Improved consideration of dynamic loads and effects in design of exposed structures

目前的结构工程实践仍然广泛依赖于静态分析方法进行设计。经过30多年的广泛使用的极限状态或基于可靠性的设计方法在大多数结构设计规范在世界各地，这种方法暴露了其弱点评估的机械安全性和完整性的关键结构暴露在极端的环境载荷。近年来引入的基于性能的设计方法在很大程度上依赖于过去的方法，基本上接受极限状态设计解决方案作为可接受的解决方案，将安全性和完整性的问题留给设计师来解释。大多数极端环境荷载对暴露结构具有潜在的动力效应，在预测结构响应时，考虑破坏或连续倒塌情况通常不能忽略这些动力效应。因此，真正的基于性能的设计排除了可靠和相对准确的响应预测，这在简化的静态方法中很少可行。本研究计划的目标是评估加拿大国家建筑规范和其他相关的加拿大结构设计标准中描述的一些简化静载荷方法的准确性，以预测暴露结构对环境载荷效应（如湍流风、大气结冰以及风和冰的综合效应）的响应。研究的结构类型限于架空输电线路支架、通信塔和桅杆，以及各种暴露的非建筑物网格结构和电缆结构（不包括桥梁）。科学方法将结合联合收割机对现有实验结果（来自风洞试验或监测）的严格审查，这些结果支持当前的简化载荷计算方法和先进的计算力学技术。特别是，将检查流体-结构相互作用，无论是裸和冰的柔性结构在模拟现实的湍流风条件。

Current structural engineering practice continues to rely extensively on static analysis methods for design. After over 30 years of extensive use of the limit states or reliability-based design method in most structural design codes worldwide, this approach has exposed its weaknesses for assessing the mechanical security and integrity of critical structures exposed to extreme environmental loads. The performance-based design approach introduced in recent years relies heavily on past methods, essentially accepting limit-states design solutions as acceptable solutions, leaving the issues of security and integrity to the interpretation of designers. Most extreme environmental loads have potentially dynamic effects on exposed structures, and consideration of failure or progressive collapse scenarios cannot generally ignore those dynamic effects when predicting structural response. As such, true performance-based design precludes reliable and relatively accurate response prediction that is rarely feasible with simplified static methods. The goal of this research program is to assess the accuracy of some simplified static load methods described in the National Building Code of Canada and other relevant Canadian structural design standards to predict the response of exposed structures to environmental load effects such as turbulent wind, atmospheric icing, and combined wind and ice effects. The types of structures to be studied are restricted to overhead transmission line supports, telecommunication towers and masts, and various exposed non-building lattice structures and cable structures (excluding bridges). The scientific approach will combine a critical review of the available experimental results (from wind-tunnel tests or monitoring) that support current simplified load calculation methods and advanced computational mechanics techniques. In particular, fluid-structure interactions will be examined, both for bare and iced flexible structures in simulated realistic turbulent wind conditions.