Recent earthquakes have highlighted the importance of earthquake ground motion recordings and rapid visual inspections (RVSs) of damaged buildings to assess the earthquake impact on the building inventory, prepare recovery plans, and provide valuable findings that could contribute to the preparedness ahead of future earthquake events. The effect of strong earthquake ground motions on the building stock is controlled by a range of interconnected factors. These include the intensity of ground motion, the effects of local soil conditions, the structural design, reinforcement and material properties, as well as the quality control during construction, among others. However, it is important to acknowledge that the earthquake ground motions recorded are dependent on local variables, such as the soil type and potential operational issues. Such an example is the major M6.4 earthquake in Durr & euml;s, Albania, in November 2019, the most significant in the region in the past four decades. The strong ground motion recorded at the sole Durr & euml;s accelerometric station was interrupted due to a power outage. As a result, the recorded accelerograms (with a PGA of 0.192 g) require thorough analysis and evaluation before they can be reliably used in assessing damage of existing structures. The current paper presents a framework for evaluating the incomplete record to ensure that the strong ground motion pulse is captured in the acceleration series. The latter is achieved by analyzing and comparing the amplitude and frequency contents of the recorded motion against ground motion accelerograms from areas with similar seismotectonic features. Ground motion recordings from stations that have soil conditions resembling those of the Durr & euml;s region are used, ensuring that the analysis is relevant to the specific study area. Next, the disrupted ground motion recording is evaluated by comparing the damage of post-earthquake inspected buildings with the results of advanced numerical analysis for the case of a typical 12-storey and a 5-storey building. The effects of pounding, the presence of infills, soil-structure interaction (SSI), and multiple failure modes are taken into consideration. Results indicate that despite the incomplete data, the seismic record retains the essential strong ground motion features and can be used for further studies. The numerical simulations aligned well with observed damage from rapid visual inspections, verifying the record's integrity. The findings show that factors such as soil-structure interaction, infill panels, and pounding effects significantly influenced building performance. The study concludes that the Durr & euml;s record, though incomplete, is reliable for seismic assessment and can aid future risk studies in the region.

Concrete gravity dams, forming a quarter of the ICOLD database with over 61,000 dams, often surpass 50 years of service, necessitating increased maintenance and safety scrutiny. Given the aging and advancing seismic safety methods, reevaluating their seismic resilience, considering material degradation and concrete heterogeneity, is imperative. This study conducts a comprehensive seismic fragility assessment of the Pine Flat Dam at lifecycle stages of 1, 50 and 100 years, accounting for material degradation due to aging and uncertainties from concrete heterogeneity. It develops a 2D dam-foundation-reservoir model with fluid-structure-soil interaction and material nonlinearity using the concrete damage plasticity model. The assessment includes 55 ground motions, selected via the conditional mean spectrum method, representing five return periods from 475 to 10,000 years. Fragility curves are developed by fitting a lognormal distribution to failure probabilities at varying intensities. These curves are compared using damage indices like crest displacement and stress at the dam's neck and heel. Aging increases failure probability, correlating with age and return period, as shown by the leftward shift of fragility curves, while concrete heterogeneity adds uncertainty. The results emphasize the critical need for ongoing seismic fragility reassessments, accounting for aging, environmental exposure, and seismic demands on dam safety.

This paper investigates the liquefaction hazard in the Port Area of Pulau Baai, Bengkulu City, during the large subduction earthquake of 2007. The study was conducted systematically, commencing with a site investigation that included shear wave velocity measurements. Spectral matching and ground motion predictions, based on a relevant attenuation model, were performed to derive representative ground motions for the study sites. Ground response analysis was carried out to examine soil behaviour under seismic loading. Non-linear finite element analysis was utilised to assess dynamic soil characteristics such as excess pore water pressure, shear stress-strain response and stress paths. Additionally, an empirical evaluation was conducted to assess the liquefaction potential. The results indicate that liquefaction at shallow depths could occur, particularly in the first two sand layers. They also suggest that potential seismic damage could range from VII to IX on the Modified Mercalli Intensity (MMI) scale. Both numerical and empirical analyses demonstrated consistent trends and alignment. The comparison of excess pore pressure ratios and safety factors aligns with findings from previous studies. These results underscore the importance of implementing seismic hazard mitigation measures for the study area.

The kinematic interaction between piles under seismic loading has been extensively studied from analytical, experimental, and numerical perspectives. Of note, within numerical modeling, the majority of the existing literature relies on simplified approaches for characterizing the soil-pile interaction, which leads to the requirement for more reliable and comprehensive research. In this paper, using FLAC3D, the seismic response of the soil-pile system was investigated with a set of fully nonlinear three-dimensional (3D) numerical analyses in the time domain. This model simulated the soil strength and stiffness dependency on the stress level and soil nonlinear behavior under cyclic loading. The Mohr-Coulomb (M-C) constitutive model described the soil's mechanical behavior, which was used with additional hysteretic damping to suit the dynamic behavior. In the framework of a parametric study, the effects of loading frequency on the response of a soil-pile system that was subjected to seismic loading were studied. The results showed that the pile response and soil characteristics, as well as the natural frequency mode of the system's dynamic behavior, are strongly affected by the frequency of the seismic loading. Therefore, the bending moment and lateral displacement along the length of a pile increase as the loading frequency approaches the natural frequency of the system. In addition, when the loading frequency reaches a threshold value far from the fundamental frequency of the system, the effect of loading frequency on the soil-pile system response becomes negligible. In addition, the relationship between the pile diameter and maximum pile bending moment at different loading frequencies is affected by the soil properties.

