A parametric study of curved incrementally launched bridges
A parametric study of curved incrementally launched bridges
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DOI：
10.1016/j.engstruct.2012.11.007
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发表时间：
2013-04
影响因子：
5.5
通讯作者：
M. Granata;Piercarlo Margiotta;M. Arici
中科院分区：
文献类型：
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作者：
M. Granata;Piercarlo Margiotta;M. Arici
渐进式桥梁在施工阶段的结构性能取决于不同的参数，包括桥面、桥头、支撑和导向装置，因为静力方案随着桥面在桥墩上方的推进而不断变化。由于这个原因，甲板上的临时应力，在下水期间，与那些在使用寿命中发生的大不相同。水平弯曲下水桥也存在几何曲率引起的扭转效应。为了分析设计参数对桥梁施工的影响，提出了参数化研究方法。分析是通过将基于传递矩阵法的程序扩展到弯曲梁上进行的，这种方法已经被用于直连续甲板。考虑了曲率、前甲板长载荷比、弯曲刚度比和扭转刚度比的影响。结果表明：最大扭转值随曲率半径R的减小和弯曲刚度与扭转刚度之比的减小而增大；此外，随着鼻梁长度比的变化，ln/l=0.60的跨度长度被确定为最优值，对于直桥也是如此。随着机头重量的变化，弯矩和扭转的显著增加只能在发射的悬臂阶段被欣赏。在刚度比和曲率半径变化的情况下，给出了施工阶段弯矩和扭转最大值的无量纲图和相关表达式。
The structural behaviour of incrementally launched bridges in the construction stages depends on different parameters involving deck, nose, supports and guide devices, because static schemes vary continuously with the advance of the deck above the piers. For this reason temporary stresses in the deck, during launching, are rather different from those occurring in service life. Horizontally curved launched bridges also present the effects of torsion induced by geometric curvature. A parametric study is presented in order to analyse the influence of design parameters on the construction of these bridges. Analyses were carried out by extending to curved beams a procedure based on the Transfer Matrix Method, already known for straight continuous decks. Effects of curvature, nose–deck ratios of length and load, bending and torsional stiffness ratio were taken into account. The results show that maximum torsion values increase with the decrease in the curvature radius R and with the decrease in the ratio between bending and torsional stiffness. Moreover, with variation in the nose length ratio, the value ln/l=0.60 with respect to the span length, is confirmed as the optimal value, as happens for straight bridges. With variation in the nose weight, a significant increase in bending moment and torsion can only be appreciated in the cantilever stages of launching. Dimensionless diagrams and related expressions are given for numerical evaluation of the maximum values of bending moment and torsion in the construction stages, with variation in the stiffness ratio and the radius of curvature.