WO2022042491A1

WO2022042491A1 - Metal beam having asymmetrical section and having damage warning function

Info

Publication number: WO2022042491A1
Application number: PCT/CN2021/114100
Authority: WO
Inventors: 赖政兴
Original assignee: 赖政兴
Priority date: 2020-08-25
Filing date: 2021-08-23
Publication date: 2022-03-03
Also published as: GB202205379D0; MX2023002174A; EP4063580A4; IL300073A; GB2613910A; KR20230052299A; JP2022549391A; CN114108944B; EP4063580A1; US20230145105A1; CA3157684A1; AU2021329983A1; CN114108944A

Abstract

The present invention provides a metal beam having an asymmetrical section and having a damage warning function. The metal beam comprises a body. A sectional shape of a body section has a neutral axis, and has a pressure region and a tension region which are present when subjected to a pure bending moment load. Within an elastic range, each point of the body has a linear relationship with the neutral axis. Two sides of the sectional shape of the body section are asymmetrical with respect to the neutral axis. At a position of the body subjected to the maximum bending moment, a section modulus of the pressure region of the body section is greater than a section modulus of the tension region of the body section. In the body section, after the pressure region yields as a result of stress acting on the pressure region reaching the elastic limit, but before the pressure region deforms plastically, stress acting on the tension region exceeds an elastic limit and therefore the tension region yields and deforms plastically. The tension region entering a plastic deformation stage serves as a warning indicating that a compression or shear failure may occur in the pressure region, and this is the effect achieved by the present invention.

Description

Asymmetrical section metal beam with damage warning function

technical field

The present invention relates to a beam member, especially an asymmetrical section metal beam with damage warning function.

Background technique

The industry's existing practice in the selection of metal beams and columns has at least the following shortcomings:

1. Regarding the reinforced concrete floor (RC DECK), it has a considerable influence on the section modulus of the steel body. In terms of symmetrical sections, when the compressive and tensile areas are subjected to bending moment and axial pressure and reach the critical load, the pressure area will be subdued first, but the industry's influence on the reinforced concrete floor slab on the steel body section modulus is usually neglected, resulting in beams and columns. The section modulus of the tension zone at the end is greater than that of the compression zone and/or the critical failure of the compression zone is unknown.

2. In addition, the existing industry also ignores the beam axial force (that is, the pressure generated by the beam member under load), and takes the steel frame beam with fixed ends (Fixed End) when it is under load. The so-called axial pressure, so that the pressure area reaches the elastic limit without knowing it.

3. In addition, the cantilever steel beam with reinforced concrete version is also combined with the version beam, so that the section modulus of the tension zone is greater than that of the pressure zone.

However, the above-mentioned methods for the selection of existing metal beams and columns in the industry include ignoring the influence of the reinforced concrete slab on the section modulus of the steel body, ignoring the axial force of the beam, and the tension of the cantilevered steel beam of the reinforced concrete slab due to the combination of slabs and beams. In the actual situation that the section modulus in the compression zone is greater than that in the compression zone, it is possible that the beam first reaches the elastic limit in the compression zone and then yields before the tension zone, so the compression shear failure occurs instantaneously, resulting in serious consequences.

Therefore, how to solve and correct the above problems and defects of the existing beam members is the main focus of the improvement of the present invention.

SUMMARY OF THE INVENTION

In order to solve the above problems, the present invention provides an asymmetrical section metal beam with a damage warning function, in which the main body section adopts an asymmetrical section configuration, so that the tension zone first reaches the elastic limit and then falls before the pressure zone and enters into plastic deformation, and can be Through the plastic deformation of the tension zone, it plays a warning function of possible compression shear failure in the compression zone.

