大跨度连续钢梁桥主梁设计方案的比选

COMPARISON OF DESIGN SCHEMES OF STEEL MAIN GIRDER OF LONG-SPAN CONTINUOUS BRIDGE

采用有限元方法,对比分析某大跨度连续钢梁桥主梁分别采用连续钢箱梁和连续组合钢箱梁两种方案时结构受力性能差异。分析结果表明:连续组合钢箱梁方案能够在保证主梁截面竖向抗弯刚度不降低前提下,显著降低中间支点附近梁高,从而节省用钢量并减小主梁承受的横向风荷载,提高钢底板和腹板的稳定性能;且通过合理设计能够使主梁的刚度和受力均趋于合理,但同时负弯矩区采用组合截面后,主梁自重增加、截面中性轴降低、施工速度减慢。

The mechanical performance differences of a long-span continuous bridge are analyzed on the assumption that it adopts different main girder,continuous steel box girder or continuous composite box girder.The analytic results indicate that near the middle supports the height of the composite box girder can be obviously lower than the steel box girder on the condition that their vertical rigidities keep the same.And as the height decreases,the steel material of the bridge can be saved and the transversal wind load acting on the main girder can be reduced.Furthermore,the stability of the bottom and the web of the box girder can also be increased.But on the other hand,comparing with the steel box girder,the composite box girder has some shortcomings such as heavier deadweight,lower neutral axis and longer construction period.