KR101932435B1 - Composite girder with enhanced stress distribution at connection between steel part and concrete part - Google Patents

Abstract

The present invention relates to a steel composite girder having improved load transferring capability in a steel material and a concrete connection portion. The steel composite girder has a first region formed in a first region including at least one of both ends and a second region formed in a central region, A first upper flange formed at an upper end of the abdomen of the first region and a second upper flange formed at an upper end of the abdomen of the second region; A steel girder including an overlapping region in which the first upper flange and a portion of the second upper flange are arranged to overlap with each other; And a height of the upper surface of the steel girder is not more than a part of the upper side of the first region of the steel girder but is synthesized in the same manner as the height of the upper surface of the first upper flange, Concrete; , Which can improve the durability and the load-bearing capacity of the composite girder by reducing the phenomenon of the concentration of stress on the concrete in the steel-concrete joint surface, thereby increasing the safety of the bridge. A steel composite girder is provided.

Description

TECHNICAL FIELD [0001] The present invention relates to a composite composite girder having improved load transfer capability at a connection portion between steel and concrete,

The present invention relates to a steel composite girder, more specifically, a steel composite girder in which a casing concrete is synthesized to a certain length on the upper side of a steel girder, and a stress concentration phenomenon caused by a bending deformation at a connection portion between the steel girder and the casing concrete To a steel composite girder with improved load transmission capability.

Generally, steel can resist effectively tensile force, but there is a problem that buckling occurs in compressive force, causing sudden collapse. Concrete can resist effectively compressive force, but is vulnerable to tensile force. There is a problem that the load-bearing capacity of the structure is rapidly reduced.

As a result, a steel composite girder having a structure that resists with a casing concrete and a structure that resists a steel is used as a structural member of a bridge.

That is, although the steel is advantageous for the structure receiving the tensile force, there is a problem that when the member is thin, the buckling occurs. However, when the member is thin, the concrete is advantageous for the structure receiving the compressive force. However, A problem arises.

Accordingly, the present applicant discloses a steel composite girder disclosed in Korean Patent Laid-Open No. 10-2016-0091465, which is supported by a casing concrete on a neutral axis on which compressive stress predominantly acts and which is supported by a neutral axis And a supporting structure supported by a steel girder in the lower part.

That is, since the abdomen portion is formed higher than the end portion of the steel girder, the casing concrete effective for supporting the compressive force is used as a compression member and a steel material effective for supporting the tensile force is used as a tensile member to secure a sufficient section. Not only can bear the shear force acting largely by the abdominal portion of the larger cross section but also the middle portion of the steel girder is formed by the abdomen of the smaller cross section to resist the small cross sectional force with a small amount of steel material usage, It is possible to maximize the economical efficiency while improving the sectional efficiency while minimizing the usage amount.

In addition, not only the effect of reducing the sectional rigidity due to the buckling caused by the use of the steel material as the compression member can be prevented in advance, but the structure can be stably maintained even if the installation of the additional reinforcement is minimized to prevent buckling.

However, as shown in Fig. 1, the steel composite girder 9 is different in the steel section cross section between the central portion 10c and the end portion 10e, and accordingly, the cross section of the casing concrete 20, The stress is repeatedly concentrated at the portion TR where the steel material and the concrete meet each other due to the deviation of the bending stiffness and the rate of temperature change due to the material difference between the steel material and the concrete, ), The concrete is damaged and it grows.

In other words, even if the damage due to stress concentration is not visually observed at the time of construction, local stress concentration occurs in the casing concrete 20 of the part TR encountered by the cyclic load due to the traffic of the vehicle at the time of public use, Causing a problem that breakage occurs. In addition, such fatigue failure has a problem in that the durability and the load bearing capacity of the bridge are reduced, posing a serious threat to the safety of the bridge.

That is, there is a need to mitigate the local stress generated in such a portion because a local stress is applied to the joint where the geometric cross section changes, the force is locally concentrated, or where the different materials are connected. Therefore, in the steel composite girder 9 in which the steel girder 10 and the casing concrete 20 are combined as described above, the stress concentrated on the casing concrete 20 at the position where the section of the steel girder 10 is cut off is alleviated Therefore, there is a great demand for improving the durability and the load-bearing capacity of bridges.