An embodiment of the present invention provides an asymmetric cross-section metal beam with a damage warning function, which includes a main body and a first floor plate, and a wing plate on the main body is fixed to the floor plate by shearing nails and is connected to an integral beam , the body has a body section, the section shape of the body section defines a neutral axis, the body section defines a pressure zone and a tension zone when subjected to pure bending moment loads, and each point of the body is neutral within the elastic range The axis is in a linear relationship, the cross-sectional shape of the body section is asymmetric on both sides according to the neutral axis, and the section modulus of the pressure zone of the body section at the maximum bending moment of the body is greater than that of the tension zone. When the stress in the pressure zone reaches the elastic limit and subsides, the stress in the tension zone first exceeds the elastic limit and subdues first, and the tension zone first subdues and then plastically deforms, which serves as a warning that the compression and shear failure may occur in the pressure zone.

Further, the cross-sectional shape of the body section is asymmetrical on two sides according to the neutral axis, the width is the same, and the thickness is thicker on one side and thinner on the other side.

Further, the cross-sectional shape of the body section is asymmetrical on two sides according to the neutral axis, the thickness is the same, and the width is wider on one side and narrower on the other side.

Further, the body is a beam and is supported by a plurality of supports to bear the load.

Further, the section of the body is H-shaped and mouth-shaped.

The beneficial effects of the present invention are:

Therefore, the section shape of the body section of the present invention is designed to be asymmetric on both sides according to the defined neutral axis, so that the section modulus of the pressure region of the body section at the maximum bending moment is greater than the section modulus of the tension region, so when When the body is under load, the tensile force area has reached the elastic limit and begins to enter into plastic deformation after yielding. Entering the plastic deformation stage through the tensile force area can play a warning role in the pressure area before the compression shear failure, so as to facilitate the evacuation of personnel or the structural repair. Time to wait for emergency treatment.

Description of drawings

1 is a schematic diagram of the support and uniform load of a metal beam according to an embodiment of the present invention;

2a is a schematic diagram of a metal beam of an H-shaped asymmetric body section according to an embodiment of the present invention, in which the body sections have the same width and different thicknesses on both sides of the neutral axis;

Figure 2b is a schematic diagram of a metal beam of a die asymmetric body section according to an embodiment of the present invention, the body section in the figure is the same width, but the thickness on both sides of the neutral axis is different;

3a is a schematic diagram of a metal beam of another H-shaped asymmetric body section according to an embodiment of the present invention, the body section in the figure has the same thickness, but the widths on both sides of the neutral axis are different;

3b is a schematic diagram of a metal beam of another die asymmetric body section according to an embodiment of the present invention, the body section in the figure has the same thickness, but the widths on both sides of the neutral axis are different;

Figure 4a is a cross-sectional view of a metal beam with an existing H-shaped symmetrical body section, and the scale in the figure is not based on actual specifications but only for illustration;

Figure 4b is a cross-sectional view of a metal beam with an H-shaped asymmetric body section according to an embodiment of the present invention, and the scale in the figure is not based on actual specifications but only for illustration;

4c is a cross-sectional view of a metal beam with another H-shaped asymmetric body section according to an embodiment of the present invention, and the scale in the figure is not based on actual specifications but only for illustration;

Figure 5 is a schematic diagram of the existing H-shaped symmetrical body section of the metal beam connecting the floor plan;

6a is a schematic diagram of the support and uniform load of another metal beam according to an embodiment of the present invention;

Fig. 6b is a bending moment diagram of the metal beam of Fig. 6a subjected to a uniform load.

Description of reference numbers:

10: body; 11: wing plate; 20: support; 30: shear nail; 40: support; D: floor plate; NA: neutral axis; L: height; W: width; t: web thickness; T, T1, T2: thickness of wing plate; A～E: interval.

detailed description

In order to facilitate the description of the central idea of the present invention expressed in the column of the above-mentioned summary of the invention, it is now expressed with specific embodiments. Various objects in the embodiments are drawn in proportions suitable for enumeration and description, rather than the proportions of actual elements, which will be described together first.

Please refer to FIG. 1 to FIG. 6b , the present invention provides an asymmetrical section metal beam with a damage warning function. As shown in FIG. 1 , it includes a main body 10 . The main body 10 is a beam in this embodiment, which is supported by a plurality of supports 20 to bear the load, and generates a plurality of sections with positive and negative bending moments.

