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1.
PLoS One ; 15(10): e0237264, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33002034

RESUMO

The precise evaluation of the potential damage caused by large commercial aircraft crash into civil structures, especially nuclear power plants (NPPs), has become essential design consideration. In this study, impact of Boeing 767 against rigid wall and outer containment building (reinforced concrete) of an NPP are simulated in ANSYS/LS-DYNA by using both force time history and missile target interaction methods with impact velocities ranging from 100 m/s to 150 m/s. The results show that impact loads, displacements, stresses for concrete and steel reinforcement, and damaged elements are higher in case of force time history method than missile target interaction method, making the former relatively conservative. It is observed that no perforation or scabbing takes place in case of 100 m/s impact speed, thus preventing any potential leakage. With full mass of Boeing 767 and impact velocity slightly above 100 m/s, the outer containment building can prevent local failure modes. At impact velocity higher than 120 m/s, scabbing and perforations are dominant. This concludes that in design and assessment of NPP structures against aircraft loadings, sufficient thickness or consideration of steel plates are essential to account for local failure modes and overall structural integrity. Furthermore, validation and application of detail 3D finite element and material models to full-scale impact analysis have been carried out to expand the existing database. In rigid wall impact analysis, the impact forces and impulses from FE analysis and Riera's method correspond well, which satisfies the recommendations of relevant standards and further ensure the accuracy of results in full-scale impact analysis. The methodology presented in this paper is extremely effective in simulating structural evaluation of full-scale aircraft impact on important facilities such as NPPs.


Assuntos
Acidentes Aeronáuticos , Aeronaves , Liberação Nociva de Radioativos , Acidentes Aeronáuticos/estatística & dados numéricos , Códigos de Obras , Simulação por Computador , Materiais de Construção/estatística & dados numéricos , Análise de Elementos Finitos , Humanos , Imageamento Tridimensional , Fenômenos Mecânicos , Modelos Teóricos , Centrais Nucleares , Fenômenos Físicos , Liberação Nociva de Radioativos/prevenção & controle , Liberação Nociva de Radioativos/estatística & dados numéricos , Aço , Colapso Estrutural/prevenção & controle , Colapso Estrutural/estatística & dados numéricos
2.
PLoS One ; 15(9): e0239830, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32991631

RESUMO

In this study, we propose a mesh-free (particle-based) Smoothed Particle Hydrodynamics model for simulating a Rayleigh collapse. Both empty and gas cavities are investigates and the role of heat diffusion is also accounted for. The system behaves very differently according to the ratio between the characteristic time of collapse and the characteristic time of thermal diffusion. This study identifies five different possible behaviours that range from isothermal to adiabatic.


Assuntos
Hidrodinâmica , Modelos Teóricos , Colapso Estrutural/prevenção & controle
3.
PLoS One ; 15(3): e0229532, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32191717

RESUMO

In this study, research on a pile group system was conducted using shaking table tests under four working conditions: a natural foundation and pile-spacing conditions of 3D, 3.5D, and 4D (D is the diameter of the pile). The time histories of the excess pore pressure ratio and settlement were analyzed. It was determined that pile foundations improved the anti-liquefaction performance of the soil, and the effect was much greater when the pile spacing was 3D. In addition, the settlement dynamic amplification factor (SDAF) was proposed and calculated at different vibration times. The result was fitted with a linear relationship, and the correlation coefficient was relatively high. During the aseismic design of the pile foundation bearing capacity, the SDAF was multiplied by the static load, and the results showed that in the dynamic design of the pile foundation, the dynamic problem can be transformed into a static analysis, which can provide a reference for the design of the vertical bearing capacity of pile foundations under seismic force.


