JP6558185B2 - Girder structure - Google Patents

Description

  The present invention relates to a girder structure, and more particularly to a girder structure to which a bending load is applied.

  Conventionally, girders formed of metal materials such as steel are used for structures such as ship superstructures, bridges, transporters, and marine structures. Patent Document 1 describes the use of steel girders for bridges, offshore structures and the like.

JP2013-189845A

  By the way, in recent years, as structures such as bridges and offshore structures increase in size, it is required to reduce the weight of the girder structure in order to improve transportation and workability.

  Accordingly, an object of the present invention is to provide a girder structure that can be further reduced in weight.

  The girder structure according to the present invention is a girder structure to which a bending load is applied. The girder structure is bonded to a metal member formed of a metal material and the metal member. A composite material member formed of a reinforced resin composite material, and in the metal member and the composite material member, a member having a larger longitudinal elastic modulus is disposed on the compression side, and a member having a smaller longitudinal elastic modulus Is arranged on the tension side.

  In the girder structure according to the present invention, the amount of deviation between the position of the joint between the metal member and the composite material member and the position of the neutral shaft is a height obtained by combining the metal member and the composite material member. It is characterized by being 1/4 or less.

  In the girder structure according to the present invention, the position of the joint portion and the position of the neutral shaft are the same.

  According to the above configuration, the girder structure can be further reduced in weight by configuring a part of the girder structure with the composite material member formed of the fiber reinforced resin composite material.

In embodiment of this invention, it is a perspective view which shows the structure of a girder structure. In embodiment of this invention, it is a figure which shows a girder structure when a bending load is loaded. In embodiment of this invention, it is sectional drawing which shows the structure of a girder structure. In embodiment of this invention, it is sectional drawing which shows the girder structure model of Example 1. FIG. In embodiment of this invention, it is sectional drawing which shows the girder structure model of Example 2. FIG. In embodiment of this invention, it is a figure which shows the loading method of the bending load to the girder structure model of Example 1,2. In embodiment of this invention, it is a graph which shows the analysis result of the girder structure model of Example 1. In embodiment of this invention, it is a graph which shows the analysis result of the girder structure model of Example 2.

  Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a perspective view showing the configuration of the girder structure 10.

  The girder structure 10 includes a metal member 12 formed of a metal material, and a composite material member 14 which is bonded to the metal member 12 and has a longitudinal elastic modulus different from that of the metal member 12 and formed of a fiber reinforced resin composite material. I have. The girder structure 10 is composed of, for example, I digits as shown in FIG. The girder structure 10 is used for structures such as ship superstructures, bridges, transporters, and marine structures, and is subjected to bending loads.

  The metal member 12 has a flange 12a and a web 12b formed integrally with the flange 12a. The metal member 12 is formed of a metal material such as a steel material (carbon steel, stainless steel, etc.), an aluminum material (aluminum alloy, etc.), a titanium material (titanium alloy, etc.), a nickel material (nickel alloy, etc.), for example. . The metal member 12 can be formed by machining or welding of a general metal material. The longitudinal elastic modulus of the metal member 12 can be adjusted by the type of metal material used, heat treatment conditions, and the like.

  The composite material member 14 includes a flange 14a and a web 14b formed integrally with the flange 14a. The composite material member 14 is joined to the metal member 12, has a longitudinal elastic coefficient different from that of the metal member 12, and is formed of a fiber reinforced resin composite material (FRP). Since the fiber reinforced resin composite material has a specific gravity smaller than that of the metal material and a higher specific strength, the girder structure 10 can be reduced in weight.

  The fiber reinforced resin composite material is composed of a reinforced fiber and a matrix resin. For example, carbon fibers, organic fibers such as aramid fibers, glass fibers, and the like can be used as the reinforcing fibers. As the matrix resin, for example, a thermosetting resin or a thermoplastic resin such as an epoxy resin, a polyimide resin, a polyester resin, or a phenol resin can be used.

  The composite material member 14 can be formed by, for example, a general fiber-reinforced resin composite material forming method. Such molding methods include, for example, a method in which a prepreg is laminated and then cured by resin curing with an autoclave or the like, or a preform formed from a woven fabric is placed in a mold, and the preform is impregnated with resin and cured. A (Resin Transfer Molding) method or the like can be applied.

