RC Beam Designer

What am I seeing?

• The stress block shows the EC2 rectangular approximation. The neutral axis depth x and lever arm z are drawn to scale on the section.
• K = M/(bd²fck) measures how hard the section is working. When K exceeds K' = 0.167 the section needs compression steel.
• The shear tab shows the variable strut angle method. A flatter strut (21.8 degrees) gives lighter links but a lower VRd,max ceiling.
• Deflection is checked by the span to depth ratio from EC2 Table 7.4N. The modification factor accounts for the steel stress.
• The BS 8110 comparison uses fcu instead of fck and slightly different partial factors, giving a similar but not identical answer.