考虑体系复杂边界的RC与钢连梁高效精细化实用计算模型研究

Due to the relatively high lateral resisting efficiency, coupled walls and core tubes become the most widely-used primary lateral resisting system for high-rise structures. As the primary energy dissipation component, the seismic behaviors of the coupling beams are very complicated and have very significant influences on the overall structural seismic performance. The RC coupling beam (including conventional, diagonal and hybrid layout) and steel coupling beam are most widely applied in construction among all the coupling beams. However, the mechanism of the coupling beams subjected to complex boundary conditions in the structural system remains unclear and the reasonable models with sufficient accuracy and efficiency for large-scale structural seismic analysis are in urgent need, which may cause remarkable influences to the rationality, economy and safety of the design of high-rise structures. This project plans to quantitatively investigate the influences of complex boundary conditions in real structures on the cyclic behavior of coupling beams by test and numerical analysis and proposes practical design methods. Beam models with satisfactory efficiency and accuracy are then proposed and developed for the two coupling beams. In addition, the model will be applied to conduct elasto-plastic time-history analysis on high-rise structures and the influences of coupling beam parameters on the key structural seismic performance indexes are intensively investigated. Based on the sensitivity analysis, the model can be properly simplified to become a reliable and practical model with satisfactory balance between efficiency and accuracy. The achievement of this project will improve the seismic design of tall buildings and provide a powerful tool for the further research of their seismic performance.

联肢剪力墙和核心筒由于其较高的抗侧效率，是高层结构中应用最广的主抗侧体系。连梁作为该类结构耗能的主体，是受力机理最复杂、对体系抗震性能影响最大的关键元件。工程中常用的连梁包括钢筋混凝土连梁（普通、对角和混合配筋）和钢连梁。目前尚缺乏对这两类连梁在体系复杂边界条件下受力机理的清晰认识和在大规模体系分析中进行高效精细化模拟的成熟手段，严重影响了高层结构设计的合理性、经济性和安全性。本项目拟针对这两类连梁，首先通过试验和精细有限元分别揭示实际结构复杂边界条件对其受力性能的影响规律，并提出相应的设计方法。随后提出能够反映连梁复杂受力特性的高效精细化杆系计算模型。最后利用该模型对体系进行地震弹塑性时程分析，研究连梁各参数变化对体系抗震性能指标的影响规律，在此基础上对模型做出合理的简化，提出一个高效又可靠的连梁实用计算模型。本项目研究将完善高层结构的抗震设计并为深入研究其抗震性能提供重要工具。

钢筋混凝土（RC）联肢剪力墙结构在高层建筑中应用广泛，但其关键构件连梁种类多样、受力机理和边界条件复杂、，一直以来都缺少相应的高效精准数值计算模型，同时也导致联肢剪力墙体系的数值模拟存在精度与效率方面的欠缺。且连梁复杂受力行为对联肢剪力墙抗震性能的定量影响规律仍不够明确。本报告针对上述联肢剪力墙结构机理与模型方面的关键问题，完成以下研究：1）体系复杂边界条件下连梁受力机理与设计方法研究，完成了4个不同剪跨比和钢筋配置比例的RC连梁抗震性能试验，揭示了各类钢筋及混凝土对连梁抗剪的贡献机制和比例，及轴向约束对连梁抗震性能的影响规律，提出了开裂后剪切刚度和抗剪承载力计算方法。基于精细壳单元模型开展参数分析，揭示了翼缘和轴向约束对钢连梁抗剪行为的影响规律。2）连梁高效精细化数值模型研究，在传统纤维模型基础上，提出了考虑剪切和斜筋滑移的对角斜筋RC连梁纤维模型和考虑翼缘贡献的钢连梁二维纤维模型。3）联肢剪力墙体系梁壳混合高效精细化模型及其应用研究，集成了联肢剪力墙体系计算模型，利用该模型开展参数分析揭示了连梁复杂受力行为对体系抗震性能的影响规律。研究发现：RC连梁最大轴压比达11.8%，考虑轴力与否对承载力有很大影响；钢连梁翼缘和腹板厚度、连梁长度、钢材强度参数等是影响翼缘剪应变的关键因素。当截面翼缘-腹板面积比大于3时，翼缘和轴向约束可导致承载力分别增加20%和35%；提出的对角配筋RC连梁计算模型能够广泛适用于跨高比1-5范围内的对角配筋连梁；提出的钢连梁模型可同时考虑影响连梁超强的三大要素：即翼缘贡献、轴向约束和钢材强化；忽略连梁的剪切滑移或斜筋滑移变形将高估体系的耗能能力，采用传统纤维模型将显著高估体系的刚度和耗能，体系受力行为对连梁下降段斜率和极限弦转角不敏感。本报告研究成果为高层结构设计和弹塑性时程分析提供了更为可靠方便的工具和方法，有助于更精准地把握结构的受力行为和破坏模式并提升其抗震性能。