In order to solve the above-described problems, the present invention provides a composite steel girder in which the abdomen is formed at a higher end than the central portion of the steel girder and casing concrete is synthesized on the upper side of the steel girder, And a concrete composite girder having a higher durability and a higher load-bearing capacity.

 It is another object of the present invention to improve the joining ability between a steel material and a concrete at a joining portion of a steel material and a concrete, the cross-section of which is discontinuously connected.

Accordingly, it is an object of the present invention to improve load transfer performance at a joint portion between steel and concrete.

SUMMARY OF THE INVENTION The present invention has been accomplished to solve the above problems, and it is an object of the present invention to provide a semiconductor device having a first region including a first region including at least one of both ends and a second region including a central region, A lower flange formed at a lower end of the abdomen, a first upper flange formed at an upper end of the abdomen of the first region, and a second upper flange formed at an upper end of the abdomen of the second region, 1) a steel girder having an overlapping region in which an upper flange and a part of the second upper flange are arranged to overlap with each other; And a height of the upper surface of the steel girder is not more than a part of the upper side of the first region of the steel girder but is synthesized in the same manner as the height of the upper surface of the first upper flange, Concrete; The present invention also provides a composite composite girder comprising:

Wherein the abdomen extends between the first upper flange and the second upper flange of the overlap region and the abdomen extending between the first upper flange and the second upper flange is formed with a through hole So that the joining performance between the steel material and the concrete can be further enhanced.

Wherein the abdomen extends between the first upper flange and the second upper flange of the overlap region and the length of the overlap region is formed to be at least twice the difference between the first height and the second height The bonding performance of the steel-concrete can be enhanced.

Above all, the abdomen extends between the first upper flange and the second upper flange of the overlap region, and the first upper flange protrudes from the end of the abdomen toward the casing concrete, The projecting length of the upper flange is formed to protrude by a difference equal to or greater than the difference between the first height and the second height so that the joining performance of the steel-concrete can be further improved and stress concentration phenomenon in the steel- have.

In addition, a stress concentration preventing member may be additionally provided on the first upper flange which meets the casing concrete.

For example, the stress concentration preventing member may be a steel plate extended from the first upper flange toward the second upper flange, and extended to a length at least 0.5 times the difference between the first height and the second height, It can be installed in a close contact with the end.

The stress concentration preventing member may extend to an upper surface of the second upper flange.

Wherein the abdomen portion is formed by an inclined surface whose upper end connects the first upper flange of the first region and the upper surface of the second upper flange of the second region in an inclined manner, And a steel plate that slopes the upper surface of the second upper flange from the end of the flange.

Here, the stress concentration preventing member is formed of a perforated steel plate having a through hole, so that the bonding ability between the steel and the concrete can be enhanced.

The upper end of the stress concentration preventing member is equal to the width of the first upper flange and the lower end of the stress concentration preventing member is equal to the width of the second upper flange, And is formed into a shape that is formed largely and changes linearly from the upper end to the lower end, thereby reducing the stress deviation at the joint portion of the steel-concrete while reducing the amount of unnecessary steel material used.

Particularly, the stress concentration preventing member is formed of an elastic material capable of elastic deformation interposed between at least one of an end of the first upper flange of the steel girder and an end of the abdomen and the casing concrete, The stress concentration due to the stress concentration due to the bending deformation or the thermal deformation can be suppressed to a large extent by the elastic material as a result of concentrating the stress on the casing concrete of the steel-concrete joint.

Inner " and similar terms in the present description and claims are defined as directions toward the center of the girder, and " outer " and similar terms in this specification and claims are defined as directions toward the ends of the girders do.

As described above, according to the present invention, there is provided an overlapping area in which a first upper flange of a girder end and a second upper flange of a center portion are disposed so as to overlap with each other at a joint portion of a steel- It is possible to obtain an effect that stress can smoothly flow in the steel-concrete joint where the dissimilar materials are combined.

First of all, since the first upper flange of the end portion extends beyond the end of the abdomen to the upper side of the second region, the bonding force of the steel-concrete joint portion is further enhanced.

Further, the present invention is characterized in that an elastic material capable of being elastically deformed between a steel girder and a casing concrete at a joining portion of steel-concrete is interposed as a stress concentration preventing member so that a concentrated stress generated in a joining portion due to discontinuity of a cross- It is possible to obtain an advantageous effect of greatly reducing the stress acting on the casing concrete of the joint portion of steel-concrete.

