WO2018012495A1 - Beam-column connection structure - Google Patents

Abstract

Provided is a beam-column connection structure that is a non-diaphragm-shaped beam-column connection structure provided with a column of steel-reinforced concrete construction or steel construction and a beam of steel construction that is connected to the column, wherein the column includes a flanged column steel frame with a cross-shaped or H-shaped cross-section that comprises a web, a flange, and a full-strength connection section and a non-full-strength connection section which connect the web and flange together; and the full-strength connection section is formed at least in the area where tensile stress acts on the flange of the column steel frame when a bending moment acts on the beam.

Description

Beam-column joint structure

The present invention relates to a column beam connection structure.
This application claims priority based on Japanese Patent Application No. 2016-137010 for which it applied to Japan on July 11, 2016, and uses the content here.

Conventionally, a column beam connection structure is adopted in a building of a steel structure (for example, refer to Patent Document 1).
The column beam connection structure of Patent Document 1 includes a non-diaphragm type steel pipe column and a beam directly connected to the steel pipe column. The steel pipe column is composed of a column beam joint where the beam is directly welded and a non-column beam joint where the beam is not connected. The outer diameter of the column beam joint and the outer diameter of the non-column beam joint are the same. The wall thickness of the column beam joint is greater than the wall thickness of the non-column beam joint.
By making the beam-column joint structure a non-diaphragm type, the number of parts constituting the beam-column joint structure is reduced. Furthermore, the manufacturing cost of the column beam connection structure can be reduced by reducing the number of parts processed.

Japanese Unexamined Patent Publication No. 2010-229660

Here, instead of the steel pipe column of Patent Document 1, a column steel frame having an H-shaped cross section or a cross-shaped cross section with a flange may be used. For example, when the thickness of the flange of the column steel frame is out of specification, the column steel frame is manufactured by welding the web and the flange instead of rolling. In this case, the beam is joined to the flange of the column steel frame by welding.

When a load is applied to the beam, a bending moment is applied to the beam-column joint structure. Due to this bending moment, a portion to be pulled and a portion to be compressed are generated in the flange of the column steel frame. At this time, if the web of the column steel frame and the flange are joined by partial penetration welding or fillet weld, there is a notched welded part where the web and flange are not joined at the joint, Due to the load acting on the joint portion, there is a possibility that the joint portion may be broken starting from the non-welded portion.

In order to prevent the welded portion from being formed at the joint between the web and the flange, the web and the flange are all joined by full penetration welding, and the web and the flange are fully joined. This full strength bonding makes it difficult for cracks to occur at the joint.
However, when the web and the flange are joined by full penetration welding, the manufacturing cost increases compared to the case where the web and the flange are joined by partial penetration welding or fillet welding. Full penetration welding requires a groove in the part where the web is butt-welded to the flange, and more weld metal is needed to fill the space created by the groove with welding. is there. Moreover, in complete penetration welding, it is necessary to perform an ultrasonic flaw detection test or the like after welding to confirm that no welded portion is formed.
Such an increase in manufacturing cost due to complete penetration welding offsets a reduction in manufacturing cost due to the non-diaphragm type, which may impair the advantages of the non-diaphragm type.

The present invention has been made in view of the above circumstances, and suppresses an increase in manufacturing cost while suppressing breakage of a joint portion between a column steel web and a flange when a load is applied to a beam. The purpose is to provide a possible beam-to-column structure.

The present invention employs the following in order to solve the above problems.
(1) A column beam connection structure according to an aspect of the present invention is a non-diaphragm column beam connection structure including a steel reinforced concrete structure or a steel structure column and a steel beam bonded to the column. The pillar has a flanged cruciform cross-section or H-section pillar steel having a web, a flange, and a full strong joint and a non-full strong joint joining the web and the flange together, In the range where a tensile stress acts on the flange of the column steel when a bending moment acts on the beam, the all strong joints are formed.

(2) In the aspect of the above (1), the all strong joints are formed in a range not less than the value of H _b + 2y obtained by using the following formula, with the center of the range of the beam being the center of the range. It may be. However, _{B c:} width of the flange of said post steel _{(mm), t cf:} thickness of the flange of said post steel _{(mm), t cw:} said web having a thickness of said post steel (mm), sigma _cfy : yield strength (N / mm ² ) of the flange of the column steel, σ _cwy : yield strength (N / mm ² ) of the web of the column steel, H _b : blame of the beam (mm), F _c : compressive strength (N / mm ² ) of the concrete of the column, d: cover thickness (mm) of the concrete with respect to the flange of the column steel, and when the column is a steel structure, F _c and d are zero And

　　　　　　　　　　　　　　　　　 

According to the aspect described in (1) above, since the full strength joint portion for joining the flange of the column steel frame and the web is formed in a range where the tensile stress acts on the flange of the column steel frame, the flange and the web are not welded. The part is not formed in this range. In column steel frames, the range in which tensile stress acts on the flange tends to cause the fracture of the joint between the flange and the web starting from the non-welded part.However, since the non-welded part is not formed in this range, the load acts on the beam. When it does, it becomes difficult to produce the fracture | rupture of a junction part. Moreover, a non-total strong junction part is formed in ranges other than the range in which the total strong junction part was formed. Therefore, an increase in manufacturing cost can be suppressed while suppressing breakage of the joint between the flange and the web in the column steel frame.

According to the aspect described in (2) above, the strength is fully increased in a range pulled by a load acting on the beam from above and below (the range of the value of H _b + 2y with the center of the beam being the center of the range). A joint is formed. Moreover, a non-total strong junction part is formed in ranges other than the range in which the total strong junction part was formed. Therefore, even if a load acts on the beam from above and below, it is possible to suppress breakage of the joint between the flange and the web in the column steel frame, and it is possible to suppress an increase in manufacturing cost.

