Bulletin of Earthquake Engineering最新文献

This paper presents the analytical formulation to investigate the seismic performance of rocking masonry walls restrained by Dissipative Tie-rods (DTs). Experimental tests on one-sided rocking walls restrained by a DT are used to validate the formulation based on the dynamics of a two-degree-of-freedom rigid-block rocking on a rigid foundation, and to calibrate the mechanical parameters entering the equations of motion. The dynamics of the rocking wall restrained by DTs is fully described by separately considering each contribution due to self-weight, metal tie-rods, fluid viscous dampers, recentering components.The framework is then applied to the main façade of a monumental building, a church damaged by the recent 2023 Turkey earthquake. The numerical analysis considering that earthquake confirmed the expected benefits offered by the DTs: reduction of the peak response at least by 60% (in comparison with the case of façade restrained by a traditional tie-rod), a reduction of the vibration time by almost 60%, avoidance of tie-rod yielding or failure, reduced punching effect against transverse walls and efficient energy dissipation (around 1/3 of the total input energy).

A major event with a magnitude of 7.7 (Mw) located in Pazarcık district of Kahramanmaraş on February 6, 2023. Approximately nine hours later, a second earthquake with a magnitude of 7.6 (Mw) located in the Elbistan region of Kahramanmaraş, approximately 100 km from the first earthquake according to the Disaster and Emergency Management Presidency (AFAD). These two earthquakes and the subsequent aftershocks caused many deaths, destruction and severe damage in areas close to the East Anatolian Fault Zone. The seismological and structural observations applied in the Malatya, one of the provinces affected by earthquakes, are presented in this study. For this purpose, acceleration data recorded at the strong motion station located in Malatya province and operated by the AFAD were examined. The seismic stations located in the Kale, Doğanşehir, and Akçadağ districts, located close to the province of the Malatya, were examined for the peak ground acceleration, the peak ground velocity, and the peak ground displacement for each station. Additionally, the spectral acceleration and the Arias intensities were calculated, also. The highest acceleration among these three stations in the Pazarcık earthquake was observed as approximately 0.16 g at station 4414 in the Kale district, and in the Elbistan earthquake, approximately 0.45 g at station 4406 in the Akçadağ district. Since the accelerations of the main shocks were not recorded at the stations in the Malatya city center, both the peak ground acceleration and the spectral acceleration values were predicted by using the ground motion prediction equations (GMPEs). The largest ground accelerations were predicted between 0.15 and 0.2 g for the Pazarcık earthquake and 0.3–0.4 g for the Elbistan earthquake in the Malatya province, also by using GMPEs, for different soil types. The peak ground acceleration that can be produced by DD-2 (the earthquake with a probability of 10% of exceed in 50 years) earthquakes in the center of the Malatya, is 0.361 g according to the Türkiye Building Earthquake Code 2018 (TBEC 2018). The Kahramanmaraş earthquakes (Mw 7.7 and 7.6) caused heavy damage to the structures in Malatya center because they exceeded the maximum ground acceleration value that could be produced according to the 2018 Türkiye Earthquake Hazard Maps (TEHM 2018). The results of the time-domain analysis applied to a collapsed building in the center of Malatya showed the necessity of obtaining site-specific earthquake spectra and making building designs and performance analyses by taking into account the structure-soil interaction. Taking these situations into consideration, it is expected that the building designs to be made based on the calculation of the largest spectrum acceleration values that may occur due to an earthquake in the worst ground conditions in the center of Malatya will be safer against earthquakes.

