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1
Zhu, Jia Wei, Dan Ting Zhou e Qiu Wei Yang. "Damage Localization for a Continuous Beam by the Displacement Variation". Applied Mechanics and Materials 744-746 (marzo 2015): 366–69. http://dx.doi.org/10.4028/www.scientific.net/amm.744-746.366.
Testo completoAbstract (sommario):
Using the static displacement data, this paper presented a damage localization method for a continuous beam. This method is based on the estimation of changes in the static displacements of the structure. The most significant advantage of the method is that it does not require development of an analytical model of the structure being tested. All predictions are made directly from the measurments taken on the structure. The efficiency of the proposed method is demonstrated using simulated data of a three-span continuous beam. The results showed that the region in which the displacement variation is maximum is the damaged region for the continuous beam. Regardless of damages being small or large, the proposed method can identify locations of structural damages accurately only using the displacement changes under the applied static load. The proposed procedure is economical for computation and simple to implement. The presented scheme may be useful for damage localization of the continuous beam.
2
Tiongson, Samuel Francisco, e Ryan Ramirez. "Mapping of ground surface deformations and its associated damage using SAR interferometry: a case study of the 2020 Masbate earthquake". E3S Web of Conferences 347 (2022): 03014. http://dx.doi.org/10.1051/e3sconf/202234703014.
Testo completoAbstract (sommario):
The 2020 Masbate earthquake in the Philippines, with a moment magnitude 6.6, occurred on August 18, 2020. The earthquake dealt considerable damage to the surrounding areas. This study uses Sentinel-1 Interferometric Synthetic Aperture Radar (InSAR) to investigate earthquake-induced damages. Conventional repeat-pass InSAR is used to quantify the ground surface displacement along the radar line-of-sight (LOS). The InSAR technique shows ground surface displacements greater than 15 cm. This study also implements a two-step coherence difference analysis coupled with a statistical temporal coherence threshold to map and delineate the locations of damages associated with the earthquake. The InSAR-derived damage locations are consistent with the actual locations of damages, as reported from a field survey. This study confirms the effectiveness and accuracy of Sentinel-1 InSAR techniques for earthquakeinduced damage mapping applications.
3
Xiao, Feng, Weiwei Zhu, Xiangwei Meng e Gang S. Chen. "Parameter Identification of Frame Structures by considering Shear Deformation". International Journal of Distributed Sensor Networks 2023 (16 agosto 2023): 1–12. http://dx.doi.org/10.1155/2023/6631716.
Testo completoAbstract (sommario):
This paper presents a method to identify the damages in frame structures with slender beams. This method adjusts the parameters of the structure to match the analytical and the measured displacements. The effect of transverse shear deformation on the nodal analytical displacement is analyzed, and the parameter identification of frame structures with slender beams is performed. The results demonstrate that parameter-identification accuracy can be considerably improved by considering the transverse shear deformation in the frame structure with slender beams. The proposed method can accurately identify the damages in frame structures with slender beams using displacement measurements.
4
Li, Cui Hong, Qiu Wei Yang e Xue Shen. "Damage Detection for Cantilever Beam Structures Using Two-Stage Method". Applied Mechanics and Materials 351-352 (agosto 2013): 1084–87. http://dx.doi.org/10.4028/www.scientific.net/amm.351-352.1084.
Testo completoAbstract (sommario):
This paper presents a two-stage method for damage identification in cantilever beam structures using the incomplete measured static and dynamic paramenters. The first stage locates damages preliminary by using the static displacement changes, which is obtained by the static test of structure. It has been shown that the point from which the static displacement difference starts increasing linearly is the location of damage. After the suspected damaged elements are determined in the first stage, the first order sensitivity of the structural natural frequency is used to identify damages more precise in the second stage. The significant advantage of the proposed method is that it is economical in computation and is simple to implement. A cantilever beam structure is analyzed as a numerical example to verify the present method. Results show that the proposed method performs well even if the measurement errors inevitably make the damage assessment more difficult. It has been shown that the presented two-stage methodology may be a promising tool to be used by research groups working on experimental damage detection.
5
Bhargav Sai, Cherukuri, e D. Mallikarjuna Reddy. "Dynamic Analysis of Faulty Rotors through Signal Processing". Applied Mechanics and Materials 852 (settembre 2016): 602–6. http://dx.doi.org/10.4028/www.scientific.net/amm.852.602.
Testo completoAbstract (sommario):
In this study, an effective method based on wavelet transform, for identification of damage on rotating shafts is proposed. The nodal displacement data of damaged rotor is processed to obtain wavelet coefficients to detect, localise and quantify damage severity. Because the wavelet coefficients are calculated with various scaled indices, local disturbances in the mode shape data can be found out in the finer scales that are positioned at local disturbances. In the present work the displacement data are extracted from the MATLAB model at a particular speed. Damage is represented as reduction in diameter of the shaft. The difference vectors between damaged and undamaged shafts are used as input vectors for wavelet analysis. The measure of damage severity is estimated using a parameter formulated from the distribution of wavelet coefficients with respect to the scales. Diagnosis results for different damage cases such as single and multiple damages are presented.
6
Zhao, Bingchao, Pan Chen, Jingbin Wang, Jingui Zhang e Di Zhai. "A Comprehensive Evaluation and Analysis of Ground Surface Damage Due to Mining under Villages Based on GIS". Applied Sciences 13, n. 18 (8 settembre 2023): 10136. http://dx.doi.org/10.3390/app131810136.
