Research on Mechanism of Concrete Creep

2014 ◽  
Vol 670-671 ◽  
pp. 441-444
Author(s):  
Guo Jun Liu
Keyword(s):  
Viscous Flow ◽  
Plastic Flow ◽  
Flow Theory ◽  
Theoretical Research ◽  
Balance Theory ◽  
Concrete Creep ◽  
Linear Creep ◽  
Sustained Loads ◽  
Internal Forces ◽  
Seepage Theory

Under sustained loads with a fixed value, the deformation of concrete will continue to increase as time increases; this phenomenon is called creep of concrete. Currently, there are several theories to explain the phenomenon of concrete creep, viscoelasticity theory, seepage theory, viscous flow theory, plastic flow theory, micro-fractures theory and internal forces balance theory. Above models mostly studied linear creep of concrete under low stress status. This paper mainly research on concrete creep mechanism, and pointed out the advantages and limitations of the various theories, which has a guiding significance for theoretical research.

Long Term Load-Carrying Capacity of Eccentrically Compressed Concrete Filled Steel Tubular Members

2006 ◽  
Vol 302-303 ◽  
pp. 651-657
Author(s):  
Bing Han ◽  
Yuan Feng Wang
Keyword(s):  
Plastic Flow ◽  
Carrying Capacity ◽  
Flow Theory ◽  
Creep Model ◽  
Load Carrying Capacity ◽  
Creep Theory ◽  
Concrete Creep ◽  
Load Carrying ◽  
Loadbearing Capacity

Based on the creep model of CFST members constructed with the Elastic Continuation and Plastic Flow theory of concrete creep and the creep theory of concrete under multi-axial stresses, the paper studies the load-carrying capacity of eccentrically compressed CFST members with consideration of creep. Some eccentrically compressed CFST members’ long-term loadbearing capacity is calculated and corresponding results are compared with the load-carrying capacity without consideration of creep. According to the analysis of calculating results, it can be concluded that creep will decrease the load carrying capacity of eccentrically compressed CFST members, and it should be paid enough attentions in actual engineering.

COMPREHENSIVE INVESTIGATION OF EXTRUSION OF П-SHAPED BRACKETS. REPORT 6. KINEMATIC AND STRESSED STATES OF BLANKET DURING RESTRICTED EXTRUSION. PART 2

2021 ◽  
pp. 38-43
Author(s):  
A. L. Vorontsov ◽  
◽  
S. M. Karpov ◽  
Keyword(s):  
Plastic Deformation ◽  
Plastic Flow ◽  
Plane Deformation ◽  
Flow Theory ◽  
Equation System ◽  
Extrusion Process ◽  
Thick Wall ◽  
Comprehensive Investigation ◽  
Flow Velocities

On the basis of the complete equation system of the plastic flow theory, the solution continuation of the determination problem of the kinematic and stressed states of a blanket during restricted extrusion of П-shaped brackets under conditions of plane deformation in the general case of a nonaligned placement of the punch and the die is stated. The determination of flow velocities and stresses in the area of plastic deformation, located under the punch end near the formed thick wall of the bracket has been carried out. The formulae were obtained, which are required for identification of the main parameters of the extrusion process of П-shaped products with a relatively thin horizontal bridge.

Computer Simulation of Kinematics of Plastic Flow and the Deformed Condition of Metal at Processes Equal-Channel Angular Pressing

2008 ◽  
Vol 584-586 ◽  
pp. 1077-1082
Author(s):  
Aleksandr V. Belevich ◽  
D.M. Babin
Keyword(s):  
Computer Simulation ◽  
Carbon Steel ◽  
Plastic Flow ◽  
Equal Channel Angular Pressing ◽  
Technological Process ◽  
Equal Channel Angular Extrusion ◽  
Theoretical Research ◽  
Angular Pressing ◽  
The Given ◽  
Local Parameters

Object of researches in the given paper is the technological process of obtaining from carbon steel method equal-channel angular extrusion (ECAE) on one pass. The purpose of theoretical research is the working of recomdations on projection of the process with the help of a designed technique of simulation of process ECAE in CAE systems. Calculations were done under variable conditions ECAE over the range changes of parameters: a corner of intersection of channels Ф from 90 up to 150 grades, speed of driving press from 0,05 m/s up to 0,2 m/s, temperature from 20°С up to 600°С. As a result quantitative links of local parameters (stresses, strains and temperature) are established with geometrical and technological ECAE parameters to one separate pass. Regularities of change of parameters to ECAE process of cylindrical preforms in diameter of 20 mm and 30 mm are established (steel 0,15%С), are investigated; character of change of a tension in the instrument and power conditions of the process was studied.

