Since the steel output of our country reached a new high of 100 million tons in 1990s and the government set forth the policy of encouraging the wide application of steel-structure buildings, the steel-structure buildings have been developed swiftly, which has brought a profound change to the building structure system and become the backbone of the times.

In his literary works, Lu Xun praised the spirit of revenge for anti-oppression by using such words as "Mara","intermediate element" and "backbone" in different historical periods and social contradictions.

Analysis of shear lag effect of great cantilever steel box beam;

By using the method of finite element,the author tries to offer the tentative analysis of the shear lag effect of cantilever box beam on the horizontal force and bend moment.

By using the method of finite element,the author tries to offer the tentative analysis of the additional effect on the stress that torsion brings to cantilever box beam.

Based on the calculation and analysis of models with structural parameters such as radius and load position discussed,the rules of longitudinal and transverse stress distribution,the shear lag effect and the variational law with parameters in up supported curved spine beam are educed.