Method of calculating allowable load

Abstract

To provide a method for calculating an allowable load capable of estimating the allowable load in a short time and at a low cost when the specification of a joint is changed.SOLUTION: An allowable load in a deck composite slab 1 joined to a steel frame beam 5 by a joining part 6 arranged in the steel frame beam 5 at a predetermined pitch is calculated. A known unit surface area allowable load is calculated by dividing a known allowable load under predetermined joining conditions by the total surface area of the joint 6 per predetermined length in the extending direction of the steel frame beam 5 under the predetermined joining conditions, and a predicted allowable load is calculated by multiplying the known unit surface area allowable load by the total surface area of the joint 6 per predetermined length in the extending direction of the steel frame beam 5 under the joining conditions to be calculated.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for calculating the allowable load of a composite deck slab joined to a beam by joints provided on the beam at a predetermined pitch. [Background technology]

[0002] Conventionally, a structure has been proposed in which concrete is poured onto a deck plate to form a composite deck slab, and studs are provided on the flanges of the beams on which the deck plate is placed (see, for example, Patent Document 1). In the composite deck slab described in Patent Document 1, headed studs are provided on the flanges of the beams, and the studs and concrete are integrated together. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-41348 Summary of the Invention [Problem to be solved by the invention]

[0004] In composite deck slabs such as those described in Patent Document 1, the allowable load is determined by the span between the beams across which the deck plates are spanned. Furthermore, even for the same span, this allowable load varies depending on the joint specifications (hereinafter referred to as "joint conditions"), such as the joint pitch in the direction of beam extension and the joint configuration (a concept that includes the type and dimensions of the joint, and examples of types include headed studs, burnt-out plug welding, and driven rivets). For this reason, when the joint conditions are changed, a process is required, such as confirming the allowable load performance through a first-stage test and then certifying it through a second-stage test.

[0005] However, in order to conduct these tests, it is necessary to actually manufacture a composite deck slab and create a test specimen, which takes time and becomes expensive, especially as the number of tests increases. Therefore, it was desirable to be able to estimate the allowable load when the joining conditions are changed in a short time and at low cost.

[0006] The present invention has been made in consideration of the above-mentioned problems, and its purpose is to provide a method for calculating an allowable load that can estimate the allowable load when the joining conditions are changed in a short time and at low cost. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, the method for calculating the allowable load of the present invention is a method for calculating the allowable load of a deck composite slab joined to a beam by joints provided on the beam at a predetermined pitch, and is characterized in that a known unit surface area allowable load is calculated by dividing a known allowable load under predetermined joint conditions by the total surface area of ​​joints per predetermined length in the extension direction of the beam under the predetermined joint conditions, and an expected allowable load is calculated by multiplying the known unit surface area allowable load by the total surface area of ​​joints per predetermined length in the extension direction under the joint conditions to be calculated.

[0008] In a method for calculating an allowable load according to one aspect of the present invention, the known allowable loads per unit surface area are calculated under a plurality of joining conditions, and the predicted allowable load is corrected based on the plurality of known allowable loads per unit surface area.

[0009] In a method for calculating an allowable load according to one embodiment of the present invention, the joining conditions of the known allowable load per unit surface area used when calculating the expected allowable load are defined as first joining conditions, the known allowable load per unit surface area is calculated under a plurality of joining conditions different from the first joining condition, each of the known allowable load per unit surface area under the plurality of joining conditions different from the first joining condition is divided by the known allowable load per unit surface area under the first joining condition to calculate a plurality of allowable load ratios, the average of the plurality of allowable load ratios is defined as a correction coefficient, and the expected allowable load calculated based on the known allowable load per unit surface area under the first joining condition is corrected by multiplying the correction coefficient.

[0010] In one embodiment of the method for calculating the allowable load of the present invention, the joint is a headed stud, and the surface area of ​​one joint is calculated as the sum of the area of ​​the upper surface and outer peripheral surface of the head and the area of ​​the outer peripheral surface of the shank. [Effects of the Invention]

[0011] According to the method for calculating the allowable load of the present invention, the allowable load when the joining conditions are changed can be estimated in a short time and at low cost. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a perspective view showing a deck composite slab that is the subject of the allowable load calculation method according to this embodiment. [Figure 2] 1 is a cross-sectional view showing a deck composite slab that is the subject of the allowable load calculation method according to this embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a perspective view showing a composite deck slab 1 that is the subject of a method for calculating an allowable load according to this embodiment, and Fig. 2 is a cross-sectional view showing the composite deck slab 1.

