Equivalent Uniaxial Strain And Stress Material Constitutive Model Under Dynamic Loading

• Main Authors: Yu-Cheng Yen, 顏昱丞
• Other Authors: Chung-Yue Wang
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/jyt44t

碩士 === 國立中央大學 === 土木工程學系 === 107 === This research presents a dynamic three-dimensional constitutive model of material equivalent uniaxial strain and stress. The purpose is to study the behavior of concrete materials under dynamic loading, because most of the structures in daily life are subject to dynamic loading such as earthquakes, impacts and explosions. This research uses the equivalent uniaxial strain concept proposed by Darwin & Pecknold to separate the Poisson's ratio of multi-axial forces. The equivalent uniaxial strain is a fictitious material index which is invented to compute the parameters such as material stiffness modulus and Poisson’s ratio. This research proposes a dynamic material failure model, which combines the three-parameter failure criterion proposed by Menetrey and Willam with the cap model proposed by Balan et al. to form the Close-Menetrey-Willam model. The dynamic failure model is expanded by the DIF (Dynamic Increase Factor). The dynamic failure model under different strain rate loading states is established, and the stress state at different moments on the dynamic material failure model to define the ultimate strength parameters at the current moment. Using the uniaxial stress-strain model proposed by Saenz, this formula only needs to define the ultimate strength parameters to describe the hardened and softened sections in concrete behavior. It is quite simple and convenient to use in numerical simulation. This study proposes a concrete deterioration model. The combination of the concrete deterioration strength formula proposed by Du Jian-min and the Close-Menetrey-Willam model, establishes a deterioration model with different damage levels, defines the ultimate strength parameters of deterioration model. The numerical examples in this study verify the high strain rate, low strain rate loading of concrete, low strain rate loading of ice, the low strain rate loading of ice at different temperatures and concrete deterioration.