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1 【本著作除另有註明外，採取創用CC「姓名標示－非商業性－相同方式分享」臺灣3.0版授權釋出】
National Taiwan University Material Mechanics Chapter Five Stresses in beams 2014 Summer 國立臺灣大學土木工程學系 黃尹男 教授 【本著作除另有註明外，採取創用CC「姓名標示－非商業性－相同方式分享」臺灣3.0版授權釋出】

2 Stresses in beams Class 6. Design of Beams for Bending Stresses
Class Introduction Class Pure bending & Non-uniform bending Class Curvature of a beam Class Longitudinal Strains in Beams Class Normal Stresses in Beams (Linearly Elastic Materials) Class Design of Beams for Bending Stresses Class Shear Stresses in Beams of Rectangular Cross Section Class Shear Stresses in Beams of Circular Cross Section Class Shear Stresses in the Webs of Beams with Flames Class 10. Built-Up Beams and Shear Flows

3 前情提要 [博升小語] 這些公式也是… 「背不出來別說你念過材力!!」的家族成員之一

4 Design of Beams for Bending Stresses
Class 6 Design of Beams for Bending Stresses

5 Design of Beams for Bending Stresses
Procedures: Calculate the required section modulus of the beam under the loadings. Select a cross section that has (slightly) greater S than required. Now include the weight of the chosen cross section to the applied loadings and recalculated the required S. 4. If the new required S is smaller than the chosen one, the design is fine. Otherwise repeat step 2 to 4 until that is the case. Design of Beams for Bending Stresses

6 Design of Beams for Bending Stresses
[Example] A cantilever beam of length L = 200cm supports a uniform load of intensity q = 0.03kN/cm and a concentrated load P = 10kN. Calculate the required section modulus S if the yielding stress σy = 25kN/cm2 considering a factor of safety n = 2 with respect to yielding. Design of Beams for Bending Stresses

7 Design of Beams for Bending Stresses
[Example] A cantilever beam of length L = 200cm supports a uniform load of intensity q = 0.03kN/cm and a concentrated load P = 10kN. Calculate the required section modulus S if the yielding stress σy = 25kN/cm2 considering a factor of safety n = 2 with respect to yielding. h b 翼板 (flange) Design of Beams for Bending Stresses 腹板 (web)

8 Design of Beams for Bending Stresses
[Example] A cantilever beam of length L = 200cm supports a uniform load of intensity q = 0.03kN/cm and a concentrated load P = 10kN. Calculate the required section modulus S if the yielding stress σy = 25kN/cm2 considering a factor of safety n = 2 with respect to yielding. Design of Beams for Bending Stresses Choose HE 140 B, which has S1 = 215.6cm3 and mass per meter 33.7 kg/m, Weight per unit length kN/cm. The new distributed load is = kN/cm.

9 Design of Beams for Bending Stresses
[Example] A cantilever beam of length L = 200cm supports a uniform load of intensity q = 0.03kN/cm and a concentrated load P = 10kN. Calculate the required section modulus S if the yielding stress σy = 25kN/cm2 considering a factor of safety n = 2 with respect to yielding. Design of Beams for Bending Stresses The new required section modulus is The design is safe.

10 重點回顧 [材力小語] 有概念就好…考試不太可能給你表格

11 6 7 頁碼 作品 版權圖示 來源/作者 1-11 版權聲明 [李星慧_2014 . 7. _高雄攝影作品] 此圖經同意已進行藍階修改。
您如需利用本作品，請另行向權利人取得授權。 6 國立交通大學機械工程系 鄭文雅 教授，本作品以創用 CC BY-NC-SA 臺灣 3.0 版授權釋出。 7 James M. Gere and Barry J. Goodno,“Mechanics of Materials”, 8th Ed., SI, Cengage Learning, 2009. 頁碼：1038 本作品依據著作權法第 46、52、65 條合理使用。 版權聲明