It is a perspective view which shows the beam-column joining structure which concerns on 1st Embodiment of this invention, Comprising: It is the figure which permeate | transmitted the part. It is sectional drawing which shows the column of the said beam-column joining structure. It is a fragmentary sectional view which shows the non-total strong junction part in the column steel frame of the said column. It is a fragmentary sectional view which shows the other non-fully strong joint part in the column steel frame of the said column. It is sectional drawing which shows the said beam-column joining structure, Comprising: It is a figure for demonstrating the collapse mechanism at the time of a total plastic yield strength. FIG. 6 is a side view seen from the line A1-A1 in FIG. 5 for explaining the cone-like fracture of the cover concrete. FIG. 6 is a side view seen from the line A1-A1 of FIG. 5 for explaining the bearing failure of concrete. It is a figure for demonstrating the actual stress-strain characteristic in steel materials. It is a figure for demonstrating the stress-strain characteristic of steel materials modeled. It is a side view of the said column steel frame, Comprising: It is a figure which shows the range in which a total strong junction part and a non-total strong junction part are formed. It is a figure for verifying the accuracy which predicted variable y in a 2nd embodiment of the present invention. In 3rd Embodiment of this invention, it is a perspective view which shows the analysis model used for the analysis of a column beam connection structure. It is a perspective view which shows the principal part of the said analysis model. It is the figure seen from the A direction of FIG. It is a figure which shows the stress-strain characteristic used for the element of a column steel frame and a beam in the finite element analysis of the said column beam connection structure. It is a figure which shows the stress-strain characteristic used for the element of the weld metal part in the finite element analysis of the said column beam connection structure. It is a figure which shows an example of the result of having calculated | required the plastic strain from the result of the finite element analysis of the said beam-column joining structure. It is a figure which shows the relationship between the flange width of a beam and the range where the plastic strain is distributed in the state which the edge part of the beam rotated 0.02 (radian). It is a figure which shows the relationship between the flange width of a beam and the range where the plastic strain is distributed in the state which the edge part of the beam rotated 0.03 (radian). It is a figure which shows the relationship between the flange width of a beam and the range where the plastic strain is distributed in the state which the edge part of the beam rotated 0.04 (radian).

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

(First embodiment)
FIG. 1 is a perspective view showing a beam-column joint structure 1 according to a first embodiment of the present invention. In FIG. 1, in order to facilitate understanding of the invention, a part of the beam-column joint structure 1 is shown in a transparent manner. As shown in FIG. 1, the column-beam joint structure 1 includes a steel reinforced concrete (SRC) column 11, a steel beam 21, and a joint 31 that joins the column 11 and the beam 21. . The column beam connection structure 1 is of a type that does not use a diaphragm (stiffener) when the beam 21 is bonded to the column 11, that is, a non-diaphragm type.

The column 11 is made of steel reinforced concrete as described above, and has a column steel frame 12 having a web 14 and a flange 13, a plurality of reinforcing bars 15 surrounding the column steel frame 12, and concrete 16. The column steel frame 12 and the plurality of reinforcing bars 15 are embedded in the concrete 16. Note that the pillar 11 is not limited to a steel-framed reinforced concrete structure, and may be a steel-framed pillar that does not include the reinforcing bars 15 and the concrete 16, for example.

FIG. 2 is a view showing the column steel frame 12 of the beam-to-column connection structure 1, and is a cross-sectional view when viewed in a cross section that is perpendicular to the material length direction (longitudinal direction) and passes through the full strength joint portion 17. FIG. 3 is a diagram showing the column steel frame 12 of the beam-column joint structure 1 and is a partial cross-sectional view when viewed in a cross section perpendicular to the material length direction and passing through the non-total strong joint 18A. FIG. 4 is a view showing the column steel frame 12 of the beam-column joint structure 1 and is a partial cross-sectional view when seen in a cross section perpendicular to the material length direction and passing through the non-total strong joint 18B.

As shown in FIGS. 1 to 4, a flanged cross-shaped column steel frame 12 is obtained by welding and joining the end of the web 14 (the end in the width direction of the web 14) and the flange 13 together. It is done. The end portion of the web 14 and the flange 13 are formed by a fully-strong welded portion 17 (a portion that is fully-strengthened) shown in FIG. 2 and a non-filled portion shown in FIG. Total strong joint 18A (part joined by a method other than full strong joint) and non-full strong joint 18B formed by fillet welding shown in FIG. 4 (joined by a method other than full strong joint) Part).
In addition, the edge part of the web 14 and the flange 13 may be joined by the full strong joint part 17 and the non-full strong joint part 18A, or joined by the full strong joint part 17 and the non-full strong joint part 18B. May be. That is, the end portion of the web 14 and the flange 13 may be joined by the all strong joint portion 17 and any one of the non-fully strong joint portion 18A and the non-fully strong joint portion 18B.

Here, “complete penetration welding” means that a weld is provided in the weld joint and the entire cross section of the base material (in the present invention, the column steel web) is completely welded, and the weld throat thickness is the thickness of the base material ( It means that all the strong joints (sheet thickness) or more (joints with a proof strength not lower than the proof stress of the base material) are formed. Further, “partial penetration welding” is a welding method in which a groove is partially provided in the weld joint and a part of a cross section of the base metal is welded, and an irregular fillet weld is given as an example. Further, the “fillet welding” is a method in which a weld metal having a triangular cross section is placed at the corners of the webs and flanges of pillar steel frames that are installed without providing a groove.

Partial penetration welding and fillet welding are welding methods that allow a weld non-welded portion to exist in the cross section of the weld joint. In addition, in the Architectural Institute of Japan edition, “Architectural Institute of Japan Standard Specification for Architectural Construction, JAS6 Steel Construction”, an ultrasonic flaw detection test is conducted to confirm that all strong joints formed by full penetration welding have no internal defects. It is described that it must be confirmed by, for example. Therefore, even when the entire cross section with the base material to be matched as a welding specification is completely welded, it is desirable to confirm that there is no internal defect by an ultrasonic flaw detection test or the like after welding.

That is, the portion where the flange 13 of the column steel frame 12 and the web 14 are fully strong-bonded is the full-strength joint portion 17 where the flange 13 of the column steel frame 12 and the web 14 are joined by complete penetration welding. On the other hand, the flange 13 of the column steel frame 12 and the web 14 are joined by a method other than full strength joining, and the flange 13 of the column steel frame 12 and the web 14 are joined by partial penetration welding (non-total strength joining). The non-fully strong joint 18A or the flange 13 of the column steel frame 12 and the web 14 are joined together by fillet welding (non-fully strong joint).

3 is formed at the end of the web 14 by, for example, SAW (Submerged Arc Welding), and the web 14 and the flange 13 are joined to each other. It consists of weld metal parts 18a and 18b. These weld metal portions 18a and 18b are formed so as to sandwich the web 14 in the thickness direction (plate thickness direction). In addition, since the non-fully strong joint 18A is formed by partial penetration welding as described above, a notch-shaped non-welded portion 18c is formed between the weld metal portion 18a and the weld metal portion 18b. Yes.

