allowable compressiblw stress

[JyothiPrakash]

hello.
in bednar page no 157 in rankines formula the "r" has to be calculated. in page no 156 the "r" value is given as 0.289*0.625 under the fig no.5.9.
any body can you please tell me what are those values(0.289 and 0.625)...normally we will use r=sqrt(I/A)

 

[JStephen]

Sqrt(I/A) for a plate is t times sqrt(1/12) = 0.289t.
The 0.625 is the thickness of the gusset shown in Fig. 5-9.

 

[JyothiPrakash]

Thank You very much..for your kind reply...

now i got another doubt from your answer...before calculating the gusset thickness we need to calculate allowable compressive stress to arrive the thickness..may i know how come it possible to calculate gusset thickness without allowable compressive stress

 

[JStephen]

Assume a thickness, calculate allowable stress, then calculate required thickness and see if it's okay.

 

[JyothiPrakash]

Thank you stephen...

Now i got one way to solve the problem...i got some value for gusset thickness by assuming a value in rankines formulae..after that i checked back the gusset thickness with the rankines formulae..this value should not exceed the allowable stress for material given in ASME code for materails section-II..please can you confirm me whether am i going right r wrong...