Assessing and improving the vibration and fatigue performance of aluminium pedestrian bridges

与竞争建筑材料相比，铝具有高耐腐蚀性和强度重量比，因此在人行天桥施工中使用铝是有利的。出于这个原因，桥梁设计师开始考虑将铝应用于其缺点（例如刚度较低和初始成本较高）以前被认为是禁止的应用中。 虽然在施工过程中，低自重可能是一个优势，但轻质人行天桥容易受到各种来源的振动，包括行人荷载。活荷载引起的过度振动导致的连接疲劳也是一个问题。在现行的加拿大设计规范中，人行天桥既不是为人群荷载设计的，也不是为行人交通引起的疲劳设计的，即使这些失效模式对轻型铝结构可能是关键的。 目前，围绕行人荷载的建模存在很大的不确定性。具体来说，在用于表示行人群体的模型上，或者在如何将单个行人模型扩展到人群上，没有达成共识。到目前为止，很少有研究成功地尝试验证全尺寸桥梁对使用荷载模型预测的响应，并且没有完全由铝建造的桥梁。 为了设计最佳的振动缓解解决方案的铝人行天桥，并建立负载模型，以方便疲劳验证，目前的建议概述了实验和分析研究范围内进行的几个研究生论文项目。这项研究将包括：开发了一种新的柔性人行天桥荷载模型，对全尺寸铝制人行天桥试件进行了测试和分析，并对铝制人行天桥接头进行了疲劳测试和分析。从这项研究中获得的知识将推进最先进的技术，并使具有成本效益的设计跨度比目前正在建设的实践中更长的铝人行天桥。

The use of aluminum for pedestrian bridge construction can be advantageous due to its high corrosion resistance and strength-to-weight ratio in comparison with competing construction materials. For this reason, bridge designers are starting to consider aluminum in applications where its disadvantages (e.g. lower stiffness and higher initial cost) would have previously been considered prohibitive. Although low self-weight can be an advantage during construction, light weight pedestrian bridges are susceptible to vibrations from a variety of sources, including pedestrian loading. Connection fatigue resulting from excessive vibrations induced by the live loads is also a concern. In the current Canadian design code, pedestrian bridges are neither designed for crowd loads, nor for fatigue due to pedestrian traffic, even though these failure modes may be critical for light aluminum structures. Currently, there is a great deal of uncertainty surrounding the modelling of pedestrian loads. Specifically, there is no consensus on the models to be used to represent groups of pedestrians, or on how to expand an individual pedestrian model to crowds. Very few studies thus far have successfully attempted to verify observed responses in full-scale bridges to predictions using load models, and none for bridges constructed completely out of aluminum. In order to design optimal vibration alleviating solutions for aluminum pedestrian bridges and establish load models to facilitate fatigue verification, the current proposal outlines experimental and analytical research to be conducted within the scope of several graduate thesis projects. This research will include: the development of a new load model for flexible pedestrian bridges, the testing and analysis of a full-scale aluminum pedestrian bridge specimen, and the fatigue testing and analysis of aluminum pedestrian bridge joints. The knowledge obtained from this research will advance the state-of-the-art and enable the cost-effective design of aluminum pedestrian bridges with longer spans than are currently being constructed in practice.