This paper outlines an empirical approach to predict the drift capacities of fully grouted reinforced masonry (RM) shear walls under in-plane loading. The RM walls are provided with centrally placed single layer of reinforcement curtain, which raises a question on their drift and ductility characteristics over double layered reinforced concrete (RC) walls. To study the drift capacities of RM walls, an experimental database was developed comprising 152 shear walls tested under in-plane loading conditions. This database was then used to assess the critical parameters that influence the in-plane drift capacities of RM walls. It was found that the shear reinforcement ratio, shear stress demand, aspect and effective slenderness ratios are most sensitive to in-plane drift capacities of RM walls. Existing analytical and empirical models to predict the in-plane drift capacities of shear walls were initially considered to verify their applicability in predicting the drift capacities of RM walls. The analyses showed that existing analytical models under-predicted and the empirical models over-predicted the ultimate drift capacities of RM walls. Consequently, this study used the developed experimental database to propose a set of empirical models to predict the in-plane drift capacities of RM walls. The proposed models would facilitate the analysis of drift capacities of RM walls with different configurations and thereby enable the implementation of displacement-based performance design approach for such walling systems.

The study focuses on seismic resilience at a sub-regional level and its effect on proactive planning of seismic strengthening. The case study for application is the sub-regional community of Agri Valley in Southern Italy. A resilience priority index is proposed and quantified, to determine the priority ranking of communities requiring retrofit interventions. In this study, the role of residential building stock is emphasized, since as this paper shows, it can strongly affect community resilience and mitigation strategies. The analysis presented in the study is only seemingly simplistic. In reality, its goal is to provide simple tools that are easy to apply. In this way, the study could improve mid and long-term resilience through the implementation of financially sustainable mitigation strategies based on a multidisciplinary approach. It considers a quantitative approach to resilience and combines the latter with socio-economic data in order to set priorities in the large-scale application of seismic risk mitigation strategies. The resilience values of the considered housing systems are calculated and are integrated with the processed economic and social data in order to prioritize retrofit interventions in the study area.

In earthquake-prone areas, structures not compliant with modern design codes significantly contribute to seismic risk. Therefore, risk mitigation strategies (e.g., seismic retrofit) should be employed to reduce the expected economic and human losses. This paper introduces a procedure for the design of retrofit solutions for reinforced concrete (RC) frame buildings to achieve - rather than be bounded by - a desired target level of earthquake-induced loss for a given site-specific seismic hazard profile. The presented methodology is “direct” because the designer and/or client can set a loss target in the first step of the procedure and no design iterations are virtually required. Direct loss-based seismic retrofit (DLBR) relies on a simplified loss assessment methodology enabled by a surrogate probabilistic seismic demand model. This defines the probability distribution of seismic deformation demand of single degree of freedom (SDoF) systems conditioned on different shaking intensity levels. The proposed design methodology enables designers to account for risk/loss-based considerations from the conceptual/preliminary design phase, thus facilitating the choice among different retrofit solutions. Starting from two under-designed case-study buildings, four illustrative applications of the procedure are provided. They involve considering different economic expected annual loss targets and different retrofit solutions involving the addition of RC walls and RC column jacketing. Benchmark loss estimates are calculated using non-linear time-history analyses of refined, multi-degree-of-freedom models showing satisfactory results: the simplified loss estimate introduces an overestimation maximum equal to 15.4% among the four illustrative applications.

The mechanical properties of masonry materials have an inherent variability which may be attributed to the type of material (brick and mortar) and workmanship. Therefore, using a stochastic approach to investigate the behavior of Un-Reinforced Masonry (URM) structures provides a more realistic insight about their behavior. In this paper, the diagonal shear behavior of square wallettes constructed with traditional lime-sand mortar and clay bricks is evaluated through a Stochastic Finite Element Analysis (SFEA) combined with Monte Carlo Simulation (MCS). For this purpose, two important mechanical properties of the masonry, including the compressive strength of the masonry prism and the brick-mortar bond strength are considered as the stochastic input variables. To find the appropriate probabilistic distributions for these parameters, extensive material tests (masonry compression test and brick-mortar shear bond cohesion test) were conducted. Furthermore, diagonal shear tests were carried out on masonry wallettes made with the same materials and workmanship. In order to conduct the stochastic analysis, a Finite Element (FE) model based on a simplified micro-modeling approach was developed in software ABAQUS and validated with the results of the diagonal shear tests. Then, the key response parameters of the masonry wallettes including shear stress-drift curve, maximum shear strength, drift capacity, and the failure mechanism, determined through SFEA, are presented. The results demonstrate that the Normal distribution is the best fitted probability of distribution model for the two stochastic input parameters. Also, for two response parameters including drift capacity and maximum shear strength, the best fitted probability distributions are Weibull and Gamma distributions, respectively. Subsequently, according to the acceptance criteria related to the lateral drifts of URM walls corresponding to the collapse performance level provided in the design codes, the probability that the drift capacity of the wallettes exceeds the allowable drift corresponding to collapse performance level is calculated and discussed.

