The Effect of Heterogeneity and Element Sizes on Rock Mechanics Properties

2011 ◽  
Vol 243-249 ◽  
pp. 2643-2646
Author(s):  
Hai Jun Lu ◽  
Guang Hua Cai ◽  
Li He ◽  
Zhu Yun Hu ◽  
Jiang Shan Li
Keyword(s):  
Numerical Simulation ◽  
Rock Mechanics ◽  
Rock Strength ◽  
Damage Model ◽  
Constitutive Relationship ◽  
Strain Relationship ◽  
Statistic Theory ◽  
Failure Models ◽  
Basic Characteristics ◽  
Relationship Of

Based on the analysis of the experiment, a statistical damage model can be established according with Weibull distribution from the basic characteristics of rocks, the statistic theory of heterogeneity and the microscopic principles of damages, analyze the constitutive relationship of rocks through the stress-strain relationship, heterogeneity, and the element sizes. According to the analysis of rock strength and failure models in numerical simulation, it is acquired the influence of heterogeneity and element sizes on rock mechanics properties. The results of numerical simulation provide a new way for the study of the medium macro behavior on the deformations and fractures.

scholarly journals Simulating the Stress-Strain Relationship of Geomaterials by Support Vector Machine

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Hongbo Zhao ◽  
Zenghui Huang ◽  
Zhengsheng Zou
Keyword(s):  
Support Vector Machine ◽  
Constitutive Relationship ◽  
Support Vector ◽  
Nonlinear Relationship ◽  
Ann Model ◽  
Stress Strain ◽  
Svm Model ◽  
Strain Relationship ◽  
Artificial Neural Network Ann ◽  
Relationship Of

Stress-strain relationship of geomaterials is important to numerical analysis in geotechnical engineering. It is difficult to be represented by conventional constitutive model accurately. Artificial neural network (ANN) has been proposed as a more effective approach to represent this complex and nonlinear relationship, but ANN itself still has some limitations that restrict the applicability of the method. In this paper, an alternative method, support vector machine (SVM), is proposed to simulate this type of complex constitutive relationship. The SVM model can overcome the limitations of ANN model while still processing the advantages over the traditional model. The application examples show that it is an effective and accurate modeling approach for stress-strain relationship representation for geomaterials.

scholarly journals Nonlinear Mechanics Study of Concrete T-beam Bridge With Cracking Damage Based on Numerical Simulation

2020 ◽  
Vol 14 ◽  
Keyword(s):  
Numerical Simulation ◽  
Constitutive Relationship ◽  
Plastic State ◽  
Nonlinear Mechanics ◽  
Element Analysis ◽  
Structural Rigidity ◽  
Beam Bridge ◽  
Relationship Of ◽  
T Beam ◽  
Selection Of

The cracking damage of concrete bridge will seriously affect the overall safety of a structure. In this study, based on the numerical simulation, finite element analysis was carried out on the concrete T beam through the ANSYS software, and the selection of elements and the constitutive relationship of materials in the numerical simulation were introduced. It was found from the results of numerical simulation that the cracks of T beam continued to develop under the action of load, the concrete entered the plastic state from the elastic state and the mid-span deflection increased with the increase of load. In the case of the change of cracks, the larger the crack height, the larger the crack range of the beam. With the increase of load, the structural rigidity continued to degenerate, and the compressive stress of the concrete also increased. The research in this paper proves the validity of numerical simulation in the study of nonlinear mechanics of beam bridge and also makes some contributions to the study of crack damage of beam bridge.

Experimental study on residual strength of concrete confined with corroded stirrups

2016 ◽  
Vol 43 (6) ◽  
pp. 583-590 ◽  
Author(s):  
Guanghui Zhang ◽  
Xinhu Cao ◽  
Qiuni Fu
Keyword(s):  
Experimental Study ◽  
Weight Loss ◽  
Confined Concrete ◽  
Constitutive Relationship ◽  
Stress Strain ◽  
Model Modification ◽  
Chloride Corrosion ◽  
Strain Relationship ◽  
Corrosion Of Steel ◽  
Relationship Of

Corrosion of steel bars is a serious issue compromising the reliability of reinforced concrete structures. Previous research has proven that confined concrete has increased confined strength, ductility, energy dissipation capacity, etc. However, existing confined concrete models cannot accurately predict the strength and stress–strain relationship of concrete confined with corroded stirrups. This paper presents an experimental study on the behavior of eight square columns confined with stirrups damaged by accelerated chloride corrosion. The weight loss of the stirrup ranges from 5% to 31.7%. The stress–strain curves of confined concrete are obtained from the concentric compression loading tests. Based on the well-established Mander model, modification factors are introduced to account for the effect of corrosion on the confined strength, confined strain, and descending branch of the curves. These modification factors predict the constitutive relationship of concrete confined with square stirrups as a function of the weight loss and localization levels of corrosion.

