Bulletin of Earthquake Engineering最新文献

To enhance the post-earthquake traffic flow capacity of bridge structures, various energy dissipation braces (EDBs) have been developed and applied. However, the effect of various EDBs on the improvement of the post-earthquake functionality of the bridge is difficult to evaluate mainly due to the imperfections in the functional indexes of bridge structures. This study aims to quantify the multi-level residual drift ratios of RC bridge piers based on traffic flow capacity, and to assess the seismic failure of RC bridge piers with different EDBs based on traffic flow capacity. To this end, the traffic flow was categorized into five levels based on the relationship between the traffic flow capacity and the seismic performance of the bridge. The post-earthquake performance states were evaluated on the basis of the residual drift ratio as a performance indicator, and the corresponding residual drift ratio thresholds for bridge structures under different function levels were determined as 0.06%, 0.24%, 0.49%, and 0.85% based on the numerical analysis results. Using traffic flow capacity as the limit states, the failure probabilities of the RC bridge bents with buckling restrained braces (BRBs) and self-centering energy-dissipation braces (SCEBs) were further investigated. The results show that traditional BRBs show better performance with respect to the maximum drift ratio while the SCEBs show better performance with respect to the residual drift ratio. It is indicated that the SCEB is much more effective in improving the repairability and post-earthquake traffic flow capacity of the bridge.

Assessment of liquefaction susceptibility of sediments in alluvial plains is considered one of the first step for infrastructure planning, hazard mitigation, and land use management in seismically active regions. Subtle geomorphological features resulting from depositional processes could greatly contribute to estimating the liquefaction likelihood since they also dictate the type and distribution of sediments. Our case study is from the Piniada Valley (Greece), where widespread liquefaction phenomena were triggered by the 2021 Mw 6.3, Damasi earthquake. As we compiled a detailed geological map for the purposes of this investigation and correlated it to the spatial distribution of the earthquake-induced liquefaction phenomena, we observed that most of liquefaction surface evidence are related to point bars and abandoned river channels formed the last century. In particular, the areal liquefaction density was estimated at 60.7 and 67.1 manifestations per km², for the point bars and abandoned channels, respectively. Following this outcome, we propose a refinement of the existing liquefaction susceptibility classifications by including point bar bodies as a distinct category, characterized by a very high susceptibility to liquefaction. In addition, we discuss the correlation between the observed liquefaction manifestations and the shallow lithofacies, sand or mud prone areas, within point bars. The outcome arisen by this research is that most of liquefaction phenomena (> 70%) occurred on the area covered by coarser materials deposited on the upstream part of high sinuosity meanders.

This research presents an interdisciplinary study on the impact of planning policies on the seismic vulnerability of historic areas, encompassing architecture, urban planning, and engineering aspects. It examines the spatial and temporal dynamics of urbanization and population growth, which alter cities' seismic exposure and vulnerability over time. Urban and engineering research methods are used to assess the seismic vulnerability variability in Yungay Quarter, a historic district west of downtown Santiago, Chile, with buildings constructed between 1839 and 2022. The study begins with a thorough review of Chilean urban planning policies and building regulations, combined with a detailed survey of the construction features in the historical neighborhood to classify building types. Next, the macro-seismic method is applied to a representative sample of 484 buildings to calculate vulnerability indices for unreinforced masonry and reinforced concrete structures, which are then used to estimate damage distributions. Seismic fragility curves for each building class are derived based on peak ground acceleration. These fragility curves are incorporated into risk assessments for potential ruptures along the San Ramon, Santiago splay and a deep intra-slab splay fault. The resulting risk scenarios can guide future urban planning policies and processes affecting this historical urban center. The innovations introduced by this work include a summary of how changes and updates to planning policies have influenced construction practices in the Yungay Quarter from 1839 to 2022 and the translation of these urban changes into variations in building fragility functions, enabling a comprehensive assessment of the potential impacts on these buildings from various potential.

