Structural behaviour and design criteria of under-deck cable-supported footbridges

桥面下斜拉桥、桥面下悬索桥和应力带等都是非常有效和经济的结构。其效率的主要原因是它们主要在轴向力下工作，利用整个截面积，从而导致所需材料的显着减少。因此，这些结构可以非常细长，在美学和可持续性方面提供令人满意的结果。然而，这些类型的人行桥，由于其细长，是非常容易受到振动的正常使用极限状态。几座桥面下缆索支撑的人行桥，如伦敦的千禧桥，由于振动而出现了适用性问题。这表明，在设计负荷模型时考虑的基本假设并不现实。因此，最近对动态人致力、人-结构动力相互作用和行人同步进行了更详细的研究[1]。使用随机分析来估计这些类型的动作可能会对克服适用性问题产生重大影响，从而导致更经济，可持续和可靠的设计。本研究项目的目的是描述桥面下缆索支撑人行桥类型的静态和动态结构行为，并提出这些结构的设计标准。研究将基于结构分析软件开发的有限元模型

The under-deck cable supported footbridges vary from under-deck cable-stayed bridges to under-deck suspensions bridges and stress ribbons, being all very effective and economic structures. The main reason for their efficiency is that they are working mainly under axial forces, taking advantage of the whole sectional area and thus leading to a significant reduction in the required materials. As a result, these structures can be very slender providing a satisfactory result in terms of aesthetic and sustainability. However, these types of footbridges, due to their slenderness, are quite susceptible to vibrations at the serviceability limit state. Several under-deck cable supported footbridges, such the Millennium Bridge in London, have had serviceability problems due to vibrations. That indicates that fundamental assumptions considered when developing load models, applied in their design, were not realistic. For that reason, a more detailed research of dynamic human-induced forces, human-structure dynamic interaction and pedestrian synchronization have been recently conducted [1]. The use of stochastic analysis for the estimation of these types of actions could have a significant impact in overcoming serviceability issues, leading to a more economic, sustainable and reliable design. The aim of this research project is to describe the static and dynamical structural behaviour of under-deck cable supported footbridge typologies and to propose design criteria for these structures. The study will be based on the FE models developed with Structural Analysis Software