Sijas šķērsgriezuma laukuma inerces moments:
I1x1=b*h3/12=40*1/12=3.33 (cm4)
I1xc=I1x1+a2*A=3,33+(19,95-0,5)2*40=15135,43 (cm4)
I2x2=642 (cm4)
I2xc=642+(19,95-8,75-1)2*61,5=7040,46 (cm4)
I3x3=106 (cm4)
I3xc= I4xc=106+(19,95-2,55-11,5-1)2*13,9=439,74 (cm4)
I5xc=I6xc=15220+(1+11,5+20-19,95)2*61,5=24906,4 (cm4)
Ixc=15135,43+7040,46+2*439,74+2*24906,4=72868,17 (cm4)
Pretestības moments
W+=72868,17/19,95=3652,54 (cm3)
W-=72868,17/32,55=2238,65 (cm3)…
