Creep behaviour of an undisturbed lightly overconsolidated clay

To fill an important gap in the knowledge of creep phenomena, the creep behaviour of the intact, overconsolidated Saint-Alban clay has been investigated by means of drained and undrained triaxial tests as well as of odometer tests.Creep deformations can be broken into volumetric and shear components. The development with time of both volumetric and shear strains can be represented by means of the phenomenological equation proposed by Singh and Mitchell in 1968. However, the stress function in that equation must be defined separately for each strain component and by reference to the limit state of the clay.A general model of the time dependent behaviour of clays might be obtained by combining the concepts of limit state and isotaches, as implied in the YLIGHT model proposed by Tavenas and Leroueil in 1977 but the effect of overconsolidation on the shape of the isotaches requires further investigation.

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Case studies considering the influence of the time-dependent behaviour of concrete on the serviceability limit state design of composite steel-concrete buildings

10.2749/sed018.ch7 ◽

2021 ◽

pp. 137-156

Author(s):

Alejandro Pérez Caldentey ◽

John Hewitt ◽

John van Rooyen ◽

Graziano Leoni ◽

Gianluca Ranzi ◽

...

Keyword(s):

Case Studies ◽

Limit State ◽

Time Dependent ◽

Commercial Building ◽

Time Effects ◽

Concrete Buildings ◽

Time Dependent Behaviour ◽

Dependent Behaviour ◽

Composite Steel

<p>This chapter presents a number of case studies that deal with the service design of composite steel-concrete buildings associated with the time-dependent behaviour of the concrete. The particular focus of this chapter is to outline key design aspects that need to be accounted for in design and that are influenced by concrete time effects. The first case study provides an overview of the design considerations related to the time-dependent column shortening in typical multi-storey buildings by considering the layout of the Intesa Sanpaolo Headquarters in Turin as reference. The second case study focuses on a composite floor of a commercial building constructed in Australia and it provides an overview of the conceptual design used to select the steel beam framing arrangement to support the composite floor system while accounting for concrete cracking and time effects. The third case study deals with the Quay Quarter Tower that has been designed for the repurposing of an existing 50-year old building in Australia while accounting for the time-dependent interaction between the existing and the new concrete components of the building.</p>

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Indentation Creep in Zirconia Ceramics under Variable Loads

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.280-283.1009 ◽

2007 ◽

Vol 280-283 ◽

pp. 1009-1012

Author(s):

X.J. Ren ◽

R.M. Hooper ◽

J.L. Henshall

Keyword(s):

Room Temperature ◽

Indentation Size Effect ◽

Creep Behaviour ◽

Time Dependent ◽

Indentation Creep ◽

Indentation Size ◽

Zirconia Ceramics ◽

Creep Tests ◽

Time Dependent Behaviour ◽

Dependent Behaviour

Time dependent deformation at room and elevated temperature is a significant property of zirconia ceramics and has a direct influence on their use. An understanding of this time dependent behaviour is therefore important in predicting the service life of a component. In this work, the indentation creep behaviour of two typical zirconia ceramics ¾ ceria stabilised polycrystalline tetragonal (Ce-TZP) and yttria (6%) stabilized polycrystalline cubic zirconia, YCPZ, have been investigated from room temperature to 600 °C. Indentation creep tests with various loads yielded identical creep rate, which indicates that indentation size effect has no significant effect on the indentation creep of zirconia ceramics. Tests with variable loads, using a spring loaded apparatus, exhibited comparable indentation creep rates to that under constant loading.

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Case studies considering the influence of the time-dependent behaviour of concrete on the serviceability limit state design of composite steel-concrete bridges

10.2749/sed018.ch8 ◽

2021 ◽

pp. 157-188

Author(s):

Alejandro Pérez Caldentey ◽

Luigino Dezi ◽

Javier Jordán ◽

Graziano Leoni ◽

Gianluca Ranzi ◽

...