Damages occurring during earthquakes may vary depending on the ground conditions in which the earthquake waves pass, the magnitude of the earthquake, the focal depth of the shaking and as well as the structural characteristics. Regional seismicity, ground movement and behavior of local soil conditions are important in earthquake-resistant building designs. Local site conditions consist of the layering, bedrock depth, and dynamic and topographic characteristics of soil that alter the bedrock waves through the soil profile during an earthquake. The change occurs in terms of amplitude, frequency and the time when the peak happens during the wave propagation. This initiates a big difference between the surface and bedrock motion. The behavior of the soil under cyclic loads resulting from seismic action is non-linear. This study aims to demonstrate the effects of strong ground motion by taking into account the nonlinear behavior of the soil layers. In addition, the results obtained from the equivalent linear and non-linear methods were compared. The results of the study showed that the characteristics of soil layers and strong ground motion (frequency content and duration) significantly affect the field response analysis and generally larger spectral parameters (about %20) have been obtained with the equivalent linear method compared to the nonlinear behavior. Finally, empirical models to estimate the soil amplification reflect different compared to the site specific analysis.

This study addresses the vital issue of the variability associated with modeling decisions in dam seismic analysis. Traditionally, structural modeling and simulations employ a progressive approach, where more complex models are gradually incorporated. For example, if previous levels indicate insufficient seismic safety margins, a more advanced analysis is then undertaken. Recognizing the constraints and evaluating the influence of various methods is essential for improving the comprehension and effectiveness of dam safety assessments. To this end, an extensive parametric study is carried out to evaluate the seismic response variability of the Koyna and Pine Flat dams using various solution approaches and model complexities. Numerical simulations are conducted in a 2D framework across three software programs, encompassing different dam system configurations. Additional complexity is introduced by simulating reservoir dynamics with Westergaard-added mass or acoustic elements. Linear and nonlinear analyses are performed, incorporating pertinent material properties, employing the concrete damage plasticity model in the latter. Modal parameters and crest displacement time histories are used to highlight variability among the selected solution procedures and model complexities. Finally, recommendations are made regarding the adequacy and robustness of each method, specifying the scenarios in which they are most effectively applied.

A careful evaluation has been carried out to reveal advantages and disadvantages of linear and nonlinear modelling in dynamic analysis. 4- and 7- story building models representing characteristics of about 500 existing buildings models in Turkey was used in analyses. In the study, displacement demand parameters such as roof drift ratio and interstory drift ratio obtained from linear and nonlinear analyses were compared using a total of 24 ground motion records including forward directivity effects (Set 2) as well as records (Set 1) recorded in type B and C soils. Although the seismic demands for Set 2 are obtained extremely high in the nonlinear models, the demand differences between Set 1 and Set 2 are not excessive for the linear models. In the region where the T/Tp ratio is close to one, the linear analysis predicts unrealistically high demands compared to the nonlinear analysis. Linear analysis results mostly show an increase or decrease depending on dynamic amplification effects. The effects of ground motion intensity and damage mechanism cannot be observed in linear analysis method. For all these reasons, it is recommended not to prefer linear modeling method when using time- history analysis.

Ground vibrations caused by soil-structure (SSI) can be magnified or de-amplified, and estimating them is essential for seismic designs and fragility assessments. Field survey reports show that SSI is an important factor causing severe damage to structural elements, especially in soft soils that have been exposed to an earthquake. The soil-structure interaction (SSI) is widely ignored, or drastically simplified, in most conventional seismic fragility assessments of RC structures. This paper presents a probabilistic approach for assessing the effects of soilstructure interaction (SSI) on the seismic response of mid -rise (four story) RC frame structures, by seismic fragility curves. RC frame response is evaluated by Static Pushover 2 Incremental Dynamic Analysis (SPO2IDA). Two basic models of typical residential buildings are modeled, without SSI (fixed base) and with SSI, and an elastic model is used to simulate linear soil behavior. The ultimate displacement results demonstrate the contrast between two cases: one with a rigid base and no soil-structure interaction (SSI), and the other involving a structure with SSI, considering different soil types including S1 (rock), S2 (stiff), S3 (soft), and S4 (very soft). The ratio of ultimate displacement between a rigid base and a structure with SSI for soil types S1, S2, S3, and S4 is 4%, 19%, 25%, and 46%, respectively. The results also demonstrate that the design of short-period frame structures (rigid structures) founded on soft soils (S3 and S4), and not taking into account the effect of soil-structure interaction (SSI) when modeling and designing, leads to a greater probability of damage and makes the structure more vulnerable in the event of a large earthquake.

The primary objective of current seismic design codes is to ensure the life safety of building occupants under extreme seismic events. These codes normally permit structural and nonstructural damage during a design-level earthquake, leading to the possibility of significant economic losses and recovery time for the building. Recovery time is a significant factor in the seismic performance of buildings because it affects not only the owner and users of a building, but also the overall recovery of the community. In designing low-rise buildings, current design requirements in different jurisdictions can produce footings with vastly different sizes, which can significantly affect building performance. Therefore, there is a need to investigate the effects of footing size on the expected recovery time of low-rise buildings. In this study, 2-storey concentrically braced frame buildings at a site class D are selected to evaluate the impact of the size of the footings on the repair time of low-rise buildings. These buildings are in Vancouver, Canada, and have X-bracing systems. The buildings are modelled in OpenSees using an advanced numerical model. Nonlinear response history analysis is performed employing a set of ground motions that match the soil condition of the site. The recovery time is estimated, including the delay time to start repairs and the time required to repair the damaged members. The findings of this study suggest that not capacity-protected (NCP) footings (i.e., rocking foundations) could be the preferred choice for short-period CBF buildings on soft soil.