Assuntos
Areia/química , Colapso Estrutural/prevenção & controle , Vibração/efeitos adversos , Terremotos , Fenômenos Mecânicos , Modelos Teóricos , Fenômenos Físicos , Solo/química , Estresse Mecânico
4.
Artigo em Inglês | MEDLINE | ID: mdl-31906513

RESUMO

As an important feature, deformation analysis is of great significance to ensure the safety and stability of arch dam operation. In this paper, Jinping-I arch dam with a height of 305 m, which is the highest dam in the world, is taken as the research object. The deformation data representation method is analyzed, and the processing method of deformation spatiotemporal data is discussed. A deformation hybrid model is established, in which the hydraulic component is calculated by the finite element method, and other components are still calculated by the statistical model method. Since the relationship among the measuring points is not taken into account and the overall situation cannot be fully reflected in the hybrid model, a spatiotemporal hybrid model is proposed. The measured values and coordinates of all the typical points with pendulums of the arch dam are included in one spatiotemporal hybrid model, which is feasible, convenient, and accurate. The model can predict the deformation of any position on the arch dam. This is of great significance for real-time monitoring of deformation and stability of Jinping-I arch dam and ensuring its operation safety.


Assuntos
Algoritmos , Teste de Materiais/métodos , Modelos Teóricos , Segurança , Colapso Estrutural/prevenção & controle , Humanos , Análise Espaço-Temporal , Água
5.
PLoS One ; 14(10): e0224436, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31648266

RESUMO

Tuned liquid column ball damper (TLCBD) is a passive control device used for controlling the building vibrations induced from wind or earthquakes. TLCBD is a modified form of conventional tuned liquid column damper (TLCD). This paper studies the effect of TLCBD on the four-storey steel frame structure. The performance of the TLCBD is also compared with conventional TLCD. The analytical model of both TLCD and TLCBD is presented here. The effectiveness of these analytical models is examined experimentally by series of shaking table tests under different excitation levels including harmonic loadings and seismic excitations. In TLCBD, the vibration is reduced significantly as compared to TLCD by using steel ball as a moving orifice. The difference in diameter of steel ball and tube, containing the liquid column, acts as an orifice which moves with the movement of the ball. This moving orifice phenomenon enhanced the vibration reduction effect by resisting the water motion in the TLCBD. Root mean square (RMS) and peak values of acceleration were calculated for each loading and each storey of uncontrolled and controlled structures. Comparison of the time histories of controlled and uncontrolled structures for different loadings is also reported. Results indicate that the TLCBD is more effective in the earthquake scenarios as compared to the harmonic excitations. The TLCBD controls the vibration of the primary structure significantly in vibration reduction.


Assuntos
Colapso Estrutural/prevenção & controle , Vibração , Aço
6.
Artigo em Inglês | MEDLINE | ID: mdl-31597381

RESUMO

Dam-break flooding is a potential hazard for reservoirs that poses a considerable threat to human lives and property in downstream areas. Assessing the dam-break flood risk of the Zipingpu Reservoir in Chengdu, Sichuan Province, China, is critically important because this reservoir is located on the Longmen Shan fault, which experiences high seismic activity. In this paper, we develop an approach based on the protected object for dam-break flood risk management. First, we perform a numerical simulation of dam-break flooding in four possible dam break scenarios. Next, the flood areas are divided into 71 analysis units based on the administrative division. Based on the numerical simulation results and the socio-economic demographic data affected by a flood, the importance and risk level of each analysis unit is confirmed, and the flood risk map is established according to the classification results. Finally, multi-level flood risk management countermeasures are proposed according to the results of the unit classification shown in the map.


