A.0.2kN/m2B.0.5kN/m2C.1.0kN/m2D.2kN/m2
A.10B.15C.20D.30
A.6 B.8 C.10 D.12
A.20kN B.30kN C.40kN D.50kN
A.0.3kN/m2 B.0.50kN/m2 C.1.10kN/m2 D.1.50kN/m2