The Constitutive Relationship of Concrete Core in Circular Concrete-Filled Steel Tubular Columns

2010 ◽  
Vol 163-167 ◽  
pp. 2063-2067
Author(s):  
Lin Lin Liu ◽  
Yong Qing Tu ◽  
Ying Hua Ye
Keyword(s):  
Numerical Simulation ◽  
Axial Load ◽  
Lateral Pressure ◽  
Confined Concrete ◽  
Constitutive Relationship ◽  
Concrete Core ◽  
Tubular Columns ◽  
Cfst Columns ◽  
Relationship Of ◽  
Concrete Model

Considering the confining mechanism in circular concrete-filled steel tubular (CFST) columns, a volume-based method for dividing the effectively and ineffectively confined area of concrete core and calculating the value of effectively confined coefficient is presented. The constitutive relationship of concrete core is developed by means of modifying the expressions of effective lateral pressure and the descending stage in Mander’s confined concrete model. Numerical simulation of several circular CFST columns under axial load is carried out in ABAQUS. The comparisons between calculated results and experimental results demonstrate that the suggested concrete constitutive relationship is appropriate for the nonlinear analysis of circular CFST columns.

scholarly journals Constitutive Modeling of Physical Properties of Coastal Sand during Tunneling Construction Disturbance

2021 ◽  
Vol 9 (2) ◽  
pp. 167
Author(s):  
Jian-Feng Zhu ◽  
Hong-Yi Zhao ◽  
Ri-Qing Xu ◽  
Zhan-You Luo ◽  
Dong-Sheng Jeng
Keyword(s):  
Constitutive Model ◽  
Constitutive Relationship ◽  
Initial Void Ratio ◽  
Coastal Cities ◽  
Disturbed State Concept ◽  
Strain Relationship ◽  
Internal Angle ◽  
Concept Theory ◽  
Relationship Of ◽  
Disturbance Function

This paper presents a simple but workable constitutive model for the stress–strain relationship of sandy soil during the process of tunneling construction disturbance in coastal cities. The model was developed by linking the parameter K and internal angle φ of the Duncan–Chang model with the disturbed degree of sand, in which the effects of the initial void ratio on the strength deformation property of sands are considered using a unified disturbance function based on disturbed state concept theory. Three cases were analyzed to investigate the validity of the proposed constitutive model considering disturbance. After validation, the proposed constitutive model was further incorporated into a 3D finite element framework to predict the soil deformation caused by shield construction. It was found that the simulated results agreed well with the analytical solution, indicating that the developed numerical model with proposed constitutive relationship is capable of characterizing the mechanical properties of sand under tunneling construction disturbance.

scholarly journals Freeze–Thaw Damage Model of Polypropylene Fiber Reinforced Cement Stabilized Waste Construction Slurry under Uniaxial Action

Minerals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 743
Author(s):  
Ping Jiang ◽  
Lin Zhou ◽  
Yue Wang ◽  
Biao Qian ◽  
Wei Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Damage Model ◽  
Polypropylene Fiber ◽  
Fiber Reinforced ◽  
Two Stage ◽  
Cement Sample ◽  
Freeze And Thaw ◽  
Reinforced Cement ◽  
Strain Relationship ◽  
Relationship Of

In order to apply the fiber reinforced cement stabilized waste construction slurry more widely, it is crucial to evaluate its mechanical behavior under freeze and thaw (F–T) cycles. The mechanical properties of fiber cement-modified waste construction slurry (FCMS) under five different F–T cycles were studied using unconfined compressive strength tests. One fixed cement sample with five different types of polypropylene fiber was used in the FCMS. Using the meso random damage model, the two-stage damage stress–strain relationship of FCMS was established using particle swarm optimization (PSO). The results were as follows: (1) The mechanical properties of FCMS at room temperature and in an F–T environment were significantly improved by fiber; (2) The elastic modulus of FCMS decreased in the form of a power function with the increase of F–T cycles; (3) The fitting results of the two-stage F–T damage model based on meso random damage theory were in agreement with the measured data.

Study on the Simulation of Damage Constitutive Relationship for High Strength and High Performance Concrete

2011 ◽  
Vol 250-253 ◽  
pp. 636-639
Author(s):  
Shan Suo Zheng ◽  
Yi Hu ◽  
Bin Liu ◽  
Ming Xie ◽  
Qing Lin Tao
Keyword(s):  
Constitutive Equation ◽  
High Performance ◽  
High Performance Concrete ◽  
Mechanical Test ◽  
Damage Model ◽  
High Strength ◽  
Constitutive Relationship ◽  
Two Parameters ◽  
Relationship Of ◽  
Stochastic Damage

The damage evolution laws of high strength and high performance concrete (HSHPC) are obtained by a large number of experiments on mechanical properties. Based on stochastic damage model, a new damage variable with two parameters is proposed to describe the damage constitutive relationship of HSHPC and the damage constitutive equation is established by boundary conditions. Compared mechanical test result of HSHPC with theoretical calculation, it is shown that the damage constitutive equation can reflect the damage characteristics of HSHPC reasonably. The research identifies a certain theoretical basis for further studying on dynamic and stochastic damage constitutive relationship of HSHPC.

Numerical Verification of Constitutive Relationship for Mechanic Behavior of Shape Memory Polymer

2011 ◽  
Vol 121-126 ◽  
pp. 3514-3519
Author(s):  
Bai Lin Zheng ◽  
Xin Ming Huang ◽  
Cong Cong Han ◽  
Qing Yang
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Shape Memory ◽  
Shape Memory Polymer ◽  
Experimental Studies ◽  
Constitutive Relationship ◽  
Numerical Verification ◽  
Strain Relationship ◽  
Viscoelastic Theory ◽  
Simulation Results

Based on the viscoelastic theory, the shape memory behavior of SMP materials is analyzed theoretically with the aid of numerical method of finite element in this paper. The stress-strain relationship depended on temperature and time of SMP materials is described by the thermal viscoelastic integral constitutive model. A numerical simulation is carried out to compare with the experiment conducted by Tobushi (2001[6], 2005[9]), and the simulation results correspond well with the experiment, thus can provide reference to experimental studies

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