In this study, we evaluate the performance of five recent Intensity Prediction Equations (IPEs) valid for Italy comparing their predictions with intensities documented at Italian localities. We build four different testing datasets using the data contained in the most recent versions of the Italian Parametric Earthquake Catalogue CPTI15 and Macroseismic Database DBMI15 and we estimate the residuals between observed and predicted intensity values for all the selected IPEs. The results are then analyzed using a measure-oriented approach to score each model according to the goodness of model prediction and a diagnostic-oriented approach to investigate the trend of the residuals as a function of the different variables. The results indicate the capability of all the tested IPEs to reproduce the average decay of macroseismic intensity in Italy although with a general underestimation of high-intensity values. In addition, an in-depth investigation of the spatial and temporal patterns of the event residual term, computed using the best predictive model, is carried out. Lastly, we provide some hints for the selection of calibration datasets for the development of future intensity attenuation models.

Seismic pounding occurs when adjacent buildings lack adequate spacing, exacerbated by Alignment eccentricity and horizontal irregularities of adjacent buildings. The seismic lateral oscillation of adjacent irregular buildings promotes a torsional response under earthquake excitation, moreover, the gap distances recommended in the regulations to prevent collisions are generally insufficient due to the pounding behavior complicated by irregularity of adjacent buildings. Hence, this research aims to evaluate the eccentric pounding effects on seismic response demands for adjacent irregular buildings with transverse alignment eccentricity. The displacement, inter-story drift, story shear force, and torsional rotation responses are investigated and compared for different levels of irregularity. Results findings reveal that increasing alignment eccentricity of adjacent buildings leads to greater lateral displacements in the rebound direction, reduced displacements in the impact direction, and increased torsional rotation of the buildings, consequently, promote eccentric pounding, higher eccentricity leads to greater horizontal floor displacements and twisting motions, which increases the chances of adjacent floors colliding.

Many seismic damage field observations of masonry structures indicate that buildings constructed in different eras differ in terms of seismic risk and vulnerability under time-varying deterioration. However, the age deterioration effect is rarely considered in structural seismic vulnerability analysis, challenging the accuracy of the developed seismic risk model assessment. This paper considers the impact of age deterioration on seismic hazard and vulnerability, and an innovative probabilistic seismic hazard and risk model was developed. Using earthquake hazard theory and 1452,582 accelerations monitored by 11 stations during the 2008 Wenchuan earthquake in China, dynamic time history and response spectrum curves were generated considering the directionality of ground motion. Using the innovative model developed, the seismic vulnerability grade of 1228 low-rise masonry structures (Dujiangyan city) affected by the Wenchuan earthquake that the author investigated was evaluated, and a failure probability matrix of low-rise masonry structures considering the influence of age deterioration was established. A nonlinear fitting function was proposed to assess the seismic vulnerability of low-rise masonry structures, and vulnerability curves were generated via the developed empirical dataset. According to multiple onsite structural damage observations, there is a correlation between adjacent vulnerability and intensity grades. To study the correlation between the adjoining vulnerability grades of low-rise masonry structures under the influence of aging and different seismic intensity measures, an innovative structural seismic risk index model considering empirical and probabilistic algorithms (vulnerability correlation index (VCI) and intensity–vulnerability correlation index (IVCI)) has been proposed. On the basis of the seismic damage dataset, seismic risk curves for low-rise masonry structures were generated, considering the influence of age deterioration.