Assuntos
Inundações/prevenção & controle , Gestão de Riscos/métodos , Gestão da Segurança/métodos , Colapso Estrutural/prevenção & controle , China
7.
PLoS One ; 13(7): e0200482, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30059506

RESUMO

This paper investigated the seismic retrofitting of an existing cable-stayed bridge through the use of a seismic isolation system. The bridge is situated in a high seismic zone. During the Saguenay earthquake 1988, one of the anchorage plates of the bridge supports failed. Herein, several configurations of seismic isolation system were considered to identify an appropriate solution for the seismic retrofitting of the bridge in both the longitudinal and transverse directions. A three-dimensional model of the bridge was created, and its seismic behavior studied through nonlinear dynamic time-history analysis. The comparative performance study among the five retrofitting configurations showed that the partial seismic isolation of the bridge led to an enhancement of the seismic response of the bridge in one direction only. However, the overall seismic response of the cable-stayed bridge substantially improved in the longitudinal and transverse directions in cases where the isolation systems were utilized between the supports and the deck-tower connection of the bridge.


Assuntos
Desastres , Terremotos , Aço , Colapso Estrutural/prevenção & controle , Canadá , Materiais de Construção , Desenho de Equipamento , Movimento (Física) , Dinâmica não Linear
8.
Proc Jpn Acad Ser B Phys Biol Sci ; 94(2): 129-138, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29434079

RESUMO

Strength, functionality and beauty are the three qualities identifying well-designed architecture. For buildings in earthquake-prone countries such as Japan, emphasis on seismic safety frequently leads to the sacrifice of functionality and beauty. Therefore, it is important to develop new structural technologies that can ensure the seismic performance of a building without hampering the pursuit of functionality and beauty. The moment-resisting frame structures widely used for buildings in Japan are likely to experience weak-story collapse. Pin-supported walls, which can effectively enhance the structural story-by-story integrity of a building, were introduced to prevent such an unfavorable failure pattern in the seismic retrofit of an eleven-story building on a university campus in Tokyo, while also greatly aesthetically enhancing the façade of the building. The slight damage observed and monitoring records of the retrofitted building during the 2011 Tohoku earthquake in Japan demonstrate that the pin-supported walls worked as intended, protecting the building and guaranteeing the safety of its occupants during the earthquake.


Assuntos
Indústria da Construção/métodos , Materiais de Construção , Desenho de Equipamento/métodos , Colapso Estrutural/prevenção & controle , Desastres , Terremotos , Meio Ambiente , Japão , Universidades
9.
Artigo em Inglês | MEDLINE | ID: mdl-29434082

RESUMO

The vibration-based monitoring of flexible civil structures and performance evaluation from this monitoring are reviewed, with an emphasis on research and practice in Japan and the author's experiences. Some new findings and unexpected vibrations from the monitoring of real bridges and buildings are reported to emphasize the importance of monitoring. Future developments and applications of vibration-based monitoring to civil infrastructure management are also described. Many examples are taken from the author's past 30 years' experience of research on bridge dynamics.


Assuntos
Indústria da Construção/métodos , Materiais de Construção , Tecnologia de Sensoriamento Remoto/métodos , Colapso Estrutural/prevenção & controle , Vibração , Desastres , Terremotos , Humanos , Japão , Vento
10.
Environ Sci Pollut Res Int ; 25(6): 5280-5297, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29260469

RESUMO

Protection of common natural goods is one of the greatest challenges man faces every day. Extracting and processing natural resources such as mineral deposits contributes to the transformation of the natural environment. The number of activities designed to keep balance are undertaken in accordance with the concept of integrated order. One of them is the use of comprehensive systems of tailings storage facility monitoring. Despite the monitoring, system failures still occur. The quantitative aspect of the failures illustrates both the scale of the problem and the quantitative aspect of the consequences of tailings storage facility failures. The paper presents vast possibilities provided by the global monitoring in the effective prevention of these failures. Particular attention is drawn to the potential of using multidirectional monitoring, including technical and environmental monitoring by the example of one of the world's biggest hydrotechnical constructions-Zelazny Most Tailings Storage Facility (TSF), Poland. Analysis of monitoring data allows to take preventive action against construction failures of facility dams, which can have devastating effects on human life and the natural environment.