 In addition, the present invention relates to a method for reducing the concentration of stress in concrete at a joint portion of steel-concrete by applying a stress concentration preventing material formed of a steel material between a steel girder and a casing concrete at a joint portion of steel- Can be obtained.

Further, the present invention provides an effect of increasing the joining force between the steel material and the concrete by forming the abutment portion of the steel material girder and the steel plate-like stress concentration preventing material in which the casing concrete is synthesized.

As described above, according to the present invention, the bonding force between steel and concrete is increased, and the phenomenon of concentration of stress on concrete from the joint surface of steel-concrete is reduced, so that the load- It is possible to obtain an advantageous effect of constructing a bridge having increased safety and improved safety.

1 is a front view showing a conventional steel composite girder,
2 is a front view showing a steel composite girder according to an embodiment of the present invention,
FIG. 3A is a cross-sectional view taken along line XX in FIG. 2,
FIG. 3B is a sectional view taken along the cutting line YY in FIG. 2,
4A is a plan view of the steel girder of FIG. 2,
Fig. 4B is a plan view showing another form of the steel girder of Fig. 2,
5 is a front view showing a steel composite girder according to another embodiment of the present invention,
FIG. 6A is an enlarged view of a portion 'A' in FIG. 2,
FIG. 6B is a perspective view of FIG. 6A,
FIG. 7A is a view showing a second embodiment of the 'A' portion of the overlapping region of FIG. 2,
FIG. 7B is a perspective view of FIG. 7A,
Fig. 7c is a view showing an 'A' portion of the steel composite girder according to another embodiment applicable to Fig. 2,
FIG. 8A is a view showing a third embodiment of the 'A' portion, which is the overlapping region of FIG. 2;
8B is a perspective view of FIG. 8A,
FIG. 9A is a view showing a fourth embodiment of the 'A' portion as the overlap region of FIG. 2,
FIG. 9B is a perspective view of FIG. 9A,
FIG. 9C is a perspective view showing a modified embodiment of FIG. 9A,
10 is a diagram showing modeling for confirming the action and effect of the present invention
11 is a longitudinal stress distribution diagram of the steel-concrete according to the modeling analysis result of FIG.

Hereinafter, a steel composite girder 100 according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail to avoid obscuring the subject matter of the present invention.

2 to 3B, the steel composite girder 100 according to an embodiment of the present invention includes a second region that is a central portion in comparison with the first region I in which the height of the abdomen portion 112 is an end portion I-shaped steel girder 110 formed at a lower portion of the steel girder 110 and casing concrete 120 synthesized at a part of the upper edge of the steel girder 110.

The steel girder 110 is formed with a first height H1 in a first region I including at least one end of both ends of the girder and a second height II including a center portion in a first region I, A lower flange 111 joined to the lower end of the abdomen 112 and extending over the entire region and a lower flange 111 formed at the upper end of the abdomen of the first region I, An upper flange 113 formed of a first upper flange 1131 and a second upper flange 1132 formed at the upper end of the abdomen of the second region II, a front end coupling member 115 protruding from the upper flange 113, And a stress concentration relieving material (114, 118) for relieving the concentration of stress at the steel-concrete joint (TR) which meets with the casing concrete (120).

6A, the first upper flange 1131 is formed at the upper end of the abdomen of the first region I whose abdomen height is the first height H1, 2 region II as shown in FIG. The overlap area DA in which the first upper flange 1131 and the second upper flange 1132 are arranged so as to overlap is formed between the first area I and the second area II as indicated by " .

The first upper flange 1131 and the second upper flange 1132 may be dimensioned to have the same widths, but according to a preferred embodiment of the present invention, the casing upper end of the second upper flange 1132 The width w1 of the first upper flange 1131 is larger than the width w2 of the second upper flange 1132 so as to reduce the amount of unnecessary steel material .

The end portion of the second upper flange 1132 is formed in the shape of an inclined end face 1132a whose width gradually decreases toward the outer end so as to alleviate the stress concentration phenomenon caused by a change in the cross section of the second upper flange 1132 . 4B, the end portion of the first flange 1131 'is also formed as an inclined end face 1131a whose width gradually decreases toward the inner end, so that the cross-sectional change of the first upper flange 1131 It is possible to mitigate the stress concentration phenomenon caused by the stress.