  The longitudinal elastic modulus of the composite material member 14 can be adjusted, for example, by changing the reinforcing fiber, fiber content, fiber orientation, and the like of the fiber reinforced resin composite material. In order to increase the longitudinal elastic modulus of the composite material member 14, for example, reinforcing fibers made of high elastic modulus fibers (for example, high elastic modulus type carbon fibers) may be used, or the fiber content may be increased. Moreover, when making the longitudinal elastic modulus of the composite material member 14 small, it consists of medium elastic modulus fiber (for example, medium elastic modulus type carbon fiber) and low elastic modulus fiber (for example, low elastic modulus type carbon fiber), for example. Reinforcing fibers may be used or the fiber content may be reduced.

  The joint portion 16 between the metal member 12 and the composite material member 14 can be formed by joining with an adhesive made of a synthetic resin such as an epoxy resin, for example. When a bending load is applied to the girder structure 10, a shearing stress is generated on the joint surface between the metal member 12 and the composite material member 14. For this reason, it is good to use what has the adhesive strength which can endure this shear stress as an adhesive agent which joins the metal member 12 and the composite material member 14. FIG.

  In the metal member 12 and the composite material member 14, a member having a larger longitudinal elastic modulus is disposed on the compression side, and a member having a smaller longitudinal elastic modulus is disposed on the tension side. As is clear from Euler's buckling load (the buckling load is proportional to the longitudinal elastic modulus of the member), etc., a member with a large longitudinal elastic modulus has better buckling resistance than a member with a small longitudinal elastic modulus. Yes. In addition, a member having a small longitudinal elastic modulus is easier to extend than a member having a large longitudinal elastic modulus, and is excellent in tensile properties. For these reasons, in the metal member 12 and the composite material member 14, a member having a larger longitudinal elastic modulus is disposed on the compression side, and a member having a smaller longitudinal elastic modulus is disposed on the tension side. The local buckling failure can be suppressed on the compression side of the body 10, and the tensile failure can be suppressed on the tension side of the girder structure 10.

  FIG. 2 is a view showing the girder structure 10 to which a bending load is applied. FIG. 2A is a view showing a case where the longitudinal elastic modulus of the metal member 12 is larger than the longitudinal elastic modulus of the composite material member 14. FIG. 2B is a diagram illustrating a case where the longitudinal elastic modulus of the metal member 12 is smaller than the longitudinal elastic modulus of the composite material member 14.

  As shown in FIG. 2A, when the longitudinal elastic modulus of the metal member 12 is larger than the longitudinal elastic modulus of the composite material member 14, the metal member 12 is disposed on the compression side, and the composite material member 14 is on the tension side. Placed in. When the longitudinal elastic modulus of the metal member 12 is greater than the longitudinal elastic modulus of the composite material member 14, the metal member 12 has better buckling resistance than the composite material member 14, and the composite material member 14 The tensile properties are superior to the member 12. For this reason, the metal member 12 is arranged on the compression side of the girder structure 10 to suppress local buckling failure, and the composite material member 14 is arranged on the tension side of the girder structure 10 to suppress tensile fracture. it can.

  As shown in FIG. 2B, when the longitudinal elastic modulus of the metal member 12 is smaller than the longitudinal elastic modulus of the composite material member 14, the metal member 12 is disposed on the tension side, and the composite material member 14 is on the compression side. Placed in. When the longitudinal elastic modulus of the metal member 12 is smaller than the longitudinal elastic modulus of the composite material member 14, the metal member 12 has superior tensile characteristics than the composite material member 14, and the composite material member 14 has the metal member 12. Better resistance to buckling than Therefore, the composite material member 14 is arranged on the compression side of the girder structure 10 to suppress local buckling failure, and the metal member 12 is arranged on the tension side of the girder structure 10 to suppress tensile fracture. it can.

  Even if the amount of deviation between the position of the joint 16 between the metal member 12 and the composite material member 14 and the position of the neutral shaft is ¼ or less of the total height of the metal member 12 and the composite material member 14. The position of the joint portion 16 and the position of the neutral shaft may be the same (the amount of deviation is zero). About the shift | offset | difference of the position of the junction part 16 and the position of a neutral axis | shaft, the junction part 16 may be shifted | deviated to the tension | tensile_strength side from the neutral axis | shaft, and may be shifted | deviated from the neutral axis | shaft to the compression side.

FIG. 3 is a cross-sectional view showing the configuration of the girder structure 10. H _Me represents the height of the metal member 12, and H _FRP represents the height of the composite material member 14. First, the neutral axis of the girder structure 10 will be described. The neutral axis is an axis where the vertical stress acting on the cross section of the girder structure 10 becomes zero when a bending load is applied to the girder structure 10.