The main body 10 of the present invention has a main body section. The cross-sectional shape of the main body section is asymmetrical on both sides according to a defined neutral axis NA, but is an asymmetrical section. In the pressure zone and a tension zone, each point of the body section has a linear relationship with the neutral axis NA within the elastic range. In the body section of the body 10 at the maximum bending moment, the section modulus of the pressure area is greater than that of the tension area. When the stress in the pressure area reaches the elastic limit (Elastic Limit) and yields, the tension area The stress first exceeds the elastic limit and then subdues to enter the plastic deformation stage, and the tension zone enters the plastic deformation stage to serve as a warning that the pressure zone expands and deforms after the tensile force reaches the elastic limit, which may cause compression shear failure. The elastic limit refers to the critical limit (tensile force and pressure are the same) that the metal beam and column can be stressed before yielding, that is, when the stress exceeds the elastic limit, the metal beam and column begin to yield and enter into plastic deformation.

The main body 10 can preferably be an H-shaped steel beam or a mouth-shaped steel beam (as shown in FIGS. 2 a to 3 b ). In one embodiment, the widths of the body sections are the same, but the thickness is thicker on one side and thinner on the other (as shown in Figures 2a-2b), and the thicker side is the pressure zone at the maximum bending moment and has a larger thickness. The section modulus of , and the thinner side is the tensile force area at the maximum bending moment, and the section modulus is smaller. The main body 10 of the present invention is not limited by the aforementioned difference in thickness. For example, in another embodiment, the cross-sectional thickness of the main body is the same, but the width is wider on one side and narrower on the other side (as shown in FIGS. 3 a to 3 b ). , at this time, the wider side is the pressure zone and has a larger section modulus, and the narrower side is the tension zone and has a smaller section modulus.

For example, there is an H-shaped metal steel beam whose cross-sectional shape is symmetrical on both sides according to the neutral axis NA. ; t is the thickness of the web; T is the thickness of the upper and lower flanges), and an H-shaped metal steel beam (as shown in Figure 4b) whose cross-sectional shape is asymmetrical according to the neutral axis NA (as shown in Figure 4b), the specification of its body section is H400L *200W*7t*12T1/10T2 (T1 is regarded as the pressure area at the maximum bending moment; T2 is regarded as the tension area at the maximum bending moment), and another H-shaped metal steel whose cross-section shape is asymmetrical according to the neutral axis NA The beam (as shown in Figure 4c), the specification of its body section is H400L*200W*7t*15T1/7T2, the cross-sectional area, unit weight, moment of inertia I _x and section modulus S _x of the three H-shaped metal steel beams , and the section modulus S _x ratio is shown in Table 1 below:

Table 1

As shown in Table 1, the cross-sectional area of Model 1, Model 2, and Model 3 are all 70.46cm ² , and the unit weight is 56.1kgf/m. The section modulus (S _x ) of Model 1 is 990cm ³ , and the ratio is 100%. Compared with Model 2, under the condition that the sectional area and unit weight remain unchanged, the thickness of the upper and lower wings 11 is asymmetric on both sides according to the neutral axis NA, that is, the upper and lower wings 11 The thickness is changed to 10mm and 12mm respectively. At this time, the section modulus of model 2 is increased to 1039cm ³ on the side of the wing plate 11 (ie the pressure area) with a thickness of 12mm, which is 5% higher than that of model 1. At the same time, the section modulus is 10mm thick. The side of the wing plate 11 (that is, the tension area) is reduced to 937cm3, which is 5% less than that of the model 1; compared with the model ³ , the thickness of the upper and lower wing plates 11 is also modified according to the size of the body section according to the neutral axis NA. Symmetric, that is, the thicknesses of the upper and lower wing plates 11 are changed to 7mm and 15mm respectively. At this time, the section modulus of the model 3 is increased to 1158cm ³ on the side of the wing plate 11 with a thickness of 15mm (ie the pressure area), and is 17 cm higher than that of the model 1. %, while the section modulus is reduced to 761 cm ³ on the side of the wing plate 11 with a thickness of 7 mm (ie, the tension zone), which is 23% lower than that of the model 1. It can be seen that the body section is used for structures with a fixed load direction at the critical point (such as building beams, side columns), and the bearing capacity can be improved on the side with a relatively large section modulus, while the section modulus is relatively small. If one side is in a tension state, it will subdue after exceeding the elastic limit and expand and deform, which can play a warning role of compression shear failure.

