Abstract Concrete-filled steel tubular (CFST) truss is now widely used in many large-span constructions. In the past, relevant studies on the reliability of CFST structures mostly focused on structural components such as individual columns and beams. In current practices, a simplified method based on the ultimate axial strengths of the chords is commonly adopted to predict the flexural strength of a CFST truss, since there is no mature system-based design regulations nor reliability evaluations on this complex composite system. This paper aims to address this gap by advanced structural reliability analysis of CFST truss through numerical approach considering both the structural nonlinearities and random uncertainties. The finite element models are validated against experimental results. Afterwards, a mass finite element simulation, taking into account the material and geometric nonlinearities, random initial imperfections and potential finite element model errors, is conducted to generate the statistics of the flexural strengths of CFST trusses. Reliability analysis is then conducted to calculate reliability indexes in respect of different resistance factors under various load cases based on AASHTO. Finally, reliability-based evaluation on the safety level of CFST truss design according to mainstream design guidelines such as ANSI/AISC 360–16, Eurocode 4:2004 and JGJ/T D65–06–2015 are carried out. Results show that the current component-based strength prediction of CFST trusses meet the target reliability while the current regulations provide uniform reliability.

中文翻译：

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基于可靠性的钢管混凝土（CFST）桁架弯曲载荷评估

摘要 钢管混凝土（CFST）桁架现已广泛应用于许多大跨度建筑中。过去，关于钢管混凝土结构可靠性的相关研究主要集中在单个柱、梁等结构构件上。在目前的实践中，通常采用基于弦杆极限轴向强度的简化方法来预测 CFST 桁架的抗弯强度，因为没有成熟的基于系统的设计规则，也没有针对这种复杂复合系统的可靠性评估。本文旨在通过考虑结构非线性和随机不确定性的数值方法对 CFST 桁架进行高级结构可靠性分析来解决这一差距。有限元模型根据实验结果进行了验证。之后，进行质量有限元模拟，考虑到材料和几何非线性、随机初始缺陷和潜在的有限元模型误差，进行了 CFST 桁架抗弯强度的统计。然后基于AASHTO进行可靠性分析，计算不同载荷工况下不同阻力系数的可靠性指标。最后，根据ANSI/AISC 360–16、Eurocode 4:2004和JGJ/T D65–06–2015等主流设计指南，对CFST桁架设计的安全水平进行了基于可靠性的评估。结果表明，当前基于构件的 CFST 桁架强度预测满足目标可靠性，而当前法规提供统一的可靠性。随机初始缺陷和潜在的有限元模型误差，用于生成 CFST 桁架抗弯强度的统计数据。然后基于AASHTO进行可靠性分析，计算不同载荷工况下不同阻力系数的可靠性指标。最后，根据ANSI/AISC 360–16、Eurocode 4:2004和JGJ/T D65–06–2015等主流设计指南，对CFST桁架设计的安全水平进行了基于可靠性的评估。结果表明，当前基于构件的 CFST 桁架强度预测满足目标可靠性，而当前法规提供统一的可靠性。随机初始缺陷和潜在的有限元模型误差，用于生成 CFST 桁架抗弯强度的统计数据。然后基于AASHTO进行可靠性分析，计算不同载荷工况下不同阻力系数的可靠性指标。最后，根据ANSI/AISC 360–16、Eurocode 4:2004和JGJ/T D65–06–2015等主流设计指南，对CFST桁架设计的安全水平进行了基于可靠性的评估。结果表明，当前基于构件的 CFST 桁架强度预测满足目标可靠性，而当前法规提供统一的可靠性。然后基于AASHTO进行可靠性分析，计算不同载荷工况下不同阻力系数的可靠性指标。最后，根据ANSI/AISC 360–16、Eurocode 4:2004和JGJ/T D65–06–2015等主流设计指南，对CFST桁架设计的安全水平进行了基于可靠性的评估。结果表明，当前基于构件的 CFST 桁架强度预测满足目标可靠性，而当前法规提供统一的可靠性。然后基于AASHTO进行可靠性分析，计算不同载荷工况下不同阻力系数的可靠性指标。最后，根据ANSI/AISC 360–16、Eurocode 4:2004和JGJ/T D65–06–2015等主流设计指南，对CFST桁架设计的安全水平进行了基于可靠性的评估。结果表明，当前基于构件的 CFST 桁架强度预测满足目标可靠性，而当前法规提供统一的可靠性。