Bulletin of Earthquake Engineering最新文献

This study investigates the seismic behavior of Masonry Infill Reinforced Concrete (RC) frames with Choh-kat-framed openings, common in the Kashmir region. It challenges traditional assumptions about infill structures, emphasizing their structural significance and providing new insights into how these infills influence seismic performance. The primary focus is on analyzing the impact of Choh-kat-framed openings on the lateral stiffness of RC frames under seismic loading and developing a novel strut model for predicting seismic response. A Finite Element (FE) approach is employed to simulate the complex interactions between the RC frame and Choh-kat-framed infills. The analysis considers several response parameters, including lateral stiffness, crack propagation patterns, load-bearing capacity, and energy dissipation. The study also examines the effects of different opening sizes, aspect ratios, locations, and multiple openings on structural performance. A key innovation is the introduction of an alteration factor (beta _{wc}) to account for stiffness, alongside a new 4-strut model for Choh-kat-framed openings. The results indicate that Choh-kat-framed openings up to 50% of the infill area contribute to decreased stiffness but delay crack propagation. The optimal opening area ratio for enhancing stiffness is 12%. Choh-kat additions significantly increase stiffness, especially at the top corners of the openings. The proposed strut model, validated by FEMA 356 guidelines, accurately predicts equivalent strut widths for pier and spandrel struts. In summary, this study offers a novel approach to understanding the seismic behavior of Masonry Infill RC frames with Choh-kat openings, providing a framework for improved design and retrofitting strategies.

On 21 August 2017, a M_w 3.9 earthquake struck the island of Ischia, causing two casualties and significant damage in the village of Casamicciola Terme and its surroundings. The earthquake was recorded by the local INGV-OV seismic network, and represents the first relevant instrumentally recorded earthquake on the island. However, it is not possible to perform a statistical analysis based on past recordings, which forms the basis of the Ground Motion Model at a local scale. The numerical simulations can help overcome this problem. Here, we first analysed the low magnitude seismicity of the island and focused on estimating the seismic attenuation and average static stress drop through spectral inversion analysis. We then used a stochastic finite-fault approach considering two source models to simulate the Casamicciola earthquake’s strong ground motion by also taking into account the site effect at the IOCA station. The numerical simulations were also extended to the localities for which observed macroseismic intensity values are available. The simulated peak ground motions, converted into intensities through empirical relationships, are somewhat higher than the observed values for both source configurations, suggesting that the regional dependence between intensity and peak ground motion cannot be overlooked. Future investigations should be undertaken to improve seismic hazard assessment at a local scale. Conversely, synthetic PGAs and PGVs show a satisfactory match with the values predicted by the generic GMM calibrated for volcanic areas in Italy. The results underscore the importance of region-specific GMMs for reliable seismic scenarios.

Activities related to energy production have been linked with felt (and in some cases damaging) earthquakes. Notable examples include hydraulic fracturing, wastewater disposal, geothermal systems, coal mining, carbon storage and hydropower dams. As the demand for energy continues to grow, new frontiers in energy exploration will emerge - some with the potential for induced seismicity. Thus, there is a clear need for a source-agnostic seismic risk protocol that can be applied to any activity or region. This study outlines one such implementation that uses scenario earthquakes to produce a priori risk thresholds that can be referenced against current seismicity levels on an ongoing basis. Our framework is designed to inform regulatory decisions by considering the consequences of earthquake scenarios on the population and the built environment, together with simplified forecasts of the next largest magnitude. The proposed framework can tackle both the screening process needed for permitting purposes and serve as a risk management plan during operations.