1, if the aforementioned main body 10 has a floor plate D on the upper wing plate 11 and is fixed with shearing nails 30, if the density and strength of the shearing nails 30 are sufficient, the floor plate D is connected to the main body 10 through the shearing nails 30 as A T-shaped integral beam (as shown in Figure 5), at this time, the span of the main body 10 between the supports 40 is a positive bending moment, and the pressure area is on the upper side and the tension area is on the lower side, because the upper wing plate 11 is affected by the floor plate D. Constrained, the section modulus of the pressure region is increased and the bearing capacity is improved; for example, according to the structural mode, the bending moment relationship (such as Equation 1) can be expressed according to the material mechanics, and as shown in Figure 6a, the two sides support 40 (also represented by the endpoints A and B) and the middle of the span are both critical points (the endpoints A and B are the characteristic critical points); as shown in Figure 6b, both M _A and M _B are negative bending moments, and M _max is a positive bending moment. moment.

Formula 1:

However, the main body 10 has a negative bending moment at the support 40 with the tension zone at the top and the pressure zone at the bottom. The upper wing plate 11 is also constrained by the floor D, which in turn increases the section modulus of the tension zone and improves the bearing capacity , and at the support 40, it becomes the pressure zone and first exceeds the elastic limit and breaks down. It can be seen from this that when the main body 10 is combined with the floor plate D, the section modulus of the tension zone is increased for the body 10 to improve the bearing capacity, causing the pressure zone to exceed the elastic limit first and may be damaged by instantaneous compression and shearing. However, according to the current structural analysis and design method used in the construction industry, the combination of the floor plan and the main body 10 is regarded as non-contribution and ignored, so the danger of instantaneous damage to the pressure area may occur when the limit is used. occur.

As an example, suppose there is a body 10 with the aforementioned supports 40 only at both ends, and the span between the two supports 40 is the span section, and the support 40 is the support section. And the uniformly distributed load of the main body 10 is 3000kgf/m, the wing plate 11 on which the main body 10 is placed is laid with the floor plate D as mentioned above and fixed with shear nails 30. As shown in Table 2, it can be found that the bearing capacity of the tension zone of the support section is increased due to the increase of the section modulus, resulting in the stress ratio not exceeding the elastic limit, but the stress ratio of the pressure zone of the support section has exceeded the elastic limit and damaged. (In Table 2, σ represents the maximum stress of the section; f _y represents the yield stress of the metal material, which is assumed to be 2500kgf/cm2; S _pressure and S _tension represent the section modulus of the compression and tension areas, the following Tables 3 and 4 , Table 5 is the same)

Table 2

In the same way, when the uniform load is increased to 3300kgf/m and the use is beyond the limit, the body section of the main body 10 is changed to the H400L*200W*7t*14T1/8T2 asymmetric section specification. At this time, as shown in Table 3, although The tension area of the support section increases the bearing capacity due to the increase of the section modulus, but the section shape of the main body section passing through the main body 10 is asymmetric on both sides according to the neutral axis NA, and the main body 10 connected with the floor plate D in the pressure area can be adjusted. The section modulus can still be greater than the section modulus of the tension zone, so that the stress ratio of the pressure zone of the support section will not exceed the elastic limit when it is used beyond the limit, but the stress ratio of the tension zone of the support section first exceeds the elastic limit and then falls. When entering plastic deformation failure, it can also serve as a warning that the pressure zone may have instant compression shear failure without warning.

table 3

Another example is the case where the uniform load is 2750kgf/m and the use is not exceeded, the wing plate 11 above the main body 10 is also laid with floor plate D and fixed with shear nails 30. According to the structural analysis of the existing industry practice (ignoring the floor Contribution of version D), the specifications above RH400L*200W*7t*11T will be selected, and the presented stress ratios are shown in Table 4:

Table 4

Continuing from the above, if the asymmetrical section metal beam of the present invention is used under the same conditions, it should be in line with the actual situation and the contribution of floor D should be added. At this time, the main body section of the main body 10 can be reduced in size and H380L*190W*7t* The specification of 14T1/8T2 asymmetric section, and as shown in Table 5, the stress ratio of the pressure zone and the tension zone are all within the elastic range (stress ratio ≤ 1), and when there is floor plate D, the pressure zone section of the support section The modulus is higher than the tension zone and still has a high bearing capacity. Even if there is over-limit use, the stress ratio in the tension zone of the support section first exceeds the elastic limit and then falls and enters into plastic deformation and failure, which can not only exert pressure There may be no warning effect of instantaneous compression and shear damage in the area, and the unit weight is reduced due to the reduction of the specification (the unit weight is reduced by 6.4% compared with the specification of H400L*200W*7t*11T). On the premise of conforming to structural safety, The material cost of the body 10 can also be saved.

table 5

It is not difficult to find the characteristics of the present invention by the above-mentioned description, and is:

1. When the main body 10 of the present invention is subjected to a critical load, due to the design of the main body section of the present invention, its cross-sectional shape is asymmetrical on both sides according to the defined neutral axis NA, so that the main body 10 is in the pressure zone of the main body section at the maximum bending moment. The section modulus is greater than the section modulus of the tension zone, so when the body 10 is under load, the tension zone has reached the elastic limit and entered into plastic deformation after being subdued. It is beneficial to gain time for emergency disposal such as personnel evacuation or structural reinforcement.

2. In the current industry, the influence of reinforced concrete floor slabs on the section modulus of the steel body is usually ignored, or the axial force of the beam (that is, the pressure generated by the beam member under load) is ignored, resulting in the section modulus of the tensile zone at the column end of the beam The problem that the cantilever steel beam of Building D is larger than the pressure area and the section modulus of the tension area is larger than that of the pressure area due to the combination of the plate and the beam can be solved by the present invention. The main body section of the main body 10 is overcome by an asymmetrical section design, thereby correcting the aforementioned doubtful operation methods in the prior art.

3. The body section of the main body 10 of the present invention is designed with an asymmetric section, and after reaching the elastic limit in the tension zone, it subdues and enters into plastic deformation, so as to play a warning role in the pressure zone before the compression shear failure, and can pass The specification of the main body section is reduced to reduce the unit weight, so the material cost of the main body 10 can also be saved under the premise of conforming to the structural safety.

Claims

An asymmetric section metal beam with damage warning function is characterized in that it includes a main body and a first floor plate, a wing plate on the main body is fixed with the floor plate by shearing nails and is connected to an integral beam, the main body has A body section, the section shape of the body section defines a neutral axis, and the body section defines a pressure zone and a tension zone when subjected to pure bending moment loads, and each point of the body is within the elastic range of the neutral axis The axis is in a linear relationship, the section shape of the body section is asymmetric on both sides according to the neutral axis, and the section modulus of the pressure zone of the body section at the maximum bending moment of the body is greater than that of the tension zone. number, before the stress in the pressure zone reaches the elastic limit and yields, the stress in the tension zone first reaches the elastic limit and then subdues and enters into plastic deformation. When the tension zone enters into plastic deformation and reaches the pressure zone, compressive shear may occur Destruction warning.
The asymmetric cross-section metal beam with damage warning function according to claim 1, wherein the cross-sectional shape of the main body section is asymmetrical on both sides according to the neutral axis, the width is the same, and the thickness is thicker on one side. The other side is thinner.
The asymmetric cross-section metal beam with damage warning function according to claim 1, wherein the cross-sectional shape of the main body section is asymmetrical on both sides according to the neutral axis, the thickness is the same, and the width is one side wider and The other side is narrower.
The asymmetrical section metal beam with damage warning function according to claim 1, wherein the body is a beam and is supported by a plurality of supports to bear the load.
The asymmetrical section metal beam with damage warning function according to claim 1, wherein the section of the body is H-shaped and mouth-shaped.