When the position of the joint portion 16 between the metal member 12 and the composite material member 14 is the same as the position of the neutral axis, the cross-sectional area of the metal member 12 is A _Me , the longitudinal elastic modulus of the metal member 12 is E _Me , and the metal member 12, the distance from the cross-sectional center of gravity position A to the neutral axis is L _Me , the cross-sectional area of the composite material member 14 is A _FRP , the longitudinal elastic modulus of the composite material member 14 is E _FRP , and the cross-section center of gravity position B of the composite material member 14 is When the distance to the vertical axis is L _FRP , there is a relationship shown in Equation 1.

  When the position of the joint portion 16 is the same as the position of the neutral axis, either the tensile stress or the compressive stress acts on the metal member 12 and the composite material member 14. When the metal member 12 has a larger longitudinal elastic modulus than the composite material member 14, the metal member 12 is arranged on the compression side from the neutral shaft, and the composite material member 14 is arranged on the tension side from the neutral shaft, the metal member 12 Compressive stress acts on the composite material member 14 and tensile stress acts on the composite material member 14. In this case, the tensile stress acting on the metal member 12 and the compressive stress acting on the composite material member 14 are substantially zero.

  Further, when the metal member 12 has a smaller longitudinal elastic modulus than the composite material member 14, the metal member 12 is arranged on the tension side from the neutral shaft, and the composite material member 14 is arranged on the compression side from the neutral shaft, the metal member A tensile stress acts on 12 and a compressive stress acts on the composite material member 14. In this case, the compressive stress acting on the metal member 12 and the tensile stress acting on the composite material member 14 are substantially zero.

  In this way, compressive stress acts on a member with a higher longitudinal elastic modulus and excellent buckling resistance, and tensile stress acts on a member with a smaller longitudinal elastic modulus and excellent tensile properties, thereby causing longitudinal elasticity. The tensile stress acting on the member having the larger modulus and the compressive stress acting on the member having the smaller longitudinal elastic modulus are substantially zero. For this reason, the girder structure 10 is rationally configured based on the longitudinal elastic modulus of the metal member 12 and the composite material member 14, and the metal member 12 and the composite material in the girder structure 10 loaded with a bending load. It becomes possible to make the member 14 function effectively.

  When the position of the joint 16 and the position of the neutral axis are shifted, both tensile stress and compressive stress act on either the metal member 12 or the composite material member 14. For example, the joining portion 16 is displaced from the neutral axis to the tension side, the metal member 12 has a larger longitudinal elastic modulus than the composite material member 14, the metal member 12 is disposed on the compression side from the joining portion 16, and the composite material member 14 is When arranged on the tension side from the joint 16, both the compressive stress and the tensile stress act on the metal member 12, and the tensile stress acts on the composite material member 14.

When the amount of deviation between the position of the joint portion 16 and the position of the neutral shaft is equal to or less than ¼ of the combined height of the metal member 12 and the composite material member 14 (H _Me + H _FRP ) 16 is located in the vicinity of the neutral axis. The vertical strain of the girder structure 10 when a bending load is applied becomes substantially zero at the position of the neutral axis, and increases as the distance from the neutral axis increases toward the outer edge. When the joint 16 is located near the neutral axis, the tensile strain of the metal member 12 is reduced. For this reason, the tensile stress acting on the metal member 12 having the smaller longitudinal elastic modulus and the tensile property acting on the metal member 12 having the smaller longitudinal elastic modulus acts on the girder structure 10. It bears most of the tensile stress. Thereby, in the girder structure 10 to which the bending load is applied, the metal member 12 and the composite material member 14 can function effectively.

On the other hand, when the amount of deviation between the position of the joint 16 and the position of the neutral shaft is larger than ¼ of the combined height of the metal member 12 and the composite material member 14 (H _Me + H _FRP ). The joint 16 is not located in the vicinity of the neutral axis but is located away from the neutral axis. For this reason, the tensile strain of the metal member 12 becomes relatively large, and the tensile stress acting on the metal member 12 also becomes relatively large. In this case, the tensile stress borne by the metal member 12 that is inferior in tensile properties with the larger longitudinal elastic modulus is increased, and the tensile stress borne by the composite material member 14 that is superior in tensile properties with the smaller longitudinal elastic modulus is decreased. Become. Thereby, in the girder structure 10 to which a bending load is applied, the burden on the metal member 12 is increased and the composite material member 14 is not fully utilized, so that the metal member 12 and the composite material member 14 function effectively. Becomes difficult.

In this way, the amount of deviation between the position of the joint 16 between the metal member 12 and the composite material member 14 and the position of the neutral shaft is set to the height (H _Me + H _FRP ) of the metal member 12 and the composite material member 14. ) Or less, the metal member 12 and the composite material member 14 can function effectively in the girder structure 10 loaded with a bending load.