The length of the overlapping area DA in which the first upper flange 1131 and the second upper flange 1132 are overlapped is set to be shorter than the difference between the first height H1 and the second height H2 of the abdomen 112 (That is, a height difference (Hc) between the first upper flange 1131 and the second upper flange 1132).

That is, the overlap length L of the first upper flange 1131 and the second upper flange 1132 is smaller than twice the height deviation Hc of the first upper flange 1131 and the second upper flange 1132 The effect of smooth transfer of the stress between the different materials by the upper flanges 1131 and 1132 in which the casing concrete is superimposed by the superposed arrangement is small and stress is concentrated on the casing concrete. Which is greater than five times the height deviation Hc of the second upper flange 1132 and the second upper flange 1132, the economical efficiency is deteriorated due to an excessive amount of steel material used.

As described above, since the first upper flange 1131 and the second upper flange 1132 are overlapped with each other by a sufficient length, the effect of suppressing the concentration of stress on the casing concrete of the steel-concrete joint portion TR can be obtained.

Although the shear connector 115 shown in the drawing is shown only for the purpose of combining with the casing concrete 120, the shear connector 115 may be formed of a bottom plate concrete (not shown) in a state where the steel composite girder 100 is mounted on a lower structure such as a pier, May be formed on the upper flange 113 to protrude therefrom.

Although the first region I is illustrated at both ends of the girder in the figure, the girder may be used in a continuous bridge or in the case of manufacturing a steel composite girder having a longer length by connecting the manufactured steel composite girder 100 The first region I may be formed only at one end of the girder.

According to another embodiment of the present invention, as shown in FIG. 5, the steel girder 110 'is formed of a second upper flange (not shown) formed in a second region II of a lower second height H2, The first region 1132 'may be formed not only in the second region II but also in the entire region of the girder by extending to the first region I.

The steel composite girder fabricated as described above can be applied to a simple bridge, a continuous bridge, a ramen bridge, etc. When applied to a continuous bridge girder bridge, the second region (II) is a region where the momentum is applied by a fixed load The first region I is defined as a region where the momentum acts due to the fixed load, and the overlap region DA is preferably disposed so as to include the boundary where the momentum and the momentum act.

Hereinafter, various types of steel girders can be applied as described above. However, for the sake of convenience, the structure of the steel girder 110 shown in FIG. 2 will be mainly described.

The casing concrete 120 is synthesized on the steel girder 110 in such a manner as to enclose the upper flange 113 of the steel girder 110 and the inner end 112e of the abdomen portion 112.

The present invention includes a construction in which the casing concrete 120 is synthesized on the upper surface of the first upper flange 1131 of the first region I but according to the preferred embodiment of the present invention, The casing concrete 120 is synthesized only on the upper side of the second region II including the first region I and the casing concrete 120 is not synthesized on the first region I of the end portion. Which is preferable in terms of formation.

 That is, the casing concrete 120 is formed so as to surround the inner end 112e of the abdomen of the first region I of the steel girder 110 but is not synthesized on the upper side of the first upper flange 1131, The height of the upper surface of the casing concrete 120 is equal to the height of the upper surface of the first upper flange 1131.

The outer end 120e of the casing concrete 120 is located on the outer side (closer to the end of the girder) than the inner end 112e of the abdomen portion 112 and the first upper flange 1131 and the second upper flange The inner end 112e of the abdomen 112 exposed between the upper and lower ends 1112a and 1132 is concealed by the casing concrete 120. [ The outer end 120e of the casing concrete 120 may form a vertical surface or may be formed as an inclined surface as shown in the figure so that the stress transmission to the steel material can be more smoothly transmitted to the steel material in response to the flexural deformation.

In the steel composite girder 100 constructed as described above, since the cross section of the steel material is not uniform over the entire girder, a phenomenon that stress is concentrated on the casing concrete 120 at the steel-concrete joint portion TR, And the load is not smoothly transmitted between the steel and the concrete.

6A and 6B, a stress concentration relieving material 114 in the form of a steel plate extending from the end of the first upper flange 1131 to the upper surface of the second upper flange 1132 is formed can do. Here, the stress concentration relieving member is formed in such a shape that a surface is coupled to the abdomen end 112e formed between the first upper flange 1131 and the second upper flange 1132, and the same material as the material of the steel girder 110 As shown in Fig.

