Efficient Reduced-Order Modeling Tools for Aeroelastic Predictions in Super Long-Span Bridges

超大跨度桥梁的风致振动问题是桥梁设计者关心的一个重要问题。风会以两种不同的方式引起有问题的振动。一种方式是由周期性脱落的旋涡引起的振动，这种旋涡通过与桥梁运动耦合而增强;这就是涡激振动。第二种方式是与严重风暴相关的高速风;在这种情况下，除了其他流体-结构相互作用现象之外，颤振是其灾难性的主要问题。因此，有必要提高设计技术，通过改进的计算能力，考虑到关键的流体力学现象，可能会引起问题的柔性桥梁的振动的发展。一个多学科的研究工作，致力于先进的柔性大跨度悬索桥建模计划。该研究的目标是开发、验证和应用相对复杂的分析工具，以模拟与均匀风和其他重要风条件相关的桥面高度非定常流，并模拟具有扭转、弯曲和轴向激励模式的非线性柔性结构。本研究的主要重点是基于非定常气动非线性指数函数的新降阶模型的开发和应用，以研究大跨度风致桥梁结构振动，主要结果有两个：（i）可获得用于桥梁气动弹性预测的功能强大且价格合理的计算工具;（ii）对空气动力学不稳定性的更好理解，它们的触发机制以及如何预防它们的提示。随着先进的气动弹性建模和计算技术的发展，工程师将能够研究大跨度桥梁固有的结构柔性，以及由于流体-结构相互作用引起的气动非线性。对弹性结构如何响应风的更广泛的理解应该导致新的设计标准和见解，用于大跨度桥梁，风力涡轮机，摩天大楼等的新设计范例。本文的研究成果将为大跨度和超大跨度桥梁以及其他柔性结构系统在气动载荷作用下的非线性流固耦合建模提供理论依据。结果也将是有用的工程师有兴趣改造现有的桥梁与被动和主动流量控制和其他修改，以及帮助有兴趣开发改进的结构健康监测策略的工程师。

Wind-induced vibration of super-long-span bridges is a major concern for bridge designers. The wind can induce problematic vibration in two different ways. One way is the vibration induced by the periodic shedding of vortices that are enhanced by coupling with bridge motion; this is Vortex-Induced Vibration. The second way is the high-speed winds associated with severe storms; in this situation, flutter, among other fluid-structure interaction phenomena, is a major concern for its catastrophic nature. Thus there is a need to enhance the design technology through the development of improved computational capability that takes into account critical fluid mechanical phenomena that potentially induce problematical vibration of flexible bridges. A multi-disciplinary research effort devoted to advanced modeling of flexible long-span suspension bridges is planned. The research is targeted to the development, validation, and application of relatively sophisticated analysis tools to model highly unsteady flow over bridge decks associated with uniform and other important wind conditions and with the nonlinear flexible structures with torsional, bending, and axial modes excited. The main focus of this research is the development and application of new reduced-order models based on unsteady aerodynamic non-linear indicial functions to investigate long-span wind-induced bridge-structure vibration with two major outcomes: (i) the availability of powerful and affordable computational tools for aeroelastic predictions in bridges and (ii) an improved understanding of the aerodynamic instabilities, their triggering mechanisms and hints on how to prevent them. With the development of advanced aeroelastic modeling and computational techniques, engineers will be able to examine the inherent structural flexibility of long-span bridges coupled with aerodynamic nonlinearities due to fluid-structure interactions. The broader understanding of how elastic structures respond to wind should lead to new design criteria and insights for new design paradigms for long span bridges, wind turbines, skyscrapers, only to name a few. The results of this research will advance the knowledge of nonlinear fluid-structure interaction modeling of long- and super-long-span bridges and many other flexible structural systems exposed to aerodynamic loading. The results will also be useful to the engineer interested in retrofitting existing bridges with passive and active flow controls and other modifications as well as help engineers interested in developing improved structural health monitoring strategies.