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This study explores comparative seismic performance of a shape memory alloy (SMA)-only device, a friction damper, and a hybrid self-centering device. The self-centering device considered in this study, named as superelastic friction dampers (SFDs), is a hybrid damper operating on a mechanism where SMA cables and frictional components are arranged in parallel. A detailed description of the device and an experimental characterization of mechanical behavior are presented first. Then, an 8-story archetype steel frame building is designed and modeled with each seismic protection device (SMA-only, hybrid self-centering, and friction only). To enable comparative performance assessment, each device is designed to have similar initial stiffness and the same maximum force at design displacement. Nonlinear time history analyses are conducted using a total of 44 ground motion records. The results are evaluated to compare performance of each frame design at design-basis and maximum considered earthquake hazard levels. Next, a risk-based seismic hazard demand analysis framework that involves comprehensive incremental dynamic analyses is employed for further assessing the performance of each system. The experimental results validate the parallel working mechanism of SMA cables and frictional components in the SFD, with 90% of the damper deformations recovered. Comparative analysis of seismic responses demonstrates the excellent performance of the SFDs in reducing interstory drift ratio, residual interstory drift ratio, and absolute acceleration responses. Furthermore, fragility analysis and risk-based seismic hazard assessment further reveal that the SFDs provide a well-balanced combination of energy dissipation capability and self-centering ability, thereby enhancing the seismic resilience of structures. • The working mechanism and mechanical performance of the superelastic friction damper have been experimentally validated. • Risk-based seismic hazard analyses have been conducted for frames equipped with various dampers. • SFD is capable of enhancing seismic resilience effectively by leveraging energy dissipation and self-centering capabilities. [ABSTRACT FROM AUTHOR]

Seismic fragility analysis is one probabilistic method that represents the conditional probabilities of exceeding different predetermined damage states for various given earthquake hazard levels, which is the essential part of probabilistic seismic risk assessment. It has gained much popularity recently because much more comprehensive and richer results than traditional probabilistic methods can be provided. The classical seismic fragility analysis of slopes is always performed through analytical approaches. In the present study, a novel seismic fragility analysis framework combined with shaking table model test results is proposed for probabilistic seismic performance and risk assessment of slopes. The shaking table model tests of a rock slope reinforced by pile-anchor structures were firstly performed subjected to a suite of real earthquake records with different intensity levels. Subsequently, the seismic responses from shaking table model tests were then gathered for the optimal analysis to determine the optimal engineering demand parameter (EDP) and earthquake intensity measure (IM) for seismic fragility analysis of slopes. At last, the identified most appropriate IM and EDP were selected to construct the scalar-valued fragility curves, vector-valued fragility surfaces and fragility surfaces considering acceleration elevation amplification effect by the proposed framework. The results indicate that using single IM to construct scalar-valued fragility functions may result in different failure probabilities depending on the chosen earthquake IM. The vector-valued fragility surfaces provide more information than ordinary fragility curves, and lead to more proper and realistic evaluations of seismic hazard of slopes. The methods and results presented in this paper also provide the basis for the probabilistic seismic risk and loss assessment of earthquake-induced slope geological disaster. • A novel seismic fragility analysis framework of slopes combined with the data from shaking table model tests is proposed. • The optimal EDP and earthquake IM for scalar- and vector-valued fragility analysis of slopes are identified. • The fragility surfaces of a slope considering acceleration elevation amplification effect are constructed. [ABSTRACT FROM AUTHOR]

• The model update process with the TSA reduces the differences between numerical and experimental dynamic characteristics. • Using quake records explicitly prepared for the region in dynamic analyses of masonry structures provides realistic results. • The most critical areas of masonry clock towers in terms of stress are the section change zones that cause sharp transitions. • Restoration prevents masonry structures from becoming vulnerable to external factors by addressing minor issues. • If the faults pass through or close to a city, the quake performances of masonry structures in that city must be evaluated. This article presents comprehensive numerical and partial experimental studies to determine the seismic performance of the recently restored masonry clock tower in Bayburt before and after restoration. The numerical dynamic characteristics of the structure are obtained by free vibration analysis conducted on the preliminary finite element model, while the experimental ones are determined through ambient vibration testing. The ultimate finite element models reflecting the actual state of the structure pre- and post-restoration are created through a model updating process based on the principle of minimizing the differences between numerical and experimental dynamic properties via the Tabu Search Algorithm. Dynamic analyses of the models are carried out by the mode superposition method in the time domain, using eleven earthquake ground motion records selected considering the tectonic structure of the region and scaled to the design spectrum explicitly established to the site. Seismic responses are evaluated based on displacement, maximum-minimum principal stress, and maximum-minimum principal strain. The maximum principal stress value, the most critical parameter jeopardizing the safety of masonry structures, is 2.069 MPa before the restoration reaches 2.489 MPa, with an increase of approximately 20.3 % after the restoration. Since this value is less than the tensile strength of the masonry material, 3.120 MPa, it is not at a level that poses any risk to the structure. Other structural reactions also remain below the limit values. Therefore, according to today's seismic hazard analysis criteria, it can be said that the clock tower is safe. However, the North Anatolian Fault Zone, with high tectonic activity passing just south of the city, has the potential to produce severe earthquakes that may affect the region in the future. Therefore, it is necessary to periodically monitor the seismic behaviors of the historical masonry structures in Bayburt and take essential precautions based on the results. [ABSTRACT FROM AUTHOR]