Testo completoAbstract (sommario):
This paper aims to evaluate the severities and causes of ground surface building and cropland damages after coal mining in a better way, and to clarify the correlation between the damage assessment indexes that influence mining. Against the backdrop of multi-seam mining in certain coal mines in China, the estimated results of each displacement and deformation were analyzed using GIS technology. The damage range determined for each deformation index is divided according to the displacement and deformation combined with the virtue of damage judgment threshold. The damage ranges on the ground surface based on the comprehensive value of each displacement and deformation index were obtained through superimposing those ranges delineated by each displacement and deformation index, and the law on influence from displacement indexes upon various levels of damage was analyzed in a quantitative manner accordingly. The results showed that coal mining destroyed 14 buildings and a cropland area of 11.96 hm2; among them, building damage was only associated with displacement indexes E (horizontal deformation) and T (inclined deformation). Seven buildings were solely destroyed by T alone; five buildings were solely damaged by E; two buildings were damaged jointly by E and T; and, moreover, with the aggravation in building damage level, the proportion of building damage due to E decreased while the proportion of building damage under the same level due to T increased. Regarding cropland destruction, the damage due to T accounted for 33.48% while the damage jointly caused by W (Subsidence), E and T accounted for 30.45%. Moreover, the proportion of damaged cropland area due to inclined deformation T was positively correlated with cropland damage level. These findings can provide a reference for rational judgment regarding civilian building and cropland destruction on the ground surface after coal mining.
7
Auersch, L. "Characteristics of train passages over slab tracks from measurements and different track–soil models: Damage detection and ground vibration reduction". Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 234, n. 2 (6 marzo 2019): 142–60. http://dx.doi.org/10.1177/0954409719835036.
Testo completoAbstract (sommario):
The characteristics of train passages over intact or damaged slab tracks on different soils have been calculated by the finite-element boundary-element method or the wavenumber-domain method. The influence of track and soil parameters on the distribution of track displacements and soil forces has been analysed. The measured and calculated displacement time histories of train passages could be used to identify track damages such as loose sleepers or a loose track plate. The time histories and spectra of soil forces can explain the measured ground vibration reduction in the slab tracks. The calculated displacement and force distributions of slab tracks on continuous soils do not fulfil the Winkler hypothesis, and Winkler models should not be used for track analysis.
8
Guo, De Ping, e Masanori Hamada. "Lessons Learnt from Seismic Damage Induced by the 2008 Wenchuan Earthquake". Applied Mechanics and Materials 226-228 (novembre 2012): 889–96. http://dx.doi.org/10.4028/www.scientific.net/amm.226-228.889.
Testo completoAbstract (sommario):
The 2008 Wenchuan earthquake with a surface wave magnitude of 8.0 induced numerous infrastructure damages. The typical seismic damages of 61 bridges, 18 tunnels and slope reinforcements are presented. The results show longitudinal or transverse displacement was the most widespread bridge seismic damage and resulted in girder dropping, shear key failure, joint expansion and support damage. Pillar was sheared off or crushed failure due to strong motions and lack of sufficient hoop steels. Tunnel damage was mainly observed at portal, which was mostly caused by slope failure. Strong ground shaking caused multi-direction cracks in the lining, shear failure of lining resulted from serious surrounding rock relative displacement. Investigation of slope reinforcements suggests anchor cable and frame beam had good anti-seismic property. Furthermore, some suggestions about resistant countermeasures to future earthquake are proposed.
9
Ruan, Zhigang, e Zuguang Ying. "Effectiveness analysis of structural anomaly diagnosis based on ANN model". Vibroengineering PROCEDIA 42 (16 maggio 2022): 21–26. http://dx.doi.org/10.21595/vp.2022.22446.
Testo completoAbstract (sommario):
Assessing and localizing damages are an important problem in structural engineering. Artificial neural networks (ANN) have an excellent pattern recognition capability. In this paper, a structural anomaly diagnosis method based on ANN model using displacement response signals is proposed to assess and localize damages, and applied to a five-story frame structure under random base excitation. The random displacement responses are used as the input to ANN for detecting structural damages, which differ from conventional methods such as using modal parameters extracted from responses. The ANN model is set up by training and then validation using random displacement responses. Damages in a structure are denoted by stiffness degradation. Detection results are mainly affected by incomplete measurement due to intensive noise, finite sampling time length and measured degree of freedom (DOF). Numerical results show the effects of the incomplete measurement on the accuracy of predicting damages based on the proposed method.
10
Çöğürcü, Mustafa Tolga, e Mehmet Uzun. "Effect of configuration of shear walls at story plan to seismic behavior of high-rise reinforced concrete buildings". Challenge Journal of Structural Mechanics 6, n. 1 (25 marzo 2020): 31. http://dx.doi.org/10.20528/cjsmec.2020.01.004.
Testo completoAbstract (sommario):
In developing countries, the need for shelter, working area, shopping and entertainment centers is increasing due to the increasing population effect. In order to meet this need, it is necessary to turn to high-rise buildings. Significant damages have been observed as a result of insufficient horizontal displacement stiffness of high-rise buildings in major earthquakes in previous years. It is known that as the height of the structure increases, the displacement demand of the structure also increases. Since it is accepted that the structure will make inelastic deformation in the design of the structure, these displacements increase to very high levels as the number of stories increases. For this reason, damages can be much higher than expected. In order to limit the level of damage that may occur in high-rise buildings, the horizontal displacement of buildings is limited in many regulations in our age. This limitation is possible by increasing the rigidity of the structures against horizontal displacement. In recent years, the use of shear wall has increased due to the horizontal displacement limitation in the regulations. The use of shear walls in buildings limits the horizontal displacement. However, the choice of where the shear walls will be placed on the plan is very important. Failure to place the shear walls correctly may result in additional loads in the structure. It can also lead to torsional irregularity. In this study, a 10-storey reinforced concrete building model was created. Shear wall at the rate of 1% of the plan area of the building was used in the building. The shear walls are arranged in different geometric shapes and different layouts. The earthquake analysis of 5 different models were performed. Equivalent Earthquake Load, Mode Superposition and Time History Analysis methods were used for earthquake analysis. The results were compared and a proposal was made for the geometry and configuration of the shear wall.
11
Samson Nitonye, Chris Feniobu e Blessing Omokhule Eragbai. "Floodable length analysis of a container vessel using computer aided design". Global Journal of Engineering and Technology Advances 14, n. 3 (30 marzo 2023): 084–98. http://dx.doi.org/10.30574/gjeta.2023.14.3.0048.
