Computational issues in biaxial bending capacity assessment of RC and composite cross-sections exposed to fire

IF 4.4 2区 工程技术 Q1 COMPUTER SCIENCE, INTERDISCIPLINARY APPLICATIONS
Cosmin G. Chiorean
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Abstract

This paper introduces an advanced computational method for assessing the biaxial bending capacities of arbitrary-shaped reinforced concrete and steel–concrete composite cross-sections under fire conditions. The proposed approach involves a strain-driven iterative method coupled with an adaptive plastic centroid providing a “fail-safe” methodology by combining the bisection and damped Newton methods to improve its global convergence properties. Several key computational issues are addressed: (1) strength assessment criteria and its impact on computational outcomes, (2) the pathological behavior of local convergent iterative methods causing divergence or spurious solutions in stress-resultant space, (3) the softening behavior of concrete in compression affecting solution uniqueness and interaction diagram convexity, (4) non-planar vertical interaction diagrams induced by a mobile centroid, and (5) computational challenges related to solution non-uniqueness or non-existence in M-M stress resultant space when axial force falls outside the iso-load contour. An additional notable feature and novelty of the proposed method lie in its unique capability to assess true plane vertical interaction diagrams enabling also both ultimate and nominal strength assessment. Validation includes comparisons with other numerical results and experimental data from international literature, extending the benchmark results for the strength capacity assessment of composite cross-sections exposed to high temperatures.

暴露于火灾中的钢筋混凝土和复合材料横截面双轴弯曲承载力评估中的计算问题
本文介绍了一种先进的计算方法,用于评估任意形状的钢筋混凝土和钢-混凝土复合截面在火灾条件下的双轴受弯能力。所提出的方法采用应变驱动迭代法,并结合自适应塑性中心法,提供了一种 "故障安全 "方法,通过结合二分法和阻尼牛顿法来改善其全局收敛特性。该方法解决了几个关键的计算问题:(1) 强度评估标准及其对计算结果的影响,(2) 局部收敛迭代法的病理行为导致应力结果空间中的发散或虚假解,(3) 混凝土在压缩过程中的软化行为影响解的唯一性和相互作用图的凸度,(4) 移动中心点引起的非平面垂直相互作用图,以及 (5) 当轴向力落在等荷载等值线之外时,M-M 应力结果空间中解的非唯一性或不存在带来的计算挑战。所提方法的另一个显著特点和新颖之处在于,它具有评估真实平面垂直相互作用图的独特能力,可同时评估极限强度和名义强度。验证包括与其他数值结果和国际文献中的实验数据进行比较,扩展了暴露在高温下的复合材料横截面强度能力评估的基准结果。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Computers & Structures
Computers & Structures 工程技术-工程:土木
CiteScore
8.80
自引率
6.40%
发文量
122
审稿时长
33 days
期刊介绍: Computers & Structures publishes advances in the development and use of computational methods for the solution of problems in engineering and the sciences. The range of appropriate contributions is wide, and includes papers on establishing appropriate mathematical models and their numerical solution in all areas of mechanics. The journal also includes articles that present a substantial review of a field in the topics of the journal.
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