The topographic amplification effect has significant impacts on structural safety since it causes inconsistencies in seismic response. Previous studies on topographical influence focus on a certain point and cross-sections, which is insufficient to comprehensively understand the topographic amplification effect. Besides, few studies analyze the relationship between seismic response and ground motion frequency. Hence, this study aims to investigate the effects of topographic irregularity of the whole site, and explore the relationship between seismic response characteristics and signal frequency. An analysis procedure for modeling and meshing an actual 3D site is proposed by combining SolidWorks, SketchUp and Abaqus. Finite element method (FEM) is applied to simulate the seismic response. Results show that the site amplification and de-amplification are associated with topographic features. Specifically, the seismic responses of ravine and ridge areas could differ by a factor of two. However, acceleration response in ravine areas shows unusual amplification under input signal frequencies over 4 Hz. Besides, the frequency of input ground motion certainly affects the seismic site amplification. Specifically, in this study, the seismic response peaks when the input frequency is in the range of 0.4–0.8 Hz, which corresponds to the resonance frequency of the numerical model. In terms of frequency, site amplification showed a correlation between actual recordings and artificial signal inputs, but lower intensities are observed when actual records are input. Therefore, the engineering risk will be underestimated when the topographic irregularity and frequency characteristic of input ground motion are inappropriately considered. The findings of this study provide a new approach to investigate the actual 3D site amplification effects and shed new insight on regional seismic risk analysis. • A method for generating numerical models of irregular 3D terrain is proposed. • The correlation between the seismic response and topographic characteristics of the valley at the actual site is investigated. • Seismic site amplification is closely related to input signal frequency. [ABSTRACT FROM AUTHOR]

Deterioration mechanisms, such as chloride-induced corrosion, affect bridges in aggressive environments, making them more vulnerable to extreme events like earthquakes. Although many studies have assessed the impact of chloride-induced corrosion on the seismic vulnerability of reinforced concrete (RC) highway bridges, several gaps still need to be addressed. Accordingly, this research primarily focuses on evaluating the seismic performance of RC highway bridges in aggressive environments susceptible to chloride-induced corrosion and earthquakes. To achieve this, a probabilistic framework is employed, which incorporates uncertainties associated with corrosion progression, seismic events, and the impact of different modeling approaches for boundary condition. The framework considers the time-dependent effects of corrosion on the physical and material properties of steel and concrete in bridge columns. Monte Carlo Simulations (MCS), probabilistic seismic hazard analysis (PSHA), and record selection strategies are utilized to address the uncertainties in corrosion and seismic demand. Nonlinear dynamic models and multiple stripe analysis (MSA) are employed to obtain fragility surfaces and curves for main bridge components and the entire system under different boundary conditions. The study focuses on a five-span highway bridge with simply-supported prestressed concrete I-girder and RC multi-column bents located in Chile. The results reveal that elastomeric bearings are the most vulnerable components, exhibiting varying vulnerability levels under different corrosion exposure and boundary conditions. Abutments, although the second most susceptible, are unaffected by corrosion uncertainty in terms of seismic fragility. Bridge columns are identified as the third most vulnerable components, with the probability of exceeding slight damage state consistently increasing with more prolonged corrosion exposure. It is noted that only flexure failure mode in column is analyzed and possible shifting to shear or flexure-shear modes is not accounted for. The findings of this study underscore the exceptional resilience of Chilean highway bridge columns to seismic demand and corrosion uncertainties, contrasting with the situation in US regions where columns are more vunerable. Additionally, the study indicates that Soil-Structure Interaction (SSI) tends to reduce bridge vulnerability under combined corrosion and earthquake effects. The insights obtained from this study and the proposed framework can inform the development of maintenance programs based on bridge performance expectations and enhance the seismic resilience of bridge systems worldwide. • Combined effects of chloride-induced corrosion and severe earthquakes are investigated. • Uncertainties in seismic demand and time-dependent corrosion process are accounted for. • State-of-the-art nonlinear numerical modeling of an actual bridge is used. • Effects of boundary conditions, fixed and with soil-structure-interaction, are analyzed. • Component and system fragility surfaces are developed. [ABSTRACT FROM AUTHOR]