of the honeycomb composite beam are provided.
Drawings
FIG. 1 is a schematic view showing the cutting of H-shaped steel used in the present invention.
Fig. 2 is a schematic sectional view of the H-shaped steel used in the present invention after cutting.
FIG. 3 is a schematic view of the welding of a honeycomb steel beam used in the present invention.
FIG. 4 is a schematic cross-sectional view of a honeycomb steel beam used in the present invention.
Fig. 5 is a construction view of the honeycomb composite girder according to the embodiment of the present invention.
Fig. 6 is a stress distribution diagram of a cross section of a support of the honeycomb composite girder according to the present invention.
FIG. 7 is a stress distribution diagram of the center section plasticity of the first opening of the honeycomb composite beam and the stress distribution diagram of the honeycomb composite beam when the middle section plasticity and the axis are positioned on the upper flange of the steel beam.
FIG. 8 is a stress distribution diagram of the center section plasticity of the first opening of the honeycomb composite beam and the stress distribution diagram of the first opening of the honeycomb composite beam when the middle and axis are positioned on the T-shaped section of the honeycomb steel beam.
Fig. 9 is a stress distribution diagram of the center section plasticity neutral axis of the first opening of the honeycomb composite beam in the invention when the center section plasticity neutral axis is positioned on a floor slab.
FIG. 10 is a force diagram of an embodiment of the invention.
FIG. 11 is a schematic view of a typical honeycomb composite beam under a negative bending moment.
Detailed Description
The present invention will be described in further detail with reference to examples and drawings, but the present invention is not limited to these examples.
FIG. 11 is a schematic view of a typical hogging moment acting honeycomb composite beam, wherein the section A-A is a support section and the section B-B is a central section of a first opening, and the honeycomb steel beam of the honeycomb composite beam is generally welded by H-shaped steel or I-shaped steel during specific construction, and particularly as shown in FIGS. 1 and 2, the beam length L is equal to the beam length K at a given expansion ratio K0In this case, the honeycomb steel beam is formed by cutting a web of H-section steel or i-section steel along a certain gullet shape, and then welding it in a staggered manner (see fig. 3 and 4), while solid steel beams of the same size are butt-welded at the pedestal, and steel beam web stiffeners of 200mm intervals are provided at the pedestal. Fig. 5 is a construction drawing of the final both-end cantilevered honeycomb composite beam.
The method for calculating the bearing capacity of the honeycomb composite beam in the hogging moment area comprises the following steps of:
the method comprises the following steps: determining a stress sketch map, namely according to the expansion ratio K and the beam length L in design0And the distance L between the first hole and the support, drawing a corresponding stress sketch (see figure 10), wherein the section (non-hole section) of the support is defined as an A-A section in figure 5, the central section (hole section) of the first hole is defined as a B-B section, and M is a cross section1And M2Bending moments on the A-A section and the B-B section, Mm1And Mm2Respectively the pure bending bearing capacity L of the A-A section and the B-B section under the action of negative bending moment0The length from the support to the beam end is shown, for the present embodiment, the right-end overhanging honeycomb composite beam is defined as the a-end, the left-end overhanging honeycomb composite beam is defined as the B-end, and the relevant parameters are given in table 1.
Table 1:
K L0(m) L(m) L0-L(m)
a terminal 1.2 1.25 0.17 1.08
B terminal 1.2 1.25 0.32 0.93
Step two: calculating the pure bending bearing capacity M under the action of the negative bending moment of the cross section of the supportm1Comprises the following steps:
Mm1＝T(as+y1)+Pyc(y2-y1)
T＝Astfst
Pyc＝Asf
wherein T is the resultant force of the steel bars when the concrete and the steel beam work together, AstCross-sectional area of longitudinal reinforcement in the area of the slab in the hogging moment region, fstIs the design value of the tensile strength of the steel bar, f is the design value of the tensile strength of the steel material, asIs the distance from the centroid of the section of the longitudinal steel bar to the surface of the upper flange of the steel beam, y1The distance from the tensile force action line of the steel beam tension area to the surface of the upper flange of the steel beam, y2The distance from the steel beam plastic neutralization shaft to the steel beam upper flange surface, PycFor compressive bearing capacity of the section of the steel beam, AsIs the cross-sectional area of the steel beam.
