Mechanical Behavior Evaluation of Tempcore and Hybrid Reinforcing Steel Bars via a Proposed Fatigue Damage Index in Long Terms

Abstract

As it is widely known, corrosion constitutes a major deterioration factor for reinforced concrete structures which are located in coastal areas. This phenomenon, combined with repeated loads and, especially, intense seismic events, negatively affect their useful service life. It is well known that the microstructure of steel reinforcing bars has a significant impact either on their corrosion resistance or on their fatigue life. In the present manuscript, an effort has been made to study the effect of corrosive factors on fatigue response for two types of steel reinforcement: Tempcore steel B reinforcing bars and a new-generation, dual-phase (DP) steel F reinforcement. The findings of this experimental study showed that DP steel reinforcement’s rate of degradation due to corrosion seemed apparently lighter than Tempcore B with respect to its capacity to bear repeated loads to a satisfactory degree after corrosion. For this purpose, based on a quality material index that characterizes the mechanical performance of materials, an extended damage material indicator for fatigue conditions is similarly proposed for evaluating and classifying these two types of rebars in terms of material quality and durability. The outcomes of this investigation demonstrated the feasibility of fatigue damage indicators in the production cycle as well as at different exposure times, once corrosion phenomena had left their mark in steel reinforcement.

Corrosion Effects on Durability of RC Structures

“…As a targeted extension of a recent European research project 'NEW dual-phase steel REinforcing BARs for enhancing capacity and durability of antiseismic momentresisting frames' (NEWREBAR) [6], M. Basdeki and C. Apostolopoulos conducted an experimental campaign investigating the corrosion resistance and fatigue behavior of two types of steel reinforcement: traditional tempcore steel and a new-generation hybrid steel with a microstructure in which a mixture of phases of martensite and ferrite coexist in a unique matrix. The outcomes reveal that the mechanical behavior of hybrid steel reinforcement is rather promising in the long term, even though, in reference conditions, it is of a lower class [2]. In addition, based on an existing quality material index that characterizes the mechanical performance of materials in quasi-static loadings, an extended damage material indicator for fatigue conditions is proposed for evaluating the overall mechanical performance of metallic materials, taking into account both strength capacity and ductility in the long term [2].…”

“…The outcomes reveal that the mechanical behavior of hybrid steel reinforcement is rather promising in the long term, even though, in reference conditions, it is of a lower class [2]. In addition, based on an existing quality material index that characterizes the mechanical performance of materials in quasi-static loadings, an extended damage material indicator for fatigue conditions is proposed for evaluating the overall mechanical performance of metallic materials, taking into account both strength capacity and ductility in the long term [2].…”

“…Five research papers have been published in Special Issue of Metals titled Corrosion Effects on the Durability of RC Structures. The collected articles deal with several aspects of the corrosion phenomenon in reinforced concrete, including the copper corrosion behavior in simulated concrete-pore solutions [1], the influence of microstructure on the corrosion resistance of steel bars and their fatigue behavior [2], the degradation of bond mechanism between steel and concrete [3,4], and the flexural capacity of corroded Prestressed Reinforced Concrete (PRC) beams [5].…”

Detection and Imaging of Corrosion Defects in Steel Structures Based on Ultrasonic Digital Image Processing

“…Corrosion is a common kind of defect in steel structures and is one of the main direct or indirect causes of structural failure [1,2]. A common case is the corrosion of buried water pipelines.…”

The Effect of the Shot Blasting Process on the Dynamic Response of Steel Reinforcement

“…Yet, current European and international regulations mainly provide design values from monotonic loading (quasi-static loading), despite the fact that cumulative damage due to fatigue loading is explicitly stated due to seismic events. In actuality, the material's strain history and especially the inelastic cycles should be considered during the seismic analysis of RC elements since they can be termed significant in cases of intense earthquakes, especially in the presence of corrosion damage; hence, over the recent years, researchers have studied the mechanical behavior of steel reinforcing bars under dynamic (fatigue) loadings considering the corrosive factor focusing on the fatigue damage accumulation in terms of energy absorption [24][25][26].…”