Abstract Synchrotron accelerator facilities such as the NSLS II require extreme stability, both transient (short-term) and quasi-static (long-term) to achieve the desired resolution performance. Consequently, even μm-level movements, particularly differential movements between locations in the concrete structure supporting the accelerator electron beam lattice (storage ring) or high sensitivity experiments (experimental floor) will lead to serious degradation of its performance. Differential settlement in the overall structure or structural movement exceeding anticipated levels will inevitably degrade the performance and will require intervention. Presented in this paper are the design philosophy of the NSLS II ring structure favoring a monolithic ring, the observed cracking behavior of the young NSLS II concrete following casting and in combination with extreme ambient temperature fluctuation, the results of a non-linear, high-fidelity numerical analysis used to emulate the observed cracking and establish the driving mechanism, the numerical analysis-based identification of the crack-arresting solution and finally the implementation of the remediation solution and the long-term performance of the adopted engineering solution. The multi-stage process revealed that computational methods such as non-linear finite element methods have the potential of providing engineering guidance even when complex structures and in combination with non-linear materials, such as steel reinforcement and concrete are involved.

中文翻译：

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NSLS II同步加速器大体积混凝土结构热致开裂及其工程修复

摘要 同步加速器设施如 NSLS II 需要极高的稳定性，包括瞬态（短期）和准静态（长期），以实现所需的分辨率性能。因此，即使是微米级的运动，特别是支撑加速器电子束晶格（存储环）或高灵敏度实验（实验地板）的混凝土结构中位置之间的差异运动，也会导致其性能严重下降。整体结构的差异沉降或超出预期水平的结构运动将不可避免地降低性能并需要干预。本文介绍了 NSLS II 环结构的设计理念，有利于整体环，在浇筑后观察到的年轻 NSLS II 混凝土的开裂行为，并结合极端环境温度波动，非线性、高保真数值分析的结果用于模拟观察到的开裂并建立驱动机制，数值分析-基于对裂缝抑制解决方案的识别，最后是修复解决方案的实施以及所采用工程解决方案的长期性能。多阶段过程表明，即使涉及复杂结构并与非线性材料（如钢筋和混凝土）结合时，非线性有限元方法等计算方法也具有提供工程指导的潜力。用于模拟观察到的裂缝并建立驱动机制的高保真数值分析，基于数值分析的裂缝抑制解决方案的识别，最终修复解决方案的实施和所采用的工程解决方案的长期性能。多阶段过程表明，即使涉及复杂结构并与非线性材料（如钢筋和混凝土）结合时，非线性有限元方法等计算方法也具有提供工程指导的潜力。用于模拟观察到的裂缝并建立驱动机制的高保真数值分析，基于数值分析的裂缝抑制解决方案的识别，最终修复解决方案的实施和所采用的工程解决方案的长期性能。多阶段过程表明，即使涉及复杂结构并与非线性材料（如钢筋和混凝土）结合时，非线性有限元方法等计算方法也具有提供工程指导的潜力。基于数值分析的裂缝抑制解决方案的识别，最终修复解决方案的实施以及所采用的工程解决方案的长期性能。多阶段过程表明，即使涉及复杂结构并与非线性材料（如钢筋和混凝土）结合时，非线性有限元方法等计算方法也具有提供工程指导的潜力。基于数值分析的裂缝抑制解决方案的识别，最终修复解决方案的实施以及所采用的工程解决方案的长期性能。多阶段过程表明，即使涉及复杂结构并与非线性材料（如钢筋和混凝土）结合时，非线性有限元方法等计算方法也具有提供工程指导的潜力。