Thermodynamic gradient-based poroplastic theory for concrete under high temperatures

Abstract

Concrete materials subjected to long term exposures to high temperatures suffer severe degradations in its mechanical properties (cohesion, friction, strength and stiffness) and changes in their failure mechanisms. These degradations may lead to irreversible damage or sudden collapse of the related structures. From the predictive analysis stand point, accurate constitutive theories are required to simulate the variations of concrete mechanical failure behavior under high and durable temperature fields. In the realm of the smeared crack approach, non-local model strategies are required to objectively reproduce failure behaviors under coupled thermo-mechanical loading conditions, while realistic descriptions of the involved characteristic lengths are needed to objectively reproduce the variation from ductile to brittle failure modes depending on the acting confining pressure and temperature. In this work, a thermodynamically consistent gradient poroplastic model for concrete subjected to high temperatures is proposed. A particular and simple form of gradient-based poroplasticity is considered whereby the state variables are the only ones of non-local character. The degradations of these variables due to coupled thermo-mechanical effects are described in the framework of the thermodynamic approach. After describing the material formulation, numerical analyses are presented which demonstrate the predictive capabilities of the proposed constitutive theory for different stress paths and thermal conditions.

Degradation of Dynamic Elastic Modulus of Concrete under Periodic Temperature-Humidity Action

“…Domestic and foreign scholars have done a lot of research on damage accumulation and performance deterioration of concrete material under temperature-humidity, but most of their works focus on the deterioration of concrete material under freeze-thaw cycles [11][12][13][14][15][16][17], the interaction of freeze-thaw cycles and other factors [18][19][20][21][22], or high-temperature environments [23][24][25][26][27][28]. In fact, besides the long-term uninterrupted freeze-thaw cycles or high temperature effects in special service environments, most concrete is subjected to cyclic moisture-heat effects determined by the local natural environment.…”

An analytical model for crack monitoring of the shape memory alloy intelligent concrete

“…The cracks occurred easily in concrete due to its low tensile strength and poor crack resistance, which will do great harm to the quality and durability of concrete structures (Červenka and Papanikolaou, 2008; Cicekli et al, 2007; Contrafatto and Cuomo, 2006; Ripani et al, 2014; Voyiadjis and Abu-Lebdeh, 1994). In order to sense the cracks in time, the intelligent concrete which possess the characteristics of the crack self-sensing characteristic is becoming one of the hottest issues in our world (Downey et al, 2018; Feng et al, 2017; Le and Kim, 2017; Ou, 2005; Sikarwar et al, 2017; You et al, 2017).…”

Meso-scale response of concrete under high temperature based on coupled thermo-mechanical and pore-pressure interface modeling

“…High temperature in concrete members represents a field of great interest due to its crucial influence in terms of induced thermal damage, affecting strength, durability and serviceability conditions of structural components. Specifically, exposure to high temperature and/or fire represents one of the most destructive events that concrete constructions and structures can suffer [1] [2]. The most relevant mechanical properties of concrete and cementitious mortar composites such as cohesion, friction, stiffness and strength show severe degradation under long term exposure to these critical conditions [3] [4].…”