摘要
将应变计组实测应变转换为应力与混凝土的应力状态有关。针对高混凝土坝应力作用水平较高,当混凝土的应力超过一定的限度,混凝土将进入塑性徐变阶段,如果仍基于弹性徐变体的应力-应变关系进行实测应变的应力转换,获得的应力与实际情况不符。该文假设混凝土在高应力作用下将产生塑性流动,根据P.Perzyna假设计算黏塑性应变率,首先推导了最大拉应力屈服准则和Hsieh-Ting-Chen屈服准则的黏塑性应变率计算公式,接着推导了考虑塑性徐变的实测应变转换应力的计算公式,进而探讨了考虑塑性徐变的高混凝土坝实测应变转换为应力。实例分析表明:由于将实测应变转换为应力采用增量法进行计算,在转换过程中,某阶段的应力失真,必然导致后续转换应力的真实性,而考虑塑性徐变的实测应变转换的应力更符合实际情况。
The strain measured by strain-gauge is transformed into stress, which is associated with the stress state of concrete. For high stress levels of high concrete dam, the concrete will enter the stage of plastic creep when the stress of concrete exceeds a certain limit. If the conversion is still based on the stress-strain relationship of elastic creep bodies, the calculated stress can not correlate with the real situation. This paper assumed that the concrete under high stress would produce plastic flow, and viscoplastic strain rate was calculated based on the assumption of P.Perzyna. Viscoplastic strain rate calculation formula of the maximum tensile stress yield criterion and Hsieh-Ting-Chen yield criterion was first deduced, and then calculation formula of transforming the measured strain into the stress was also deduced under plastic creep. Furthermore, the transition from measured strain to stress for high concrete dams considering plastic creep was discussed in this paper. The analysis of an example showed that a stage of stress distortion would inevitably lead to the subsequent conversion of authenticity during the conversion process from measured strain to stress by stress increment, while the stress from the conversion of the measured strain was more consistent with the actual situation under plastic creep.
出处
《工程力学》
EI
CSCD
北大核心
2016年第9期103-108,共6页
Engineering Mechanics
基金
国家自然科学基金项目(51209124)
关键词
高混凝土坝
实测应变
真实应力
塑性徐变
屈服准则
high concrete dams
measured strain
real stress
plastic creep
yield criterion