Accordingly, when stress concentration occurs in the steel-concrete joint portion TR due to the temperature change due to the self weight of the steel composite girder 100, external force acting on the girder, seasonal change, etc., The stress is transferred to the casing concrete 120 through the narrow area of the upper end of the upper flange 1131 and the abdomen end 112e so that the stress is not concentrated and the stress is transferred to the increased pressure area between the steel and the concrete, It is possible to alleviate the phenomenon that stress concentrates on the concrete of the joint portion TR.

6B, the stress concentration relieving member 114 in the form of a steel plate has the same upper end as the width W1 of the first upper flange 1131 and the lower end of the stress concentration relieving member 114 having the width of the second upper flange 1132 (W2), and the width thereof is continuously decreased. Therefore, the cross section of the stress concentration mitigating member 114 is not abruptly changed or cut off, and the load transfer efficiency can be further increased. For example, the stress concentration relieving member 114 may be formed in a trapezoidal shape in which the width thereof is linearly decreasing continuously.

Here, as shown in FIGS. 6A and 6B, the stress concentration relieving member 114 may be formed by connecting the first upper flange 1131 and the second upper flange 1132 vertically. The abdomen end 112e located between the first upper flange 1131 and the second upper flange 1132 to which the plate surface of the stress concentration relieving member 114 is coupled is formed in a vertical shape.

7A and 7B, according to the second embodiment of the present invention, the stress concentration relieving member 114 'is formed by connecting the first upper flange 1131 and the second upper flange 1132 in an inclined manner . To this end, the abdominal end 112e 'located between the first upper flange 1131 and the second upper flange 1132, to which the plate surface of the stress concentration relieving member 114' is coupled, is formed with an inclined slope.

The end portion of the abdomen located between the first upper flange 1131 and the second upper flange 1132 is formed with the front end hole 112a and the stress concentration relieving member 114 ' May be formed as a perforated steel plate. Accordingly, when the casing concrete is poured, the unhardened concrete can penetrate all the way through the front end holes 112a and the through holes 114a, and by the concrete synthesized in the front end holes 112a and the through holes 114a , The coupling force between the steel girder 110 and the casing concrete 120 in the overlapping area DA can be increased.

The through holes 112a and 114a are formed in such a manner as to penetrate the reinforcing bars supporting the coupling between the steel girder 110 and the casing concrete 120 so that the coupling strength between the steel girder 110 and the casing concrete 120 Can be further increased.

The abdominal front end hole 112a and the through hole 114a of the stress concentration relieving member 114 'may be applied to the structure of the first embodiment described above and other embodiments described later.

8A and 8B, in the third embodiment of the present invention, the stress concentration preventing member 114 in the form of a steel plate is disposed between the first upper flange 1131 and the second upper flange 1132 The first upper flange 1131 may be further extended from the abdominal end 112e by a length indicated by 'S'. Accordingly, the stress concentration preventing member 114 may be configured to extend from the position spaced apart from the inner end of the first upper flange 1131 by the distance S to the second upper flange 1132.

Thus, the first upper flange 1131 extends further inward than the inner end 112e of the abdomen 112, so that the overlap length L (L) is maintained regardless of the position of the inner end 112e of the abdomen 112 ) Can be formed longer than that of the concrete material, whereby the effect of smoothly transferring the stress between the concrete and the steel material, which are different materials, can be obtained.

9A and 9B, according to the fourth embodiment of the present invention, the stress concentration relieving member 118 has an inner end of the first upper flange 1131 and an inner end of the abdomen 112, The elastic member 112e may be formed of an elastic material capable of elastic deformation.

That is, the stress concentration relieving member 118 formed of an elastic material is provided so as to be interposed at a position where the steel material and concrete, which are different materials, are in contact with each other. As shown in the figure, the first upper flange 1131 Or may be provided only at the inner end of the first upper flange 1131 and a part of the inner end 112e of the abdomen.

The elastic material may be formed of various materials that accommodate the difference in displacement between the concrete and the steel. For example, the elastic material may be rubber, silicone, or urethane.

