Evaluation Of Seismic Capacity Research Articles

Calculation of Characteristic Point Parameters for Restoring Model of Corroded Short-Pier RC Shear Walls

Based on the quasi-static tests of 12 corroded RC (reinforced concrete) shear walls, it was found that reinforcement corrosion has a great influence on the skeleton curve of RC shear walls. With an increase in the degree of corrosion, the bearing capacity of specimens decreases, and the deformation capacity worsens. Increasing the diameter of longitudinal reinforcements can significantly improve the bearing capacity of corroded RC shear walls, while the deformation capacity of corroded specimens can be improved by increasing the lateral distributed reinforcement or the transverse reinforcement in the embedded column. In order to accurately evaluate the seismic performance of corroded RC shear walls, we considered descent segments of four broken-line models to estimate the skeleton curve. After considering the influence of corrosion on the parameters of the characteristic point for the skeleton curve, the calculation formulas of the characteristic point parameters of the skeleton curve for the corroded RC shear wall were determined based on the test data fitting. It was proven that the formula for the characteristic point parameters for the skeleton curve of corroded RC shear walls has good applicability. This study lays a theoretical foundation for the seismic performance evaluation of an RC shear wall structure in a salt fog environment. It provides a theoretical basis for further improving the life-cycle seismic capacity evaluation system for RC structures.

Evaluation of Building Seismic Capacity Based on Improved Naive Bayesian Algorithm

The influencing factors of building seismic capacity are analyzed, the basic cause events of the assessment target based on fault tree analysis (FTA) are determined, the basic cause events in the FTA model are classified and summarized, and a judgment system of building seismic capacity is built. The weight of each index factor in the Gini index calculation system is used, and the importance of the index is analyzed. On the basis of the Spearman correlation coefficient calculation of the index, the improved naive Bayesian algorithm is combined with the importance of the index to build a judgment model for the seismic capacity of housing buildings. The sample set is constructed based on the judgment system with the basic data of some housing buildings in Huoshan County. In order to improve the generalization ability and avoid overfitting, the K-SMOTE algorithm for mixed sampling was modified to improve sample balance, and random k -fold cross validation method was used for sample division and model optimization, achieving the determination of seismic capacity level of building. The research results indicate the following: (1) the accuracy of model evaluation is 93%, with model accuracy and recall rates of 0.913 and 0.93, respectively, indicating strong generalization ability of the model. (2) Selecting some actual examples of a building, the model judgment results are consistent with the actual results, verifying the correctness of the proposed method for building the model, which can be effectively used for determining the seismic capacity of building structures. (3) Applying the proposed method to the seismic capacity assessment of buildings in the Ta-pieh Mountains of Lu’an, it is concluded that the seismic capacity of urban buildings is common, while that of rural buildings is poor.

Seismic Capacity Evaluation of Rectangular RC Columns Strengthened with Steel Bars

Seismic Capacity Evaluation of Rectangular RC Columns Strengthened with Steel Bars

Seismic capacity evaluation of existing reinforced concrete buildings strengthened with a novel prestressing steel frame system for increasing lateral strength