Testo completoAbstract (sommario):
The floodability of a container vessel is investigated to determine the maximum volume of compartments that can be flooded without causing the container vessel to capsize. In this project, Maxsurf modeler was used for the hull design and Maxsurf stability enterprise for the floodable length analysis of a container vessel at several displacements, number of transverse water tight bulkheads and its positions from AP to FP and a constant permeability value for the compartments. Floodable length is the preliminary check on damage survival. It is used at the initial concept design phase because it is faster than a full damage stability analysis, it checks if the vessel has sufficient buoyancy to sustain damage and stop from sinking straight to the bottom. Maxsurf Enterprise marine design software is used to determine the results. The output of the analysis shows a floodable length curve and the curves that represent different displacements, if a displacement line is below the allowable floodable length of a compartment then the vessel will not survive damages but if the line is above the allowable floodable length then the vessel will survive damages. The result also shows that it is easier for the vessel to survive heavily loaded conditions with more compartments.
12
Otsuka, Yuichi, Takuya Sakonju e Yukio Miyashita. "Interactive Evaluation of Interfacial Damages on Loosening Behavior of Acetabular Cup Loosening Using AE and IR Method". Key Engineering Materials 967 (5 dicembre 2023): 171–76. http://dx.doi.org/10.4028/p-iqi1pq.
Testo completoAbstract (sommario):
We aim at revealing the damage behavior of HAp sprayed coating on the surface of acetabular cup subjected to cyclic loading using AE (Acoustic Emission) method and IR (Infrared thermography) methods. Fatigue test was conducted in SBF(simulated body fluid), and the displacement of acetabular cup embedded in simulated bone was measured by two cantilever pairs. Acoustic emissions from delamination or wear of HAp coating were also measured by AE method, and the temperature change due to friction and wear near the top was measured by IR method. The analysed result could estimate the process in which delamination occurs in the initial stage of test and then friction and wear occur. The rotation displacement of acetabular cup could be associated with cracking or delamination of the HAp sprayed coating, friction and wear at the interfaces between simulated bone and acetabular cup. The subsidence displacement of acetabular cup can be caused by collapse of the simulated bone accompanied by an increase in AE energy as well as an increase in dissipated energy. Combined analyses using AE method and IR method clarified that the inelastic damages in simulated bone at the top of acetabular cups could lead the acceleration of both normal and rotational displacement of the acetabular cup whereas interface damages also attributed to exaggerate the displacement by deteriorated fixation.
13
Cheng, Chang Ming. "Analysis Carrying Capacity of Hydraulic Concrete Dam". Applied Mechanics and Materials 716-717 (dicembre 2014): 400–405. http://dx.doi.org/10.4028/www.scientific.net/amm.716-717.400.
Testo completoAbstract (sommario):
This paper makes analysis on accelerated speed overload and hydraulic pressure after earthquake, as well as the relationship between the ground motion peak acceleration and the dam body displacement, dam body damage volume ratio, and dam facing damage volume ratio. According to dam body partition, this paper takes the ratio of over stress accumulative duration and stress required capacity as parameters, and studies arch local earthquake damage evaluation of dam body partition. After analysis, it is found that after arch dam experiences different geological process, there are damages in both sides of dam abutment and upper part of dam body, overstressed area expands continuously and local damages take place.
14
Troev, T., N. Nankov, L. Petrov e E. Popov. "Computer Modeling of Displacement Cascades in Beryllium Irradiated with Intensive Neutron Flux". Research Letters in Physics 2008 (7 febbraio 2008): 1–4. http://dx.doi.org/10.1155/2008/746892.
Testo completoAbstract (sommario):
Computer simulations of the radiation defects created in beryllium irradiated by fast neutrons (E>0.1 MeV) using the Geant4 and SRIM packages were carried out. The atom cascade displacements in Be at a neutron fluence of 1.6×1020 n/cm2 were determined to be 0.06 dpa and the helium concentration was calculated to be 168 appm. The concentration of 6Li has been estimated to be 5% in comparison to the He concentration. Nanoscale calculations were done in 30×30×30 nm cube of fast neutron-irradiated Be. A correlation between the Be primary knock-on atom (PKA) energies and the damage cascades has been established. The final defect distributions of single vacancies, divacancies, and small vacancy clusters were examined. Our results indicate that the damages caused by He atoms are about 3 times less than damages caused by Be primary knock-on atoms (PKAs).
15
Gorgin, Rahim, e Ziping Wang. "Structural Damage Identification Based on Principal Curvatures of Mode Shape". International Journal of Acoustics and Vibration 25, n. 4 (30 dicembre 2020): 566–76. http://dx.doi.org/10.20855/ijav.2020.25.41714.
Testo completoAbstract (sommario):
This paper presents a procedure for damage identification and characterization on plates, based on the principal curvatures of their first mode shape. Each mode shape represents the displacement of the structure at its corresponding natural frequency. Since, variations in the geometry due to cracks or material property degradation, make changes in the mode shapes of the structure, such changes can be used for damage identification methods. The presented procedure only requires the first mode shape of the intact and damaged structure. It is shown that the principal curvatures of the surface defined by the first mode shape of the structure, are sensitive to damage and the maximum principal curvature can be used to highlight damages on the structure. The performance of the developed method is firstly evaluated using finite element analysis. To this aim, the procedure is applied to highlight both single and multi-damages in different locations of the plate with different boundary conditions. It is shown that the location of the maximum curvature variation coincides well with the location of damages and the amount of the maximum curvature change can be used as a parameter to describe damage severity. The accuracy of the proposed method is also experimentally verified by test on an aluminum plate and it is demonstrated that the proposed method remains effective even in experimental condition when only a limited number of measurements are available.
16
Zhao, Jiu Ling, Bo Gao, Xue Ren Wang e Bao Shun Zhou. "Numerical Analysis of Multiscale Progressive Damage for Solid Rocket Motor Composite Shell". Applied Mechanics and Materials 574 (luglio 2014): 219–23. http://dx.doi.org/10.4028/www.scientific.net/amm.574.219.
