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Purlin DIY Problem #1

Purlin DIY Problem #1. Find M y , M cr l , M crd and M cre for 72”. centerline dimensions h = 7.507 in. b = 1.889 in. d = 0.795 in. r = 0.217 in. t = 0.059 in. properties E = 29500 ksi n = 0.3 G = 11346 ksi f y = 55 ksi. DSM for Purlin DIY Problem #1.

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Purlin DIY Problem #1

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  1. Purlin DIY Problem #1 • Find My, Mcrl, Mcrd and Mcre for 72” centerline dimensions h = 7.507 in. b = 1.889 in. d = 0.795 in. r = 0.217 in. t = 0.059 in. properties E = 29500 ksi n = 0.3 G = 11346 ksi fy = 55 ksi

  2. DSM for Purlin DIY Problem #1

  3. Remember Distortional Buckling Gotcha!- comparison of two series of tests Test 8.5Z092 P Local buckling test Distortional buckling test 99% of NAS 83% of NAS Δ Test 8C043 P Local buckling test Distortional buckling test 106% of NAS 90% of NAS Δ

  4. Review DB in AISI Specification • Distortional buckling provisions are integral to the Direct Strength Method of Appendix 1 • The main Specification now has distortional buckling provisions as well, see Ballot 227B 227B Spec. 227B Comm.

  5. Distortional Buckling Commentary • “Testing on 8 and 9.5 in. (203 and 241 mm) deep Z-sections with a thickness between 0.069 (1.75 mm) and 0.118 in. (3.00 mm), through-fastened 12 in. (205 mm) o.c., to a 36 in. (914 mm) wide, 1 in. (25.4 mm) and 1.5 in. (38.1 mm) high steel panels, with up to 6 in. (152 mm) of blanket insulation between the panel and the Z-section, results in a kf between 0.15 to 0.44 kip-in./rad./in. (0.667 to 1.96 kN-mm/rad./mm) (MRI 1981).”

  6. Purlin DIY Problem #1 with spring • Find My, Mcrl, Mcrd and Mcre for 72” with kf=0.15 kip-in/rad/in centerline dimensions h = 7.507 in. b = 1.889 in. d = 0.795 in. r = 0.217 in. t = 0.059 in. properties E = 29500 ksi n = 0.3 G = 11346 ksi fy = 55 ksi

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