In this study, a new concept of seismic retrofit, the Prestressing Steel Frame (PSF) system, is proposed to improve and compensate for the weaknesses of the existing strength-enhancing seismic retrofit method. The PSF system, a construction method that maximizes the advantages of the H-shaped steel frame, innovatively improves the constructability and integrity of existing reinforced concrete (R/C) frames and reinforcement joints. This method is a type of typical strength-increasing reinforcement method that facilitates calculation of the required seismic reinforcement amount, and easily enhances the horizontal strength of shear collapse-type R/C buildings with non-seismic detailing. To review the seismic performance of the proposed PSF method, pseudo-dynamic tests were conducted on a real two-story frame based on an existing R/C building without seismic detailing, and seismic performance was evaluated in terms of load and displacement characteristics, seismic damage level, strength enhancement effect, and displacement control. In addition, based on the results of pseudo-dynamic testing, a hysteresis model was proposed to perform non-linear dynamic analysis of the seismically reinforced structure (two-story frame) with the PSF method. Non-linear dynamic analysis was performed based on the proposed hysteresis model, and the results were compared against that of pseudo-dynamic testing. For the commercialization of the method, non-linear dynamic analysis was conducted on the entire R/C building reinforced with PSF, and the effectiveness of seismic reinforcement was verified by comparing the seismic response load and displacement response before and after reinforcement. In the event of an earthquake with a maximum ground acceleration of 200 cm/s2, which is 2/3 of major earthquakes with a 2400-year recurrence interval stipulated in Korea Design Standard (KDS) 41, shear failure is expected for R/C buildings with non-seismic detailing, while small-scale damage is predicted for buildings reinforced with the PSF method. This shows that the PSF strengthening method is effective in minimizing earthquake damage.

Probabilistic Seismic Capacity Model of Pier Columns: A Semiparametric Regression Approach

Piers are usually the most vulnerable components in a bridge structure and generally undergo excessive deformation, which will lead to damage and even whole structural collapse. This paper investigates the probabilistic seismic deformation capacities of reinforced concrete piers under different limit states for two engineering demand parameters, i.e., the drift ratio and displacement ductility. Based on sample data from the UW-PEER database, a penalized generalized additive model is used for predictor variable selections and to determine whether the mechanism of each predictor on the seismic capacity is linear or nonlinear. The influence of a predictor that illustrated a nonlinear pattern is modeled by a Gaussian process, and Bayesian semiparametric regression is conducted in the R environment to obtain posteriori estimations of the capacity measures. The results indicate that the ratios of the model predictions to the experimental observations are all around 1.0, which proves the unbiasedness of the models. Compared with previous seismic capacity models, the prediction of seismic capacity measures shows higher accuracy, lower dispersion, and better portrayal of uncertainties. The proposed model based on Bayesian semiparametric regression provides a performance improvement in the seismic capacity evaluation of the bridge structures, which can be used for the subsequent bridge seismic fragility and risk assessment.

Seismic capacity and performance of code-conforming single-story RC precast buildings considering multiple limit states and damage criteria

The seismic capacity and performance of code-conforming precast buildings is assessed in the study. The case study consists in single-story precast buildings designed according to Italian building code considering low to high seismicity sites and varying both geometry layout and soil conditions. The seismic behavior of the buildings is assessed through multiple-stripe analyses performed through nonlinear three-dimensional modeling. Fragility of the buildings is computed by considering several methods, and performance evaluation is based on capacity margin ratios, failure probabilities, and reliability indexes. Damage limitation, life safety prevention, and near collapse prevention performance levels are considered by accounting for multiple damage criteria and damage states, including both local and global approaches and both ductile and brittle failure of beam-to-column connections.The paper provides guidance for implementation of seismic capacity and performance evaluation of precast buildings according to latest advances, considering both European and US approaches. The study proves that the current code prescriptions might not supply adequate seismic performance, especially in the case of more critical soil conditions (i.e., C soil type compared to A soil type). A relatively critical performance was observed for damage limitation and life safety prevention performance levels, whereas collapse performance of the buildings was adequate. The extremely critical condition associated with brittle failure of the beam-to-column connection was also confirmed. The study stresses the need for an enhancement of current design requirements and highlights the need for further investigation into the adequacy of seismic performance of precast buildings and reliability of related code-conforming design.