Testo completoAbstract (sommario):
In this study, the evolution of laminates in four damages are analyzed based on the established multiscale reinforced composite material damage model from a single cell model, single plate model to multilayer fiber model of carbon fiber. The validity of the model is verified by numerical simulation of laminate tensile test. Based on the established model to calculate the [±26/902]3 damage evolution of SRM due to withstand pressure in the straight section and the results show that: the calculation is consistent with the experimental results of displacement, and the role of a variety of common damages result in reduced performance of the housing.
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Aljorany, Ala Nasir, e Ghusoon Sadiq Al-Qaisee. "Field observations and finite element 3-D analysis of soil displacements close to unsupported excavation". MATEC Web of Conferences 162 (2018): 01029. http://dx.doi.org/10.1051/matecconf/201816201029.
Testo completoAbstract (sommario):
Soil displacements due to unsupported deep excavation may cause severe damages to the nearby structures and foundations systems. Such excavations affect the state of stresses and displacements field of the surrounding soil. In this study, the soil displacements at five observation points were continuously monitored for23 days, which was the time period of excavation of about 7 m deep open tunnel. The reference points were installed on the ground surface at horizontal distance ranging from 1.25 to 3.25 m from tunnel excavation edge. The construction work was related to the project of developing the Army Channel/ Zeyouna section in the Eastern part of Baghdad City. The field observations indicate upward vertical displacement and outward lateral displacements during the first 10 days when the excavation depth was within 4 m. After that, the displacement trend was generally reversed. The displacement values were within 12 mm and vary from one observation point to another depending on the lateral distance of each point from excavation edge. The finite element package PLAXIS 3D was used to simulate the problem after obtaining the required soil parameters by an extensive site investigation. The analysis results in general, compare well with the field observations in terms of soil displacements at the reference points, especially during the first 10 days. This finding may reveal the reliability of the analysis results at other locations in the surrounding soil.
18
Lu, Chih-Heng, Chuen-Fa Ni, Chung-Pai Chang, Jiun-Yee Yen e Ray Chuang. "Coherence Difference Analysis of Sentinel-1 SAR Interferogram to Identify Earthquake-Induced Disasters in Urban Areas". Remote Sensing 10, n. 8 (20 agosto 2018): 1318. http://dx.doi.org/10.3390/rs10081318.
Testo completoAbstract (sommario):
This study proposes a workflow that enables the accurate identification of earthquake-induced damage zones by using coherence image pairs of the Sentinel-1 satellite before and after an earthquake event. The workflow uses interferometric synthetic aperture radar (InSAR) processing to account for coherence variations between coseismic and preseismic image pairs. The coherence difference between two image pairs is useful information to detect specific disasters in a regional-scale area after an earthquake event. To remove background effects such as the atmospheric effect and ordinal surface changes, this study employs the two-step threshold method to develop the coseismic coherence difference (CCD) map for our analyses. Thirty-four Sentinel-1 images between January 2015 and February 2016 were collected to process 30 preseismic image pairs and two coseismic image pairs for assessing multiple types of disasters in Tainan City of southwestern Taiwan, where severe damages were observed after the Meinong earthquake event. The coseismic unwrapping phases were further calculated to estimate the surface displacement in east-west and vertical directions. Results in the CCD map agree well with the observations from post-earthquake field surveys. The workflow can accurately identify earthquake-induced land subsidence and surface displacements, even for areas with insufficient geological data or for areas that had been excluded from the liquefaction potential map. In addition, the CCD details the distribution of building damages and structure failures, which might be useful information for emergency actions applied to regional-scale problems. The conversion of 2D surface displacement reveals the complex behavior of geological activities during the earthquake. In the foothill area of Tainan City, the opposite surface displacements in local areas might be influenced by the axis activities of the Kuanmiao syncline.
19
Mahendran, G., Chandrasekaran Kesavan e S. K. Malhotra. "Damage Detection in Laminated Composite Beams, Plates and Shells Using Dynamic Analysis". Applied Mechanics and Materials 787 (agosto 2015): 901–6. http://dx.doi.org/10.4028/www.scientific.net/amm.787.901.
Testo completoAbstract (sommario):
Vibration-based technique to detect damage in laminated composite beams, rectangular plates and cylindrical shells is presented in this paper.A parameter called damage indicator calculated based on mode shape curvature isused in this studyto detect the location and size of small damages accurately in laminated composite structures. Through numerical analysis of laminated compositecantilevered beam, plate and cylindrical shell models with edge crack as damage, the absolute change inthe damage indicator is localized in the region of damage. Thechange in damage indicatorincreases withincreasing size of damage. Thisinformationis obtained by considering two cases of damage sizes (case-1 and case-2)in the structures. Finite element methodbased commercial analysis package ANSYSis used to obtain thenormalized displacement mode shapesof the three models both for intact and damaged states and then the damage indicator is calculated from the mode shapes data.The numerical analysis to detect damage is followed by validation by experimental modal testing.
20
MacLaughlin, Mary, Steve Berry, Michael Petro, Katherine Berry e Anders Bro. "Characterization of peak shear strength of rough rock joints using limited displacement multi-stage direct shear (LDMDS) tests". E3S Web of Conferences 92 (2019): 13011. http://dx.doi.org/10.1051/e3sconf/20199213011.
Testo completoAbstract (sommario):
Current standard direct shear test methods for rock joints do not account for damage to the specimens' asperity profiles; tests require shearing of a single specimen to large displacements under successive normal stresses (the multistage test), or the use of similar specimens in multiple tests. Due to the inherently unique nature of rock joints and corresponding difficulty in obtaining specimens with identical or even similar geometries, multistage tests are more common. A major issue with the multistage test is that successive shearing of the specimen damages the surface asperities and changes its overall roughness profile, reducing the peak shear stress and consequently resulting in underestimation of the friction angle and overestimation of the joint shear intercept (cohesion). The limited displacement multistage direct shear (LDMDS) test method minimizes these testing imperfections by allowing shearing of a single specimen without extensive asperity damage, accomplished by immediately pausing shear displacement once peak shear stress has been reached, then proceeding to shear the specimen under the following normal stress value, and shearing into the post-peak region only after identifying multiple values of peak shear strength. The authors have validated the LDMDS procedure using cement replicates of rock joints, demonstrating that it yields more accurate strength parameters than the standard multistage direct shear test.
