Numerical analysis of high and low‐cycle flexural fatigue for reinforced concrete beams under full‐range of varying amplitudes

Abstract

Structural reinforced concrete (RC) experiences cyclic loads during their service life, and in practice, the load amplitude can always change, which will lead to a mixed high and low-cycle fatigue failure. This paper aims to investigate the fatigue behaviors of RC beams under different load levels and more importantly, their sequential effects. Based on the path-dependent constitutive models, the structural degradation under different repeated loads are comprehensively investigated by numerical simulation of higher consistency with the reality. It is fairly indicated that a clear bi-linear character may exist in the socalled S-N diagram, of which the high-cycle fatigue failure is attributed to rupture of main reinforcement under tension, while the low-cycle fatigue failure is controlled by the concrete failure in flexural compression zone. A simple design method to consider mixed low and high cycle fatigue is proposed to quantify this bi-linear character. For the varying amplitude of cyclic loads, the high-to-low loading sequence may cause a shortened fatigue life. More interestingly, if a rather high heavy load (0.85 or 0.95 of the static capacity) is applied just once before ordinary fatigue loads (ex. 0.6), the deflection may significantly increase, while the stiffness and final fatigue life would be slightly reduced in view of nonlinear mechanics.

Stress configuration‐based classification of current research on fatigue of reinforced and prestressed concrete

“…To enable fatigue simulations of full-scale RC structures-encompassing both tensile and compressive fatigue degradation-a multi-scale modeling framework was introduced in Maekawa et al 131 This framework provides simplified stiffness degradation laws for compressive, tensile, and shear behaviors, capturing the nuances of fatigue loading. This approach has proven effective in simulating the fatigue response of RC beams and bridge decks subjected to moving traffic loads, as presented in Tanaka et al 132 and Huang et al 133 Furthermore, the framework integrates environmental loading effects, offering a comprehensive durability assessment. Specifically, it predicts the remaining fatigue life of RC slabs by considering the cumulative effects of frost damage and alkali-silica reaction, as detailed in Takahashi et al 134 and Gong et al 135 Additionally, there have been notable research initiatives focused on fatigue simulations pertaining to the deterioration mechanisms of RC road bridge slabs in both dry and wet conditions, as elaborated in Fang et al 136 In order to accelerate the cycle-by-cycle fatigue simulations, algorithms that allow jumps along the lifetime have been proposed in the literature, for example, Cojocaru and Karlsson, 137 and Maekawa et al 138 and Kristensen.…”

The Influence of Construction Methods on the Stability of Tunnels and Ground Structures in the Construction of Urban Intersection Tunnels

“…Existing studies and fieldwork indicate that appropriate construction methods can mitigate stress concentrations and rock strata deformation, making them essential for addressing these challenges [21,22]. The New Austrian Tunneling Method (NATM), known for its minimal construction disturbance and rapid closure, is frequently employed in tunnel projects characterized by complex geological and construction conditions [23].…”

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“…The main reasons for debonding failure can be summarized as follows: 1) the interfacial stress exceeds the bonding capacity when the applied load is large to a certain extent; 2) the interfacial force transmission performance deteriorates due to the shear creep of the adhesive layer for long-term service (Huang et al, 2021; Smith and Teng, 2001); and 3) the bonding strength of the adhesive layer decreases under high ambient temperature (Boeer et al, 2014; Karbhari et al, 2003). Among them, the quality of the strengthening operation plays an important role because it is related to the bonding capacity (Kalamkarov et al, 2000; Xiong et al, 2006).…”