Assuntos
Conservação dos Recursos Naturais/métodos , Monitoramento Ambiental , Mineração , Colapso Estrutural/prevenção & controle , Polônia
11.
Environ Monit Assess ; 190(1): 15, 2017 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-29234976

RESUMO

Riverbed scour of bridge piers can cause rapid loss in foundation strength, leading to sudden bridge collapse. This study used multi-beam echo sounders (Seabat 7125) to map riverbed surrounding the foundations of four major bridges in the lower, middle, and upper reaches of the 700-km Yangtze River Estuary (YRE) during June 2015 and September 2016. The high-resolution data were utilized to analyze the morphology of the bridge scour and the deformation of the wide-area riverbed (i.e., 5-18 km long and 1.3-8.3 km wide). In addition, previous bathymetric measurements collected in 1998, 2009, and 2013 were used to determine riverbed erosion and deposition at the bridge reaches. Our study shows that the scour depth surrounding the bridge foundations progressed up to 4.4-19.0 m in the YRE. Over the past 5-15 years, the total channel erosion in some river reaches was up to 15-17 m, possessing a threat to the bridge safety in the YRE. Tide cycles seemed to have resulted in significant variation in the scour morphology in the lower and middle YRE. In the lower YRE, the riverbed morphology displayed one long erosional ditch on both sides of the bridge foundations and a long-strip siltation area distributed upstream and downstream of the bridge foundations; in the middle YRE, the riverbed morphology only showed erosional morphology surrounding the bridge foundations. Large dunes caused deep cuts and steeper contours in the bridge scour. Furthermore, this study demonstrates that the high-resolution grid model formed by point cloud data of multi-beam echo sounders can clearly display the morphology of the bridge scour in terms of wide areas and that the sonar technique is a very useful tool in the assessment of bridge scours.


Assuntos
Engenharia/métodos , Monitoramento Ambiental/métodos , Estuários , Sedimentos Geológicos/análise , Rios , Colapso Estrutural/prevenção & controle , China , Simulação por Computador , Materiais de Construção , Hidrodinâmica
12.
ScientificWorldJournal ; 2015: 250562, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26451387

RESUMO

Nanjing Dashengguan Bridge, which serves as the shared corridor crossing Yangtze River for both Beijing-Shanghai high-speed railway and Shanghai-Wuhan-Chengdu railway, is the first 6-track high-speed railway bridge with the longest span throughout the world. In order to ensure safety and detect the performance deterioration during the long-time service of the bridge, a Structural Health Monitoring (SHM) system has been implemented on this bridge by the application of modern techniques in sensing, testing, computing, and network communication. The SHM system includes various sensors as well as corresponding data acquisition and transmission equipment for automatic data collection. Furthermore, an evaluation system of structural safety has been developed for the real-time condition assessment of this bridge. The mathematical correlation models describing the overall structural behavior of the bridge can be obtained with the support of the health monitoring system, which includes cross-correlation models for accelerations, correlation models between temperature and static strains of steel truss arch, and correlation models between temperature and longitudinal displacements of piers. Some evaluation results using the mean value control chart based on mathematical correlation models are presented in this paper to show the effectiveness of this SHM system in detecting the bridge's abnormal behaviors under the varying environmental conditions such as high-speed trains and environmental temperature.


Assuntos
Arquitetura , Eletrônica/instrumentação , Modelos Estatísticos , Reconhecimento Automatizado de Padrão , Colapso Estrutural/prevenção & controle , China , Indústria da Construção , Materiais de Construção , Humanos , Segurança
13.
ScientificWorldJournal ; 2014: 757608, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25405232

RESUMO

Integral abutment bridges (IABs) have many advantages over conventional bridges in terms of strength and maintenance cost. Due to the integrity of these structures uniform thermal and seismic loads are known important ones on the structure performance. Although all bridge design codes consider temperature and earthquake loads separately in their load combinations for conventional bridges, the thermal load is an "always on" load and, during the occurrence of an earthquake, these two important loads act on bridge simultaneously. Evaluating the safety level of IABs under combination of these loads becomes important. In this paper, the safety of IABs--designed by AASHTO LRFD bridge design code--under combination of thermal and seismic loads is studied. To fulfill this aim, first the target reliability indexes under seismic load have been calculated. Then, these analyses for the same bridge under combination of thermal and seismic loads have been repeated and the obtained reliability indexes are compared with target indexes. It is shown that, for an IAB designed by AASHTO LRFD, the indexes have been reduced under combined effects. So, the target level of safety during its design life is not provided and the code's load combination should be changed.