Step three: calculating the pure shear bearing capacity V of the cross section of the supportm1Pure shear bearing capacity V of support sectionm1Provided by its steel beam web:
Vm1＝0.6fAw，
in the formula AwThe area of the section of the steel beam web plate of the non-opening section of the honeycomb composite beam is shown, and f is the design value of the tensile strength of steel.
Step four: when the cross section of the support bears the negative bending moment and the shearing force at the same time, the nominal bending-resistant bearing capacity of the cross section of the support at the moment is defined as a first nominal bending-resistant bearing capacity Mn1Calculate Mn1The calculation formula is as follows:
Figure GDA0002970020060000071
step five: calculating the pure bending bearing capacity M of the central section of the first holem2The method specifically comprises the following steps:
when the plastic neutralizing shaft is arranged in the steel beam and is positioned in the upper flange, the pure bending bearing capacity of the central section of the first hole is (the stress distribution is shown in figure 7):
Figure GDA0002970020060000081
Figure GDA0002970020060000082
in the formula, asThe distance from the center of gravity of the steel bar to the bottom surface of the concrete slab, x is the distance from the plastic neutralization shaft of the composite beam to the top surface of the upper flange of the steel beam, H is the beam height of the honeycomb beam, bf、tfRespectively upper flange width and thickness, twIs the web thickness, stWeb height for a T-section; a. thesnThe cross-sectional area of the honeycomb steel beam representing the central cross section of the first opening, AstCross-sectional area of longitudinal reinforcement in the area of the slab in the hogging moment region, fstF is the design value of the tensile strength of the steel bar, and f is the design value of the tensile strength of the steel;
when the plastic neutralizing shaft is positioned in the T-shaped section on the honeycomb steel beam, the pure bending bearing capacity of the central section of the first hole is as follows:
Figure GDA0002970020060000083
Figure GDA0002970020060000084
in the formula, S represents the area moment from the T-shaped section to the neutral axis of the honeycomb steel beam;
when the plastic neutral axis is not in the steel beam, the pure bending bearing capacity of the central section of the first hole is (the stress distribution is shown in figure 9):
Figure GDA0002970020060000085
step six: calculating the pure shear bearing capacity V of the central section of the first holem2The sum of the shear-resistant bearing capacity of the upper T-shaped section and the lower T-shaped section of the steel beam is as follows:
Vm2＝∑Vt
in the formula VtThe shear-resistant bearing capacity of the T-shaped section can be obtained by the following steps:
when in use
Figure GDA0002970020060000091
And then the shearing-resistant bearing capacity of the central section of the first hole is as follows:
Figure GDA0002970020060000092
when in use
Figure GDA0002970020060000093
And then the shearing-resistant bearing capacity of the central section of the first hole is as follows:
Vm2＝∑Vpt
wherein λ ═ a0/st，a0Indicating the length of the opening (or the length of the T-section in the direction of the beam length), VptShowing the plastic shear-bearing capacity of the T-section web,
Figure GDA0002970020060000094
f is the design value of tensile strength of steel material, twIs the web thickness, stWeb height of T-shaped cross-section, ∑ VptRepresenting the sum of the plastic shear-bearing capacity of the two T-section webs.
Step seven: when the central cross section of the first opening simultaneously bears the negative bending moment and the shearing force, the nominal bending bearing capacity of the central cross section of the first opening is defined as a second nominal bending bearing capacity Mn2Calculating the second nominal bending-resistant bearing capacity Mn2The calculation formula is as follows:
Figure GDA0002970020060000095
in this embodiment, the actual measured values of the material strength are adopted in the second to seventh steps, and the calculation results are given in table 2:
table 2:
Figure GDA0002970020060000096
step eight: obtaining M according to the stress diagram1And M2In which M is1And M2Respectively showing the negative bending moments of the A-A section and the B-B section. Assuming that the A-A section has been broken, M is now present1＝Mn1The results of the calculations are given in table 3.
