Behaviour of unpropped composite girders curved in plan under construction loading
Behaviour of unpropped composite girders curved in plan under construction loading
复制标题
施工荷载下平面弯曲无支撑组合梁的行为
DOI：
10.1016/s0141-0296(00)00097-3
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发表时间：
2001
影响因子：
5.5
通讯作者：
Y. Pi
中科院分区：
文献类型：
--
作者：
M. Bradford;B. Uy;Y. Pi
钢-混凝土组合曲线桥梁经常用于高速公路，特别是在高速要求平稳换向的高速公路互通立交中。钢-混凝土组合曲线桥梁通常由水平弯曲的钢梁和混凝土桥面板组成。由于经济和施工方便，工字形钢梁的使用是很常见的。在施工过程中，曲线钢梁承受由自重和湿混凝土桥面组成的均布荷载。在这一阶段，每根梁分别充当单独的简支曲线梁，其大部分荷载作用于顶部翼缘水平。通常认为，线性分析可以用来预测平面曲线工字形组合梁在施工过程中的结构性能。然而，当平面上弯曲的工字形截面梁受到竖向均布荷载时，它会经历一次弯曲和非均布扭转作用。正因为如此，垂直于梁平面的竖直挠度与横截面的扭转转动相耦合。主要的弯曲和扭转作用、垂直挠度和扭转旋转耦合在一起，在曲线梁的平面内和平面外产生二阶弯曲作用。这些行为之间的相互作用可以迅速发展，并产生早期的非线性行为，甚至早期屈服。因此，线性理论的预测对于施工过程中平面曲线的组合钢和混凝土工字形截面梁的性能可能具有很大的误导性。本文采用作者建立的高效非线性弹塑性曲梁有限元模型，对平面曲线工字形组合梁的施工过程中的结构性能进行了研究。结果表明，在施工荷载作用下，需要对梁的结构性能进行非线性分析。为了防止组合曲线梁在施工过程中的破坏，必须确定施工过程中钢结构曲线梁的承载能力，并采取预防措施。
Composite steel and concrete curved bridges are often used in highways, particularly for motorway interchanges where high speeds require smooth changes in direction. A composite steel and concrete curved bridge often consists of horizontally curved steel girders and concrete deck slabs. The use of steel I-section curved girders is commonplace because of their economy and ease of construction. During construction, the curved steel girder carries a uniformly distributed load, comprising its self-weight and the wet concrete deck. At this stage, each girder acts separately as an individual simply supported curved beam, with much of its load acting at the top flange level. It is often considered that linear analysis may be used to predict the structural behaviour of composite steel and concrete I-section girders curved in plan during construction. However, when an I-section girder curved in plan is subjected to a vertical uniformly distributed load, it experiences primary bending and non-uniform torsion actions. Because of this, the vertical deflections perpendicular to the plane of the girder are coupled with the twist rotations of the cross-section. The primary bending and torsion actions, vertical deflections and twist rotations couple together to produce second-order bending actions in and out of the plane of the curved girder. The interactions between these actions can grow rapidly, and produce early nonlinear behaviour and even early yielding. Hence, the predictions of a linear theory may be very misleading for the behaviour of composite steel and concrete I-section girders curved in plan during construction. This paper uses an efficient nonlinear inelastic curved beam finite element model developed by the authors to investigate the structural behaviour of composite steel and concrete I-section girders curved in plan during construction. It is found that a nonlinear analysis is needed to predict the structural behaviour of the girders under construction loading. The load carrying capacity of the steel curved girders during construction has to be ascertained and precautions may have to be taken to prevent the failure during construction of the composite curved girders.