Assuntos
Materiais de Construção/estatística & dados numéricos , Desastres , Terremotos , Colapso Estrutural/prevenção & controle , Códigos de Obras , Indústria da Construção , Temperatura Alta , Segurança/legislação & jurisprudência
14.
ScientificWorldJournal ; 2014: 474728, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25401141

RESUMO

The punching shear failure often governs the strength of the footing-to-column connection. The punching shear failure is an undesirable failure mode, since it results in a brittle failure of the footing. In this study, a new method to increase the strength and ductility of the footing was proposed by inserting the punching shear preventers (PSPs) into the footing. The validation and effectiveness of PSP were verified through a series of experimental studies. The nonlinear finite element analysis was then performed to demonstrate the failure mechanism of the footing with PSPs in depth and to investigate the key parameters that affect the behavior of the footing with PSPs. Finally, the design recommendations for the footing with PSPs were suggested.


Assuntos
Materiais de Construção/normas , Teste de Materiais/normas , Resistência ao Cisalhamento , Resistência à Tração , Teste de Materiais/métodos , Colapso Estrutural/prevenção & controle
15.
ScientificWorldJournal ; 2014: 802605, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25309957

RESUMO

The seismic performance of RC columns could be significantly improved by continuous spiral reinforcement as a result of its adequate ductility and energy dissipation capacity. Due to post-earthquake brittle failure observations in beam-column connections, the seismic behaviour of such connections could greatly be improved by simultaneous application of this method in both beams and columns. In this study, a new proposed detail for beam to column connection introduced as "twisted opposing rectangular spiral" was experimentally and numerically investigated and its seismic performance was compared against normal rectangular spiral and conventional shear reinforcement systems. In this study, three full scale beam to column connections were first designed in conformance with Eurocode (EC2-04) for low ductility class connections and then tested by quasistatic cyclic loading recommended by ACI Building Code (ACI 318-02). Next, the experimental results were validated by numerical methods. Finally, the results revealed that the new proposed connection could improve the ultimate lateral resistance, ductility, and energy dissipation capacity.


Assuntos
Arquitetura/métodos , Materiais de Construção/análise , Desastres , Terremotos , Colapso Estrutural/prevenção & controle , Simulação por Computador , Materiais de Construção/economia , Análise Custo-Benefício , Desenho de Equipamento , Humanos , Teste de Materiais , Vibração
16.
ScientificWorldJournal ; 2014: 189106, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25301387

RESUMO

This paper presents the evaluation of seismic performance and cost-effectiveness of a multiple slim-type damper system developed for the vibration control of earthquake excited buildings. The multiple slim-type damper (MSD) that consists of several small slim-type dampers and linkage units can control damping capacity easily by changing the number of small dampers. To evaluate the performance of the MSD, dynamic loading tests are performed with three slim-type dampers manufactured at a real scale. Numerical simulations are also carried out by nonlinear time history analysis with a ten-story earthquake excited building structure. The seismic performance and cost-effectiveness of the MSD system are investigated according to the various installation configurations of the MSD system. From the results of numerical simulation and cost-effectiveness evaluation, it is shown that combinations of the MSD systems can effectively improve the seismic performance of earthquake excited building structures.