The non-fully strong joint 18B formed by fillet welding shown in FIG. 4 is formed at the end of the web 14 and welds the web 14 and the flange 13 together, as with the non-fully strong joint 18A. It consists of metal parts 18d and 18e. Since the non-fully strong joint 18B is formed by fillet welding as described above, a notch-like welded portion 18f is formed between the weld metal portion 18d and the weld metal portion 18e. Yes.
In the present specification, when the non-total strong joint portion 18A and the non-total strong joint portion 18B are referred to without being distinguished, they are collectively referred to as the non-total strong joint portion 18.

On the other hand, in the all strong joint portion 17 formed by complete penetration welding, a pair of weld metal portions are integrated without forming a non-welded portion therebetween (see FIG. 2).

In the column steel frame 12 of the column beam connection structure 1, the web 14 and the flange 13 to which the beam 21 is bonded are all strongly bonded within a predetermined range in the material length direction (longitudinal direction) of the column steel frame 12. Bonding is performed by a method other than full strength bonding in a range other than the predetermined range. In other words, in the column steel frame 12 of the beam-column joint structure 1, the entire strong joint 17 that joins the flange 13 and the web 14 is formed in the predetermined range, and the flange 13 and the web are in a range other than the predetermined range. 14 is formed (see FIG. 10). That is, in the column steel frame 12, when viewed along the material length direction (longitudinal direction), the full strong joint 17 and the non-full strong joint 18 that join the flange 13 and the web 14 are formed. There is no gap between the total strong joint 17 and the non-total strong joint 18 (the total strong joint 17 and the non-total strong joint 18 are continuous).
Details of the predetermined range will be described later. The column steel frame 12 is not limited to the above-mentioned cross-shaped cross section with a flange, and may have an H-shaped cross section in which the end of the web 14 and the flange 13 are welded to each other.

The plurality of reinforcing bars 15 are arranged on a rectangular reference line when viewed from the length direction of the column steel frame 12 shown in FIG.
The concrete 16 has a square or rectangular cross section perpendicular to the material length direction.

As shown in FIG. 1, the beam 21 is made of H-shaped steel, and includes a web 24 and a pair of flanges 23 joined to both ends of the web 24. The beam 21 is joined to the outer surface of the flange 13 of the column steel frame 12 and extends perpendicular to the flange 13. Note that the beam 21 is a steel frame, and is made of, for example, a steel plate.

The flange 23 of the beam 21 is joined to the flange 13 of the column steel frame 12 by welding at the joint 31. The web 24 of the beam 21 is joined to the flange 13 of the column steel frame 12 by welding or high strength bolt friction joining via a shear plate. A joint portion 31 (including the welded portion and the column steel frame 12 and the beam 21 in the vicinity of the welded portion) where the flange 13 and the beam 21 of the columnar steel frame 12 are joined is surrounded by the concrete 16. That is, a part of the beam 21 is embedded in the concrete 16 of the column steel frame 12.

In the present specification, it is assumed that the web 14 of the column steel frame 12 and the flange 13 are joined by welding. However, the present invention is not limited to welding joining, for example, adhesive joining, pressure welding, or amorphous joining. It may be used. That is, the total strong joint 17 that joins the web 14 and the flange 13 may be formed by adhesive bonding, pressure welding, amorphous bonding, or the like. Similarly, the non-fully strong joint 18 that joins the web 14 and the flange 13 may be formed by adhesive bonding, pressure welding, amorphous bonding, or the like.

[1. Collapse mechanism proposed in the present invention]
Next, the collapse mechanism of the column beam connection structure 1 will be described. In the present invention, the mechanism shown in FIGS. 5 to 7 is assumed. In FIGS. 5 to 7, a load is applied from above the beam 21 (a load is applied to the upper flange 23 of the pair of flanges 23 of the beam 21). The state after the beam-column joint structure 1 is deformed by the bending moment generated in FIG. FIG. 5 is a partial cross-sectional view when seen in a cross-section perpendicular to the flange 23 of the beam 21 and is a view for explaining a collapse mechanism at the time of full plastic yield strength. FIG. 6 is a side view as seen from A1-A1 in FIG. 5, for explaining the cone-shaped fracture of the cover concrete. FIG. 7 is a side view seen from the line A1-A1 of FIG. 5 and is a view for explaining the bearing pressure failure of concrete.

As shown in FIG. 5, the plastic hinges 13 ₁ and 13 ₃ above the flange 13 of the pillar steel 12, the plastic hinge 13 ₂ and 13 ₄ are formed downward. That is, the pair of flanges 23 of the beam 21 in the flange 13 of the beam 21 is joined to the connection portions, a pair of plastic hinge _{13 1,} 13 _3, 13 2, 13 ₄ are respectively formed. From the state described later plastically rotation angle theta ₁ and theta ₂ is 0 (radian), the plastic rotational angle theta ₁ and theta ₂ shown in FIGS. 5-7 is deformed to a positive state.
The flange 23 on the tension side of the beam 21 (in this example, the flange 23 ₁ located on the upper side of the pair of flanges 23 of the beam 21, hereinafter also referred to as the upper flange 23 ₁ ) is out of plane with the flange 13 of the column steel frame 12. For the pulling force, the column steel 12 which is a steel frame causes out-of-plane deformation of the flange 13 and local yielding of the web 14. As a result, a local yield 14 a is formed on the web 14 of the column steel frame 12. Further, the flange 13 of the column steel 12, plastic hinge 13 ₁ is formed.
When the flange 13 of the column steel frame 12 is deformed out of plane, the cover concrete 16a outside the flange 13 is broken in a cone shape. A side surface 16a1 of the cover concrete 16a is shown with hatching in FIG.

As shown in FIG. 5, a flange 23 on the compression side of the beam 21 (in this example, of the pair of flanges 23 of the beam 21, a flange 23 ₂ positioned on the lower side: hereinafter also referred to as a lower flange 23 ₂ ). Assuming that the flange 13 of the column steel frame 12 is pushed out of the plane, the flange 13 is deformed out of the plane to cause local yielding of the web 14, and the concrete 16 inside the flange 13 is subjected to bearing failure. Yes. In other words, the bearing fracture portion 16 b is formed in the concrete 16. The bearing fracture portion 16b is shown with hatching in FIG. Further, the flange 13 of the column steel 12, plastic hinge 13 ₂ is formed.
In general, the bearing strength of concrete is larger than the cone-shaped fracture strength. Therefore, the neutral axis C1 that satisfies the balance condition in the cross section of the joint portion 31 is made of the beam stake H _b (beam stake (composition)) (mm). than the vertical center located in the flange 23 ₂ side of the compression side.

