Bulletin of Earthquake Engineering最新文献

In Almaty, the largest city in Kazakhstan lying on a high seismic region, many residential buildings constructed during the Soviet Union are still in service. These buildings were not properly designed against earthquakes and special seismic detailing was not well considered according to the local design code. Therefore, this paper presents an analytical seismic assessment of two typical reinforced concrete moment frame residential structures constructed in this era, representing 812 buildings with almost identical construction materials, geometries, and structural details. Two-dimensional nonlinear models were developed for these buildings in each orthogonal direction based on the structural details collected from a Kazakh government agency. Incremental dynamic analyses were then performed using 24 historical strong ground motions with fault characteristics similar to those in the Almaty region. Structural global and local seismic responses were investigated. A new approach was proposed to define structural global inter-story drift limits at different damage states based on local seismic demands considering uncertainties of earthquakes and structural nonlinear dynamic responses. Based on these inter-story drift limits, the structural fragility curves were then developed to identify the damage probability of these buildings, which were further used to roughly estimate repair costs at different earthquake intensity levels. It has been found that these buildings are vulnerable to destructive earthquakes due to poor structural details. They possess a high probability of incurring extensive damage (high repair cost) or even collapsing (irreparable) at the earthquake intensity level, with a return period of 475 years or 2475 years, respectively.

The rapid and accurate prediction of earthquake Strong-Shaking Zone (SSZ) is crucial for issuing precise early warnings to regions at high risk of strong ground shaking. Generally, the SSZ is derived from the real-time spatial distribution of observed ground motions. However, during the initial stages of large earthquakes, the SSZ is often underestimated and provide alerts without enough lead-time (the time interval between the alert declaration and the S-wave arrival to the target area). In this study, we propose an innovative approach termed Near-epicenter-based Partial Matching Crossover. Leveraging the characteristic that reliable magnitude estimates for large earthquakes are available earlier than accurate predictions of the peak ground velocity (PGV) distribution, this approach utilizes near-epicenter station data to rapidly estimate the SSZ. It achieves this by matching a segment of the fault, defined by a predetermined length, with the predicted PGV map within a 120 km radius centered at the epicenter. Application of our method to strong motion data from China, Japan and Turkey demonstrates its efficacy in quickly anticipating the post-earthquake intensity distributions for large earthquakes. Specifically, it offers a lead time of 5 s or more for 51.5% (39,354 km²), 43.3% (5772 km²), 31%(47,107 km²) and 75.3% (81,966 km²) of the I_MM = V region during the M 8 Wenchuan earthquake, the M 7.3 Kumamoto earthquake, the M 7.8 Syria earthquake and M 7.6 Turkey earthquake, respectively. The presented approach introduces a novel methodology to extend the lead time for earthquake early warnings.

Post-earthquake safety assessment of buildings and infrastructure poses significant challenges, often relying on time-consuming visual inspections. To expedite this process, safety criteria based on a demand-capacity model are utilized. However, rapid assessment frameworks require accurate estimations of intensity measures (IMs) to estimate seismic demand and assess structural health. Unfortunately, post-earthquake IM values are typically only available at monitored locations equipped with sensors or monitoring systems, limiting broader assessments. Simple spatial interpolation methods, while possible, struggle to consider crucial physical factors such as earthquake magnitude, epicentral distance, and soil type, leading to substantial estimation errors, especially in areas with insufficient or non-uniform seismic station coverage. To address these issues, a novel framework, BN-GMPE, combining a Bayesian network (BN) and a ground motion prediction equation (GMPE), is proposed. BN-GMPE enables inference and prediction under uncertainty, incorporating physical parameters in seismic wave propagation. A further novelty introduced in this work regards separating the near and far seismic fields in the updating process to attain a clearer understanding of uncertainty and more accurate IM estimation. In the proposed approach, a GMPE is employed for the estimation, and the bias and standard deviation of the prediction error are updated after any new information is entered into the network. The proposed method is benchmarked against a classic Kriging interpolator technique, considering some recent earthquake shocks in Italy. The proposed BN framework can naturally extend for estimating the probability of failure of various structures in a targeted region, which represents the ultimate aim of this research.

This study aims to evaluate the factors controlling the sensitivity of fine-grained soils to seismic stresses and revise the criteria previously proposed by the authors to diagnose liquefaction. To this end, dynamic tests have been performed on artificial mixes as well as natural soils from a wide area of an earthquake devastated city (Adapazari) using two types of dynamic testing. Studies have led to findings suggesting that the gray area between susceptible and non-susceptible soils proposed by several investigators in the past can now be dispensed with. Although physical properties of fine-grained soil supply sufficient information for diagnosis, the dynamic simple shear test is found to be a convenient and rapid way to confirm the judgement. However, it has been seen that dynamic testing alone may not be the last word in the determination of liquefaction, and physical properties should also be addressed. Anomalies observed in test results are also discussed. Conclusions show significant differences from existing proposed criteria in the literature.