Earthquake causes severe impact in the social property, and its damage to the aged buildings is one of the most disastrous consequences. Thus, seismic upgrading techniques and advanced design approaches are continuously proposed for a better structural performance, of which the externally-attached sub-system is an effective strategy. The authors formerly proposed a high-performance external sub-system for seismic upgrading, namely, the self-centering precast bolt-connected steel-plate reinforced concrete (SC-PBSPC) buckling-restrained braced frame (BRBF), and experiments have been performed to validate its feasibility and superiority. In this paper, a novel design framework for the external SC-PBSPC BRBF sub-system considering combined demand-capacity uncertainties under nonstationary excitation is further investigated. The novel design framework is derived from the incremental dynamic analysis and capacity spectrum method (IDA-CSM), and it is an organic integration and an effective improvement for a better upgrading solution. The proposed stochastic IDA-CSM based design framework consists of three stages (i.e., the performance evaluation before upgrading, the component design of sub-systems, and the performance verification after upgrading) and two primary analyzing approaches [i.e., the stochastic pushover analysis (POA) for capacity-demand spectra curves, and the stochastic IDA for fragility curves]. During the procedure, the design factors are regarded to be stochastic variables and multiple uncertainties are incorporated for a probabilistic estimation, both before and after upgrading, respectively. An application example via a three-dimensional frame building is also implemented to verify the feasibility of the design framework, and multiple uncertainties provide a probabilistic prediction of the upgraded behavior in a more realistic way. The proposed research serves as a reference for the related design exploration and plays a key role for further probabilistic work from a macro perspective.

The fling step, a significant near-field effect, has an adverse impact on long-period engineering structures. Despite early recognition by pioneers, identifying and processing the ground motions containing the fling step remains challenging due to conventional data filtering methods that ignore low-frequency components. This study investigates the recovery of the fling step from near fault records and by modifying and/or adding processing steps to previous methods, proposes a robust processing scheme for strong ground motion recordings in capturing fling amplitude. The proposed scheme’s capability is verified through GNSS-derived displacements from global and Turkiye earthquakes. Subsequently, the method is applied to strong motion recording in the Turkish dataset (Mw ≥ 6 shallow crust earthquakes recorded at R_JB≤50 km), resulting in a comprehensive inventory of fling amplitudes across multiple motion components. This inventory serves both engineering and earth sciences research by facilitating the evaluation of existing predictive models. In addition, a Türkiye-specific performance evaluation of existing predictive models is conducted using the presented database. Lastly, a refined fling amplitude prediction model, based on conformity with the presented fling inventory, is proposed. This work addresses critical gaps in strong ground motion analyses, promoting improved seismic resilience through accurate characterization of near-fault effects.

The central Apennines are renowned for their active NW-SE striking and SW-dipping normal-fault systems responsible for significant seismic events. However, uncertainties persist in attributing some past destructive earthquakes to seismogenic sources, as in the case of the 1706 Maiella earthquake (Mw 6.8, Abruzzi region). This study comprehensively assesses competing source hypotheses derived from the literature and uses geological and geophysical data to constrain their possible fault geometry. Employing a 3D seismogenic source model approach, we rigorously analyze the earthquake-fault association, assessing the misfit between the simulated site intensities and the macroseismic values estimated from the historical accounts. Our findings highlight the complexities in determining a reliable source for the 1706 earthquake. Finally, the best-fit source model was adopted to produce ground motion predictions regarding Peak Ground Acceleration (PGA), Peak Ground Velocity (PGV), and macroseismic intensity, including site effects, coupling the ground motion model (GMM-ITA18; Lanzano et al. 2019) and the ground motion intensity conversion equation (GMICE; Gomez Capera et al., 2020). The presented outcomes possibly unveil the shaking scenario that occurred in the past and perhaps in the future. These results, shedding light on one of the most relevant unknowns of the Apennine seismicity, offer valuable insights to better constrain the seismic hazard of this region, with implications for seismic risk mitigation strategies.