This collapse mechanism assumes a state in which the joint 31 is rotated by an angle θ (radian) with respect to the bending moment at the end of the beam 21. However, the angle θ is a minute angle and can be approximated as tan θ = θ or the like.
The variables used in this collapse mechanism are x, y, and z (mm) shown in the figure. The variable x is a coefficient that determines the position of the neutral axis C <b> 1 with respect to the bending moment at the end of the beam 21, and can take any value between 0 and 1. Specifically, the variable x, when the bending moment on the end of the beam 21 is applied from the tension side of the flange 23 ₁ of the outer surface of the beam 21 in the ratio Sei Ryo H _b of the distance to the neutral axis C1 is there. Furthermore, the variable y is between plastic hinge 13 ₁ and plastic hinge 13 ₃ located above the upper flange 23 ₁ of the beam 21, the length in the wood longitudinal direction of the column steel 12. Further, the variable z is between plastic hinge 13 ₂ and plastic hinge 13 ₄ located below the lower flange 23 _{and second} beam 21, the length in the wood longitudinal direction of the column steel 12. Note that the variables y and z can take any positive number (a value greater than 0).
Using these variables x, y, and z, the out-of-plane deformation amounts δ ₁ and δ ₂ (mm) at the intersections of the flange 13 of the column steel frame 12 and the flanges 23 ₁ and 23 ₂ of the beam 21 are as follows: Using the formulas (1) and (2), the following formulas (3) and (4) can be used. Here, it is assumed that the plate thickness of the flange 23 of the beam 21 is t _bf (mm) and the width of the rigid zone assumed at the intersection of the flange 13 and the flange 23 is t ′ (mm).

 

The plastic rotation angles θ ₁ and θ ₂ (radian) generated in the yield hinge line of the flange 13 of the column steel frame 12 can be expressed by the following equations (5) and (6).

 

[2. Collapse bending moment)
FIG. 8 shows actual stress-strain characteristics of steel materials such as the column steel frame 12 and the beam 21. The horizontal axis in FIG. 8 represents the strain of the steel material, and the vertical axis represents the stress acting on the steel material. The steel material has an elastic region R1 in which the stress increases proportionally as the strain increases from a state where the strain is zero. The range where the strain is larger than that of the elastic region R1 is the non-elastic region R2. In the inelastic region R2, the rate of increase in stress is lower than in the elastic region R1. Stress at the boundary between the elastic region R1 and the non-elastic region R2 is a yield stress sigma _1.
In inelastic regions R2, stress becomes maximum at the maximum stress sigma _2. When the strain becomes larger than the strain corresponding to the maximum stress σ ₂ , the stress is lower than the maximum stress σ ₂ . Steel, breaks in strain epsilon _1.

On the other hand, in this embodiment, in obtaining the theoretical solution using the limit analysis method, a model having a rigid-plastic relationship indicated by a line L1 in FIG. 9 is used as the stress-strain characteristics of the column steel 12 and the beam 21. Assumes. The horizontal axis in FIG. 9 represents the strain of the steel material, and the vertical axis represents the stress acting on the steel material.
In this model, the stress increases with zero strain. When the stress becomes the yield stress σ ₁ , the steel material yields. After the steel yields, the strain increases without changing the stress. In this model, strain hardening is not considered.

Next, details of the collapse bending moment will be described.
The yield moment M ⁰ (N) per unit length of the yield hinge line of the flange 13 of the column steel 12 and the yield axial force N ⁰ _c (N N per unit length of the discontinuous line generated in the web 14 of the column steel 12 / Mm) is given by the following equations (7) and (8), respectively.
Here, the plate thickness of the flange 13 of the column steel 12 is t _cf (mm), the plate thickness of the web 14 of the column steel 12 is t _cw (mm), and the yield strength of the flange 13 of the column steel 12 is σ _cfy (N / Mm ² ), and the yield strength of the web 14 of the column steel frame 12 is σ _cwy (N / mm ² ).

 

The internal work W _cf due to the out-of-plane deformation of the flange 13 of the column steel frame 12 is given by the following formula (9) as the sum of work due to plastic rotation of each yield hinge line. Further, the internal work W _cw due to local yielding of the web 14 of the column steel frame 12 is given by the following equation (10) as the sum of work due to plastic flow generated on each discontinuous line.
Internal work _{W RC1} by cone breakage occurring tensile side of the flange 23 ₁ around the concrete cover 16a of the beam 21 is given by (11) below. Internal work _{W RC2} according Bearing destruction within the concrete 16 occurring in the compression side of the flange 23 ₂ around the beam 21 is given by the following equation (12).
Here, the width of the flange 13 of the column steel frame 12 is B _c (mm), the cover thickness of the concrete 16 with respect to the flange 13 of the column steel frame 12 is d (mm) (see FIG. 2), and the compressive strength (design criteria) of the concrete 16 Strength) is F _c (N / mm ² ), and the bearing effect coefficient of concrete 16 is λ (−) (1.5 in this embodiment). The compression strength _{F c} of the concrete 16 can be obtained by the "Test Method of Compressive Strength for concrete" described in JIS A1108.

 

From the principle of virtual work, the collapse bending moment M (Nmm) for the joint 31 is given by the following equation (13). That is, the sum of the internal work W _cf , the internal work W _cw , the internal work W _RC1, and the internal work W _RC2 is a joint portion with respect to the collapse bending moment M of the joint portion 31 and the bending moment of the end portion of the beam 21. A first equation according to the following equation (13) that is equal to the product of the rotation angle θ of 31 is derived.
The total plastic bending moment _j M _p (Nmm), which is the minimum value of the collapse bending moment M, is obtained by simultaneously solving the following equation (14) and is given by the following equations (15) to (18): It is done.
The following equation (14) is an equation representing that values obtained by partial differentiation of the collapse bending moment M with respect to the variables x, y, and z are each equal to zero. The variables x, y, and z are obtained from the following equations (16) to (18).
The total plastic bending moment _j M _p represents the bending moment when the steel material yields in FIG. 9 and corresponds to the total plastic yield strength of the joint portion 31. Basically, the variable y is larger than the variable z. This is because the bearing strength of concrete becomes larger than the cone-shaped fracture strength as described above. If compression strength F _c of the concrete 16 is zero (if the pillars 11 of the steel frame of the pillar without a reinforcing bar 15 and concrete 16), and the variable y and the variable z is equal.

