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

超长跨度桥梁的风振问题一直是桥梁设计人员关注的问题。风会以两种不同的方式引起有问题的振动。一种是由旋涡周期性脱落引起的振动，旋涡周期性脱落与桥梁运动耦合增强；这就是涡激振动。第二种方式是与强风暴相关的高速风；在这种情况下，颤振和其他流固耦合现象一样，由于其灾难性的性质而引起了人们的关注。因此，有必要通过改进计算能力的发展来提高设计技术，考虑到可能引起柔性桥梁问题振动的关键流体力学现象。针对柔性大跨度悬索桥的先进建模问题，开展了多学科的研究工作。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动，以及受扭、弯和轴向模态激励的非线性柔性结构。本研究的主要重点是基于非定常气动非线性指示函数的新型降阶模型的开发和应用，以研究大跨度风致桥梁结构振动，主要有两个结果：(i)为桥梁气动弹性预测提供了功能强大且价格合理的计算工具；（ii）提高了对气动不稳定性、其触发机制和如何预防它们的理解。随着先进的气动弹性建模和计算技术的发展，工程师们将能够研究大跨度桥梁固有的结构灵活性，以及由于流固耦合引起的气动非线性。对弹性结构如何对风做出反应的更广泛的理解应该会导致新的设计标准和对大跨度桥梁，风力涡轮机，摩天大楼等新设计范例的见解。本研究结果将促进大跨度和超长跨度桥梁以及许多其他受气动载荷影响的柔性结构系统的非线性流固耦合建模。结果也将有助于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，以及帮助工程师有兴趣开发改进的结构健康监测策略。

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.