Predicting soil behavior under dynamic load due to earthquakes is pivotal for engineering structures and human life. Due to various limitations, such as insufficient computers and difficulties in generating models, the third-dimension effect is generally neglected in many studies. Conversely, the third-dimension effect in regions with high topographic differences, deep basins, three-dimensional heterogeneous and anisotropic environments, and alluvium is at a level that cannot be neglected. This study created a three-dimensional model of the northwest of Turkey for the first time by including surface topography. Soil properties were added to this model, and dynamic analysis was performed. This new model aims to increase the accuracy of ground motion predictions in Northwest Turkey. The accuracy of this model was analyzed using real earthquake data recorded in the study area. In addition, a new software (SiteEffect3D) with various features has been developed to create a three-dimensional mesh with topography using digital elevation model data and to perform dynamic analysis more effectively. This software has been tested comparatively with “Plaxis 3D” software using synthetic terrain models. The importance of this study is that in addition to its contributions to site response analysis and seismic hazard assessment, new software has been developed that can be used in similar studies. The findings will provide valuable information for seismic design and construction practices and facilitate the development of more effective strategies to reduce the potential damage from earthquakes in the region.

This study aims to determine probabilistic seismic demand-based optimal intensity measures (IMs) for seismic fragility evaluation of corrosion-damaged reinforced concrete (RC) bridge piers. Toward this goal, a methodology is presented to select optimal IMs based on four criteria: efficiency, practicality, proficiency and sufficiency. Thirty-eight intensity measures in five categories of (i) acceleration-related, (ii) velocity-related, (iii) displacement-related, (iv) hybrid, and (v) general IMs are studied. The methodology is demonstrated in a case study of an RC bridge with various corrosion levels. The finite element model of a reference bridge pier is developed and verified by experimental results. Incremental dynamic analyses (IDAs) are carried out on the studied corrosion-damaged bridge piers using 22 ground motion records selected employing the conditional mean spectrum (CMS) methodology. The outcomes of IDAs are then used to develop linear probabilistic seismic demand models (PSDMs) for each bridge pier with varying corrosion damage. The obtained results show the high sensitivity of optimal IMs on the corrosion level of RC bridge piers. For instance, while the optimal IMs for the pristine bridge pier are sustained maximum acceleration (SMA) and effective peak acceleration (EPA), for the severely corroded pier peak ground acceleration (PGA) and acceleration level containing up to 95% of the Arias intensity (A95) are the most optimal IMs.

Traditional ancient Tibetan buildings (TATBs) date back hundreds of years. The seismic performance of TATBs constructed with stones and mud was analyzed by utilizing structural subscale features (materials, walls, and structures). The key to load-bearing in TATBs is the three-leaf stone wall. Based on the mechanical properties of materials, compression tests and quasistatic static tests of walls, this paper confirms that the seismic resistance capacity of the three-leaf stone wall of TATBs is unable to meet Chinese standards. The aims of this study are to present the dynamic behavior of TATBs by shaking table tests. According to the experimental data, the transcendence intensity magnification calculation method is modified to calculate the seismic vulnerability of TATBs. The results show that when the peak acceleration of ground motion is 1.042 m/s², 1.598 m/s² and 2.881 m/s², TATBs undergo slight damage, moderate damage, and severe damage, respectively.

Strong seismic events frequently strike Chile. The last three significant events that caused considerable damage and losses are the 2010 (({M}_{w}) 8.8, Maule), 2014 (({M}_{w}) 8.2, Iquique), and 2015 (({M}_{w}) 8.3, Illapel) earthquakes. Therefore, reliable fragility curves are necessary to evaluate the threat of earthquakes to the built environment. This study aims to develop empirical fragility curves of Chilean houses using damage from the 2014 and 2015 earthquakes. The data from 9085 and 7431 damaged houses from the 2014 and 2015 earthquakes, respectively, was obtained by the government. The fragility curves were estimated for reinforced concrete, reinforced masonry, timber, and adobe houses. Additionally, the fragility curves were constructed using three different Peak Ground Acceleration (PGA) maps to quantify the variation of the fragility parameters based on the selected PGA map and to identify which PGA map generates the highest correlation with observed damage. Additionally, fragility curves obtained in this study are compared with curves from other studies. The median (theta) values of the fragility curves obtained in this study are larger than those from other reported studies.

Architectural aspects of buildings, such as the shape of the plan, play an important role in defining the seismic behavior of the building and the future damages structural and non-structural elements may go through. Several items, like the aesthetic aspects and limitations in the field under construction, make an irregular plan shape to be selected as a desirable option. Correctly understanding the building’s behavior on the irregular plan is necessary in this case. With that being said, this research aims to evaluate the seismic performance of buckling restrained braced frames (BRBFs) steel structures having an L-shaped irregular plan. An irregular L-shaped plan amplifies the torsional response of the building and causes stress concentration because of the re-entrant corners. Since the lack of a comprehensive study on the L-shaped plan irregularity in buildings equipped with BRBs and the effect of Soil-structure interaction (SSI) would be felt, three types of buildings, low-, mid-, and high-rise, were considered to study the demands of this system on an L-shaped plan. SSI effects were also considered by the cone method in the frequency domain for a more accurate evaluation of the building’s behavior during an earthquake event. Each building is studied having three different base conditions: 1- fixed base, 2- SSI with soil type C, and 3- SSI with soil type D. Structural demands, including base shear, overturning and torsional moment, lateral displacement, inter-story drift, and column capacity were measured for different models with fixed and flexible bases by performing time history analyses. The results signify the significant SSI’s impact on the building’s demands.