[0014] The method for calculating the allowable load according to an embodiment of the present invention is a method for calculating the allowable load of a deck composite slab 1 joined to a steel beam 5 by joints 6 provided on the steel beams 5 at a predetermined pitch, in which a known allowable load per unit surface area is calculated by dividing the known allowable load under predetermined joint conditions by the total surface area of ​​the joints 6 per predetermined length in the extension direction of the steel beam 5 under these predetermined joint conditions, and the expected allowable load is calculated by multiplying this known allowable load per unit surface area by the total surface area of ​​the joints 6 per predetermined length in the extension direction of the steel beam 5 under the joint conditions to be calculated. The method for calculating the allowable load will be described in detail below.

[0015] 1 and 2 show an example of a composite deck slab 1 that is the subject of the allowable load calculation method of this embodiment. The composite deck slab 1 comprises a corrugated deck plate 2, a concrete section 3 poured on the deck plate 2, and reinforcing bars 4 for preventing cracks from spreading. The end of the deck plate 2 rests on the flange of a steel beam 5, and a joint 6 with the concrete section 3 is provided on the flange of this steel beam 5.

[0016] The joints 6 are provided at a predetermined pitch along the extension direction of the beam 5. Note that this pitch is constant between multiple joints 6. In the illustrated example, the joints 6 are headed studs, but other types of joints may also be used.

[0017] Among such composite deck slabs 1, those with predetermined joint conditions (type, dimensions, and pitch of joints 6) have already undergone allowable load tests, and the allowable loads are known. Below, we will explain a method for calculating the allowable load under joint conditions that are different from the joint conditions for which the allowable loads are known. Note that the allowable load to be calculated in the calculation method of this embodiment is the load for fire resistance certification or the load for a composite deck slab structure.

[0018] [First calculation method] First, let B0 be the known allowable load, and A0 be the total surface area of ​​the joints 6 per given length in the extension direction of the beam 5 under these joint conditions. Here, the surface area of ​​one joint 6 is the surface area of ​​the main portion of the joint 6 that is embedded in the concrete 3. For example, if the joint 6 is a burn-out plug weld, the sum of the area of ​​its side and the area of ​​one end face is the surface area of ​​the main portion that is embedded in the concrete 3. Also, if the joint 6 is a headed stud, the sum of the area of ​​the top and outer peripheral surface of the head and the area of ​​the outer peripheral surface of the shank is the surface area of ​​the main portion that is embedded in the concrete 3. The total surface area A0 of the joints 6 per given length in the extension direction of the beam 5 can be calculated by dividing the surface area of ​​one joint 6 by the pitch of the joints 6.

[0019] The allowable load B0 is divided by the total surface area A0 to calculate the allowable load C0 per known unit surface area (B0 / A0=C0).

[0020] Next, using the same method as for the total surface area A0, the total surface area A' of the joint 6 per predetermined length in the extension direction of the beam 5 under the joining conditions to be calculated is calculated. Furthermore, this total surface area A' is multiplied by the known allowable load per unit surface area C0 to calculate the expected allowable load E (A' × C0 = E).

[0021] For example, it is possible to determine whether the predicted allowable load E calculated in this way satisfies a standard value, and if it does, it is possible to omit the process of a specified test (for example, performance verification and certification test). Even if the test for certification cannot be omitted, by making a prototype under the joining conditions and actually conducting the test, it is possible to reduce the number of prototypes and tests compared to making prototypes under multiple joining conditions.

[0022] [Calculation example for the first calculation method] A specific example of calculation using the first calculation method will be described below. First, Table 1 shows the types and dimensions of joints in examples of joining conditions for joints with known allowable loads (known specification examples 1 to 3).

[0023] [Table 1]

[0024] Next, for known specification examples 1 to 3, the areas and characteristics (particularly the total surface area A0, allowable load B0, and allowable load per unit surface area C0) calculated according to the above calculation method based on each dimension are shown in Table 2.