Impulsive Motion of a Moving Circular Cylinder in a Viscous Flow by the Numerical Simulation

1998 ◽  
Vol 14 (3) ◽  
pp. 119-123
Author(s):  
D. L. Young ◽  
J. T. Chang
Keyword(s):  
Circular Cylinder ◽  
Viscous Fluid ◽  
Viscous Flow ◽  
Drag Force ◽  
Moving Boundary ◽  
Stokes Equations ◽  
Flow Theory ◽  
Infinite Domain ◽  
Constant Acceleration ◽  
Element Method

ABSTRACTAn innovative computation procedure is developed to solve the external flow problems for viscous fluids. The method is able to handle the infinite domain so that it is convenient for the external flows. The code is based on the projection method of the Navier-Stokes equations. We use the three-step explicit finite element method to solve the momentum equation by extracting the boundary effects from the finite computation domain. The pressure Poisson equation for the external field is treated by the boundary element method. The arbitrary Lagrangian-Eulerian (ALE) scheme is employed to incorporate the present algorithm to deal with the moving boundary, such as the motion of an impulsively moving circular cylinder in a viscous fluid. The model demonstrates that drag force is well predicted for a circular cylinder moving in a still viscous fluid starting from rest, to a constant acceleration, and then maintaining at a uniform velocity. In the constant acceleration phase, the drag force is closed to the added mass effect from the ideal flow theory. On the other hand, the drag force is equal to viscous flow theory in the constant velocity phase.

scholarly journals Creep of Concrete According to Creep Prediction Models and Own Research

2018 ◽  
Vol 196 ◽  
pp. 02024
Author(s):  
Agnieszka Wypych ◽  
Krzysztof Klempka ◽  
Marek Jędrzejczak
Keyword(s):  
Compressive Stress ◽  
Prediction Models ◽  
Laboratory Research ◽  
Concrete Creep ◽  
Model Code ◽  
Eurocode 2 ◽  
Linear Creep ◽  
Model Code 2010

The paper presents the currently used procedures for calculating the deformation of concrete and creep coefficients. Laboratory research was conducted on the creep of concrete. Creep coefficients were calculated on the basis of experimentally obtained data and later compared to the ones acquired by using previously demonstrated procedures. In the case of the sample subjected to the influence of compressive stress and not exceeding the limit of linear creep, the models in Eurocode 2 and fib Model Code 2010 did not correspond to the experimentally obtained data.

COMPREHENSIVE INVESTIGATION OF EXTRUSION OF П-SHAPED BRACKETS. REPORT 6. KINEMATIC AND STRESSED STATES OF BLANKET DURING RESTRICTED EXTRUSION. PART 4

2021 ◽  
pp. 51-54
Author(s):  
A. L. Vorontsov ◽  
◽  
S. M. Karpov ◽  
Keyword(s):  
Plastic Flow ◽  
Geometric Parameter ◽  
Plane Deformation ◽  
Flow Theory ◽  
Equation System ◽  
Extrusion Process ◽  
Technological Parameters ◽  
Comprehensive Investigation

On the basis of the complete equation system of the plastic flow theory, the solution of the determination problem of the kinematic and stressed states of a blanket during completely restricted extrusion of П-shaped brackets under the conditions of plane deformation in the general case of a nonaligned placement of the punch and the die is stated. The determination of the force and geometric parameter of the process was carried out. The formulae were obtained, which are required for determination of the main technological parameters of the extrusion process of П-shaped products with a relatively thin horizontal bridge.

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