The elastic-plastic displacement response of structures under long-period ground motions including far-field long-period ground motions (FLGM) and near-fault pulse-like ground motions (NPGM), are significantly different from ordinary ground motions (OGM), and the post-yield stiffness ratio of structures is a crucial index that determines the residual displacements and repairability of structures after earthquakes. Studying the influence of the post-yield stiffness ratio on the maximum and residual displacements of structures under long-period ground motions is crucial for post-earthquake repairs. This paper selected 25 OGM, 25 FLGM, and 25 NPGM to calculate the elastic-plastic displacement response of single degree of freedom (SDOF) systems, analyzing the influence of ground motion types, post-yield stiffness ratio, natural periods, and strength reduction coefficients on normalized elastic-plastic displacement. And the influence of design parameters and loading paths on the post-yield stiffness ratio of components was analyzed by finite element analysis based on the method of calculating the post-yield stiffness ratio of components. The results show that the normalized maximum displacement decreases with the increase of the period, the increase of post-yield stiffness ratio and the decrease of strength reduction coefficient. Nevertheless, the variation degree of the normalized maximum displacement is distinguishing under different ground motions. The normalized residual displacement of SDOF system under the NPGM is the most significant and the variation of normalized residual displacement with post-yield stiffness ratio, strength reduction coefficient and natural period is different under different ground motions. Moreover, post-yield stiffness ratio of components is significantly influenced by design parameters and loading path.

The southern Türkiye and northern Syria areas were hit on February 2023 by a large earthquake with M_w = 7.8, followed by another large aftershock with M_w = 7.5. The two-earthquake sequence, coupled with a series of smaller aftershocks, caused severe structural and geotechnical damage and fatalities. The objective of this study is to investigate the characteristics of near-fault ground motions observed in the earthquake sequence. To this end, the ground motion intensity measures are firstly compared with existing models; it is shown that PGA and spectral accelerations from both the non-pulse-like and the pulse-like motions are overall captured by the Zhao et al. (Bull Seismol Soc Am 96(3):898–913, 2006, https://doi.org/10.1785/0120050122) model. Subsequently, the velocity pulses in near-fault ground motions are not only quantitatively identified, but are also parameterized using the progressive iterative approach. The identified pulses are then empirically categorized into two groups of records with different causative effects according to the criterion of whether or not non-zero displacements could be visually inspected at the end of the integrated pulse displacement traces. Pulse-like ground motions containing baseline offset are also corrected, and final permanent displacements due to fling-step effects are accordingly derived. To determine the orientations at which the strongest pulses can be observed, two different approaches are employed. It is revealed that the indirect method by seeking the orientation of the maximum PGV appears to be not reliable if it is to find the strongest pulse, at least with respect to the 2023 Türkiye earthquake sequence.

Catastrophic earthquakes in Uganda have the potential for detrimental consequences on the socio-economic welfare and resilience of communities. Despite considerable efforts in predicting earthquake risk across Africa, a national comprehensive seismic risk study for Uganda does not exist. With increasing population, urbanisation and rapid construction, seismic risk is escalating fast and is compounded by the high vulnerability of buildings and scanty disaster prevention and mitigation strategies. This study uses the probabilistic event-based risk calculator of the OpenQuake-engine to assess potential risks resulting from future earthquakes. Although the building exposure model is largely inferred and projected from the national population and housing census of 2014, total replacement costs are obtained by performing series of interviews with local engineering practitioners. Analytical vulnerability curves are selected from Global Earthquake Model (GEM) database. Seismic hazard studies confirm that western Uganda is exposed to the highest level of seismicity where peak ground accelerations on rock ground can reach up to 0.27 g over a 475-year return period. Relative to Uganda’s gross domestic product, the associated seismic risk estimates indicate mean economic loss ratios of 0.36%, 2.72% and 4.94% over 10, 50 and 100-year return periods respectively; with mean annual economic loss of US$ 74.7 million (0.34% relative to the total replacement value) and annual deaths averaging 71 persons across the whole country. It is envisaged that the findings will inform strategic land use planning patterns, earthquake insurance pricing and foster the continuous improvement of Uganda’s National Policy for Disaster Preparedness and Management.