Estimating earthquake ground motions at reference bedrock is a major issue in site-specific seismic hazard assessment. Deriving or adjusting empirical ground motion models (GMMs) for reference bedrock is challenging and affected by large epistemic uncertainties. We propose a methodology to simulate region-specific reference bedrock time histories by combining spectral decompositions of ground motions with Empirical Green’s Functions (EGFs) simulation technique. First, we adopt the nonparametric spectral decomposition approach to separate the contribution of source, path, and site. We remove the average source and site effects from observed small-magnitude recordings in the target region through deconvolution in the Fourier domain. This way, the obtained deconvolved EGFs represent path term only. Then, we couple the EGFs with k^− 2 kinematic rupture models for target scenario events. For each target magnitude, a set of rupture models following a ω-squared source spectrum are generated sampling the uncertainties in kinematic source parameters (e.g., slip distribution, rupture velocity, hypocentral location, stress drop, and rupture dimensions). The proposed approach is validated using recorded ground motions at reference sites from multiple earthquakes in Central Italy. The power of this approach lies in its ability to map the path-specific effects into the ground-motion field, providing 3-component time histories covering a wide frequency range, without the need for computationally expensive approaches to simulate 3D wave propagation. The region-specific, site-effects-free dataset produced by this approach can be used alone or in combination with existing empirical datasets to adjust existing GMMs, derive new GMMs, or select hazard-consistent time histories to be used in soil and structural response analyses.

The sustainable renovation of existing buildings is currently at the top of the agenda of the European Union. Sustainability is typically defined as the result of the interaction of environmental, economic, and social aspects, and it is now considered a major target objective in all sectors of our economy, including the construction one. The concept of sustainable renovation has changed significantly over time, leading to the current interpretation that considers the need to simultaneously improve safety and resilience against natural hazards and minimise energy and resource consumption, as well as to reduce impacts along the life cycle of the building. This manuscript presents insights into combined/integrated environmental and seismic retrofitting techniques and assessment methods for the sustainable renovation of the existing building stock, specifically focussing on those conceived according to a Life Cycle Thinking (LCT) approach. This manuscript goes beyond the current available state of the art by highlighting the evolution of the concept of building sustainability throughout time, as well as defining a comprehensive taxonomy of available retrofitting strategies, while also identifying common clusters among available research papers. This research effort is part of the mission of the European Association of Earthquake Engineering (EAEE) Working Group 15 (WG15), which focusses on ‘combined seismic and environmental upgrading of existing buildings”.

In the year 1999, two devastating earthquakes (M_w 7.4 Kocaeli earthquake in August and M_w 7.2 Düzce earthquake in November) occurred in Northwest Türkiye. These two earthquakes led to a very large number of casualties and building collapses. When the 1999 earthquakes occurred, most of the structures in the earthquake-impacted region were not designed according to modern seismic design codes. During the 25 years following those earthquakes, there have been significant advances in building construction in the light of earthquake engineering, including adequate seismic codes, new regulations, and effective code enforcement in the earthquake impacted region. These advances have been reflected in the construction of new structures in the region and the retrofitting of existing ones. As a result, 70–80% of the current building stock in Düzce was designed, constructed, or retrofitted after the 1999 earthquakes. Almost 23 years later, in 2022, an M_w 6.1 earthquake occurred in Düzce, with ground shaking close to the seismic design code life safety performance level. The 2022 earthquake provided a great opportunity to evaluate the effectiveness and consequences of the advances in earthquake engineering and the relevant policy-making and regulations. This paper provides a comparative overview of the 1999 and 2022 earthquakes that struck the city of Düzce in terms of hazard, vulnerability, and consequences. Furthermore, other key lessons learned from the 2022 Düzce earthquake are documented based on field reconnaissance and numerical simulations. The lessons learned are expected to provide useful guidance for the reconstruction efforts after the 2023 Kahramanmaraş Türkiye earthquake sequence or in similar efforts in other parts of the world.

Seismic damage indices (SDIs) quantify damages in civil structures at local or global level due to seismic activities with the help of various demand and capacity parameters. Conventionally, SDI estimation requires complex and computationally demanding nonlinear time-history analysis (NTA) to find the values of the demand parameters. Nowadays, buildings are equipped with sensors to monitor their responses during seismic activity. Therefore, a novel method utilizing such recorded floor-displacement data of reinforced concrete (RC) plane frames along with local and global capacity-based parameters to predict combined global damage index (GDI) is presented here. Two different GDI formulas, depending on the type of capacity parameters, are developed following the proposed method. Multilinear regression analysis is performed to develop the proposed formulas such that they can predict the (GDI_{textrm{PA}}) calculated from hysteresis energy-based weighted average of modified Park and Ang local damage indices. The application of the new method does not need dynamic responses of RC frames obtained from NTA. However, for establishing the new method in the present study, the output of NTAs for different RC frames due to several design spectrum-compatible ground motions are used for training and validation. Also, the explicit expressions for the regression coefficients are provided in terms of some structural properties (e.g., fundamental period, total height) and local soil type for wider applicability. It has been found that the estimated GDI values using the proposed method can satisfactorily represent global damage states based on the limiting values of (GDI_{textrm{PA}}) for the RC frames.