Correction factors for stress intensity of CFRP-strengthened wide-flange steel beams with various crack configurations
Correction factors for stress intensity of CFRP-strengthened wide-flange steel beams with various crack configurations
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DOI：
10.1016/j.conbuildmat.2014.08.008
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发表时间：
2014-11-15
影响因子：
7.4
通讯作者：
Yazdani, Siamak
中科院分区：
文献类型：
--
作者：
Hmidan, Amer;Kim, Yail J.;Yazdani, Siamak
本文研究了碳纤维增强聚合物（CFRP）板加固宽法兰W4 × 13钢梁的裂纹尖端行为。在梁的跨中处创建缺口，以表示不同程度的初始损伤（或裂纹扩展）。我们感兴趣的是影响加固梁承载力的应力强度修正系数。建立了三维有限元模型来预测裂纹尖端的应力奇异性，包括自适应网格公式以及等周二次元。在通过先前进行的实验程序验证建模方法之后，进行了广泛的参数研究，以评估加固梁的缺口深度与高度比（a(0)/h）、cfrp与钢的面积比（psi）和cfrp与钢的模比（eta）的影响。CFRP的存在降低了受损（缺口）梁的应力强度，从而产生了裂缝的桥接效应。当a(0)/h大于0.3时，加固梁和未加固梁的应力强度修正系数存在明显的差异。碳纤维布的层数和模量等性能对加固梁的裂纹尖端塑性有影响。基于75个数值模型的响应面回归分析，提出了加固梁的修正系数。(C) 2014 Elsevier Ltd.版权所有。
This paper presents the crack-tip behavior of wide-flange W4 x 13 steel beams strengthened with carbon fiber reinforced polymer (CFRP) sheets. A notch is created at midspan of the beams to represent various levels of initial damage (or crack propagation). Of interest is the correction factor of stress intensity that affects the capacity of the strengthened beams. Three-dimensional finite element models are developed to predict stress singularity at the crack tip, including an adaptive mesh formulation along with isoperimetric quadratic elements. Upon validating the modeling approach with a previously conducted experimental program, an extensive parametric study is conducted to evaluate the effect of the notch-depth-to-height ratio (a(0)/h), CFRP-to-steel area ratio (psi), and CFRP-to-steel modular ratio (eta) of the strengthened beams. The stress intensity of the damaged (notched) beams is reduced with the presence of the CFRP, which generates a crack-bridging effect. The correction factor of stress intensity for the unstrengthened and strengthened beams noticeably diverges from each other beyond an a(0)/h of 0.3. CFRP properties such as the number of layers and modulus influence the crack-tip plasticity of the strengthened beams. A correction factor is proposed for the strengthened beams, based on the response surface-regression analysis procedures associated with 75 numerical models. (C) 2014 Elsevier Ltd. All rights reserved.