TY  - JOUR
A1  - Tran, Ngoc Trinh
A1  - Trinh, Tu Luc
A1  - Dao, Ngoc Tien
A1  - Giap, Van Tan
A1  - Truong, Manh Khuyen
A1  - Dinh, Thuy Ha
A1  - Staat, Manfred
T1  - FEM shakedown analysis of structures under random strength with chance constrained programming
JF  - Vietnam Journal of Mechanics
N2  - Direct methods, comprising limit and shakedown analysis, are a branch of computational mechanics. They play a significant role in mechanical and civil engineering design. The concept of direct methods aims to determine the ultimate load carrying capacity of structures beyond the elastic range. In practical problems, the direct methods lead to nonlinear convex optimization problems with a large number of variables and constraints. If strength and loading are random quantities, the shakedown analysis can be formulated as stochastic programming problem. In this paper, a method called chance constrained programming is presented, which is an effective method of stochastic programming to solve shakedown analysis problems under random conditions of strength. In this study, the loading is deterministic, and the strength is a normally or lognormally distributed variable.
KW  - limit analysis
KW  - shakedown analysis
KW  - chance constrained programming
KW  - stochastic programming
KW  - reliability of structures
Y1  - 2022
U6  - http://dx.doi.org/10.15625/0866-7136/17943
SN  - 0866-7136
SN  - 2815-5882
VL  - 44
IS  - 4
SP  - 459
EP  - 473
PB  - Vietnam Academy of Science and Technology (VAST)
ER  - 
TY  - JOUR
A1  - Zhen, Manghao
A1  - Liang, Yunpei
A1  - Staat, Manfred
A1  - Li, Quanqui
A1  - Li, Jianbo
T1  - Discontinuous fracture behaviors and constitutive model of sandstone specimens containing non-parallel prefabricated fissures under uniaxial compression
JF  - Theoretical and Applied Fracture Mechanics
N2  - The deformation and damage laws of non-homogeneous irregular structural planes in rocks are the basis for studying the stability of rock engineering. To investigate the damage characteristics of rock containing non-parallel fissures, uniaxial compression tests and numerical simulations were conducted on sandstone specimens containing three non-parallel fissures inclined at 0°, 45° and 90° in this study. The characteristics of crack initiation and crack evolution of fissures with different inclinations were analyzed. A constitutive model for the discontinuous fractures of fissured sandstone was proposed. The results show that the fracture behaviors of fissured sandstone specimens are discontinuous. The stress–strain curves are non-smooth and can be divided into nonlinear crack closure stage, linear elastic stage, plastic stage and brittle failure stage, of which the plastic stage contains discontinuous stress drops. During the uniaxial compression test, the middle or ends of 0° fissures were the first to crack compared to 45° and 90° fissures. The end with small distance between 0° and 45° fissures cracked first, and the end with large distance cracked later. After the final failure, 0° fissures in all specimens were fractured, while 45° and 90° fissures were not necessarily fractured. Numerical simulation results show that the concentration of compressive stress at the tips of 0°, 45° and 90° fissures, as well as the concentration of tensile stress on both sides, decreased with the increase of the inclination angle. A constitutive model for the discontinuous fractures of fissured sandstone specimens was derived by combining the logistic model and damage mechanic theory. This model can well describe the discontinuous drops of stress and agrees well with the whole processes of the stress–strain curves of the fissured sandstone specimens.
KW  - Constitutive model
KW  - Damage mechanics theory
KW  - Discontinuous fractures
KW  - Uniaxial compression test
KW  - Non-parallel fissures
Y1  - 2024
U6  - http://dx.doi.org/10.1016/j.tafmec.2024.104373
SN  - 0167-8442
VL  - 131
PB  - Elsevier
CY  - Amsterdam
ER  -