摘要：to save material circle and hexagon are often used shapes for web opening in praxis; horizontal plates are often welded on web for stiffening large web opening. These common used shape of opening and stiffening way for large opening are proved as inefficient by finite element analyze. There are new shape of opening and new type of stiffener for large opening, which proved to have the best load bearing behavior respectively. More details will be introduced in following.