Evaluation of the Residual Seismic Capacity of Post-Earthquake Damaged RC Columns Based on the Damage Distribution Model

Evaluation of the residual seismic capacity (RSC) of post-earthquake damaged buildings is instrumental to the formation of reasonable recovery strategies. At present, incremental dynamic analysis (IDA) that considers the mainshock and aftershock is the method most frequently used to evaluate the RSC of damaged structures. However, the mainshock-induced structural damage determined using the IDA method may be inconsistent with the damage observed in actual engineering. This inconsistency could potentially lead to an unreasonable evaluation result. To overcome this drawback, it is necessary to evaluate the RSC of damaged structures according to their observed damage instead of that obtained by the IDA. In this paper, a method of evaluating the RSC of damaged reinforced concrete (RC) columns is proposed. First, the damage degree and distribution of the damaged columns were evaluated via visual inspection after mainshocks. Then, a numerical model was developed to predict the residual behavior of damaged columns subjected to aftershocks. After that, the RSC of damaged columns was estimated based on fragility analysis. The degradation of the collapse capacity of damaged columns was quantified by the collapse fragility index (CFI), and a parameter analysis was conducted to study the effect of structural parameters on the CFI of damaged columns. Lastly, an empirical model for predicting the CFI was proposed, facilitating the application of this study in actual post-earthquake assessments. The parameter analysis indicates that the axial load ratio of the columns and the degree of damage degree accumulated during mainshocks have a significant effect on the CFI. Additionally, the proposed empirical model can effectively predict the degradation of the collapse capacity of RC columns in existing test data, with an accuracy of 0.82.

Experimental investigation of ultra-low cycle fatigue behaviors of laminated rubber bearings in spatial grid structures

Ultra-low-cycle fatigue failure of laminated rubber bearings in steel grid structures is likely to occur due to an earthquake, which leads to a failure or even complete collapse. The present paper investigates the effects of different variables on the hysteretic behavior, skeleton curves, and stiffness degradation of bearings and anchor bolts. The variables include the vertical force and diameter of anchor bolts. For these purposes, ultra-low-cycle fatigue tests on laminated rubber bearings were carried out under constant vertical loading and horizontal reciprocating variable loading. In addition, the morphological analysis of fatigue fractures was performed to investigate the failure mechanism of anchor bolts in the bearings. It was found that the anchor bolt is the weakest part of the bearings during strong earthquakes. Cracks originate at the root of the anchor bolt and expand as the stress concentration increases, and a typical ultra-low-cycle fatigue fracture micro-morphology appears. Also, it was also found that increasing the vertical pressure can increase the peak value of the horizontal reaction force of the specimen and increase the energy consumption. It means that increasing the diameter of the anchor bolt can increase the stiffness of the bearing, increase the peak value of the horizontal reaction force, and slow down the stiffness degradation. Furthermore, a formula for the relationship between horizontal stiffness degradation and cumulative damage of a bearing is established. This formula can provide a reference for the seismic capacity evaluation of laminated rubber bearings used in spatial grid structures.

Dynamic characteristics and seismic response analysis of the bottle-shaped masonry ancient pagoda

To study the dynamic performance and seismic response of the bottle-shaped masonry ancient pagoda of Mafo Temple, the numerical model of the pagoda was established using the finite element software ABAQUS with a hierarchical modeling method. By inputting the El-Centro wave, Taft wave, and Lanzhou artificial wave, the seismic response of the pagoda was calculated, and the seismic damage mechanism was analyzed, as well as the distribution characteristics of the principal tensile stress and the seismic weak area. The results show that the stiffness and mass distribution of the pagoda are consistent in the height direction, and the deformation of the Sumeru throne and the top of the pagoda is significant under the earthquake. The pagoda bottom exceeds the limits of the material's tensile damage factor and principal tensile stress under moderate and large earthquakes. The stiffness of the top of the pagoda is severely degraded under large earthquakes. Therefore, the Sumeru throne and the top of the pagoda are the seismic weak parts of the ancient masonry pagoda. These results provide a basis for the seismic capacity evaluation of the bottle-shaped masonry pagodas.

