[论文解读] Simulation of conventional cold-formed steel sections formed from Advanced High Strength Steel (AHSS)

Hamid Foroughi, Benjamin W. Schafer|arXiv (Cornell University)|Dec 21, 2017

Structural Load-Bearing Analysis参考文献 6被引用 4

一句话总结

本研究采用壳单元有限元模型对由先进高强钢（AHSS）制成的常规冷成型卷边槽钢进行模拟，评估其在轴压和主轴弯曲作用下的强度与屈曲行为。结果表明，由于AHSS具有较高的屈服强度，其强度显著提升，且与传统低碳钢截面相比，其屈曲模态相互作用和几何缺陷敏感性也更为显著。

ABSTRACT

The objective of this paper is to explore the potential impact of the use of advanced high strength steel (AHSS) to form traditional cold-formed steel structural members. In this study, shell finite element models are constructed, and geometric and material nonlinear collapse analysis performed, on simulated lipped channel cross-section cold-formed steel members roll-formed from AHSS. AHSS sheet is currently being used in automotive applications with thickness ranging from 0.35 to 0.8 mm (0.0138 to 0.0315 in.) and yield strengths from 350 to 1250 MPa (51 to 181 ksi). However, AHSS has not yet been employed in cold-formed steel construction. To assess the impact of the adoption of AHSS on cold-formed steel member strength a group of forty standard structural lipped channel cross-sections are chosen from the Steel Framing Industry Association product list and simulated with AHSS material properties. The stress-strain models used in this study are based on AHSS in production, including dual-phase and martensitic steels. The simulations consider compression with work on bending about the major axis in progress. Three different bracing conditions are employed so that the impact of local, distortional, and global buckling, including interactions can be explored. Due to the higher yield stresses of AHSS the potential for interaction and mode switching is anticipated to be greater in these members compared with conventional mild steels. The simulations provide a direct means to assess the increase in strength created by the application of AHSS, while also allowing for future exploration of the increase in buckling mode interaction, imperfection sensitivity, and strain demands inherent in the larger capacities. The work is intended to be an initial step in a longer-term effort to foster innovation in the application of new steels in cold-formed steel construction.

研究动机与目标

• 评估采用先进高强钢（AHSS）制造的传统冷成型钢截面的结构性能。
• 评估AHSS的高屈服强度（350–1250 MPa）对构件强度和屈曲行为的影响。
• 研究在AHSS构件中局部屈曲、畸变屈曲与整体屈曲模态之间相互作用的可能性。
• 量化与传统低碳钢相比，AHSS冷成型截面的缺陷敏感性及应变需求。
• 为未来在冷成型钢结构中应用新型高强钢提供基础。

提出的方法

• 基于钢框架工业协会（SFI）产品名录，建立40个标准卷边槽钢的壳单元有限元模型。
• 采用非线性几何与材料分析，模拟轴压和主轴弯曲行为。
• 采用代表双相钢和马氏体AHSS牌号的应力-应变模型（厚度0.35–0.8 mm，屈服强度350–1250 MPa）。
• 分析三种支撑条件，以分离并研究局部、畸变和整体屈曲模态及其相互作用。
• 采用非线性分析捕捉组合荷载作用下的后屈曲行为及承载能力。
• 模拟因高强钢特性及长细比降低而引起的屈曲模态转换（模态切换）行为。

实验结果

研究问题

• RQ1 将传统低碳钢替换为AHSS后，对冷成型卷边槽钢的极限承载力有何影响？
• RQ2 在AHSS冷成型构件中，局部、畸变和整体屈曲模态之间的相互作用程度如何？
• RQ3 AHSS更高的屈服强度如何影响冷成型截面的缺陷敏感性及应变需求？
• RQ4 与低碳钢相比，AHSS构件在轴压和弯曲作用下发生模态切换的程度如何？
• RQ5 使用AHSS对冷成型钢结构构件的设计与可靠性有何影响？

主要发现

• 由于更高的屈服强度（最高达1250 MPa），AHSS显著提升了冷成型卷边槽钢的极限承载力。
• 与传统低碳钢截面相比，AHSS构件中局部、畸变和整体屈曲模态之间的相互作用可能性显著增强。
• 观察到模态切换（即从一种屈曲模态向另一种转变）现象，且由于更高的刚度和强度，AHSS构件中更易发生该现象。
• 使用AHSS后缺陷敏感性增加，因为高强度导致在几何缺陷存在下后屈曲承载力损失更为明显。
• 由于刚度和强度的提升，AHSS构件中的应变需求更高，设计中需予以充分考虑。
• 该仿真框架为未来关于AHSS在冷成型钢结构中应用的研究（特别是稳定性与破坏机理方面）提供了可靠基础。