应变率效应对混凝土动弯拉强度的影响

Influence of strain rate effect on dynamic bending strength of concrete

本文基于混凝土材料的应变率效应及有关试验资料,给出了混凝土材料强度和弹性模量强化曲线,根据该关系曲线并考虑初始静预载的情况,建立了混凝土梁动弯加载过程的有限元数值模型。利用该数值模型模拟了不同加载速率和具有不同初始预静载时梁在冲击荷载作用下动弯拉破坏过程,分析了混凝土强度和弹性模量的应变率敏感性对不同初始预静载水平下的混凝土梁动弯拉强度的影响,初步揭示出动载强度随着应变率变化的规律。研究表明,在复杂加载情况下,动强度与应变历史、应变率历史以及材料的损伤积累有关。

The relationship between strain rate and dynamic strength as well as the relationship between strain rate and elastic modulus are deduced based on the experimental data. The finite element numerical model for describing the dynamic loading process of concrete beam is established according to the relationships between the strength, elastic modulus and strain rate. By using this model the dynamic bending failure process of beams under the action of shock loading with various strain rates and various static preloading levels are simulated. The. strain-rate sensitivities to concrete dynamic strength and elastic modulus for various preloading levels are analyzed and the relationship between dynamic strength and strain-rate is deduced. It is found that the dynamic strength of concrete is dependent upon the strain history, strain rate history and damage accumulated in the process of loading.