Cyclic Performance of Structural Steels after Exposure to Various Heating–Cooling Treatments

The cyclic performance of structural steels after exposure to various elevated temperatures and cooling-down methods was experimentally investigated in this paper. Four types of frequently used structural steels were tested including Chinese mild steel Grade Q235, Chinese high-strength steel Grade Q345, and Chinese stainless steel Grade S304 and S316. A total of eighty specimens were prepared using three different heating–cooling processes before being subjected to cyclic loads. The post-fire basic features and hysteretic performances of the four types of structural steels exposed to various target temperatures (100–1000 °C), heat soak times (30 min or 180 min) and cooling-down methods (natural air or water) were recorded and discussed. The results show that all the tested structural steels prepared using different heating–cooling treatments exhibited proper ductility and energy dissipation capacity, while the heat soak times and cooling-down methods had a definite effect on their energy dissipation capacity; no Masing phenomenon was found in the tested structural steels. Finally, a set of skeleton curves were proposed for the four types of structural steels under cyclic loading based on the Ramberg–Osgood model, which could serve as the foundation for the seismic capacity evaluation of steel structures after a fire.

Seismic Capacity Evaluation of Existing Residential Buildings Based on Big Data

Based on big data, the seismic capacity of existing residential buildings is evaluated in this paper. More than 60 representative large and medium cities in China are selected. Key indexes of buildings are extracted by investigating the Internet data, government statistics and business data, and the logical relationship between the indexes is clarified. Then the dynamic analysis model based on probability theory is applied for seismic disaster prediction. Considering changes of seismic fortification level and proportions of different ages of residential buildings, a new evaluation method based on big data is presented to obtain the seismic capacity index of a city. It will provide data support for the reinforcement and reconstruction of existing residential buildings.

Damage Survey and Residual Seismic Capacity Evaluation of Reinforced Concrete School Buildings after the 2018 Hokkaido Eastern Iburi Earthquake

ABSTRACT In this study, a damage survey was conducted on the buildings of two schools located in the town of Abira, where a Japanese seismic intensity of 6 upper was recorded during the 2018 Hokkaido Eastern Iburi Earthquake. The damage classes of the reinforced concrete structural members and residual seismic capacity ratios were examined. Both schools had performed seismic evaluation and retrofitting before the earthquake, and no serious damage occurred, but flexural and shear cracks in columns and walls were observed. Analysis using drone photographs was conducted to perform crack detection and crack width evaluation and create point cloud models.

Analisis Kapasitas Seismik Struktur Gedung Kantor Dinas KetahananPangan Provinsi Sumatra Barat

The office building of the food security office of West Sumatra Province is a multi-storey building with reinforced concrete structures built in earthquake-prone areas that have the potential for large-scale earthquakes such as the one that occurred in 2009. Based on USGS data, from December 2004 to October 2009 There have been 10 earthquakes measuring more than 5 on the Richter scale that rocked Indonesia and resulted in damage to buildings, both minor damage to heavy damage and evencollapsing. The big earthquake that occurred on September 30, 2009 in Padang City, West Sumatra, was measuring 7.6 on the Richter scale. In this study, evaluated the seismic capacity of a reinforced concrete building 4 (four) floors built in earthquake-prone areas in the city of Padang. The seismic capacity of the building is evaluated based on the standard published by Japan, namely The Standard for Seismic Evaluation of Existin Reinforced Concrete Building, 2001. In this evaluation, it only looks at the structural elements of the column on the first floor. Seismic capacity is expressed in terms of the lateral strength index and the ductility index of the building. The results of the evaluation of seismic capacity obtained the total strength index value of the building is 0.707. The seismic capacity of this building can be shown to be adequate or strongin earthquake-prone areas compared to the seismic capacity of reinforced concrete buildings that survived the massive earthquake of 7.6 on the Richter Scale in West Sumatra in September 2009. From the evaluation results on this building which is located in an area including the prone to strong earthquakes can be stated to be able to behave ductile and able to withstand an earthquake or not experience sudden collapse

Experimental investigation of ultra-low-cycle fatigue behaviors of plate bearings in spatial grid structures

