Time-dependent behaviour of steel tubular columns filled with recycled coarse aggregate concrete

Experimental and theoretical investigation on the fire performance of concentrically loaded recycled aggregate concrete–filled square steel tubular columns with or without fire protective coating is reported in this article. Tests of nine specimens were conducted with the variation in the recycled coarse aggregate replacement ratio, axial compressive load ratio and thickness of fire protective coating. The failure pattern, typical temperature development, axial displacement and fire resistance of the tested specimens are presented and analysed. The experimental results reveal that the temperatures of the core concrete decrease with increasing recycled coarse aggregate replacement ratio and decreasing thickness of fire protective coating under the same fire exposure time. In general, the specimens with the recycled coarse aggregate replacement ratio of 50% have a similar behaviour as the corresponding specimen with normal concrete; however, the performance of specimens with the recycled coarse aggregate replacement ratio of 100% is clearly different from the reference specimen with normal concrete. Moreover, the fire resistance of recycled aggregate concrete–filled square steel tubular columns increases with an increase in the thickness of fire protective coating and a decrease in axial compressive load ratio. A finite element analysis model was developed for simulating the performance of recycled aggregate concrete–filled square steel tubular columns exposed to fire, and the finite element analysis model was validated against the experimental results.

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Time-dependent behaviour of concrete-filled steel tubular columns: analytical and comparative study

Magazine of Concrete Research ◽

10.1680/macr.2012.64.1.55 ◽

2012 ◽

Vol 64 (1) ◽

pp. 55-69 ◽

Cited By ~ 20

Author(s):

Yue Geng ◽

Gianluca Ranzi ◽

Yuyin Wang ◽

Sumei Zhang

Keyword(s):

Comparative Study ◽

Time Dependent ◽

Tubular Columns ◽

Time Dependent Behaviour ◽

Dependent Behaviour

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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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Carbonization Durability of Two Generations of Recycled Coarse Aggregate Concrete with Effect of Chloride Ion Corrosion

Sustainability ◽

10.3390/su122410544 ◽

2020 ◽

Vol 12 (24) ◽

pp. 10544

Author(s):

Chunhong Chen ◽

Ronggui Liu ◽

Pinghua Zhu ◽

Hui Liu ◽

Xinjie Wang

Keyword(s):

Compressive Strength ◽

Coarse Aggregate ◽

Chloride Ion ◽

Total Porosity ◽

Recycled Concrete ◽

Carbonation Depth ◽

Aggregate Concrete ◽

Recycled Coarse Aggregate ◽

Carbonation Resistance ◽

Two Generations

Carbonation durability is an important subject for recycled coarse aggregate concrete (RAC) applied to structural concrete. Extensive studies were carried out on the carbonation resistance of RAC under general environmental conditions, but limited researches investigated carbonation resistance when exposed to chloride ion corrosion, which is an essential aspect for reinforced concrete materials to be adopted in real-world applications. This paper presents a study on the carbonation durability of two generations of 100% RAC with the effect of chloride ion corrosion. The quality evolution of recycled concrete coarse aggregate (RCA) with the increasing recycling cycles was analyzed, and carbonation depth, compressive strength and the porosity of RAC were measured before and after chloride ion corrosion. The results show that the effect of chloride ion corrosion negatively affected the carbonation resistance of RAC, and the negative effect was more severe with the increasing recycling cycles of RCA. Chloride ion corrosion led to a decrease in compressive strength, while an increase in carbonation depth and the porosity of RAC. The equation of concrete total porosity and carbonation depth was established, which could effectively judge the deterioration of carbonation resistance of RAC.

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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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