Keyword(s):

Case Studies ◽

Limit State ◽

Concrete Bridges ◽

Time Dependent ◽

Serviceability Limit State ◽

Limit State Design ◽

First Case ◽

Time Dependent Behaviour ◽

Dependent Behaviour

<p>This chapter introduces three case studies that describe how aspects related to the serviceability limit state design associated with the time-dependent behaviour of concrete can be considered in a design situation. The first case study considers the Oxec II Bridge in Guatemala. It provides an overview of the stress verification of the steel section of the composite bridge and accounts for concrete time effects to capture the stress redistribution that occurs between the concrete and the steel components. The second case study deals with the Yalquincha Viaduct in Chile and provides an overview of the type of long-term analyses that can be carried out when considering the influence of different cross-sectional arrangements on the time-dependent response of the bridge. The last case study focusses on the Serra Cazzola Viaduct in Italy and highlights the opportunities available to designers in exploiting optimised casting sequences to reduce the time-dependent stresses induced in the concrete and, therefore, mitigate the likelihood of concrete cracking.</p>

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Application of shotcrete constitutive model to the time dependent behavior of TBM tunnel lining

International Journal of Engineering & Technology ◽

10.14419/ijet.v7i3.11293 ◽

2018 ◽

Vol 7 (3) ◽

pp. 1826

Author(s):

Heyam H. Shaalan ◽

Mohd Ashraf Mohamad Ismail ◽

Romziah Azit

Keyword(s):

Constitutive Model ◽

Steel Fibre ◽

Tunnel Lining ◽

Time Dependent ◽

Elastic Behaviour ◽

Elastic Analysis ◽

Time Dependent Behaviour ◽

Shotcrete Lining ◽

Creep And Shrinkage ◽

Dependent Behaviour

Shotcrete is ordinary concrete applied to the surface under high pressure. It demonstrates a highly time-dependent behaviour after few hours of application. Traditional approaches assume a simple linear elastic behaviour using a hypothetical young modulus to investigate the time-dependency and creep effects. In this paper, a new constitutive model of shotcrete is applied to evaluate the time-dependent behaviour of a TBM tunnel lining and investigate the parameters that can influence this behaviour. The Shotcrete model is based on the framework of Elasto-plasticity and designed to model shotcrete linings more realistically. The basic data of Pahang-Selangor Raw Water Transfer Project is used for the analysis study. An attempt is made to investigate the influence of some input parameters of the shotcrete model on the time-dependent behaviour of the shotcrete lining. These parameters include the time-dependent stiffness/strength parameters, creep and shrinkage parameters and steel fibre parameters. The variation in shotcrete strength classes causes a noticeable influence on the development of shotcrete compressive strength with time, particularly during the first days of application. The creep and shrinkage strain cause a considerable reduction in the development of the shotcrete stress with time. The impact of steel fibre content is determined, and the result indicated that the development of plain shotcrete stresses with time is lower than that of the reinforced shotcrete. In addition, a comparison study is performed to analyse the tunnel lining behaviour using both shotcrete model and an elastic analysis. Significant differences in shotcrete lining stresses are achieved when using the elastic analysis while the shotcrete model results in a reasonable result that can be used for the design requirements.

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Application of micro-computer tomography and inverse finite element analysis for characterizing the visco-hyperelastic response of bulk liver tissue using indentation

SN Applied Sciences ◽

10.1007/s42452-021-04577-6 ◽

2021 ◽

Vol 3 (5) ◽

Author(s):

Rajeswara R. Resapu ◽

Roger D. Bradshaw

Keyword(s):

Finite Element ◽

Liver Tissue ◽

Loading Rate ◽

Time Dependent ◽

Nonlinear Material ◽

Computational Time ◽

List Type ◽

Prony Series ◽

Time Dependent Behaviour ◽

Dependent Behaviour

Abstract In-vitro mechanical indentation experimentation is performed on bulk liver tissue of lamb to characterize its nonlinear material behaviour. The material response is characterized by a visco-hyperelastic material model by the use of 2-dimensional inverse finite element (FE) analysis. The time-dependent behaviour is characterized by the viscoelastic model represented by a 4-parameter Prony series, whereas the large deformations are modelled using the hyperelastic Neo-Hookean model. The shear response described by the initial and final shear moduli and the corresponding Prony series parameters are optimized using ANSYS with the Root Mean Square (RMS) error being the objective function. Optimized material properties are validated using experimental results obtained under different loading histories. To study the efficacy of a 2D model, a three dimensional (3D) model of the specimen is developed using Micro-CT of the specimen. The initial elastic modulus of the lamb liver obtained was found to 13.5 kPa for 5% indentation depth at a loading rate of 1 mm/sec for 1-cycle. These properties are able to predict the response at 8.33% depth and a loading rate of 5 mm/sec at multiple cycles with reasonable accuracy. Article highlights The visco-hyperelastic model accurately models the large displacement as well as the time-dependent behaviour of the bulk liver tissue. Mapped meshing of the 3D FE model saves computational time and captures localized displacement in an accurate manner. The 2D axisymmetric model while predicting the force response of the bulk tissue, cannot predict the localized deformations.

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