Ultra-low-cycle fatigue failure of plate bearings in steel grid structures is likely to occur due to an earthquake, which leads to a failure or even complete grid collapse. In this study, the effects of different variables on the hysteretic behavior, skeleton curves, stiffness degradation, and angles of inclination of the bearings and the anchor bolts were investigated. These variables included the vertical force, diameter of anchor bolts and extra baffles. For these purposes, ultra-low-cycle fatigue tests on six groups of plate bearings were carried out under constant vertical loading and horizontal reciprocating variable loading. In addition, the morphological analysis of fatigue fractures was performed to investigate the failure mechanism of anchor bolts in the bearings. It was found that the anchor bolt is the weakest part of the plate bearings during strong earthquakes. Cracks originate at the root of the anchor bolt and expand as the stress concentration increases and a typical ultra-low-cycle fatigue fracture micro-morphology appears. Also, it was also found that adding a baffle in an appropriate position on the bearings can improve the resistance ability against falling from the base supports providing that the baffle capacity is designed properly. Furthermore, a formula for the relationship between horizontal stiffness degradation and cumulative damage of a plate bearing is established. This formula can provide a reference for the seismic capacity evaluation of plate bearings used in spatial grid structures.

Seismic capacity evaluation of fire-damaged cabinet facility in a nuclear power plant

This study is to evaluate the seismic capacity of the fire-damaged cabinet facility in a nuclear power plant (NPP). A prototype of an electrical cabinet is modeled using OpenSees for the numerical simulation. To capture the nonlinear behavior of the cabinet, the constitutive law of the material model under the fire environment is considered. The experimental record from the impact hammer test is extracted trough the frequency-domain decomposition (FDD) method, which is used to verify the effectiveness of the numerical model through modal assurance criteria (MAC). Assuming different temperatures, the nonlinear time history analysis is conducted using a set of fifty earthquakes and the seismic outputs are investigated by the fragility analysis. To get a threshold of intensity measure, the Monte Carlo Simulation (MCS) is adopted for uncertainty reduction purposes. Finally, a capacity estimation model has been proposed through the investigation, which will be helpful for the engineer or NPP operator to evaluate the fire-damaged cabinet strength under seismic excitation. This capacity model is presented in terms of the High Confidence of Low Probability of Failure (HCLPF) point. The results are validated by the proper judgment and can be used to analyze the influences of fire on the electrical cabinet.

Research on Seismic Performance of Bottom Frame Structure Based on Pushover Method

To study the seismic performance and seismic capacity evaluation method of the bottom frame structure, this paper adopts a five-story bottom frame structure as an example, and uses SAP2000 finite element software to establish an analytical model on Pushover analysis. The results show that Pushover analysis is an effective method to evaluate the seismic performance of the structure. The impact on the bottom frame structure of the high-order vibration modes under the earthquake is negligible, mainly because the first-order vibration mode plays a controlling role, and the lateral force adopts the inverted triangle Load distribution mode loading is feasible, and the bottom frames structure after formal construction and design according to the specifications can meet the requirements of seismic performance.

Seismic capacity evaluation of NPP electrical cabinet facility considering grouping effects

ABSTRACT This study investigates the fragility assessment of the electrical cabinet facility, a steel structural form that exhibits behavior and response patterns distinct from the normal structure. To evaluate this cause, a set of 40 ground motions was spectrally matched to the design response spectra (RG 1.60) and incremental dynamic analysis was considered. The two design guidelines including earthquake loss estimation methodology (HAZUS) and Nuclear Regulatory Commission (NUREG) were followed. Using the response statistics with the consideration of different damage states, the corresponding fragility curves were developed. For validation, the developed fragility functions were found to be consistent with the fragilities available in the HAZUS and NUREG. Subsequently, the seismic capacity for the group of cabinets was evaluated, which manifests a great influence on the probabilistic seismic risk assessment of the facility. The main thrust of this study was the significant alteration in the seismic capacity due to the grouping effects that account for 28% and 50% reduction in the probability of failure for two and three cabinets together. This effect can be considered as one of the important aspects that can induce a considerable impact on the seismic capacity evaluation and performance of the NPP electrical components.

