146 



COMBINED AND ECCENTRIC STRESSES 



u, 



A 



Area 1 4"x4'*PI- =3-50 sq-in. 

 .2-IO"[|@l5*=832 > 

 * Total Area =12 42 " " 



To locate neutral axisA-A take momer ^s about lower edge of channels 



Yo 



.Eccentricity.e = 6.44-5.OO = 1.44 



Moment of Inertia, IA, about AA 

 Let IB *I of labout axis I- 1 = 133.8 

 Ip/.=IofPJ-aboutaxis -2 = .02 

 Ag = Area of H = a-9 sq-in- 

 Apl.=Area of Pi- =3-50 sq- in- 

 lE tAge 2 tIpi. +Api.d 2 



= 199.8 



Radius of gyration , r A =y'39.8- = 4.0 



Moment of Inertiajs, about B-B 

 Let IE =1 of d about ax is 5-3 = 4.6 

 Ipi. =1 of PI- about axis B-B = 57.17 

 A(j=Area of H - 8-9^ sq-in- 

 ApUAreaof P|.=550 sq in- 

 ThenlB = Ig+Ai(4,25+.64)-h I pi- 

 = 4-6 -I- S-92 (4.89) 2 + 57- 1 7 

 = 275-0 



Radius of gyration , r B 



STRESS DUE To WEIGHT OF MEMBER 



The total weight of The member is as foHows:- 



2-10" @ 15* -30-0' long = 900. Ibs. 

 H4"X4 H P|.@ 1 1-9*30-0' = 357 

 Details and Lacing-26/ = 38 

 Total wei'gbt,W, = l585 " 



Bending Moment due to weight of the member, M =sWlsin6 

 Stress due to weight,f w = ^p',2 = 8^1 sine.Y. 



TOE "-JOE 



Stress due to weight in upper fibre 



X 1585 X 358 X-633X 3-81 



fw= , 95300 x558^ tnoo Ibs. (compression) 



'"10X28000000 



.Stress due To weight in lower fibre 



HOO =-1860 Ibs-Ctensjon) 