 

When the yield moment M ⁰ and the yield axial force N ⁰ _c per unit length given by the above formulas (7) and (8) are substituted into the above formula (17) and rearranged, the following (19) The formula is obtained.
When the column 11 is a steel-framed column that does not include the reinforcing bar 15 and the concrete 16, the calculation is performed with the compressive strength F _{c of} the concrete 16 and the cover thickness d of the concrete 16 being zero in the following equation (19). do it.

 

As described above, the flange 13 of the column steel frame 12 corresponding to the range of the variable y above the beam 21 indicated by the plastic hinge, the range of the fault of the beam 21, and the range of the variable z below the beam 21, respectively. Only is pulled or compressed. Basically, the variable y is larger than the variable z. The value range obtained by the expression (H _b / 2 + y) upward from the center P1 due to the beam 21 and the value range obtained by the expression (H _b / 2 + z) downward from the center P1. The range of values obtained by the expression (H _b + 2y) with P1 as the center of the range is wider. For this reason, even if a load is applied to the beam 21 from above and below, the column in the range of values obtained by the expression (H _b + 2y) with the center P1 (see FIG. 10) of the beam 21 as the center of the range. It can be seen that only the flange 13 of the steel frame 12 is pulled by the beam 21.

For this reason, as shown in FIG. 10, in the length direction of the column steel 12, the flange 13 of the column steel 12 and the web 14 are all connected in a range R6 including the range in which the flange 13 of the column steel 12 is pulled by the beam 21. It joins by the strong junction part 17. FIG. On the other hand, the range R7 other than the range R6 in the material length direction of the column steel frame 12, that is, the range R7 that is not joined by the full strong joint 17 is joined by the non-total strong joint 18. In FIG. 10, the reinforcing bars 15 of the pillars 11 and the concrete 16 are shown in a transparent manner.
Here, the range R6 is a range of values obtained by the formula (H _b + 2W) with the center P1 of the beam 21 as the center of the range. And W is y or more by said (19) Formula.

In the design method of the column beam connection structure 1 of this embodiment, in the column steel frame 12, the range in which the web 14 and the flange 13 to which the beam 21 is bonded is fully strong bonded, and the center P <b> 1 of the beam 21 is set as the range. The value is set in the range obtained by the formula of (H _b + 2W) as the center. Further, in the column steel frame 12, a range other than the above range (a range in which the web 14 and the flange 13 to which the beam 21 is bonded is not fully bonded) is non-fully bonded (bonded other than the fully bonded). To set).
That is, in the beam-column joint structure 1, when viewed along the material length direction, it is obtained by an expression of (H _b + 2y) with at least the center P1 of the beam 21 (see FIG. 10) as the center of the range. The total strong joint 17 is formed in the range of values, and the non-total strong joint 18 is formed in a range other than the above range. From the viewpoint of further reducing the manufacturing cost, the total strong joint 17 is within the range of the value obtained by the expression (H _b + 2y) with the center P1 (see FIG. 10) of the beam 21 as the center of the range. It is preferable that the non-fully strong joint 18 is formed in a range other than the above range. In this case, since the range in which the web 14 and the flange 13 are joined by full strength joining can be limited to the range in which the flange 13 is pulled by the load acting from above and below the beam, the joining of the web 14 and the flange 13 is possible. An increase in manufacturing cost can be further suppressed while suppressing breakage of the part.

As described above, the variable W is a value greater than or equal to the variable y according to the above equation (19). The variable W may be longer than the variable y by, for example, 50 (mm) or more. Further, the value obtained by the expression (H _b + 2W) may be, for example, 1.1 to 1.2 times the value obtained by the expression (H _b + 2y).
In addition, at the start of arc welding, outside air may enter the shield used for arc welding. For this reason, since the spark of arc welding is difficult to stabilize and the proof stress of the part which started arc welding is not stabilized, it is preferable to provide a run-up section at the start of arc welding.
Further, in the range R6 where the all strong joints 17 are formed, it is preferable that a groove processing is performed on the end of the web 14 and the like in advance. Furthermore, it is preferable that an ultrasonic flaw detection test or the like is performed on the range R6 to confirm that the infusible portion between the web 14 and the flange 13 is not formed.

As described above, according to the column-beam joint structure 1 and the design method of the column-beam joint structure 1 of the present embodiment, even if a load acts on the beam 21 from above and below, the center of the fault of the beam 21 is obtained. Only the flange 13 of the column steel frame 12 within the range of the value obtained by the formula of (H _b + 2y) as the center of the range is pulled by the beam 21. Therefore, in the material length direction of the column steel 12, at least the flange 13 and the web 14 in the range where the flange 13 of the column steel 12 is pulled are strongly joined, so that the web 14 and the flange 13 are connected to the column steel 12 in this range. No welded part is formed. And the web 14 and the flange 13 of the column steel frame 12 in the remaining range are non-fully joined.
Thereby, when a load acts on the beam 21 and a bending moment is generated, it is possible to suppress breakage of the welded portion that joins the web 14 and the flange 13 in the column steel frame 12. Moreover, compared with the case where all the webs 14 and the flanges 13 are all strongly joined, the manufacturing cost can be reduced.
Therefore, the web 14 and the flange 13 of the column steel frame 12 are fully strongly joined in a necessary range, and the range in which the full strength is joined is narrowed, thereby suppressing breakage of the welded portion joining the web 14 and the flange 13. And the increase in the manufacturing cost of the column beam junction structure 1 can be suppressed.

