钢筋混凝土梁动态剪切性能及尺寸效应细观研究

A meso-scale study on dynamic shear performance and size effect of RC beams

基于ABAQUS有限元数值计算平台,考虑混凝土材料的非均质性以及钢筋和混凝土的应变率效应,建立了钢筋混凝土(reinforced concrete,RC)梁三维细观数值分析模型,探究了RC梁在不同应变率和配箍率条件下的剪切性能及其尺寸效应行为。结果表明:剪切承载力随着应变率和配箍率的增加均有不同程度的提高;名义抗剪强度随梁高的增大而减小,存在显著的尺寸效应现象;应变率和配箍率的增大一方面可以提高RC梁的名义抗剪强度,另一方面会削弱名义抗剪强度的尺寸效应行为;提出的RC梁静/动态剪切统一尺寸效应律同时考虑了尺寸效应、应变率效应和配箍率的影响,能够较好地预测RC梁在静态和动态作用下的名义抗剪强度,具有一定的准确性和合理性。

Based on the ABAQUS finite element numerical calculation platform,considering the heterogeneity of concrete materials and the strain rate effect of reinforcement and concrete,a three-dimensional(3D)meso-scale numerical analysis model of a reinforced concrete(RC)beam was established,and then the shear performance and size effect of the RC beam under different strain rates and stirrup ratios were investigated.Results show that:with the increase of strain rate and stirrup ratio,the shear bearing capacity increases to various degrees;the nominal shear strength decreases with beam height,and there is a significant size effect phenomenon;the increase of strain rate and stirrup ratio can both increase the nominal shear strength of RC beams and weaken the size effect of nominal shear strength;the proposed static/dynamic shear uniform size effect law of RC beams considers the influence of size effect,strain rate effect and stirrup ratio at the same time,which can well predict the nominal shear strength of RC beams under static and dynamic loads,with certain accuracy and rationality.