rigid inverted roof with compound exhaust and drainage functions
Changing flat roof to slope roof
diagonal ridge for hip roof，vertical ridge for gable roof
flat- roof-to- slope-roof
flat-roof-to-slope-roof
flat-roof-to-sloping roof
roof pressure roof weight
roof prism (=roof-angle prism)
2D rigid body spring model
3D rigid limit equilibrium method
3-D rigid limited-equilibrium method
3-D rigid visco plastic FEM