Table 3:
test piece number M1/kN·m M2/kN·m
A terminal 78.3 67.6
B terminal 78.3 58.2
Step nine: considering the strength failure of the cross section of the support and the central cross section of the first opening, the nominal bending resistance of the cross section of the support is defined as a third nominal bending resistance MnCalculate MnThe specific calculation process is as follows:
when L is equal to LcAt this time M2＝Mn2Showing that the cross section of the support and the central cross section of the first hole are simultaneously damaged, and at the moment, MnComprises the following steps:
Mn＝Mn1；
when L is<LcAt this time M2>Mn2Indicating that the central section of the first opening is firstly damaged, and M is at the momentnComprises the following steps:
Figure GDA0002970020060000101
when L is>LcAt this time M2<Mn2Indicating that the cross-section of the support is broken first, at which time MnComprises the following steps:
Mn＝Mn1。
the results are given in table 4.
Table 4:
Figure GDA0002970020060000102
Figure GDA0002970020060000111
note: in table M0And the measured value of the bending moment of the cross section of the support when the test piece is damaged is shown.
When the honeycomb composite beam member is designed, in order to prevent the central section of the first hole from being damaged firstly, the design of the test pieces preferably satisfies that L is more than or equal to LcI.e., L is not less than 0.17M, when M is presentn＝Mn1。
For test piece a end there are: l is approximately equal to Lc、M2≈Mn2Indicates a proximity ofThe cross section of the support and the central cross section of the first hole are damaged simultaneously; for test piece B end there are: l is>Lc、M2<Mn2The result shows that the near support cross section is damaged before the first opening center cross section, and both the near support cross section and the first opening center cross section are consistent with the test result. Meanwhile, the error of the calculated value of the bearing capacity of the beam end is within 10% compared with the tested value, which shows that the calculated value of the bearing capacity formula can accurately calculate the hogging moment bearing capacity of the honeycomb combined beam, and meanwhile, the calculated value of the bearing capacity formula is smaller than the tested value, which shows that the calculated value of the bearing capacity formula is safer.
The above examples of the present invention are merely examples for clearly illustrating the present invention and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.

Claims (5)

1. A method for calculating hogging moment bearing capacity of a honeycomb composite beam is characterized by comprising the following steps:
the method comprises the following steps: given expansion ratio K, determining the calculated length L of the beam in the hogging moment area0And on the assumption that the distance between the central section of the first opening and the support is L, drawing a corresponding stress sketch map, and obtaining M according to the stress sketch map1And M2Relation of (1), M1And M2Bending moments borne by the cross section of the support and the central cross section of the first hole are respectively;
step two: calculating the pure bending bearing capacity M when the cross section of the support is only acted by the negative bending momentm1；
Step three: calculating the pure shear bearing capacity V when the section of the support is only under the action of the shear forcem1；
Step four: when the cross section of the support bears the negative bending moment and the shearing force simultaneously, the bending resistance bearing capacity of the cross section of the support is weakened by considering the shearing force, and the nominal bending resistance bearing capacity of the cross section of the support at the moment is defined as a first nominal bending resistance bearing capacity Mn1Calculate Mn1The calculation formula is as follows:
Figure FDA0002970020050000011
step five: calculating the pure bending bearing capacity M of the central section of the first holem2；
Step six: calculating the pure shear bearing capacity V of the central section of the first holem2；
Step seven: when the central cross section of the first opening simultaneously bears the negative bending moment and the shearing force, the nominal bending bearing capacity of the central cross section of the first opening is defined as a second nominal bending bearing capacity Mn2Calculating the second nominal bending-resistant bearing capacity Mn2The calculation formula is as follows:
Figure FDA0002970020050000012
step eight: when the cross section of the support and the central cross section of the first hole are simultaneously damaged, the distance between the central cross section of the first hole and the support is defined as a critical distance LcLet M stand for1＝Mn1，M2＝Mn2Solving for Lc；
Step nine: considering the strength failure of the cross section of the support and the central cross section of the first opening, the nominal bending resistance of the cross section of the support is defined as a third nominal bending resistance MnCalculate MnThe calculation method is as follows:
when L is equal to LcAt this time M2＝Mn2Showing that the cross section of the support and the central cross section of the first hole are simultaneously damaged, and at the moment, MnComprises the following steps:
Mn＝Mn1；
when L is<LcAt this time M2>Mn2Indicating that the central section of the first opening is firstly damaged, and M is at the momentnComprises the following steps:
Figure FDA0002970020050000021
when L is>LcAt this time M2<Mn2Indicating that the cross-section of the support is broken first, at which time MnComprises the following steps: mn＝Mn1。
2. The method for calculating hogging moment bearing capacity of a honeycomb composite beam according to claim 1, wherein the second step specifically comprises:
the hogging moment bearing capacity of the support section is composed of two parts of moment of internal force of the tension steel bar to the neutral axis of the combined beam and moment of steel beam stress to the neutral axis of the combined beam:
Mm1＝T(as+y1)+Pyc(y2-y1)
T＝Astfst
Pyc＝Asf
wherein T is the resultant force of the steel bars when the concrete and the steel beam work together, AstCross-sectional area of longitudinal reinforcement in the area of the slab in the hogging moment region, fstIs the design value of the tensile strength of the steel bar, f is the design value of the tensile strength of the steel material, asIs the distance from the centroid of the section of the longitudinal steel bar to the surface of the upper flange of the steel beam, y1The distance from the tensile force action line of the steel beam tension area to the surface of the upper flange of the steel beam, y2The distance from the steel beam plastic neutralization shaft to the steel beam upper flange surface, PycFor compressive bearing capacity of the section of the steel beam, AsIs the cross-sectional area of the steel beam.