  The girder structure 10 may be composed of I-digits, box girder, or the like. Further, the cross-sectional shape of the girder structure 10 is not limited to a rectangular shape, but may be another polygonal shape, a circular shape, or the like.

  According to the girder structure having the above-described configuration, the girder structure includes a metal member and a composite material member joined to the metal member. By comprising the composite material member formed of the fiber reinforced resin composite material, it is possible to reduce the weight as compared with the metal girder structure. Moreover, according to the girder structure having the above configuration, since the metal member is provided, it can be joined to another structure by welding or the like.

  According to the girder structure having the above configuration, in the metal member and the composite material member, the member having the larger longitudinal elastic modulus is disposed on the compression side, and the member having the smaller longitudinal elastic modulus is disposed on the tension side. The buckling resistance is improved on the compression side of the girder structure, the tensile characteristics are improved on the tension side, and the breakage of the girder structure when a bending load is applied can be suppressed.

  According to the girder structure configured as described above, the amount of deviation between the position of the joint between the metal member and the composite material member and the position of the neutral shaft is ¼ of the combined height of the metal member and the composite material member. By setting it as the following, it becomes possible to make a metal member and a composite material member function effectively in the girder structure to which the bending load was loaded.

Structural analysis was performed on the girder structure under bending load. First, an analysis model of a girder structure will be described. FIG. 4 is a cross-sectional view showing the girder structure model 20 of the first embodiment. For the girder structure model 20 of Example 1, an I-digit was used. Regarding the dimensions of the girder structure model 20, the length was 1200 mm, the width was 80 mm, and the height was 100 mm. The girder structure model 20 includes a steel member 22 formed of mild steel and a CFRP member 24 formed of a carbon fiber reinforced resin composite material (CFRP). Table 1 shows the material constant of each member. It should be noted that E _x and E _y of the CFRP member 24 represent the longitudinal elastic modulus in the in-plane direction, and Ez represents the longitudinal elastic modulus in the out-of-plane direction (thickness direction). Further, G _xy , G _xz , and G _yz of the CFRP member 24 represent shear elastic modulus (lateral elastic modulus).

  In the girder structure model 20, the steel member 22 has a greater longitudinal elastic modulus than the CFRP member 24, so that the steel member 22 is disposed on the compression side and the CFRP member 24 is disposed on the tension side. Regarding the steel member 22, the width was 80mm, the height was 15mm, the thickness of the flange 22a was 6mm, and the thickness of the web 22b was 4.5mm. Regarding the CFRP member 24, the width was 80 mm, the height was 85 mm, the thickness of the flange 24a was 4 mm, and the thickness of the web 24b was 4.5 mm. The position of the joint portion 26 between the steel member 22 and the CFRP member 24 is the same as the position of the neutral shaft.

  Next, an analysis model of the girder structure according to the second embodiment will be described. FIG. 5 is a cross-sectional view showing the girder structure model 30 of the second embodiment. The girder structure model 30 of the second embodiment is different from the girder structure model 20 of the first embodiment in the height of the steel member 32 and the CFRP member 34 and the position of the joint 36. Same as above. In the girder structure model 30 of the second embodiment, the height of the steel member 32 is 50 mm, the height of the CFRP member 34 is 50 mm, and the position of the joint 36 between the steel member 32 and the CFRP member 34 is pulled from the neutral shaft. The position was shifted 32 mm to the side. The position of the joint portion 36 between the steel member 32 and the CFRP member 34 is from 25 mm where the amount of deviation from the position of the neutral shaft is 1/4 of the combined height (100 mm) of the steel member 32 and the CFRP member 34. I tried to get bigger.

  FIG. 6 is a diagram illustrating a method of applying a bending load to the girder structure models 20 and 30 according to the first and second embodiments. The bending load applied to the girder structure models 20 and 30 of Examples 1 and 2 was four-point bending with a concentrated load. The structural analysis by the finite element method (FEM) was performed, and the vertical strain distribution in the axial direction and the vertical stress distribution in the axial direction in the girder structure models 20 and 30 of Examples 1 and 2 were obtained.

