1. The problem statement, all variables and given/known data Stress = 320 MPa Max Elastic Moment = Stress*Z Max Plastic Moment = Stress*S Solve the maximum moments and compare the % increase Beam is an I beam with dimensions: (b and d) Top Flange = 25*10 web = 10*180 Bottom Flange = 200*8 2. Relevant equations see above 3. The attempt at a solution Ybar elastic = 63.3mm Ybay plas = 30.5mm Ix=1.687*10^7 Zx = 266501.107 S = 191868.75 S is lower than Zx and this makes the plastic M smaller than M elastic. How is that possible? S= (25*10*162.5)+(10*157.5*67.5)+(22.5*10*11.25)+(200*8*26.5) this is the only value I had to manually generate without computer aid so there must be an error here? Can't seem to find out whats going wrong.