摘要
为研究由混凝土非均匀收缩徐变效应引起的钢筋混凝土梁沿梁高度方向的非均匀自应力效应,基于非线性温度自应力方法和按照龄期调整的有效模量法,推导非均匀收缩徐变效应作用下沿梁高度方向上的钢筋混凝土梁自应力计算公式,并用有限元方法对其进行验证;以某混凝土简支试验梁为算例,进行收缩、徐变自应力分析;探讨非均匀收缩徐变效应下曲率和截面应力随时间变化特征;最后研究不同温度和相对湿度梯度下钢筋混凝土梁的应力重分布效应。研究结果表明:在非均匀收缩和徐变作用下,截面的轴向应变和曲率随时间显著变化,且沿着梁高度方向将产生较大的不均匀收缩徐变自应力;温度梯度值增加能增加顶面的非均匀收缩徐变自应力,但影响幅度较相对湿度梯度小;相对湿度梯度能显著影响收缩徐变自应力,前期养护作用对于减小自应力十分重要。
In order to study the non-uniform self-stress effect of reinforced concrete ( RC) beam along the height of the beam caused by the non-uniform concrete shrinkage and creep effect,based on the nonlinear thermal self-stress method and the age adjusted effective modulus method,the formulas to calculate the self-stresses of RC beam caused by the non-uniform shrinkage and creep effect were derived and verified by the finite element method.Based on the numerical example of a simply supported RC beam,the shrinkage and creep self-stresses were analyzed. The time-dependent features of curvatures and sectional stresses in the beam under non-uniform shrinkage and creep effect were discussed.Finally,the stress redistribution effect of the RC beam under different temperature and relative humidity gradients were studied.The results show that under the non-uniform shrinkage and creep,the axial strain of the cross section and curvature in the beam change significantly with time.There will be greater non-uniform shrinkage and creep self-stress along the height of the beam.Greater temperature gradient will increase the non-uniform shrinkage and creep self-stress in the top surface of the beam.But its effect was smaller than relative humidity.Relative humidity gradients can significantly affect the shrinkage and creep self-stress.Curing at early age plays an important role in reducing the self-stress.
作者
王永宝
廖平
贾毅
赵人达
吴德宝
WANG Yongbao;LIAO Ping;JIA Yi;ZHAO Renda;WU Debao(College of Architecture and Civil Engineering,Taiyuan University of Technology,Taiyuan 030024,China;School of Civil Engineering,Southwest Jiaotong University,Chengdu 610031,China)
出处
《铁道学报》
EI
CAS
CSCD
北大核心
2019年第2期137-145,共9页
Journal of the China Railway Society
基金
国家自然科学基金(51778531)
关键词
钢筋混凝土梁
非均匀收缩徐变
自应力
温度
相对湿度
RC beam
non-uniform creep and shrinkage
self-stress
temperature
relative humidity
