A confinement-dependent load-induced thermal strain constitutive model for concrete subjected to temperatures up to 500 °C

Abstract

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.ACCEPTED MANUSCRIPT A C C E P T E D M A N U S C R I P T 1 Highlights  LITS development for temperatures up to 500°C is strongly confinement-dependent  A confinement-dependent LITS model for this temperature range is presented  The model is numerically implemented, validated applied to a test case  The behaviour of nuclear vessels is affected by the confinement-dependency of LITS ACCEPTED MANUSCRIPT A C C E P T E D M A N U S C R I P T AbstractThis paper proves that, given a Load-Induced Thermal Strain (LITS) curve able to accurately describe the uniaxial LITS development for a specific type of concrete and temperatures up to 500°C, a more accurate prediction of the 3D LITS state is obtained through a confinement-dependent 3D implementation than through the classic confinement-independent approach. In particular, a new model is presented, obtained by extending to 3D a fourth order polynomial LITS derivative function in a way that allows the effects of the stress confinement to be taken into account. For comparison purposes, the same fourth order polynomial LITS derivative function is also implemented in 3D through the classic confinement-independent modelling approach. These constitutive relationships are adopted to model transient experiments performed on concrete subjected to constant uniaxial and biaxial compressive loads. The results show that the confinementdependent modelling approach gives a better prediction of the LITS state developing in the case of biaxial compression than the classic confinement-independent approach. Finally, the validated confinementdependent model is applied to evaluate the LITS-related stress redistribution taking place in a typicalPrestressed Concrete Pressure Vessel (PCPV) subjected to heating to 500°C and cooling back to the normal operating temperature of 50°C. It is found that including the effects of three dimensional LITS behaviour has significant effects on the predicted stress states.

A moisture-dependent thermomechanical constitutive model for concrete subjected to transient high temperatures

“…The qualitative development of the components of FTS and LITS in the case of heating-cooling cycles is illustrated in Figure 5 and Figure 6 respectively. In line with previous work [17,27], the temperature history of the material is taken into account through an internal variable which stores the maximum temperature ever reached by the material.…”

“…The uniaxial LITS model described by Eq. (3-8), (3-9), (3-10), (3)(4)(5)(6)(7)(8)(9)(10)(11) and (3)(4)(5)(6)(7)(8)(9)(10)(11)(12) has been extended to 3D through the confinement dependent approach presented by the authors in [17,27], which captures the dependency of LITS on stress confinement through a confinement coefficient :…”

On the effect of thermal expansion coefficient in prestressed concrete beams

“…The prestressing stress state is modified adding, to a non-regular cross section, transient thermal stresses that are source of the strains due to the temperature profile that are, besides, restrained by the prestressed structural system. Concrete temperature-dependent coefficient of thermal expansion shows this property has wide dispersion and research is ongoing [24][25][26][27][28][29][30].…”

A Dynamic Elastoplastic Model of Concrete Based on a Modeling Method with Environmental Factors as Constitutive Variables

“…The constitutive model is established in the form of incremental stress-strainenvironment to describe the mechanical response of concrete under the coupled action of load and environment (Lu et al, 2020). Especially, the mechanical response, i.e., , caused by the changes in the environment can be captured (Hossain and Weiss, 2004;Rahnavard et al, 2022;Torelli et al, 2018). The viscoplastic model is a representative model established by this method.…”