Assuntos
Arquitetura/métodos , Materiais de Construção/análise , Desastres , Terremotos , Colapso Estrutural/prevenção & controle , Simulação por Computador , Materiais de Construção/economia , Análise Custo-Benefício , Desenho de Equipamento , Humanos , Vibração
17.
ScientificWorldJournal ; 2014: 128635, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25247201

RESUMO

The present study examines the use of collars and geobags for reducing local scour around bridge piles. The efficiency of collars and geobags was studied experimentally. The data from the experiments were compared with data from earlier studies on the use of single piles with a collar and with a geobag. The results showed that using a combination of a steel collar and a geobag yields the most significant scour reduction for the front and rear piles, respectively. Moreover, the independent steel collar showed better efficiency than the independent geobag below the sediment level around the bridge piles.


Assuntos
Materiais de Construção/normas , Teste de Materiais/normas , Colapso Estrutural/prevenção & controle , Teste de Materiais/métodos
18.
ScientificWorldJournal ; 2014: 567619, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25180203

RESUMO

Reinforced concrete (RC) box girders are a common structural member for road bridges in modern construction. The hollow cross-section of a box girder is ideal in carrying eccentric loads or torques introduced by skew supports. This study employed acoustic emission (AE) monitoring on multicell RC box girder specimens subjected to laboratory-based torsion loading. Three multicell box girder specimens with different cross-sections were tested. The aim is to acquire AE analysis data indicative for characterizing torsion fracture in the box girders. It was demonstrated through appropriate parametric analysis that the AE technique could be utilized to effectively classify fracture developed in the specimens for describing their mechanical behavior under torsion. AE events localization was presented to illustrate the trend of crack and damage propagation in different stages of fracture. It could be observed that spiral-like patterns of crack were captured through AE damage localization system and damage was quantified successfully in different stages of fracture by using smoothed b-value analysis.


Assuntos
Materiais de Construção/normas , Som , Torção Mecânica , Acústica/instrumentação , Colapso Estrutural/prevenção & controle
19.
ScientificWorldJournal ; 2014: 325759, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25126595

RESUMO

Deformation of quay walls is one of the main sources of damage to port facility while liquefaction of backfill and base soil of the wall are the main reasons for failures of quay walls. During earthquakes, the most susceptible materials for liquefaction in seashore regions are loose saturated sand. In this study, effects of enhancing the wall width and the soil improvement on the behavior of gravity quay walls are examined in order to obtain the optimum improved region. The FLAC 2D software was used for analyzing and modeling progressed models of soil and loading under difference conditions. Also, the behavior of liquefiable soil is simulated by the use of "Finn" constitutive model in the analysis models. The "Finn" constitutive model is especially created to determine liquefaction phenomena and excess pore pressure generation.


Assuntos
Terremotos , Gravitação , Modelos Teóricos , Software , Solo/química , Colapso Estrutural/prevenção & controle
20.
ScientificWorldJournal ; 2014: 292450, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25121115

RESUMO

The parameters of the constitutive model, the creep model, and the wetting model of materials of the Nuozhadu high earth-rockfill dam were back-analyzed together based on field monitoring displacement data by employing an intelligent back-analysis method. In this method, an artificial neural network is used as a substitute for time-consuming finite element analysis, and an evolutionary algorithm is applied for both network training and parameter optimization. To avoid simultaneous back-analysis of many parameters, the model parameters of the three main dam materials are decoupled and back-analyzed separately in a particular order. Displacement back-analyses were performed at different stages of the construction period, with and without considering the creep and wetting deformations. Good agreement between the numerical results and the monitoring data was obtained for most observation points, which implies that the back-analysis method and decoupling method are effective for solving complex problems with multiple models and parameters. The comparison of calculation results based on different sets of back-analyzed model parameters indicates the necessity of taking the effects of creep and wetting into consideration in the numerical analyses of high earth-rockfill dams. With the resulting model parameters, the stress and deformation distributions at completion are predicted and analyzed.


Assuntos
Algoritmos , Teste de Materiais/métodos , Modelos Teóricos , Redes Neurais de Computação , Colapso Estrutural/prevenção & controle , China , Água
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