21
Tan, D., ZR Lu e JK Liu. "A two-step method for damage identification in beam structures based on influence line difference and acceleration data". Advances in Mechanical Engineering 10, n. 7 (luglio 2018): 168781401878740. http://dx.doi.org/10.1177/1687814018787404.
Testo completoAbstract (sommario):
This article presents a two-step approach for structural damage identification in beam structure. Damages are located using the influence line difference before and after damage, the calculation of damage severity is accomplished by acceleration data and bird mating optimizer algorithm. Local damages are simulated as the reduction of both the elemental Young’s modulus and mass of the beam. The technique for damage localization based on displacement influence line difference and its derivatives for beam structure has been outlined. An objective function that comprises dynamic acceleration is utilized in bird mating optimizer. All data are originated from only a few measurement points. Two numerical examples, namely, a simply supported beam and a four-span continuous beam, are investigated in this article. Identification results from different objective functions are compared with results from objective function conventional modal assurance criterion, which shows the superiority of the proposed function. In addition, results of dynamic responses under different types of excitation are presented. The effect of measurement noise level on damage identification results is studied. Studies in the article indicate that the proposed method is efficient and robust for identifying damages in beam structures.
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Liu, Xianglei, Peipei Wang, Zhao Lu, Kai Gao, Hui Wang, Chiyu Jiao e Xuedong Zhang. "Damage Detection and Analysis of Urban Bridges Using Terrestrial Laser Scanning (TLS), Ground-Based Microwave Interferometry, and Permanent Scatterer Interferometry Synthetic Aperture Radar (PS-InSAR)". Remote Sensing 11, n. 5 (9 marzo 2019): 580. http://dx.doi.org/10.3390/rs11050580.
Testo completoAbstract (sommario):
This paper presents a practical framework for urban bridge damage detection and analysis by using three key techniques: terrestrial laser scanning (TLS), ground-based microwave interferometry, and permanent scatterer interferometry synthetic aperture radar (PS-InSAR). The proposed framework was tested on the Beishatan Bridge in Beijing, China. Firstly, a Digital Surface Model (DSM) of the lower surface of the bridge was constructed based on the point cloud generated by using TLS to obtain the potential damage area. Secondly, the dynamic time-series displacement of the potential damage area was acquired by ground-based microwave interferometry, and the Extreme-Point Symmetric Mode Decomposition (ESMD) method was applied to detect damages by the use of signal decomposition and instantaneous frequency calculation. Lastly, the PS-InSAR technique was applied to obtain the surface deformation around Beishatan Bridge by using COSMO-SkyMed images with a ground resolution of 3 m × 3 m, and finally, we analyzed the causes of bridge damage. The experimental results showed that the proposed framework can effectively obtain the potential damage area of the bridge by the DSM from the point cloud by TLS and further judge whether the bridge was damaged by the ESMD method, based on the time-series displacement data. The results also showed that the subway shield construction may be the reason for damage to Beishatan Bridge.
23
Zheng, Zhong Lang, e Qin Da Zeng. "Damage Identification of Cantilevered Beam Based on Multi-Resolution Analysis". Applied Mechanics and Materials 487 (gennaio 2014): 267–71. http://dx.doi.org/10.4028/www.scientific.net/amm.487.267.
Testo completoAbstract (sommario):
As a derivative parameter of the structural displacement mode, damage factor matrix was adopted to investigate the detection of structural crack location and damage. A methodological strategy by combination of the damage factor matrix and the wavelet multi-resolution analysis is presented in the paper, in order to identify structural damages of the cantilevered beam. The results show that damage can be identified by the damage factor matrix and the wavelet multi-resolution analysis, and the damage degree can be estimated by damage frequency band energy of the wavelet analysis. A reference to damage identification in current structure engineering is provided.
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Putra, Risma, e Winarputro Adi Riyono. "Risk analysis of seismic bridge damage: case study after Lombok and Palu earthquake". E3S Web of Conferences 156 (2020): 03008. http://dx.doi.org/10.1051/e3sconf/202015603008.
Testo completoAbstract (sommario):
Indonesia is known as an earthquake-prone region, lies in the ring of fire zone. This potential hazard can impact several infrastructures, including bridges. Seismic bridge damages could possibly disrupt traffic flow furthermore cut off the regional connectivity. In this study, risk analysis is carried out on several bridges after Lombok and Palu earthquake. Visual inspection has been undertaken on 38 bridges on-site, and several damages identification are reported. Risk analysis was then carried out according to the severity of element damages and the frequency of occurrence. From the analysis, it is concluded that embankment settlement in the approach road is found to be the most potential element with the highest risk of damage due to earthquakes. Besides, the superstructure displacement and crack in the wing wall are at moderate risk. This finding makes the substructure become the most vulnerable element which needs more attention. Therefore, it is recommended to specify a higher design specification for substructure to mitigate seismic bridge damages, especially for bridges located in the high seismic zone area.
25
Liu, Bin, Nongyue Gao, Bosen Tang, Yidi Gao, Peng Jin, Zhixian Lu e Zaiguo Fu. "Progressive damage behaviors of the stepped-lap composite joints under bending load". Journal of Composite Materials 54, n. 14 (21 novembre 2019): 1875–87. http://dx.doi.org/10.1177/0021998319889119.
