Bulletin of Earthquake Engineering最新文献

Gravelly soils were traditionally considered either non-susceptible or significantly more resistant to seismic liquefaction due to their typically denser depositional characteristics and/or their enhanced capacity to dissipate excess pore water pressures. As a result, their liquefaction initiation assessments were occasionally overlooked. However, case histories starting with as early as the 1891 Mino-Owari (Japan, M7.9) and followed by events including the 1983 Borah Peak-U.S.A. M7.3, 1995 Kobe-Japan M7.2, 2008 Wenchuan-China M7.9, and 2016 Kaikoura-New Zealand M7.8, 2023 Kahramanmaras-Turkiye M7.8, have demonstrated that they can undergo significant reductions in shear strength and stiffness as a result of liquefaction. With the intent of developing liquefaction triggering models, a database consisting of 215 gravelly case histories, 99 liquefied and 116 non-liquefied, was compiled. Dynamic Cone Penetration (DPT) blow counts or shear wave velocity (({V_S})) along with median grain size (({D_{50}})) were utilized as resistance, whereas cyclic resistance ratio ((CSR)), earthquake moment magnitude (({M_w})) and vertical effective stress ((sigma _v^prime)) as the demand parameters of probability-based liquefaction triggering predictive models. The resulting models incorporate adjustments for variability in a) earthquake duration, b) vertical effective stress, and c) median grain size.

The evaluation of the in-plane displacement capacity of URM walls at different performance levels is of primary importance for the seismic design and assessment of masonry buildings since drift limits represent one of the main parameters for the control of the damage at serviceability and ultimate conditions and affect the non-linear models used in the structural analyses and the evaluation of other significant seismic parameters, such as the q-factors for linear elastic analyses. The values of drift limits of masonry walls are still under discussion and updated as more experimental data become available and the performance objectives in design codes are updated. In order to contribute to this task, a new definition of specific performance levels for URM walls is provided in this work. Four limit states are introduced based on the increasing extent of damage due to in-plane actions derived from the results of some significant examples of in-plane tests, and are associated to different points on the experimental envelope curves. Then, the evaluation of the deformation capacity at the different limit states is carried out on in-plane cyclic tests on URM walls taken from an existing dataset. The results are provided both in aggregate form and as a function of different masonry typologies and main failure mechanisms. Statistical evaluation of the drift capacity and safety factors developed using a consistent approach have been derived to determine design values. The effects of these outcomes on the seismic design and assessment of masonry buildings are underlined, in relation with the drift limits to adopt in codified procedures.

Reinforced concrete (RC) structures are widely recognized for their favorable formability, fire resistance, and structural performance. Nevertheless, numerous collapse cases have been reported under both natural hazards and human-induced incidents. Many of these failures were disproportionate and progressive, where the loss of a primary structural member triggered a chain reaction of failures. Although seismic loading can initiate such local damage and disrupt load paths, progressive collapse has conventionally been treated only as an abnormal loading case. Consequently, its occurrence during major earthquakes—often considered rare—has not been systematically included in standard seismic design procedures. This study reassesses progressive collapse from the perspective of seismic design. A historical review of earthquake-induced failures is presented, extracting lessons from past collapses. The adequacy of special seismic detailing in providing the required redundancy and integrity is critically evaluated in this context. A state-of-the-art review of experimental, numerical, theoretical, and probabilistic studies is also provided, bridging the gap between progressive collapse research and seismic design practices. Current code provisions are discussed and compared to highlight their shortcomings. Furthermore, innovative preventive approaches and risk-mitigation strategies are examined, with their advantages and limitations briefly outlined. Finally, recommendations are offered to guide the future development of seismic design codes. The novelty of this work lies in reframing progressive collapse as an integrated component of seismic design procedure and highlighting the path toward developing future standards that explicitly address this critical failure mechanism.

Significant advancement has been accomplished in recent years in developing simplified multimodal procedures for the seismic evaluation of buildings. However, many of these methods are complex and computationally intensive for practical applications. Moreover, the extension of some of these methods for structures with complicated geometries, like geometrically irregular buildings, is not practically feasible due to the exponential increase in the number of analyses required. This paper introduces an efficient nonlinear-analysis-free multi-mode procedure, referred to as AMPD, for the direct estimation of story drifts in buildings. Rooted in structural dynamics theory and leveraging the concept of modal combination, the AMPD procedure is user-friendly and straightforward and can be readily extended to buildings with various configurations since no nonlinear analysis is required in the process of its implementation. The proposed method computes nonlinear drift demands by enveloping the results obtained from a series of equations that rely solely on the modal properties of the structure deriving from an eigenvalue analysis of a linearly elastic system and the spectral parameters of earthquake ground motions. Therefore, this procedure eliminates the need for elaborate nonlinear numerical models, sophisticated software, and robust computer processors. The performance of the AMPD procedure is examined using an extensive database of code-compliant low-, mid-, and high-rise SMRFs representative of regular building configurations without extreme weak or soft stories. Comparison of the AMPD results with those from nonlinear time history analysis (NTHA), as the most accurate available method, at two seismic hazard levels reveals that the proposed approach can reliably estimate the story drift demands of buildings.