[0025] [Table 2]

[0026] Table 3 shows the types of joints and their dimensions in examples of joint conditions (new specification examples 1 to 4) that are the subject of calculation.

[0027] [Table 3]

[0028] For New Specification Examples 1 to 4, the areas and characteristics (particularly the total surface area A' and the expected allowable load E) calculated according to the above calculation method based on each dimension are shown in Table 4.

[0029] [Table 4]

[0030] [Second calculation method] In the second calculation method, the predicted allowable load E calculated by the first calculation method is further multiplied by a correction coefficient D to calculate a corrected predicted allowable load E'.

[0031] The correction coefficient D is calculated using the allowable load per unit surface area under three or more known joining conditions. One of the three or more joining conditions is designated as the first joining condition, and the allowable load per unit surface area C0 is calculated based on this first joining condition to calculate the expected allowable load E. Based on the other joining conditions, the allowable loads per unit surface area C1, C2, ..., Cn for correction are calculated using the same calculation as in the first calculation method.

[0032] A plurality of allowable load ratios D1, D2, ..., Dn are calculated by dividing each of the plurality of allowable loads per unit surface area C1, C2, ..., Cn by the allowable load per unit surface area C0. Furthermore, an average value of the plurality of allowable load ratios D1, D2, ..., Dn is calculated as a correction coefficient D. The expected allowable load E calculated based on the first joining condition is corrected by multiplying it by the correction coefficient D to calculate a corrected expected allowable load E'.

[0033] It is preferable that the type of joint is the same under the three or more joining conditions used to calculate the correction coefficient. That is, the allowable load per unit surface area may be calculated under three or more joining conditions for burn-out plug welding that differ only from each other, where only the pitch is different, or under three or more joining conditions for drive rivets that differ only from each other, where only the pitch is different. Also, for headed studs, the allowable load per unit surface area may be calculated under three or more joining conditions that differ only from each other, or under three or more joining conditions that differ only from each other, where only the pitch is different, or under three or more joining conditions that differ only from each other.

[0034] Instead of the expected allowable load E calculated by the first calculation method, it is determined whether the corrected expected allowable load E' satisfies the standard value, and if it satisfies the standard value, the process of a specified test (for example, performance verification and certification test) may be omitted. Even if the test for certification cannot be omitted, the number of prototypes and tests may be reduced (compared to when prototypes are made for multiple joining conditions) by making a prototype under those joining conditions and actually conducting the test.

[0035] [Calculation example using the second calculation method] A specific example of calculation using the second calculation method will now be described. First, Table 5 shows the types and dimensions of the joints in examples of joining conditions (new specification examples 1 to 4) that are used to calculate the expected allowable load E' using the second calculation method.

[0036] [Table 5]

[0037] For New Specification Examples 5 to 8, the areas and characteristics (particularly the total surface area A' and the expected allowable load E) calculated according to the first calculation method are shown in Table 6.

[0038] [Table 6]

[0039] Next, Table 7 shows the dimensions of the three or more joining conditions (known specification examples 4 to 9) other than the first joining condition among those for calculating the correction coefficient D. The joining conditions of known specification examples 1 to 3 are the first joining conditions.

[0040] [Table 7]

[0041] Next, for known specification examples 4 to 9, the areas and characteristics (particularly the allowable load per unit surface area Cn) calculated according to the first calculation method are shown in Table 8.

[0042] [Table 8]

[0043] Table 9 shows the allowable load ratios D1 and D2 calculated according to the second calculation method based on the allowable load per unit surface area Cn for each type of joint, and the correction coefficient D, which is the average value of the allowable load ratios D1 and D2.

[0044] [Table 9]

[0045] Table 10 shows the corrected expected allowable load E' calculated by multiplying the expected allowable load E for each of the new specification examples 5 to 8 calculated as above by the correction coefficient D for the corresponding type of joint.

[0046] [Table 10]

[0047] In this way, according to the method for calculating the allowable load of an embodiment of the present invention, by calculating the predicted allowable load E based on the allowable load B0 and its total surface area A0 under the known specifications and the total surface area A' under the new specifications, it is possible to estimate the allowable load when the joint specifications are changed without actually manufacturing a composite deck slab. This reduces the number of times that a composite deck slab is actually manufactured and tested, thereby shortening the time and reducing costs.