It should be noted that the flange 13 and the web 14 are fully joined in a range in which tensile stress acts on the flange 13 of the column steel frame 12, and the flange 13 and the web 14 are in a range where the flange 13 and the web 14 are not fully joined. May be joined by a method other than full strength joining. The range in which the tensile stress acts on the flange 13 of the column steel frame 12 to cause local yielding in the web 14 of the column steel frame 12 is a range R9 shown in FIG. That is, in the wood longitudinal direction of the column steel 12 is in the range of up to the neutral axis C1 from plastic hinge 13 _1.
Since the flange 13 of the column steel 12 and the web 14 are fully strongly joined within the range where the tensile stress is applied to the flange 13 of the column steel 12, the web 14 and the flange 13 are connected to the column steel 12 within this range R9. No welded part is formed. In the range R9 in which the tensile stress is applied to the flange 13, the welded portion is likely to break starting from the non-welded portion. However, since the non-welded portion is not formed in this range R9, a load is applied to the beam 21. Sometimes, the welded portion between the web 14 and the flange 13 in the column steel frame 12 is less likely to break.
Therefore, it is possible to reduce the manufacturing cost of the column beam connection structure 1 by performing full strength joining within a necessary range and narrowing the range of full strength joining.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. In addition, about the component same as the component mentioned above, the duplicate description below is abbreviate | omitted by attaching | subjecting the same code | symbol.
In the present embodiment, as in the first embodiment, the theoretical solution is obtained by using the limit analysis method, and by limiting to the specifications such as the thickness of the column-beam joint structure 1 that is frequently used, The range to be strongly joined is easily obtained.

Specifically, the following restrictions (i) to (iii) and assumptions (iv) are made.
(I) The yield strength σ _cfy of the flange 13 of the column steel 12 is equal to the yield strength σ _cwy of the web 14 of the column steel 12.
(Ii) The ratio of the width B _c of the flange 13 of the column steel 12 to the plate thickness t _cf of the flange 13 of the column steel 12 is 3.0 or more.
The ratio of the thickness _{t cf} of the flange 13 of the pillar steel 12 against the plate thickness _{t cw} web 14 (iii) column steel 12 is 3.33 or less.
(Iv) ignoring the effect of the concrete cover (the _{F c} is zero).

In addition, it has been found that the influence of the cover concrete is about 10% on the frequently used specifications of the column beam connection structure 1.
The following equation (20) is obtained by modifying the above equation (19) using the limitation of (i) and the assumption of (iv).
That is, the variable y is the ratio of the width B _c of the flange 13 of the column steel 12, the plate thickness t _cf of the flange 13 of the column steel 12 to the plate thickness t _cw of the web 14 of the column steel 12, and the flange of the column steel 12. It can be seen that this is represented by the ratio of the width B _c of the flange 13 of the column steel frame 12 to twice the plate thickness t _cf of 13.

 

The ratio of the thickness _{t cf} of the flange 13 of the pillar steel 12 against the plate thickness _{t cw} web 14 pillars steel 12, substituting 3.33 upper limit value (20) of said at Limited (iii) . For the ratio of the width B _c of the flange 13 of the column steel 12 to twice the plate thickness t _cf of the flange 13 of the column steel 12, the lower limit value 3.0 in the limitation of (ii) is expressed by the above equation (20). substitute. As a result, the following equation (21) is obtained.
In the following formula (20), the lower limit value of 3.0 obtained by the formula (B _c / (2t _cf )), which is the limit of (ii), and the limit of (iii) (t _cf By substituting 3.33 which is the upper limit of the value obtained by the equation of / t _cw ) into the following equation (20), the maximum value of the variable y in the limitation of (ii) and (iii) is about 0.75B. _c .

 

That is, the range R6 of the all strong joints 17 in the present embodiment is a range of values obtained by the formula (H _b + 2W) with the center P1 of the beam 21 being the center of the range. However, W is not less than y according to the above equation (21).

Note that the ratio of the width B _c of the flange 13 of the column steel 12 to twice the plate thickness t _cf of the flange 13 of the column steel 12 is 2.0 or more, and the column steel frame with respect to the plate thickness t _cw of the web 14 of the column steel 12 When the ratio of the plate thickness t _cf of the 12 flanges 13 is 4.0 or less, the value of the variable y is 1.0 B _c . The ratio of the width B _c of the flange 13 of the column steel 12 to twice the plate thickness t _cf of the flange 13 of the column steel 12 is set to 5.0 or more, and the column steel 12 has a ratio t _cw of the web 14 of the column steel 12 when the ratio of the thickness _{t cf} of the flange 13 is 2.5 or less, the value of the variable y becomes 0.5B _c.

As described above, according to the beam-column joint structure 1 of the present embodiment, the range in which the web 14 and the flange 13 of the column steel frame 12 are fully strong-bonded in the specifications such as the frequently used plate thickness, It depends only due _{H b} of width _{B c} and beam 21 of the flange 13 of the pillar steel 12. For this reason, it is possible to easily obtain a range in which the web 14 and the flange 13 of the column steel frame 12 are fully joined.
Note that FIG. 11 the variable y in this embodiment to verify the accuracy of the evaluation that the 0.75B _c may be described in the third embodiment.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIGS. In addition, about the component same as the component mentioned above, the duplicate description below is abbreviate | omitted by attaching | subjecting the same code | symbol.
In the first embodiment and the second embodiment, a theoretical solution is obtained using a limit analysis technique, and the plasticity of the web 14 of the column 11 having the total plastic bending moment _j M _p at the joint portion 31 between the column 11 and the beam 21 is obtained. The range of all strong joints 17 was set based on the conversion range. However, after the joint portion 31 yields, the plasticizing range may be expanded by strain hardening of the steel material.
On the other hand, in this embodiment, even when the junction part 31 deform | transforms greatly and the plasticization range of the junction part 31 expands, the conditions for the range of the above-mentioned all the strong junction parts 17 are examined. . In this embodiment, the range in which the plastic strain corresponding to the variable y is distributed is obtained by finite element analysis.

The analysis model used for the finite element analysis is shown in FIGS. The analysis model in FIG. 12 is a ¼ model representing the column-beam joint structure 1. In the ¼ model, the first surface S1 and the second surface S2 are symmetric surfaces under analysis conditions.
The analysis model of FIG. 12 shows a case where the column 11 of the beam-column joint structure 1 is a steel frame and is a column steel frame 12 having an H-shaped cross section.

The conditions for finite element analysis are shown below.
(I) The element of the analysis model was an 8-node solid element.
(II) The extra height of the weld metal portion of the portion where the end portion of the beam 21 is welded to the column steel frame 12 is set to ¼ of the plate thickness of the flange 23 of the beam 21. However, when the plate thickness of the flange 23 of the beam 21 is 40 mm or more, the extra height is set to 10 mm.
(III) The weld metal part between the web 14 of the column steel frame 12 and the flange 13 has a leg length and an extra height of 10 mm.