3. The method for calculating hogging moment bearing capacity of a honeycomb composite beam according to claim 1, wherein the third step specifically comprises:
pure shear bearing capacity V when the cross section of the support is only acted by shear forcem1Provided by its steel beam web:
Vm1＝0.6fAw
in the formula, AwThe section area of a steel beam web plate of the non-opening section of the honeycomb composite beam is f, and the f is steelTensile strength design value of (1).
4. The method for calculating hogging moment bearing capacity of a honeycomb composite beam according to claim 1, wherein the step five specifically comprises:
when the plastic neutralizing shaft is arranged in the steel beam and positioned in the upper flange, the pure bending bearing capacity of the central section of the first hole is as follows:
Figure FDA0002970020050000031
Figure FDA0002970020050000032
in the formula, asThe distance from the center of gravity of the steel bar to the bottom surface of the concrete slab, x is the distance from the plastic neutralization shaft of the composite beam to the top surface of the upper flange of the steel beam, H is the beam height of the honeycomb beam, bf、tfRespectively upper flange width and thickness, twIs the web thickness, stWeb height for a T-section; a. thesnThe cross-sectional area of the honeycomb steel beam representing the central cross section of the first opening, AstCross-sectional area of longitudinal reinforcement in the area of the slab in the hogging moment region, fstF is the design value of the tensile strength of the steel bar, and f is the design value of the tensile strength of the steel;
when the plastic neutralizing shaft is positioned in the T-shaped section on the honeycomb steel beam, the pure bending bearing capacity of the central section of the first hole is as follows:
Figure FDA0002970020050000033
Figure FDA0002970020050000034
in the formula, S represents the area moment of the T-shaped section to a neutral axis of the honeycomb steel beam;
when the plastic neutralizing shaft is not arranged in the steel beam, the pure bending bearing capacity of the central section of the first hole is as follows:
Figure FDA0002970020050000035
5. the method for calculating hogging moment bearing capacity of a honeycomb composite beam according to claim 1, wherein the sixth step specifically comprises: pure shear bearing capacity V of central section of first holem2The sum of the shear-resisting bearing capacity of the upper T-shaped section and the lower T-shaped section of the steel beam is as follows:
Vm2＝∑Vt
in the formula VtThe shear-resistant bearing capacity of the T-shaped section can be obtained by the following steps:
when in use
Figure FDA0002970020050000041
And then the shearing-resistant bearing capacity of the central section of the first hole is as follows:
Figure FDA0002970020050000042
when in use
Figure FDA0002970020050000043
And then the shearing-resistant bearing capacity of the central section of the first hole is as follows:
Vm2＝∑Vpt
wherein λ ═ a0/st，a0Indicating the length of the opening or of the T-section in the direction of the beam axis, VptShowing the plastic shear-bearing capacity of the T-section web,
Figure FDA0002970020050000044
f is the design value of tensile strength of steel material, twIs the web thickness, stWeb height of T-shaped cross-section, ∑ VptTo representThe sum of the plastic shear-resisting bearing capacity of the two T-shaped section webs.
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