A Shape of the Response Spectrum for Evaluation of the Ultimate Seismic Capacity of Structures and Equipment including High-frequency Earthquake Characteristics

In 2016, an earthquake occurred at Gyeongju, Korea. At the Wolsong site, the observed peak ground acceleration was lower than the operating basis earthquake (OBE) level of Wolsong nuclear power plant. However, the measured spectral acceleration value exceeded the spectral acceleration of the operating-basis earthquake (OBE) level in some sections of the response spectrum, resulting in a manual shutdown of the nuclear power plant. Analysis of the response spectra shape of the Gyeongju earthquake motion showed that the high-frequency components are stronger than the response spectra shape used in nuclear power plant design. Therefore, the seismic performance evaluation of structures and equipment of nuclear power plants should be made to reflect the characteristics of site-specific earthquakes. In general, the floor response spectrum shape at the installation site or the generalized response spectrum shape is used for the seismic performance evaluation of structures and equipment. In this study, a generalized response spectrum shape is proposed for seismic performance evaluation of structures and equipment for nuclear power plants. The proposed response spectrum shape reflects the characteristics of earthquake motion in Korea through earthquake hazard analysis, and it can be applied to structures and equipment at various locations.

Evaluation of seismic capacity on the building law Faculty Tadulako University due to Palu earthquake 2018

Indonesia is located in a high level of the earthquake risk area. According to USGS data, from December 2004 to October 2009, more than ten large earthquakes occurred and exceeded 5.0 Scale Richter in magnitude. Recently, the major earthquake occurred on September 28, 2018, in Palu City, Central Sulawesi, with 7.4 on the Scale Richter in magnitude and triggered a lot of building damaged. In this study, the seismic capacity of a 3-story reinforced concrete building, which collapsed due to a large earthquake in the city of Palu, was evaluated. The Standard for Seismic Evaluation of Existing Reinforced Concrete Buildings, 2001 from Japan, was used to evaluate the seismic capacity of reinforced concrete. In this analysis only reviews the column structure elements. However, the brick wall elements are considered to determine net column height. The analysis has been done only for the first floor, where there is the maximum shear force on the structure. Seismic capacity is determined by the relationship between the lateral strength and the ductility index. The obtained results of the seismic capacity analysis showed that the total strength index value of the building was 0.307 for the north to south and 0.455. The seismic capacity of this building is compared with the seismic capacity of a reinforced concrete building that survived due to a large earthquake with 7.6 on the Scale Richter in West Sumatra in September 2009. The obtained results show that the strength index value of this building is smaller than that of a building that could survive the 2009 West Sumatra earthquake.

Seismic capacity evaluation of the damaged reinforced concrete building during Palu earthquake 2018

This paper presents an evaluation of the seismic capacity of the Dean Building of The Faculty of Social and Political Science of Tadulako University due to the Palu Earthquake 2018. The building was built in 2016 and went into use in 2017. The building is made from a reinforced concrete frame consisting of three floors and collapsed after the earthquake. Data for the analysis are taken from the Detail Engineering Design of the Dean Building of The Faculty of Social And Political Science of Tadulako University in 2015. Seismic capacity evaluated based on Standard for Seismic Evaluation of Existing Reinforced Concrete Buildings issued by the Japan Country. The analysis are done on the 1st-floor structure because the most significant sliding force happens on the first floor. Seismic capacity is invoked in the form of a link between the lateral strength and the ductility index. By using Japanese standards, the building's seismic capacity is relatively small in withstanding the earthquake load and collapsed the building. Based on observations in the field by conducting non-destructive testing using hammer tests, the concrete material had relatively low quality and a failure to connect the column beams by insufficiently reintegrating and resulted in a collapse of the building.