Axial compression behavior of square concrete-filled steel tube slender columns with concrete defects

IF 8.3 1区工程技术 Q1 ENGINEERING, CIVIL

Thin-Walled Structures Pub Date : 2026-05-01 Epub Date: 2026-02-13 DOI:10.1016/j.tws.2026.114667

Jiahang Xu, Ting Zhou, Zhihua Chen, Yutong Zhang

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Abstract

Defects formed during concrete casting can degrade the composite action of square concrete-filled steel tube (SCFST) columns, such as interfacial debonding and internal voids. The sensitivity of slender columns to concrete defects differs from that of short columns. This study reports axial compression tests on 34 slender SCFST columns (150 mm × 150 mm × 1500 mm) with five defect types and controlled defect ratios from 0% to 10.12%. The experimental program examines failure modes, load-displacement responses, ultimate capacity, initial stiffness and strain analysis. The disparity between separate distribution (SD) and uniform distribution (UD) defects at equivalent defect ratios is investigated. Results show local outward bulging of the steel tube with crushing of the infilled concrete as the dominant failure mode, while corner-located defects are more prone to induce brittle responses. Capacity reductions range from approximately 0% to 38.50% over the tested defect range. UD defects reduce the bearing capacity more than SD defects under the same defect ratio. The average bearing capacity of slender columns is 7.11% lower than that of short columns with the same defect type and defect ratio, which shows the amplification by second-order effects and the reduction of effective stiffness, especially when defects lie near the mid-height. A three-dimensional FE model is developed and validated against the tests, and a parametric study under pinned-pinned ends is conducted. Based on a validated FE database (63 samples), a unified defect reduction-factor model dependent on defect ratio, distribution pattern, defect type, and relative slenderness is established and incorporated into a defect-adjusted strength formulation. A conservative lower-envelope expression is further provided for design. When the effective length factor is taken as K=0.65 recommended by AISC 360-22, the predictions for 31 defective test specimens show good agreement with the measurements (mean prediction-to-test ratio≈0.997, standard deviation≈0.091).

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含混凝土缺陷方钢管混凝土细长柱轴压特性研究

混凝土浇筑过程中形成的缺陷会降低方钢管混凝土柱的复合作用，如界面剥离和内部空隙。细长柱对混凝土缺陷的敏感性不同于短柱。本文报道了34根细长SCFST柱（150 mm × 150 mm × 1500 mm）的轴压试验，缺陷类型为5种，缺陷率控制在0% ~ 10.12%。实验程序检查失效模式，载荷-位移响应，极限能力，初始刚度和应变分析。研究了在等效缺陷比下，均匀分布缺陷和分离分布缺陷之间的差异。结果表明：钢管局部向外胀形破坏以填充混凝土破碎为主要破坏模式，而角部缺陷更容易诱发脆性响应；在测试缺陷范围内，容量减少范围从大约0%到38.50%。在相同缺陷比下，UD缺陷对承载能力的降低大于SD缺陷。在缺陷类型和缺陷比相同的情况下，细长柱的平均承载力比短柱低7.11%，表现出二阶效应的放大和有效刚度的降低，特别是当缺陷位于中高附近时。建立了三维有限元模型，并进行了试验验证，并进行了钉-钉端下的参数化研究。基于已验证的有限元数据库（63个样本），建立了基于缺陷比率、分布模式、缺陷类型和相对长细度的统一缺陷缩减因子模型，并将其纳入缺陷调整强度公式。进一步为设计提供了保守的下包络表达式。当有效长度系数取AISC 360-22推荐的K=0.65时，31个缺陷试件的预测值与实测值吻合较好（平均预测与试验比≈0.997，标准差≈0.091）。

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来源期刊

Thin-Walled Structures 工程技术-工程：土木

CiteScore

9.60

自引率

20.30%

发文量

801

审稿时长

66 days

期刊介绍： Thin-walled structures comprises an important and growing proportion of engineering construction with areas of application becoming increasingly diverse, ranging from aircraft, bridges, ships and oil rigs to storage vessels, industrial buildings and warehouses. Many factors, including cost and weight economy, new materials and processes and the growth of powerful methods of analysis have contributed to this growth, and led to the need for a journal which concentrates specifically on structures in which problems arise due to the thinness of the walls. This field includes cold– formed sections, plate and shell structures, reinforced plastics structures and aluminium structures, and is of importance in many branches of engineering. The primary criterion for consideration of papers in Thin–Walled Structures is that they must be concerned with thin–walled structures or the basic problems inherent in thin–walled structures. Provided this criterion is satisfied no restriction is placed on the type of construction, material or field of application. Papers on theory, experiment, design, etc., are published and it is expected that many papers will contain aspects of all three.