Structures designed to withstand an earthquake of significant magnitude, aftershocks provide additional challenges in such cases. The aftershocks are not isolated incidents; they commonly occur after the major earthquake and cause additional seismic losses. The current study examines the impact of multiple earthquakes on the likelihood of structure collapse from a probabilistic perspective. In the present study, stiffness irregular four-storey Reinforced Concrete (RC) framed structure with fixed and isolated bases were examined and evaluated using recorded fourteen single and seven multiple earthquakes with distinct characteristics. The Incremental Dynamic Analysis (IDA) method is used to generate fragility curves for fixed base and base-isolated structures. An equation is proposed based on the deaggregated fragility curves to determine the seismic loss of the structures. The results emphasize the significance of multiple earthquakes. When multiple earthquakes are experienced by stiffness irregular structures with base isolation, the likelihood of collapse is significantly decreased. In seismically active areas with frequent multiple earthquakes, base-isolated structures are more effective and also reduce the post-earthquake repair cost and time.

To improve the seismic behaviour and service durability of reinforced concrete bridge piers in corrosive environments, stainless materials are used in RC components of coastal bridges. In this work, a damage observation-informed seismic vulnerability assessment method of stainless steel-reinforced concrete bridge piers is proposed to address the limitations of conventional numerical limit state definitions. The method integrates experimental damage observations into fragility analysis, ensuring more accurate damage state thresholds. A stainless steel reinforced concrete bridge pier is presented as case study. Duplex stainless steel is selected to replace conventional carbon steel as reinforcement. A validated numerical model is used to simulate seismic responses under near-fault excitations. Results show that SS-reinforced piers generally exhibit lower fragility than CS-reinforced piers, though this advantage is influenced by reinforcement ratio and axial load. The presence of velocity pulses in near-fault motions significantly increases seismic vulnerability.

The rising demand for renewable energy has significantly driven the expansion of offshore wind farms in the Indian coastal regions, with monopile foundations as the dominant support system for wind turbines in shallow coastal waters. On the Indian coastline, Gujarat and Tamil Nadu are identified as the most potential regions for harnessing wind energy. However, adequate assessment of the capacity of monopile foundations for these regions is a challenging task considering the combined effects of vertical (V), horizontal (H), and moment (M) loading. This study presents the combined V-H-M capacity curves for monopile foundations for Gujarat and Tamil Nadu coastal regions for multi-megawatt offshore wind turbines (OWT) with capacities of 5 MW, 10 MW, and 15 MW. Nonlinear three-dimensional finite element investigations are carried out for this purpose. V-H-M capacity envelopes for the monopile foundations of OWT systems are developed for different vertical load ratios of 0, 0.25, 0.50, 0.75, and 1.00. The capacity envelopes indicate that the monopiles for the Tamil Nadu region have a higher combined capacity compared to the Gujarat coast. For the vertical load ratio of 1.0, the horizontal capacity of the monopile foundations in the Tamil Nadu region is about 1.20–2.32 times more than that in the Gujarat region, whereas the moment capacity is 1.08–2.33 times more for OWT capacities considered in the study. Compared to the capacity of the 5 MW OWT, the horizontal capacity monopile foundations of 10 MW and 15 MW OWTs are greater by about 1.75–2.90 times for the Gujarat coast and 1.18–1.70 times for the Tamil Nadu coast. Furthermore, combined capacity envelopes for seismic loading are obtained through pseudo-static analyses considering the region-specific seismicity values. The effects of seismic loading on the capacity envelopes are found to be asymmetric and more evident for the Gujarat region. Overall, the study will benefit designers for assessing the capacity of monopiles considering different combinations of loading for Indian coastal regions for both static and seismic conditions.

Outer Engineered Cementitious Composites (ECC) jackets have been proven to significantly enhance the seismic performance of columns while facilitating rapid damage repair and jacket replacement. To promote its engineering application, there is still a lack of a complete calculation model for rapid estimation of strength and deformation, as well as an economic model for feasibility analysis, and no comparative analysis with traditional reinforcement methods has been conducted either. This study proposed a strength calculation model for outer ECC jacketed composite columns based on the “Equivalent Stiffness Method,” validated against the sectional integration method, finite element analysis (FEA), and experimental results. The FEA considered two jacket thicknesses, three jacket heights, and two equivalent cross-sections. Additionally, an economic evaluation index was introduced to assess the feasibility of applying outer ECC jacketed composite columns, along with a proportional reduction factor to account for the influence of ECC jacket height on the confinement of core concrete. Based on the theories of elastic mechanics and material mechanics, a displacement calculation model was proposed, and the skeleton curve model was modified. The results showed that the computational error of the mechanical model was less than 10%. Compared to ordinary concrete columns, outer ECC jacketed composite columns can more than double the energy dissipation. While increasing the column cross-section achieved similar bearing capacity, its ductility coefficient and energy dissipation were only half and 60% of the ECC jacketed columns, respectively, with a lower economic evaluation index. This study provides technical guidance for engineering applications and theoretical support for the design optimization of structures.

This paper explores the application of deep learning (DL) techniques to strong motion records for single-station epicenter localization. Often underutilized in seismology-related studies, strong motion records contain rich information for source parameter inference. We investigate whether DL-based methods can effectively leverage this data for accurate epicenter localization. Our study introduces AFAD-1218, a collection comprising more than 36,000 strong motion records sourced from Turkey. To utilize the strong motion records represented in either the time or the frequency domain, we propose two neural network architectures: deep residual network and temporal convolutional networks. Our findings highlight significant reductions in prediction error achieved through the exclusion of low signal-to-noise ratio records, both in nationwide experiments and regional transfer-learning scenarios. Overall, this research underscores the promise of DL techniques in harnessing strong motion records for improved seismic event characterization and localization. Our codes are available via this repo: https://github.com/melekturkmen/EarthQuakeLocalization