Welded lightweight H-beam is welded with the upper flange, the lower flange and the web using the high-frequency automatic welder. Welded lightweight H-beam is thinner than rolled steel and has excellent cross-sectional and bending resistance. As shown in the table below, when comparing the welded H-beam with the rolled steel with similar cross-sectional performance and cross-sectional area, the secondary moment and section modulus of the welded H-beam in the direction of the steel axis are 2.98 times and 1.78 times higher than those of Rolled H-beam.  
Therefore, using large H-shaped steel for the primary member(Column/Beam) of the long span structure where the bending stress and flexural deformation determine the member size, and using the welded H-shaped steel for the secondary member(Joint Beam/Sub Beam/Purlin), it has 30~ 40% of steel reduction effect.
In addition, Welded lightweight H-beam can use high tensile strength steel sheet such as SM400-> SM490-> SM520 to increase tensile strength and to reduce steel weight. And because it can be produced with exact order length even in small quantity in the manufacturing process, it can reduce material loss and is very economical. It is possible to produce a special size such as a small section(web length 50~75mm, thickness 2.3mm) that can not be supplied by rolling steel and a T-section with only one flange etc., so the economical side of the product can be increased.