This paper presents the formulation of a time-dependent seismic fragility format for bridges, as well as new insights into the potential effects of aging and deterioration on seismic vulnerability traditionally neglected in fragility modeling, including joint impacts of multiple component deterioration not investigated to date The study evaluates the impact of lifetime exposure to chlorides from deicing salts on the seismic performance of multispan continuous highway bridges, considering corrosion of reinforced concrete columns and steel bridge bearings The components' degradation and their influence on seismic response are illustrated through three-dimensional nonlinear dynamic analysis A full probabilistic analysis accounting for variation in bridge, ground motion, and corrosion parameters is conducted to develop time-dependent seismic fragility curves These fragility curves indicate the evolving potential for component and system damage under seismic loading considering time-dependent corrosion-induced deterioration The results indicate that while corrosion may actually decrease the seismic vulnerability of some components, most critical components suffer an increase in vulnerability Quadratic models depicting the change in lognormal seismic fragility parameters are proposed to capture the time-dependent effect of aging on the fragility of the bridge system Overall, the seismic vulnerability significantly increases throughout the lifetime of the representative bridge geometry, with a 32% shift in the median value of complete damage fragility near the end of the bridge's life

Aging Considerations in the Development of Time-Dependent Seismic Fragility Curves

Consequences of steel corrosion on the ductility properties of reinforcement bar

Chloride-induced corrosion of steel reinforcement – Mechanical performance and pit depth analysis

Probabilistic capacity models and seismic fragility estimates for RC columns subject to corrosion

An experimental study on the bond strength between reinforcement bars and concrete as a function of concrete cover, strength and corrosion level

Corrosion influence on bond in reinforced concrete

Recycled aggregate concrete with the incorporation of rice husk ash: Mechanical properties and microstructure

Study on the chloride ion transport mechanism of recycled mixed aggregate concrete based on evolution characteristics of pore structure

Based on the modified compression field theory, this paper considers the
 inter-locking force between recycled concrete aggregates and their effective
 grain sizes, and establishes a shear model to describe accurately the
 actual force of recycled concrete beams with web reinforcement.
 Mathematical formulas for calculation of the interlocking force are
 deduced, and the shear capacity of the recycled concrete beams can be
 estimated. The data of five test beams and 20 test beams in open literature
 are in good agreement with the theoretical prediction, which proves that
 this method can be used to calculate the ultimate shear capacity for
 practical applications.

/pdf/calculation-of-shear-capacity-of-recycled-concrete-beams-252tbttf.pdf

Calculation of shear capacity of recycled concrete beams with web reinforcement based on modified compression field theory

WIt has great environmental potential to replace natural aggregates by
 recycled brick aggregates. To investigate the deterioration mechanism of
 recycled brick aggregate concrete, this paper designed eight groups of
 recycled brick aggregate sub-lightweight concrete with different
 water-cement ratios, maximum aggregate sizes and coarse aggregate type
 ratios, and carried out mechanical property test to analyze the aggregate
 interface characteristics and the damage mechanism of recycled brick
 aggregate concrete. The results show that the increase of replacement ratio
 and water-cement ratio leads to a significant decrease of compressive
 strength and splitting tensile strength of concrete, and the influence of
 the maximum aggregate size on strength is small. Unlike the recycled
 concrete aggregate - mortar interface, the microstructure of recycled brick
 aggregate - mortar interface is dense and the interface performance is
 enhanced. Recycled brick aggregate concrete is in non-interface damage
 mode, and the strength of brick aggregate is the main influence to determine
 the mechanical properties of concrete factor.

/pdf/damage-mechanism-of-concrete-with-recycled-brick-aggregate-19s70js2.pdf

Chaoying Zhu

Papers

Corrosion influence on bond in reinforced concrete

Recycled aggregate concrete with the incorporation of rice husk ash: Mechanical properties and microstructure

Study on the chloride ion transport mechanism of recycled mixed aggregate concrete based on evolution characteristics of pore structure

Calculation of shear capacity of recycled concrete beams with web reinforcement based on modified compression field theory

Damage mechanism of concrete with recycled brick aggregate