Laminar tearing of steel plates generally occurs when there is a high tensile stress in the thickness direction of the plate.In welded joints, shrinkage deformation occurs when the weld cools down.If the plate is thin or there is no constraint on the deformation, the plate will deform and thus release the stress.However, if the plate is very thick or there are stiffening ribs, the constraints of neighbouring plates, the plate is constrained not to deform freely, will be perpendicular to the direction of the plate surface to produce a large amount of stress.In the region of very strong constraints, due to weld contraction caused by the local stress may be several times the yield limit of the material, resulting in laminar tearing of the steel plate.