外包内翻U形钢-混凝土简支组合梁负弯矩区有效翼缘宽度分析

Analysis of effective flange width in negative moment area of U-shaped steel concrete simply supported composite beams with external inversion

外包内翻U形钢-混凝土简支组合梁作为一种新型组合梁,其负弯矩区有效翼缘宽度被研究得甚少。为了探索该种新型组合梁负弯矩区有效翼缘宽度的影响因素,在本课题组负弯矩区受弯性能试验研究的基础上,采用有限元软件ABAQUS分析了有效翼缘宽度的变化规律,并针对跨中截面详细研究了荷载类型、宽跨比(b_(f)/L_(0))和高厚比(h/h_(f))对弹性和弹塑性阶段有效翼缘宽度的影响规律。研究结果表明:不同荷载类型下,均布荷载作用下的有效翼缘宽度大于非均布荷载作用下的有效翼缘宽度;当b_(f)/L_(0)<0.40时,有效翼缘宽度系数β近似等于1.00且不随宽跨比变化,当0.40≤b_(f)/L_(0)≤1.00时,β随宽跨比的增大而近似线性减小,弹塑性阶段的β略大于弹性阶段的β,且减小率小于后者;高厚比对有效翼缘宽度的影响可以忽略。基于有限元分析结果,提出了有效翼缘宽度的简化计算公式,并与《钢结构设计标准》(GB 50017—2017)中的公式进行了对比。对比结果表明:相较于《钢结构设计标准》(GB 50017—2017)的计算结果,本文公式的计算结果与有限元计算结果吻合得更好;规范计算结果与另外2种方法的计算结果差别较大,偏于保守。

As a new type of composite beam,the effective flange width in negative moment area of U-shaped steel concrete simply supported composite beams with external inversion has been rarely studied.In order to explore the influencing factors of the effective flange width in negative moment area of this new type composite beam,based on the experimental research on the bending performance of negative moment area in our research group,the variation law of the effective flange width was analyzed using finite element software ABAQUS.The influence law of load type,width to span ratio(b_(f)/L_(0))and height to thickness ratio(h/h_(f))on the effective flange width in the elastic and elastic-plastic stages was studied in detail for the mid span section.The research results indicate that under different load types,the effective flange width under uniformly distributed loads is greater than that under nonuniform loads.When b_(f)/L_(0)<0.40,the value of β(effective flange width coefficient)is approximately equal to 1.00 and does not vary with the width to span ratio.When 0.40≤b_(f)/L0≤1.00,the value of β decreases approximately linearly with the increase of the width to span ratio,during the elastic-plastic stage the value of β is slightly greater than that during the elastic stage,and the reduction rate is smaller than the latter.The effect of height to thickness ratio on the effective flange width can be ignored.Based on the finite element analysis results,a simplified calculation formula for the effective flange width was proposed and compared with the formula in Steel structure design standard(GB 50017—2017).The comparison results show that the calculation results of the formula in this article are better consistent with the finite element calculation results compared to the calculation results in Steel structure design standard(GB 50017—2017).The standardized calculation results differ significantly from the other two methods and tend to be conservative.