(IV) The material characteristics of the column steel frame 12 and the beam 21 were stress-strain characteristics that modeled the tensile test results of SN490, which is a rolled steel for building structures. FIG. 15 shows stress-strain characteristics used for the elements of the column steel frame 12 and the beam 21. The horizontal axis in FIG. 15 represents strain, and the vertical axis represents stress. In FIG. 15, an alternate long and short dash line L6 is a line representing the average stress-average strain of the tensile test result. A solid line L7 is a line modeling the average stress-average strain of the tensile test result. A dotted line L8 is a line obtained by converting the modeled average stress-average strain into true stress-true strain. In the finite element analysis, the average stress-average strain characteristic indicated by the dotted line L8 was used.

(V) As the material characteristics of each weld metal part, stress-strain characteristics modeling the tensile test result of YGW18 wire were used. FIG. 16 shows the stress-strain characteristics used for the weld metal element. The horizontal axis in FIG. 16 represents strain, and the vertical axis represents stress. In FIG. 16, an alternate long and short dash line L11 is a line representing the average stress-average strain of the tensile test result. A solid line L12 is a line modeling the average stress-average strain of the tensile test result. A dotted line L13 is a line obtained by converting the modeled average stress-average strain into true stress-true strain. In the finite element analysis, the average stress-average strain characteristic represented by the dotted line L13 was used.
(VI) The yield strength of the column steel frame 12 and the beam 21 was 380 MPa, and the tensile strength was 519 MPa.
(VII) The yield strength of the weld metal part was 526 MPa, and the tensile strength was 606 MPa.
(VIII) The load F (see FIG. 12) was applied to the end of the beam 21 opposite to the column steel frame 12 to provide a load condition for applying a unidirectional forced displacement in the vertical direction.

Table 1 shows a list of analysis variable ratios of the analysis model. The dimensions of the column steel frame 12 and the beam 21 were set so that each ratio is a combination of the values shown in Table 1 that are frequently used.
That is, the ratio value was determined as follows.
(A) The ratio of the width B _{c to} the plate thickness t _cf in the flange 13 of the column steel frame 12 is 3.0 or more and 8.0 or less.
(B) The ratio of the width (thickness ratio) of the column steel frame 12 to the plate thickness t _cw of the web 14 is 12.0 or more when the column steel frame 12 has a cross-shaped cross section with a flange. When the column steel frame 12 has an H-shaped cross section, this ratio is 24.0 or more.
(C) The ratio of H _c to the width B _c of the flange 13 in the column steel frame 12 is 1.7 or more and 3.5 or less.
(D) the ratio of the fault _{H b} of the beam 21 relative to blame _{H c} pillar steel 12, is 0.7 to 1.5.
(E) The ratio of the width B _b of the flange 23 of the beam 21 to the width B _c of the flange 13 of the column steel frame 12 is 0.5 or more and 1.0 or less.
(F) The ratio of the plate thickness t _bw of the web 24 of the beam 21 to the plate thickness t _cw of the web 14 of the column steel frame 12 is 0.5 or more and 1.0 or less.

 

Specifically, the dimensions were determined as follows.
(G) _{H c} due pillar steel 12 was set to a fixed value of 600 mm.
(H) The width B _c of the flange 13 in the column steel frame 12 was determined by the variable of the ratio of the claw H _c to the width B _c of the flange 13 in the column steel frame 12.
(I) _Depending on the variable of the ratio of the width of the column steel frame 12 to the plate thickness t _cw of the web 14 and the ratio of the width B _{c to} the plate thickness t _cf of the flange 13 of the column steel frame 12, the plate thickness t _cw of the web 14 and The plate thickness _{tcf of the} flange 13 was determined.
(J) By the variable of the ratio of the _width H _b of the beam 21 to the thickness H _c of the column steel frame 12 and the ratio of the thickness t _bw of the web 24 of the beam 21 to the thickness t _cw of the web 14 of the column steel frame 12, decided width _{B b} of the flange 23 of the fault _{H b} and the beam 21 of the beam 21.

(K) The plate thickness t _bw of the web 24 of the beam 21 is determined by the variable of the ratio of the width B _b of the flange 23 of the beam 21 to the width B _c of the flange 13 of the column steel frame 12.
(L) The plate thickness t _bf of the flange 23 of the beam 21 was determined so that the bending strength of the beam 21 was 1.2 times or more the local strength of the joint 31. At this time, when the ratio of the width B _{b to} the plate thickness t _{bf at} the flange 23 of the beam 21 is the FD rank, the plate thickness t of the flange 23 of the beam 21 is set to the boundary value between the FD rank and the FC rank. _{The bf} was thickened. When the plate thickness t _bf of the flange 23 of the beam 21 is thinner than the plate thickness t _bw of the web 24 of the beam 21, the plate thickness t _bf of the flange 23 of the beam 21 is set to the plate thickness of the web 24 of the beam 21. equal to t _bw .
(M) In the case where the ratio of the plate thickness t _cf of the flange 13 to the plate thickness t _cw of the web 14 in the column steel frame 12 exceeds 3.33, the analysis case is excluded. The excluded analysis cases are cases where the frequency of use is low.

A list of dimensions of the column steel frame 12 and the beam 21 determined by these procedures is shown as analysis case 1 to analysis case 56 in Tables 2 and 3.
In Tables 2 and 3, the analysis case number in which the ratio of the width of the column steel 12 to the plate thickness t _cw of the web 14 is 12.0 is the case where the column steel 12 has a cross-shaped cross section with a flange. The analysis case number in which the ratio of the width of the column steel frame 12 to the thickness t _cw of the web 14 is 32.0 is the case where the column steel frame 12 has an H-shaped cross section.

 

 

A total of 56 analysis cases shown in Table 2 and Table 3 were subjected to finite element analysis. In each analysis case, the equivalent plastic strain of the weld toe portion 19a of the weld metal portion 19 shown in FIGS. 13 and 14 was obtained over the length direction of the column steel frame 12.
FIG. 17 shows an example of the result of obtaining the plastic strain in the case of analysis case 2 (because the _{Hb of the} beam 21 is 900 mm). The horizontal axis in FIG. 17 represents the equivalent plastic strain, and the vertical axis represents the position of the beam 21 relative to the center of the fault. Note that the upper position is positive.
Further, in FIG. 17, a line L <b> 16 represented by a square plot indicates a state when the yielding of the joint portion 31 of the column beam joint structure 1 starts. On the other hand, a line L17 represented by a rhombus plot shows a state when the end of the beam 21 is rotated by 0.02 radian (about 1.15 °).