  7 is a graph showing an analysis result of the girder structure model 20 of Example 1, FIG. 7A is a graph showing a vertical strain distribution, and FIG. 7B is a graph showing a vertical stress distribution. It is a graph. In the graph of FIG. 7A, the horizontal strain is taken as the vertical strain, the vertical axis is taken as the position in the height direction of the girder structure model 20, and the vertical strain for each position in the height direction of the girder structure model 20 is taken. It is indicated by a white circle. In the graph of FIG. 7 (b), the vertical stress is taken on the horizontal axis, the position in the height direction of the girder structure model 20 is taken on the vertical axis, and the vertical stress for each position in the height direction of the girder structure model 20 is taken. It is indicated by a white circle. Further, regarding the position in the height direction of the girder structure model 20, the outer edge of the CFRP member 24 (outer surface of the flange 24a) is 0 mm, and the outer edge of the steel member 22 (outer surface of the flange 22a) is 100 mm. In the normal strain and the normal stress, positive represents the tension side and negative represents the compression side.

  In the girder structure model 20 of Example 1, the vertical strain and the normal stress became zero at the position of the joint portion 26 between the steel member 22 and the CFRP member 24. A compressive stress acts on the steel member 22 having a larger longitudinal elastic modulus, a tensile stress acts on the CFRP member 24 having a smaller longitudinal elastic modulus, and a tensile stress acting on the steel member 22 and the CFRP member 24. The acting compressive stress was substantially zero. In the steel member 22 and the CFRP member 24, the stress acting on the outer edge of each member became the maximum stress. Further, the magnitude of the edge stress acting on the steel member 22 and the magnitude of the edge stress acting on the CFRP member 24 are substantially the same. Thus, in the girder structure model 20 of Example 1, the steel member 22 and the CFRP member 24 were able to function effectively in the girder structure model 20 to which the bending load was applied.

  FIG. 8 is a graph showing an analysis result of the girder structure model 30 of Example 2, FIG. 8A is a graph showing a vertical strain distribution, and FIG. 8B is a graph showing a vertical stress distribution. It is a graph. In the graph of FIG. 8A, the horizontal axis represents vertical strain, the vertical axis represents the position in the height direction of the girder structure model 30, and the vertical strain for each position in the height direction of the girder structure model 30. It is indicated by a white circle. In the graph of FIG. 8B, the horizontal stress is taken as the vertical stress, the vertical axis is taken as the position in the height direction of the girder structure model 30, and the vertical stress for each position in the height direction of the girder structure model 30 is taken. It is indicated by a white circle. In addition, regarding the position in the height direction of the girder structure model 30, the outer edge of the CFRP member 34 (the outer surface of the flange 34a) is 0 mm, and the outer edge of the steel member 32 (the outer surface of the flange 32a) is 100 mm. In the normal strain and the normal stress, positive represents the tension side and negative represents the compression side.

  In the girder structure model 30 of Example 2, compressive stress and tensile stress acted on the steel member 32, and tensile stress acted on the CFRP member 34. The tensile stress acting on the steel member 32 was the largest at the position of the joint portion 36 and was larger than the edge stress that is the maximum tensile stress of the CFRP member 34. In the girder structure model 30 of the second embodiment, the amount of deviation between the position of the joint portion 36 and the position of the neutral shaft is larger than ¼ of the combined height (100 mm) of the steel member 32 and the CFRP member 34. The joint 36 is not located in the vicinity of the neutral axis but is located away from the neutral axis. For this reason, the tensile strain of the steel member 32 became relatively large, and the tensile stress acting on the steel member 32 also became relatively large. As a result, the tensile stress borne by the steel member 32 having inferior tensile properties with the larger longitudinal elastic modulus was increased, and the tensile stress borne by the CFRP member 34 having superior tensile properties with the smaller longitudinal elastic modulus was decreased. As a result, in the girder structure model 30 of the second embodiment in which a bending load is applied, the burden on the steel member 32 becomes larger and the CFRP member 34 is fully utilized than in the girder structure model 20 of the first embodiment. It was found that the steel member 32 and the CFRP member 34 are not functioning effectively.

10 Girder Structure 12 Metal Member 14 Composite Material Member 16 Joint

Claims (2)

A girder structure to which a bending load is applied,
A metal member formed of a metal material;
A composite material member that is joined to the metal member, has a longitudinal elastic modulus different from that of the metal member, and is formed of a fiber reinforced resin composite material,
In the metal member and the composite material member, a member having a larger longitudinal elastic modulus is disposed on the compression side, and a member having a smaller longitudinal elastic modulus is disposed on the tension side ,
The amount of deviation between the position of the joint between the metal member and the composite material member and the position of the neutral shaft is ¼ or less of the total height of the metal member and the composite material member. A digit structure. The girder structure according to claim 1 ,
The position of the said junction part and the position of a neutral axis are the same, The girder structure characterized by the above-mentioned.

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