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

与竞争对手的建筑材料相比，铝的耐腐蚀性和强度重量比高，因此在人行天桥建设中使用铝可能是有利的。出于这个原因，桥梁设计者开始考虑将铝材应用于其缺点(例如，较低的刚度和较高的初始成本)的应用中。 虽然自重低是施工过程中的一个优势，但轻质人行天桥容易受到各种来源的振动，包括行人荷载。由活载引起的过度振动导致的连接疲劳也是一个令人担忧的问题。在目前的加拿大设计规范中，人行天桥既不是为人群荷载而设计的，也不是为行人交通造成的疲劳而设计的，即使这些破坏模式对于轻型铝结构可能是关键的。 目前，行人负载的建模存在很大的不确定性。具体地说，对于用于表示行人群体的模型，或者如何将单个行人模型扩展到人群，还没有达成共识。到目前为止，很少有研究试图成功地验证在全尺寸桥梁中观察到的使用荷载模型预测的反应，还没有一项研究完全用铝建造的桥梁。 为了设计铝合金人行天桥的最佳减振方案，并建立便于疲劳验证的荷载模型，本提案概述了将在几个研究生论文项目范围内进行的实验和分析研究。本文的研究内容包括：柔性人行天桥新型荷载模型的建立、足尺铝制人行天桥试件的试验与分析、铝制人行天桥节点的疲劳试验与分析。从这项研究中获得的知识将促进最先进的技术，并使铝人行天桥的成本效益设计比目前正在建设的跨度更长的实践。

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.