Nonlinear model for early age creep of concrete under compression strains

Han, Bing; Xie, Huibing; Zhu, Li; Jiang, Peng

doi:10.1016/j.conbuildmat.2017.04.119

Cited by 47 publications

(15 citation statements)

References 26 publications

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“…Therefore, the viscosity coefficient is no longer a fixed value, but rather is a variable that decreases with the increase in the degree of damage. The damage variable is a negative exponential function [37] that considers the influence of damage growth on the creep process, which can be expressed as. D=1−expfalse(−αtfalse) where D is the damage variable, and its value range is 1], which corresponds to the concrete failure state without damage, and the complete damage, respectively.…”

Section: Construction Of Concrete Nonlinear Creep Damage Constitutmentioning

confidence: 99%

Nonlinear Creep Damage Constitutive Model of Concrete Based on Fractional Calculus Theory

Zhang

Zhu

et al. 2019

Materials

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Concrete creep has become one of the major problems that threatens concrete structural development and construction. However, a reasonable and accurate calculation model for numerical analysis is the key to control and solve the creep deformation of concrete. To better describe the concrete nonlinear creep damage evolution rule, the visco-elasticity Plasticity Rheological Theory, Riemann Liouville Theory and Combined Model Theory are quoted, and the Able dashpot is used to reconstruct fractional-order soft-body composite elements to propose the expression of the stress-strain relationship of the elastomer, visco-elasticity plasticity body, and Viscoplasticity body, considering the evolution of the concrete compression damage process. A nonlinear creep damage constitutive model of concrete, based on fractional calculus theory, is conducted, and the parameters of the specific calculation method of the model are given. The influence of stress level σ, fractional order n and material parameter α on the concrete creep process is determined by a sensitivity analysis of the model parameters. The creep process and deformation amount of concrete in practical engineering can be effectively controlled by the results of the proposed sensitivity analysis. The research results can be used to provide guidance and reference for the safe construction of concrete engineering in actual practice.

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Section: Construction Of Concrete Nonlinear Creep Damage Constitutmentioning

confidence: 99%

Nonlinear Creep Damage Constitutive Model of Concrete Based on Fractional Calculus Theory

Zhang

Zhu

et al. 2019

Materials

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“…Through the combination of the various rheological elements, which can characterize the basic properties of materials, such as elasticity, viscoelasticity, viscidity or damage, a comprehensive performance of materials could be depicted (Han et al 2017 Where 1 E is the elastic modulus of the Maxwell model, and SSR is the stress-strength ratio.…”

Section: Establishment Of the Modelmentioning

confidence: 99%

Deformation and instability properties of cemented gangue backfill column under step-by-step load in constructional backfill mining

Yao

Ran

Feng

et al. 2021

Environ Sci Pollut Res

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Abastract：Constructional backfill mining with cemented gangue backfill column can solve the environmental issues caused by mining activities and the accumulation of waste gangue at a low cost. To study the deformation and instability properties of cemented gangue backfill columns during the advancement of coal mining face, five step-by-step loading paths were adapted to mimic the different loading processes of the roof. The lateral deformation at different heights and axial deformation of the sample were monitored. The results show that the deformation and instability of the backfill column have the properties of loading paths and are affected by the step-by-step loading path. When stress-strength ratio (SSR) is less than 0.6, the lateral of backfill column shrinks during the creeping process. In high-stress levels, lateral creep strain develops faster than axial creep strain. The backfill column has characteristics of axial creep hardening and lateral creep softening during the step-by-step loading process. The instantaneous deformation modulus and instantaneous Poisson's ratio show an upward trend. The bearing capacity of backfill column under the step-by-step load is related to loading paths and is no less than uniaxial compressive strength. The non-uniformity of the lateral deformation of backfill column leads to excessive localized deformation that mainly occurs in the middle, causing the overall instability. The development of cracks of backfill column under step-bystep load could be divided into 4 stages according to SSR. Under different step-by-step loading paths, the axial creep strain rate is nearly a constant before entering the accelerated creep stage. A nonlinear creep constitutive model with a creep strain rate trigger was proposed to depict the development of axial strain under step-by-step load. This research will provide a scientific reference for the design of the advancing distance and cycle for the hydraulic support, and reinforcement of the backfill column. Keywords：Cemented gangue backfill column; step-by-step load; deformation; instability; nonlinear creep constitutive model 1 IntroductionCemented gangue backfill mining technology is an important part of the "green mining" system for coal mining, it not only controls the movement of the overlying strata and the surface subsidence effectively, but also consumes a large amount of coal gangue (Chen et al. 2016a).The material used for coal mine backfill mining is made of coal gangue, cement, fly ash, and water. Generally, the method of full backfilling is used in coal mining, that is, all mined-out space is filled with cemented gangue backfill material. However, the cost of cement and fly ash is relatively high, and the production of coal gangue only accounts for about 20% of the output of raw coal (Liu et al. 2020). The high cost and limited raw materials impede the promotion of coal mine full backfill mining; thus, partial backfill mining (Zhu et al. 2017) and constructional backfill mining (Feng et al. 2019;Du et al. 2018) are proposed, and ...

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“…Rheological models for evaluating creep were developed by Sellier et al (2016), who performed a series of computational simulations in an FEM environment. A viscoelasticplastic model that superposes the strains obtained using the Maxwell, Kelvin, Bingham, and Saint-Venant models was proposed by Han et al (2017b) to describe early-age creep in concrete. This model essentially represents a modified version of a system that maintains the conventional initial viscoelastic behavior of concrete.…”

Section: Overviewmentioning

confidence: 99%

Analytical determination of the vibration frequencies and buckling loads of slender reinforced concrete towers

Wahrhaftig

Silva

Brasil

2019

Lat. Am. j. solids struct.

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This study focused on improving the design of slender structures with reinforced concrete (RC) telecommunication towers as the main application. Analytical procedure based on Rayleigh's method to compute the first natural vibration frequency and the critical buckling load was development. All the nonlinearities present in the system were considered, in addition to the soil-structure interaction and the variation of the geometric properties along the length of the structure. The geometric nonlinearity and imperfections of the tower structure were computed as functions of the axial load using a geometric stiffness matrix. Further, the material nonlinearity was accounted for by reducing the flexural stiffness. As concrete structures exhibit viscoelasticity, creep was calculated using the Eurocode 2 model. The soilstructure interaction was modeled as a set of distributed springs. To validate the proposed method, the first frequency and critical buckling load were compared with those yielded by FEM simulations. The frequency results were in good agreement with those of the FEM simulations, indicating that the proposed method is sufficiently accurate for use in engineering design applications and easy to implement. On the other hand, the buckling load results obtained using the proposed method and FEM differed significantly, motivating further investigation.

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Nonlinear model for early age creep of concrete under compression strains

Cited by 47 publications

References 26 publications

Nonlinear Creep Damage Constitutive Model of Concrete Based on Fractional Calculus Theory

Nonlinear Creep Damage Constitutive Model of Concrete Based on Fractional Calculus Theory

Deformation and instability properties of cemented gangue backfill column under step-by-step load in constructional backfill mining

Analytical determination of the vibration frequencies and buckling loads of slender reinforced concrete towers

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