Testo completoAbstract (sommario):
Due to the high connecting strength and excellent load-transferring efficiency, the adhesively stepped-lap composite bonding has been widely used as joints and repairs in advanced aircraft structures. In the service life of composite structures, they frequently subject to bending loads which are rarely reported by the available reference. Hence, in this paper, three-point and four-point bending experiments are performed on composite stepped-lap structures. Typical damage mode of adhesive on the stepped surface has been found in experiments. And the failure of composite fiber, matrix, interlamination and adhesive materials appeared as competitive behavior. Furthermore, numerical models of stepped-lap composite joints, which used cohesive zone model and 3D Hashin criteria to simulate the inter- and intralaminar damages, were utilized to predict the bending strength and progressive damage. The FEM model, based on progressive damage method, captured the detailed failure as the loading displacement was increasing. The simulation results of load displacement and damage have good agreement with the experiments.
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Carfagnini, Carmela, Simonetta Baraccani, Stefano Silvestri e Dimitris Theodossopoulos. "Pseudo-Static Response of Masonry Cross Vaults to Imposed Shear Displacements at the Springings". Key Engineering Materials 747 (luglio 2017): 456–64. http://dx.doi.org/10.4028/www.scientific.net/kem.747.456.
Testo completoAbstract (sommario):
The static and dynamic performances of historical masonry churches are closely related to the behaviour of each substructure, as well as to the mechanical properties of the constituent materials. Information on damage location and extent, collected after recent violent Italian earthquakes, highlighted that masonry vaults are among the most vulnerable elements. The investigation of their dynamic behaviour under earthquake excitation (stress and deformation states) is a fundamental issue for effective structural interventions. During an earthquake ground motion, cross vaults are basically subjected to two phenomena: (i) the "shaking"/dynamic response of the vault system itself, vibrating above the lateral walls and piers, and (ii) the response of the vault to imposed displacements at its springings, accommodating the significant movements of the lateral walls and piers. Within this context, this paper aims at improving the knowledge of the structural behaviour of cross vaults under static shear deformation at the springings, by means of an experimental test representative of a Gothic cross vault from the aisle of the Holyrood Abbey in Edinburgh (UK). The experimental test was performed on a 1:4 scaled specimen built with timber and lime mortar. The shear displacement was applied by moving two abutments until failure. The deformation of the vault was recorded in space with a Total Station. The results of the tests are reported in this paper in terms of crack pattern evolution, vertical displacements of the transverse ridge, identifying the shear displacement levels corresponding to significant damages in the vault.
27
Ma, Lifeng, Kilho Eom, Jean Geringer, Tea-Sung Jun e Kyungmok Kim. "Literature Review on Fretting Wear and Contact Mechanics of Tribological Coatings". Coatings 9, n. 8 (7 agosto 2019): 501. http://dx.doi.org/10.3390/coatings9080501.
Testo completoAbstract (sommario):
This article reviews fretting wear damage in industries and in the contact mechanics of coated systems. Micro-slip motion resulting in fretting damage is discussed along with major experimental factors. The experimental factors, including normal force, relative displacement, frequency and medium influence are directly compared. Industrial solutions to reduce fretting damages are then discussed. The contact mechanics of a coated system are reviewed to quantify stress states in a coating layer and the substrate. Finally, a literature review on simulation for fretting is carried out. This review study provides useful methods and practical solutions to minimize fretting wear damage.
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Zhang, Yanrong, Kai Wu, Chao Yu, Shuang Zhang e Xiaopei Cai. "Application of Statistical Process Control for Structural Health Monitoring of a High-Speed Railway Track System". Applied Sciences 12, n. 12 (14 giugno 2022): 6046. http://dx.doi.org/10.3390/app12126046.
Testo completoAbstract (sommario):
To make full use of the massive monitoring data accumulated in China high-speed railways, an improved statistical process control (SPC) framework was introduced to analyze the discontinuous monitoring data of the track system on a high-speed railway elevated station. Multilinear regression models and time series difference equation (TSDE) models were first developed to separate common-cause variations in the monitoring data. Then, individual control charts, moving range control charts, and exponentially weighted moving average control charts were constructed to detect special-cause variations. Results showed that the variations of girder displacement and track slab–girder relative displacements mainly resulted from temperature effects and linear trends related with material damages. Moreover, visible serial dependence was found in the regression model residuals, which could be effectively captured by the TSDE model. Numerous outliers were detected at the measuring points of rail–track slab displacement 15 and track slab–girder relative displacement 17 by more than three control charts, implying higher sensitivity to special causes. With respect to the special causes triggering the anomalous responses of local and overall track systems, sixteen and twenty-eight significant special events were detected, respectively.
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Huang e Zang. "Damage Detection Using Modal Rotational Mode Shapes Obtained with a Uniform Rate CSLDV Measurement". Applied Sciences 9, n. 23 (20 novembre 2019): 4982. http://dx.doi.org/10.3390/app9234982.
Testo completoAbstract (sommario):
With the rapid development of a continuously scanning laser Doppler vibrometer (CSLDV) technique, the full-field mode shapes of structures with high accuracy can be obtained. In this paper, a novel damage detection method using modal rotational mode shapes obtained with a uniform rate CSLDV measurement is proposed. The modal rotational damage indicators considering the changes of modal rotational mode shapes between the damaged and the undamaged states are established. Because the modal rotational mode shapes are obtained through the derivative of the detailed displacement mode shapes of transitional degree-of-freedoms (DOFs) with respect to the orthogonal directions, they are more sensitive than the normal displacement mode shapes. The uniform rate CSLDV measurement is essentially a uniform straight-line scanning technique and the measured mode shapes can be directly obtained through the demodulation of vibration signals. Besides, taking it for granted that a priori knowledge of the undamaged structure is not known, the undamaged mode shapes can be reconstructed from the measured damaged data using the fitted polynomial functions in which the minimum number of polynomial function coefficients are determined by a fit value threshold. The proposed method is firstly demonstrated by numerical simulation of the crack plate and then a plate structure with three damaged cases is taken as an example for further experimental study. The experimental results indicate the following: (1) The uniform rate CSLDV measurement can obtain the high accuracy modal rotational mode shapes with the advantage of eliminating the contaminated noise in the measurement; (2) the modal rotational damage indicators of the torsional modes are the most sensitive to the crack damage and they can clearly identify single, multiple damages and locations of the plate, and even slight crack damage, respectively. The effectiveness of the method paves the way for practical applications, such as ultra-light or composite structures.