The thickness (t) of the elastic material is determined by the strain caused by the stress concentration occurring at the joint portion between the steel and concrete according to the amount of flexural deformation of the steel composite girder 100 and the difference in thermal strain between the steel and concrete And the longer the distance of the steel composite girder 100 is, the thicker it is determined. As shown in the drawing, the stress concentration relieving member 118 provided on one girder may be formed to have a uniform thickness as a whole, but at a position where the strain due to the stress concentration of the steel and concrete is large, the strain of the steel and concrete It may be formed thicker than a small position.

On the other hand, the stress concentration relieving material 118 formed of an elastic material may be applied together with the stress concentration relieving material 114 formed of the steel sheet shown in Figs. 6A to 8B. That is, the load transfer of the steel material and the concrete is transmitted by the stress concentrating damping material 114 in the form of a steel plate to a wider pressure area, and at the same time, the elastic material A plate shape 118 may be provided so that a concentrated stress (strain) between the steel material and the concrete can be accommodated by the elastic material.

As a result, in the process of transferring the load from the high-strength steel to the low-strength concrete, the stress concentration relieving material 118 formed of the elastic material capable of being elastically deformed receives the local deformation due to the concentrated stress between the steel material and the concrete , The concentration of stress on the concrete at the joint surface (TR) of the steel-concrete can be significantly lowered, so that a favorable effect of reliably preventing the compression fracture of the concrete at the joint surface of the steel-concrete can be obtained.

In order to verify the effect of dispersing the stress acting on the concrete in the steel-concrete joint part TR as described above, the applicant of the present invention performed the following numerical analysis. 10A is a model of a configuration in which the first upper flange 1031 and the second upper flange 1032 are overlapped, and the configuration shown in FIG. 10B is a configuration in which the first upper flange 1031 and the second upper flange 1032 overlap each other, 6A and 6B) of the first embodiment in which the upper flange 1032 is joined to the inner end 112e of the abdomen with a stress concentration preventing member 114 in the form of a steel plate. The structure of the fourth embodiment (FIGS. 9A and 9B) in which the stress concentration preventing member 118 in the form of an elastic material is interposed between the inner end of the first upper flange 1031 and the inner end 112e of the abdomen 112 is modeled It is.

Specific resource and load conditions for the analysis of the modeling configuration shown in FIGS. 10A to 10C are as follows.

- Span of the girder: 29.8 (m)

- Deformation of girder: 0.960 (m)

- Thickness of bottom plate: 0.240 (m)

- Specification of steel girder: 1st upper flange: 700 * 20 (mm)

  Second upper flange: 300 * 20 (mm)

Abdomen: 10 * 940 (mm)

Lower flange: 700 * 30 (mm)

Steel type: SM520 (elastic modulus Es = 205,000 MPa)

- Bottom plate concrete: design compressive strength fck = 30MPa, elastic modulus Ec = 27,537MPa,

- casing concrete: design compressive strength fck = 80 MPa, elastic modulus Ec = 37,519 MPa

- Girder weight at end: 19.6 kN / m, girder weight at center: 22.3 kN / m

- Bottom plate concrete load: 9.8 kN / m (all the same)

- Live load: DB24, calculated by maximum lateral load distribution analysis (38.4kN - 153.5kN - 153.5kN)

- boundary condition: simple support

As a result of analyzing the stress distribution under the same conditions as described above, the highest stress value appeared on the upper surface of the steel-concrete joint (TR in FIG. 6A), and the stress distribution in the vertical section of the concrete in the steel- 11a to 11c. Here, the stress distribution diagram for modeling in FIG. 10A is shown in FIG. 11A, the stress distribution diagram for modeling in FIG. 10B is shown in FIG. 11B, and the stress distribution diagram for modeling in FIG.

As a result of the analysis, the maximum generated stress of the casing concrete 120 joined to the end of the first upper flange 1131 of the steel girder is the same as that of the first upper flange 1131 and the second upper flange 1132 The value of -6.334 MPa (FIG. 11A), and the value of -5.397 MPa (FIG. 11B) for the configuration of the first embodiment in which the stress concentration preventing member 114 in the form of a trapezoidal steel plate was provided. 10B) of the steel plate type stress concentration preventing member 114 has a stress relaxation effect of about 19% as compared with the structure in which the upper flanges 1131 and 1132 are superposed (FIG. 10A) Respectively.

