Abstract
In this study, the chemical compositions, mechanical properties and structural bending tests of cold rolled carbon steel square pipe in accordance with their width-thickness ratio are quantitatively estimated. Each material test(chemical compositions, mechanical test, charphy impact test, welding performance etc) are conducted under the S test conditions. The main results show that : 1) the ultimate bending strength is much great, and the energy dissipation capacity is very well, which can make to consume great energy in earthquake. 2) the final modes of bending specimens are obtained by the local buckling and fracture of welding vicinity.