[0048] Furthermore, if the corrected predicted allowable load E' is calculated by multiplying the correction coefficient D, the accuracy of the allowable load estimation can be improved.

[0049] Furthermore, when the joint 6 is a headed stud, the accuracy of estimating the allowable load can be improved by calculating the sum of the area of ​​the top surface and outer peripheral surface of the head and the area of ​​the outer peripheral surface of the shank as the surface area of ​​one joint.

[0050] The present invention is not limited to the above-described embodiment, and includes other configurations that can achieve the object of the present invention, including modifications such as those described below. For example, in the above-described embodiment of the present invention, when the joint 6 is a headed stud, the surface area of ​​one joint is calculated as the sum of the areas of the upper and outer peripheral surfaces of the head and the outer peripheral surface of the shank, but the area of ​​the underside of the head (the surface facing the shank) may also be added. Furthermore, if the joint has parts that contribute easily to the allowable load and parts that do not, the calculation may be made using the area of ​​the parts that contribute easily, or the calculation may be made by weighting the area of ​​each part according to its degree of contribution.

[0051] In the above-described embodiment of the present invention, the average value of multiple allowable load ratios is used as the correction coefficient, but the method of calculating the correction coefficient based on multiple joining conditions is not limited to this. For example, instead of a simple average value, the average value may be calculated by weighting the allowable load ratio according to the pitch under the joining conditions to be calculated. In other words, weighting may be performed so that the contribution of the allowable load ratio increases under joining conditions in which the allowable load is less likely to contribute. Furthermore, for example, if there is a large amount of data on the allowable load ratio and the relationship between the pitch and the allowable load ratio can be approximated by a predetermined function, correction may be performed based on this function.

[0052] Although the embodiments of the present invention have been described above, the present invention is not limited to the method for calculating the allowable load according to the above-described embodiments of the present invention, and includes all aspects included in the concept and scope of the claims. Furthermore, each configuration may be appropriately and selectively combined to achieve at least some of the above-described problems and effects. For example, the shape, material, arrangement, size, etc. of each component to be calculated in the above-described embodiments may be appropriately changed depending on the specific use of the present invention. [Explanation of symbols]

[0053] 1...Deck composite slab, 2...Deck plate, 3...Concrete section, 4...Reinforcement bar, 5...Steel beam (beam), 6...Joint

Claims

1. A method for calculating the allowable load of a deck composite slab joined to a beam by joints provided on the beam at a predetermined pitch, Calculating a known allowable load per unit surface area by dividing a known allowable load under predetermined joining conditions by a total surface area of ​​the joint per predetermined length in the extension direction of the beam under the predetermined joining conditions; A method for calculating an allowable load, characterized in that the known allowable load per unit surface area is multiplied by the total surface area of ​​the joint per predetermined length in the extension direction under the joining conditions to be calculated to calculate an expected allowable load.

2. Calculating the known allowable load per unit surface area under a plurality of joining conditions; 2. The method for calculating an allowable load according to claim 1, wherein the predicted allowable load is corrected based on a plurality of known allowable loads per unit surface area.

3. a joining condition of the known allowable load per unit surface area used when calculating the expected allowable load is defined as a first joining condition, and the known allowable load per unit surface area is calculated under a plurality of joining conditions different from the first joining condition; calculating a plurality of allowable load ratios by dividing each of known allowable loads per unit surface area under a plurality of joining conditions different from the first joining condition by the known allowable load per unit surface area under the first joining condition; 3. The calculation method for the allowable load according to claim 2, wherein an average value of the plurality of allowable load ratios is used as a correction coefficient, and the predicted allowable load calculated based on the known allowable load per unit surface area under the first welding condition is corrected by multiplying the correction coefficient.

4. 4. The method for calculating an allowable load according to any one of claims 1 to 3, wherein the joint is a headed stud, and the surface area of ​​one joint is calculated as the sum of the area of ​​the upper surface and outer peripheral surface of the head and the area of ​​the outer peripheral surface of the shank.

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