In the structure of the fourth embodiment in which the stress concentration preventing member 114 in the form of an elastic material was provided, it was -4.241 MPa (FIG. 11C). 10C), a stress relaxation effect of about 36% as compared with the structure in which the upper flanges 1131 and 1132 are superimposed (FIG. 10A) .

As described above, the present invention has the overlap region DA in which the first upper flange 1131 at the center portion of the girder and the second upper flange 1132 at the end portion are arranged so as to overlap with each other at the joint portion TR of the steel- The stress concentration preventing members 114 and 118 are additionally provided in this structure so that the stress-preventing members 114 and 118 can be formed in the steel-concrete joint portion, It is possible to obtain an effect of relieving the stress concentration phenomenon largely acting on the upper surface of the casing concrete of FIG.

In addition, the present invention is also applicable to a structure in which the abdomen portion 112 of the steel girder 110 in which the casing concrete 120 is synthesized and the stress concentration preventing member 114 in the form of a steel plate are formed into a pierced cross section in which the through holes 112a and 114a are formed The reinforcement force of the steel material 110, which is a different material, and the casing concrete 120 can be increased by placing the reinforcing bars through the through holes 112a and 114a.

Accordingly, the present invention increases the bonding force between steel and concrete, reduces the concentration of stress on the concrete in the steel-concrete joint surface, increases the durability and the load-bearing capacity as the load- So that a bridge having improved safety can be constructed.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention.

100: Steel composite girder 110: Steel girder
111: lower flange 112: abdomen
112e, 112e ': the inner end of the abdomen
113: upper flange 1131: first upper flange
1132: second upper flange 114: steel plate type stress concentration preventing material
115: Shear connector 118: Stress concentration preventing material
120: casing concrete TR: steel-concrete joint
DA: overlap area H1: first height
H2: second height
120, 120 ': casing concrete 199: bottom plate concrete

Claims (13)

And a lower flange formed at a lower end of the abdomen, and a second flange formed at a lower end of the abdomen, wherein the abdomen is formed at a first height in a first region including at least one of both ends, A first upper flange formed at an upper end of the abdomen of the first region and a second upper flange formed at an upper end of the abdomen of the second region, wherein the first upper flange and a portion of the second upper flange are arranged A steel girder provided with an overlapped region;
A casing concrete synthesized on the upper side of the second region of the steel girder;
And an elastic material capable of elastic deformation interposed between at least one of an end of the first upper flange of the steel girder and an end of the abdomen and the casing concrete;
And a steel composite girder.
The method according to claim 1,
Wherein the casing concrete is synthesized such that the height of the upper surface is equal to the height of the upper surface of the first upper flange without being synthesized over a part of the upper side of the first region of the steel girder.
The method according to claim 1,
Wherein the abdomen extends between the first upper flange and the second upper flange of the overlap region and the abdomen extending between the first upper flange and the second upper flange has a piercing cross section Wherein the steel composite girder is made of steel.
The method according to claim 1,
Wherein the abdomen extends between the first upper flange and the second upper flange of the overlap region and the length of the overlap region is at least twice the difference between the first height and the second height Steel composite girders.
The method according to claim 1,
Wherein the abdomen extends between the first upper flange and the second upper flange of the overlap region and the first upper flange projects from the end of the abdomen toward the casing concrete, And the protruding length is protruded by at least the difference between the first height and the second height.
The method according to claim 1,
And the second upper flange extends to an end of the steel girder.
The method according to claim 1,
Wherein the stress concentration preventing member further comprises a steel plate extending from the first upper flange toward the second upper flange and extending at a length of at least 0.5 times the difference between the first height and the second height, Further comprising a reinforcing member provided so as to be in close contact with the end of the abdomen.
8. The method of claim 7,
And the steel plate extends to the upper surface of the second upper flange.
8. The method of claim 7,
Wherein the abdomen is formed by an inclined surface whose upper end slants the upper end of the first upper flange of the first region and the upper surface of the second upper flange of the second region,
And the steel plate connects the upper surface of the second upper flange in an inclined manner from an end of the first upper flange along the inclined surface.
8. The method of claim 7,
Wherein the steel plate is a perforated steel plate having a through hole.
9. The method of claim 8,
Wherein the upper end of the steel plate is equal to the width of the first upper flange and the lower end of the steel plate is equal to the width of the second upper flange, Of the steel composite girder (1).
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