变截面箱梁
box girder with variable cross section
variable cross-section box girder
双箱截面
twin Box Cross - sections
梯形截面箱梁
trapezoidal box section girder
box girder with trapezoidal section
Ⅱ型截面主梁
cross-section main girder
H型截面钢梁的弹性稳定
elastic stability of steel beams
N系列新机型面面观
full aspects of n series models