Understanding the Load Transfer Mechanisms between Parallel Wires in Suspension Bridge Cables using Neutron Difraction Measurements and Numerical Modelling

使用中子衍射测量和数值建模了解悬索桥电缆中平行线之间的载荷传递机制

• 批准号: 1233885
• 负责人: Ismail Noyan
• 金额: $ 34.99万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-01 至 2017-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1233885&HistoricalAwards=false
• 关键词: Understanding; Load; Transfer; Mechanisms; between

In suspension bridges the main cables, with many thousands of steel wires compacted together, are crucial for the overall safety; they transfer the entire load--more than several thousand tons-- including the weight of the bridge deck and of any traffic that might be on it, the wind induced forces, etc. to the towers and to the anchorage blocks. If the cable fails, the entire bridge is lost. Full inspection of cables during service is not feasible; assessing the strength of a main cable is accomplished through partial inspections and numerical models. The goal of this research is to provide bridge engineers with experimental and numerical tools to assess the remaining strength of suspension bridge cables. The experimental part of the study will use deeply-penetrating, non-destructive, neutron beams to measure position-specific stress/strain data from model bridge cable strands under realistic boundary conditions. These data will, then, be used to develop numerical and theoretical models for predicting the load carrying capacity, safety factors and reliability, as well as service life, of parallel-wire suspension bridge cables, both under design and currently in service. In neutron diffraction the lattice parameter of the steel is utilized as an internal strain gage. The change in this parameter as a function of applied load yields the elastic strain. In the experimental phase focussed neutron beams will be used to measure the strain partitioning within individual wires of model cables while they are loaded past failure. Thermal neutrons can easily penetrate 45 mm of steel and, thus, measurement of the local strains within the inner wires is possible. The experiments will be carried out for various bundle configurations with selected lubricant/corrosion preventative treatments. The data obtained from the experiments will then be utilized in an extended 3-D finite element model being developed on the supercomputing facilities available at Columbia University. Once finished, this model is expected to yield accurate predictions on the load carrying capabilities of parallel wires and can be extendable to the assessment of the ultimate strength of the overall main cable in a suspension bridge.

在悬索桥中，主缆与数千根钢丝紧密结合在一起，对整体安全至关重要；它们将整个荷载--超过数千吨--包括桥面和可能在其上的任何交通的重量、风力等传递到塔架和锚固块。如果电缆发生故障，整个桥都会丢失。在服役期间对电缆进行全面检查是不可行的；评估主缆的强度是通过部分检查和数值模型来完成的。本研究的目的是为桥梁工程师提供评估悬索桥拉索剩余强度的实验和数值工具。该研究的实验部分将使用深度穿透、无损的中子束来测量实际边界条件下的模型桥梁缆索的特定位置的应力/应变数据。然后，这些数据将被用来建立数值和理论模型，以预测设计中和目前在役的平行钢丝悬索桥缆索的承载能力、安全系数和可靠性，以及使用寿命。在中子衍射法中，钢的点阵参数被用作内部应变计。作为施加载荷的函数，该参数的变化产生弹性应变。在实验阶段，聚焦中子束将被用来测量模型电缆在加载到失效后的单个导线内的应变分配。热中子可以很容易地穿透45毫米厚的钢，因此，测量内部导线内的局部应变是可能的。试验将针对具有选定的润滑剂/防腐处理的各种束状结构进行。然后，从实验中获得的数据将被用于在哥伦比亚大学现有的超级计算设施上开发的扩展三维有限元模型。一旦完成，该模型有望对平行钢丝绳的承载能力做出准确的预测，并可推广到悬索桥主缆整体极限强度的评估。