Here, the time when the yielding of the joint 31 starts is defined as a state where the tilt is reduced to 1/3 with respect to the initial rotation angle-bending moment of the joint 31. The state in which the end of the beam 21 is rotated 0.02 (radian) means the maximum displacement that occurs in the building when an earthquake occurs.

It was found that in both the line L16 and the line L17, the equivalent plastic strain of the weld toe portion 19a, that is, the plastic strain of the web 14 of the column steel frame 12 is distributed around the position of the flange 23 of the beam 21. .
When the yielding of the joint 31 began, it was found that the plastic strain was distributed to the range X of about 105 mm outside the beam 21. On the other hand, in the state where the end portion of the beam 21 is rotated 0.02 (radian), it has been found that the plastic strain is distributed to the range X of about 150 (mm) on the outer side of the beam 21.

FIG. 18 shows the result of obtaining the range X in which the plastic strain is distributed in each analysis case in a state where the end of the beam 21 is rotated 0.02 (radian). The horizontal axis of FIG. 18 represents the width B _c of the flange 13 of the pillar steel 12, the vertical axis represents the range X in which the plastic strain is distributed.
Range X in which the plastic strain is distributed has been found to be in the range of 1.1 times or less of the width B _c in the flange 13 of the column steel 12.
For this reason, the range R6 of the above-described strong joint portion 17 in the present embodiment is a range of values obtained by the formula (H _b + 2W) with the center P1 of the beam 21 being the center of the range. However, W is equal to or greater than 1.1B _c. That is, in the analytical model of the beam-column joint structure 1, the weld metal portion 19 in the range of the value obtained by the expression (H _b + 2W) with the center P 1 of the beam 21 as the center of the range is defined as the total strong joint 17. The weld metal part 19 other than the full strong joint 17 is defined as a non-full strong joint 18.

As described above, according to the beam-column joint structure 1 of the present embodiment, the column steel frame 12 is a cross-shaped cross section with a flange or an H-shaped cross section, and the specifications such as a thickness that is frequently used are column steel frames. The plastic strain is distributed in the column steel frames 12 in the range below the value obtained by the formula (H _b + 2.2B _c ) with the center of the range of the beam 21 as the center of the range with respect to the 12 material length directions. By fully joining the flange 13 and the web 14 in the range where the plastic strain in the column steel frame 12 is distributed, the welded portion between the web 14 and the flange 13 is not formed on the column steel frame 12 in this range. The web 14 and the flange 13 of the column steel frame 12 in the remaining range are joined by non-fully strong joining. For this reason, when a load acts on the beam 21, the welded portion that joins the web 14 and the flange 13 in the column steel frame 12 is less likely to break.
In addition, the range in which the web 14 and the flange 13 are completely strongly joined in the column steel frame 12 is determined only by the width B _c of the flange 13 of the column steel frame 12 and H _{b of the} beam 21. Therefore, it is possible to easily obtain a range in which the web 14 of the column steel frame 12 and the flange 13 are fully joined.

In addition, the result of having calculated | required the range X in which the plastic strain is distributed in each analysis case in the state which the edge part of the beam 21 rotated 0.03 (radian) is shown in FIG. Further, FIG. 20 shows a result of obtaining the range X in which the plastic strain is distributed in each analysis case in a state where the end portion of the beam 21 is rotated by 0.04 (radian).
0.03 (radian) rotation state, and, 0.04 (radian) in a rotating state, 1.2 times the range X are both width in the flange 13 of the column steel 12 _{B c} which plastic strain is distributed It was found that the following range.
That is, Rael considered the end of the beam 21 also increases the angle rotated, the range X in which the plastic strain is distributed is saturated in a range of less than 1.2 times the width B _c. In this case, it is possible to withstand a sufficiently large earthquake by fully joining in the range of the value obtained by at least the formula (H _b + 2.4B _c ) with the center of the H _{b as} the center of the range. I found out that

Here, FIG. 11 of the second embodiment will be described. Among the analysis cases shown in Tables 2 and 3, the range X in which the plastic strain is distributed was obtained for 56 analysis cases corresponding to the second embodiment.
Range plastic strain is distributed X was found to be in the range of 0.75 times the width B _c in the flange 13 of the column steel 12. It was found that the plasticization range at the time of yield strength in the finite element analysis results could be evaluated on the safe side.

As mentioned above, although each embodiment of this invention was described, these embodiment is shown as an example and the range of this invention is not limited only to these embodiment. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope of the present invention and the gist thereof, and are also included in the invention described in the claims and the equivalent scope thereof.

1: Column beam connection structure 11: Column 12: Column steel 13, 23: Flange 13 ₁ , 13 ₂ , 13 ₃ , 13 ₄ : Plastic hinge 14, 24: Web 17: Total strength joint 18: Non-total strength joint 21: Beam

Claims (2)

1. A non-diaphragm-type column beam connection structure comprising a steel reinforced concrete or steel frame column and a steel beam bonded to the column,
   The column has a flanged cruciform or H-shaped column steel frame having a web, a flange, and a full strong joint and a non-full strong joint joining the web and the flange to each other;
   The beam-to-column connection structure is characterized in that the strong joint portion is formed at least in a range in which a tensile stress is applied to the flange of the column steel when a bending moment is applied to the beam.
2. The all strong joints are formed in a range not less than a value of H _b + 2y obtained by using the following formula, with the center of the range being the center of the extent of the beam. Column beam connection structure of description.
   However, _{B c:} width of the flange of said post steel _{(mm), t cf:} thickness of the flange of said post steel _{(mm), t cw:} said web having a thickness of said post steel (mm), sigma _cfy : yield strength (N / mm ² ) of the flange of the column steel, σ _cwy : yield strength (N / mm ² ) of the web of the column steel, H _b : blame of the beam (mm), F _c : compressive strength (N / mm ² ) of the concrete of the column, d: cover thickness (mm) of the concrete with respect to the flange of the column steel, and when the column is a steel structure, F _c and d are zero And
   

   

Images