Design of structural steel members by advanced inelastic analysis with strain limits
Design of structural steel members by advanced inelastic analysis with strain limits
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通过带有应变极限的高级非弹性分析设计结构钢构件
DOI：
10.1016/j.engstruct.2019.109624
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发表时间：
2019
影响因子：
5.5
通讯作者：
L. Macorini
中科院分区：
文献类型：
--
作者：
Andreas Fieber;L. Gardner;L. Macorini
钢结构设计通常分为两个步骤：首先，通过结构分析确定结构中的内力和力矩。然后，进行一系列的设计检查，以评估个别成员的强度和稳定性。结构分析通常使用梁有限元进行，梁有限元通常不能明确地捕获局部屈曲。相反，局部屈曲和旋转能力的评估是通过横截面分类的概念进行的，该概念对分析类型（即塑性或弹性）进行了特定类别的限制，并根据理想化的应力分布（例如弯曲时的塑性、弹性或有效弯矩能力）定义了横截面阻力。然而，这种方法被认为是过于简单化，并创建人工步骤的能力预测的结构构件。本文提出了一种更一致的方法，即使用梁有限元对结构或结构部件进行二阶非弹性分析，并采用应变极限来模拟局部屈曲的影响，控制塑性的扩展并最终定义结构阻力。应变极限由连续强度法得到。它示出，不仅可以准确地表示在经历均匀的横截面变形沿着长度的成员，但局部屈曲，通过施加应变限制的应变，平均超过一个定义的特征长度，也可以利用的有益效果的局部力矩梯度。所提出的方法进行评估对基准壳有限元结果的孤立成员进行弯曲，压缩和组合加载。与传统的钢结构设计规定相比，甚至与现有的利用二阶弹性分析的先进设计方法相比，所提出的设计方法始终提供更准确的容量预测。
Structural steel design is traditionally a two step process: first, the internal forces and moments in the structure are determined from a structural analysis. Then, a series of design checks are carried out to assess the strength and stability of individual members. The structural analysis is typically performed using beam finite elements, which are usually not able to capture local buckling explicitly. Instead, the assessment of local buckling and rotation capacity is made through the concept of cross-section classification, which places class-specific restrictions on the analysis type (i.e. plastic or elastic) and defines the cross-section resistance based on idealised stress distributions (e.g. the plastic, elastic or effective moment capacity in bending). This approach is however considered to be overly simplistic and creates artificial steps in the capacity predictions of structural members. A more consistent approach is proposed herein, whereby a second-order inelastic analysis of the structure or structural component is performed using beam finite elements, and strain limits are employed to mimic the effects of local buckling, control the spread of plasticity and ultimately define the structural resistance. The strain limits are obtained from the continuous strength method. It is shown that not only can local buckling be accurately represented in members experiencing uniform cross-sectional deformations along the length, but, by applying the strain limits to strains that are averaged over a defined characteristic length, the beneficial effects of local moment gradients can also be exploited. The proposed method is assessed against benchmark shell finite element results on isolated members subjected to bending, compression and combined loading. Compared to conventional steel design provisions and even to existing advanced design approaches utilising second-order elastic analysis, the proposed design approach provides consistently more accurate capacity predictions.