Bolting down system
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Posted by: rickwhk ® 04/03/2006, 12:22:30 Author Profile eMail author Edit

Anybody can help me something... I prepared a structual calculation for approval, but the client have a little question on my figure "Where and How to find out the proof load on 4 nos. of M24 A4-80 stainless steel thread rod fix into aluminum shoe base plate with 250mm diameter for 8" flagpole... Material : A4-80 Thread Rod with Tests report under ISO3506-1 with tensile strength over 800 Mpa and Yeild Stress over 600 Mpa I used "Material strength as Tension = 464 Mpa and Shear = 384 Mpa which were come from my job's calculation. I tried and spent over 3 months to solve this problem by myself via books and internet...but failed. I only find some calculation example for proof load on Grade 4.6 bolts or H.S.G.B. - M24 (284 Mpa) but no indication for Stainless Steel bolt. Somebody just said : 0.58 x 800 Mpa = 464 Mpa...How and where to calculate for the factor = "0.58" Looking forward to hearing from you soon.

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Re: Bolting down system
Re: Bolting down system -- rickwhk	Post Reply	Top of thread	Forum

Posted by: Kelly_Bramble ® 04/03/2006, 16:56:44 Author Profile eMail author Edit

That is just a rough 58% of 800Mpa proof load...

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Re: Bolting down system
Re: Re: Bolting down system -- Kelly_Bramble	Post Reply	Top of thread	Forum

Posted by: rickwhk ® 04/03/2006, 22:23:17 Author Profile eMail author Edit

Hi Kelly, Thank you very much for your quick advise....But I got back from consultant, he said that it should be calculated from equation or formula from bolt's standard or type of material. What do you thing ! Cheer Rick

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Re: Bolting down system
Re: Re: Bolting down system -- rickwhk	Post Reply	Top of thread	Forum

Posted by: Kelly_Bramble ® 04/04/2006, 16:37:38 Author Profile eMail author Edit

Well, maybe there is an equation. Proof load is equal that load or tensile force which will not cause a permanent elongation or distortion. This load is directly proportional to the cross section area of the fastener and the fastener's material proof strength. The equation is Fp = A x Sp Where: Fp = Proof load A = Cross section area Sp = Proof Strength Proof strength (Sp) is given within the material specification sheet. I happen to have a chart for metric mechanical-property classes for steel fasteners: For class 4.6 M16 - M36, Minimum Proof Strength is 225MPa, Minimum tensile strength is 400MPa, and Minimum Yield is 240 MPa. Looks to me like you need to know the following: Maximum Bolt load (tension, shear) for each bolt. This os so you can compare the working load with the actual proof load Specification Proof strength Bolt cross section area. Modified by Kelly_Bramble at Tue, Apr 04, 2006, 16:38:58

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Re: Bolting down system
Re: Re: Bolting down system -- Kelly_Bramble	Post Reply	Top of thread	Forum

Posted by: rickwhk ® 04/05/2006, 12:00:41 Author Profile eMail author Edit

Thank you very much your details....I faced the problem from consultant's question is "how to proof/konw the "material proof strength" (proof load) for A4-80", he said that it is calculate out, not just say to "rough on 58%"... e.g. I got a equation (most likes only because the book in my office not in hand - I cannot fully remeber the details)from books : 1.1 x 1.0 x 0.45 x proof load of M24 diameter (High strength grip bolt "H.S.G.B." come from table - proof load is only 284 Mpa) x 0.5... Ps = K x u x 1 x proof load Because I need to complete my equation and calculation : - (tension work load/proof tension load) + (shear load/proof shear load) <= 1 I knew the working load for flagpole's shoe base (wind load, shear load and tension) is less than proof load of A4-80 bolts (4 nos. of M24) but I need to proof by equation completely otherwise he will not accept my calculation. Fp = A X Sp Fp = 353 X ??? Mpa Thank you in advance for your kind attention. Best Regards Rick Wong

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Re: Bolting down system
Re: Re: Bolting down system -- rickwhk	Post Reply	Top of thread	Forum

Posted by: rickwhk ® 04/06/2006, 06:34:40 Author Profile eMail author Edit

Hi kelly and others, I attached the legend of approved calculation for your review and comment. Example : Grade 4.6 bolts and Grade 8.8 bolts are given in Table 32 as : - Shear capacity =160 N/mm2 and 375N/mm2 Bearing capacity = 460N/mm2 and 1035N/mm2 Tension capacity = 195N/mm2 and 450N/mm2 Where can find Capacity for Grade 8 stainless steel bolt (ie.ISO 3506)

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