30
Zhou, Xiwu, Yushen Gao, Guoxue Zhang e Shixiang Xu. "Mechanical properties of equal-strength stainless reinforced replacement piers under lateral impact loading". Advances in Mechanical Engineering 10, n. 6 (giugno 2018): 168781401877863. http://dx.doi.org/10.1177/1687814018778635.
Testo completoAbstract (sommario):
Stainless reinforced equal-strength replacement piers are used to solve the problems of steel corrosion, surplus strength, and resource waste for piers in marine environments. In this study, an ultrahigh drop weight impact test system was applied for a comparative experimental model of the horizontal impacts between two groups of stainless reinforced replaced concrete piers. The impact forces and displacements, strain time–history curves, crack propagations and distributions, and concrete damages, were analyzed during the experimental test. The results showed that the original specimen had consistent change trends with the stainless reinforced equal-strength replaced specimens in regard to maximum impact, steel bar and concrete strains, displacement peaks, and other aspects. Furthermore, under equal impact energies, the relative ratios were found to all range at ±5%, and the fracture quantities and distributions, as well as the concrete damages, were approximately consistent. These research results will potentially provide technical support for the future designs of anti-impact stainless reinforced concrete piers.
31
Baran, Marta, Piotr Synaszko, Janusz Lisiecki e Sylwester Kłysz. "Comparative Study on Fatigue Life of CFRP Composites with Damages". Fatigue of Aircraft Structures 2019, n. 11 (1 dicembre 2019): 28–38. http://dx.doi.org/10.2478/fas-2019-0004.
Testo completoAbstract (sommario):
AbstractIn this work, the compressive residual strength tests results, Compression After Impact (CAI), are presented. The specimens were made of carbon-epoxy prepreg E722-02 UHS 130-14. Two variants of specimens were tested: samples undamaged and samples with damage that was centrally introduced by a drop-weight impact, as per the ASTM D7136/7136M standard. An impactor with potential energy equal to 15J and the type of support required by the standard were used. The size of impacted damages, defined as an area of damage on a plane perpendicular to the impact direction, and the equivalent diameter were specified using the flash thermography method.The tests were performed using the fixtures manufactured according to the ASTM D7137/7137M standard. The specimens were compressed to determine the residual strength. This value was afterwards used to specify the force levels for the fatigue tests. The fatigue tests were carried out under force control – with a sinusoidal shape, stress ratio R equal to 0.1 and frequency f 1Hz. Maximum force in a loading cycle Pmax was being increased after each thousand of cycles N until its value was close to the residual strength determined in the previously mentioned tests. In this work, the following relationships were presented: force-displacement P-δ for both static and fatigue tests and displacement-loading cycles δ-N for fatigue tests.A method of conducting the fatigue tests of CFRP composite was proposed, in which both the CAI specimens and CAI fixture were used. This allowed researchers to accelerate making initial comparisons between the two groups of specimens with damages – grouped relative to the way of conditioning.
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Sanabria, M. P., C. Guardiola-Albert, R. Tomás, G. Herrera, A. Prieto, H. Sánchez e S. Tessitore. "Subsidence activity maps derived from DInSAR data: Orihuela case study". Natural Hazards and Earth System Sciences 14, n. 5 (27 maggio 2014): 1341–60. http://dx.doi.org/10.5194/nhess-14-1341-2014.
Testo completoAbstract (sommario):
Abstract. A new methodology is proposed to produce subsidence activity maps based on the geostatistical analysis of persistent scatterer interferometry (PSI) data. PSI displacement measurements are interpolated based on conditional Sequential Gaussian Simulation (SGS) to calculate multiple equiprobable realizations of subsidence. The result from this process is a series of interpolated subsidence values, with an estimation of the spatial variability and a confidence level on the interpolation. These maps complement the PSI displacement map, improving the identification of wide subsiding areas at a regional scale. At a local scale, they can be used to identify buildings susceptible to suffer subsidence related damages. In order to do so, it is necessary to calculate the maximum differential settlement and the maximum angular distortion for each building of the study area. Based on PSI-derived parameters those buildings in which the serviceability limit state has been exceeded, and where in situ forensic analysis should be made, can be automatically identified. This methodology has been tested in the city of Orihuela (SE Spain) for the study of historical buildings damaged during the last two decades by subsidence due to aquifer overexploitation. The qualitative evaluation of the results from the methodology carried out in buildings where damages have been reported shows a success rate of 100%.
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Johan, O., Idris, Fakhrurrozi e O. Sianipar. "The impact of Manta Mae Phinisi ship grounding at Gili Lawa Darat Marine National Park of Komodo, West Manggarai, East Nusa Tenggara". IOP Conference Series: Earth and Environmental Science 967, n. 1 (1 gennaio 2022): 012048. http://dx.doi.org/10.1088/1755-1315/967/1/012048.
Testo completoAbstract (sommario):
Abstract Coral reefs are distributed widely around Indonesia waters which has various functions as fisheries sources and tourism benefits. Coral reefs are very vulnerable to various threats, such as ship grounding in several areas in Indonesia. The measurement of damage width of coral reefs used the irregular polygon method. In contrast, the impact and the level of damage were measured using the underwater photo transect (UPT) method. The grounding of the ship has caused massive damage to coral reefs with a width area of 46.89 m2. Types of damage include physical and biological damages that make the coral split, break, and shift. The ship grounding caused the coral colonies to be uprooted and blown from the substrate, destroying coral skeletons, lifting, and sediment displacement. Coral condition at the control area was 35.13% (bad condition), whereas condition on the damaged area as the impact of ship grounding was 14% in trajectory zone. The total width to be claimed was 11.92 m2. The degradation of coral reefs can affect and reduce the functions and benefits of ecosystems both ecologically and economically. The shipowner has to do the rehabilitation and compensation of the damaged area.
