Steel Beam Design Example
Design strength check of the steel beam named PL019 is done under the most unfavorable internal forces as a result of general analysis determined according to TBDY 2018 9.3.1.4. The material and section information of the beam is as follows:
Steel material: S275 Fy =275 N/mm 2 Fu =430 N/mm 2
Cross section: IPE 450
Ix = 33740 cm4 | Iy = 1676 cm4 | Jx = 66.87 cm4 | Cw = 791000 cm6 |
Wex = 1500 cm3 | Wpx = 1702 cm3 | A= 98.80 cm4 |
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d=450 mm | h=378.8 mm | bf = 190 mm | tf = 14.6 mm |
tw = 9.4 mm | ix=184.8 mm | iy=41.2 mm |
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Control of Cross Section Conditions (TBDY 9.3.1)
It should be checked whether the flange width/thickness and web height/thickness values of the beam cross-section exceed λhd value given in Table 9.3 .
Cross section flange;
koşulu sağlar.
Cross-section web;
The result of the analysis was accepted as 0 because the axial force value was low.
koşulu sağlar.
The control of the cross-section conditions is done according to TBDY 2018 Table 9.3 in the steel beam report and summarized in tabular form.
![](../__attachments/2021820049/e1.png?inst-v=e297b259-93ee-4526-bee7-06170d782e4d)
Lateral Supporting of Beam Flange
![](../__attachments/2021820049/70.png?inst-v=e297b259-93ee-4526-bee7-06170d782e4d)
The longest unsupported beam segment in the lateral direction is Lb = 2.0 m. According to TBDY 2018 9.2.8.1(a), the distance between the points where the lower and upper ends of special beams are supported, Lb should meet the following condition.
![](../__attachments/2021820049/68.png?inst-v=e297b259-93ee-4526-bee7-06170d782e4d)
![](../__attachments/2021820049/69.png?inst-v=e297b259-93ee-4526-bee7-06170d782e4d)
It provides the condition. In the steel beam report, the control results are given in tables.
![](../__attachments/2021820049/e2.png?inst-v=e297b259-93ee-4526-bee7-06170d782e4d)
Flexural Moment Strength
While checking the beam design flexural moment strength, since the lateral supported lengths are different, station-by-station should be done for each section. For the convenience of manual check, it will be done for the section Lb = 0.75 m, which is exposed to the most unfavorable flexural moment.
![](../__attachments/2021820049/72.png?inst-v=e297b259-93ee-4526-bee7-06170d782e4d)
Because of the condition, the characteristic of flexural moment strength is determined according to yield limit condition. According to the CYTHYE equation 9.2, the check is done as follows:
![](../__attachments/2021820049/73.png?inst-v=e297b259-93ee-4526-bee7-06170d782e4d)
As a result of the analysis, the required flexural moment strength obtained as a result of 1.2G+Q-Ex-0.3Ey+0.2S+0.3Ez loading is Mu = 203.637 kNm.
![](../__attachments/2021820049/74.png?inst-v=e297b259-93ee-4526-bee7-06170d782e4d)
Shear Strength of The Beam
According to ÇYTHYE 10.2.1(a) in I-cross section with double symmetry axes,
![](../__attachments/2021820049/75.png?inst-v=e297b259-93ee-4526-bee7-06170d782e4d)
![](../__attachments/2021820049/96.png?inst-v=e297b259-93ee-4526-bee7-06170d782e4d)
With the load combination Q-Ex-0.3ey + 1.2G + 0.2S + 0.3ez, required shear force is determined as Vu = 12818 kN. It has been shown above that the cross-sectional capacity is sufficient.
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