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Kamal, Muhammet, e Mehmet Inel. "Correlation between Ground Motion Parameters and Displacement Demands of Mid-Rise RC Buildings on Soft Soils Considering Soil-Structure-Interaction". Buildings 11, n. 3 (19 marzo 2021): 125. http://dx.doi.org/10.3390/buildings11030125.
Testo completoAbstract (sommario):
This paper investigates the correlation between ground motion parameters and displacement demands of mid-rise RC frame buildings on soft soils considering the soil-structure interaction. The mid-rise RC buildings are represented by using 5, 8, 10, 13, and 15-storey frame building models with no structural irregularity. A total of 105 3D nonlinear time history analyses were carried out for 21 acceleration records and 5 different building models. The roof drift ratio (RDR) obtained as inelastic displacement demands at roof level normalized by the building height is used for demand measure, while 20 ground motion parameters were used as intensity measure. The outcomes show velocity related parameters such as Housner Intensity (HI), Root Mean Square of Velocity (Vrms), Velocity Spectrum Intensity (VSI) and Peak Ground Velocity (PGV), which reflect inelastic displacement demands of mid-rise buildings as a damage indicator on soft soil deposit reasonably well. HI is the leading parameter with the strongest correlation. However, acceleration and displacement related parameters exhibit poor correlation. This study proposed new combined multiple ground motion parameter equations to reflect the damage potential better than a single ground motion parameter. The use of combined multiple parameters can be effective in determining seismic damages by improving the scatter by at least 24% compared to the use of a single parameter.
35
Ren, Peng, Zhi Zhou e Jinping Ou. "Non-baseline method for damage detection in truss structures using displacement and strain measurements". Advances in Structural Engineering 22, n. 3 (28 settembre 2018): 818–30. http://dx.doi.org/10.1177/1369433218800949.
Testo completoAbstract (sommario):
Realistic problems restrict the application of many existing structural damage detection methods. Due to the requirement of a comparison between two system states, lack of appropriate baseline data may become one of the limitations to undertake structural health monitoring strategy. This article suggests a non-baseline damage detection approach based on the mixed measurements and the transmissibility concept and demonstrates it in truss structures. The algorithm uses the measurement data from the strains of the truss elements and the displacements of the truss joints, in which the displacements are utilized to estimate the baseline strains based on the transmissibility matrix from an initial finite element model. Wavelet-based damage-sensitive features are extracted from both estimated and measured strains to detect damages of the target elements. Numerical and experimental studies are performed to investigate the feasibility and effectiveness of the proposed approach. It is concluded from the instances that the robustness of the algorithm is realized when handling the measurement noise, modeling errors and the operational condition variability. These permit the potential development of the damage detection method for real structures in site.
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Takamatsu, Hiroyuki, Shingo Sumie, Yoshiro Nishimoto e Takefumi Horiuchi. "A New Laser Photothermal Displacement Measurement for Evaluation of Semiconductor Lattice Damages". IEEJ Transactions on Electronics, Information and Systems 112, n. 11 (1992): 656–64. http://dx.doi.org/10.1541/ieejeiss1987.112.11_656.
Testo completo
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Xiang, Chang Sheng, Yu Zhou, Sheng Kui Di, Li Xian Wang e Jian Shu Cheng. "Detection Indicator of Structural Nondestructive Damage Based on Flexibility Curvature Difference Rate". Applied Mechanics and Materials 744-746 (marzo 2015): 46–52. http://dx.doi.org/10.4028/www.scientific.net/amm.744-746.46.
Testo completoAbstract (sommario):
Applied to the structural damage identification, Modal Flexibility is better than the Modal Frequency and Modal Displacement, the indicators of Flexibility Curvature are effective and sensitive. This paper proposes a new detection indicator which is Flexibility Curvature Difference Rate (FCDR) that by using the change rate of diagonal elements of flexibility curvature difference when before and after damage. The numerical examples of a simple beam, a continuous beam and a frame with the damage conditions of the different positions and different degrees are used to verify FCDR. The result shows that FCDR can well identify the numerical examples damages, and sensitively diagnose the damage near the supports of beam and the nodes of framework.
38
Ikpe, Aniekan Essienubong, Ejiroghene Kelly Orhorhoro e Abdulsamad Gobir. "Design and Reinforcement of a B-Pillar for Occupants Safety in Conventional Vehicle Applications". International Journal of Mathematical, Engineering and Management Sciences 2, n. 1 (1 marzo 2017): 37–52. http://dx.doi.org/10.33889/ijmems.2017.2.1-004.
Testo completoAbstract (sommario):
This paper is focused on B-pillar design and reinforcement with certain criteria that the final reinforcement design weight does not exceed 6Kg and the maximum displacement must be less than 40mm on the application of 140KN load. Surface welding method was applied on the first and second design while spot welding was used for the third design, whereas, seam welding was applied on the fourth design which happened to have the least maximum displacement, least maximum stress and weight compared to the other designs. The welding methods applied in each of the design gave different displacement values with the fourth design showing the least maximum displacement of 13.8mm and the third design showing highest maximum displacement of 31.9mm, while there was proximity in displacement values obtained for the first design (15.2mm) and second design (16.4mm). Hence, for the purpose of design against unforeseen damages during side collision, auto manufacturers may consider employing seam welding techniques when manufacturing a B-Pillar for occupant safety.
39
Cui, Zhen, Maochu Zhang, Kai Wu e Hongsheng Ma. "Evaluating the Performance and Stability of the Highway Subgrades in Seismic Events, a Case Study of the Changning Earthquake, Sichuan". International Journal of Environmental Research and Public Health 19, n. 21 (3 novembre 2022): 14379. http://dx.doi.org/10.3390/ijerph192114379.
Testo completoAbstract (sommario):
On 17 June 2019, an M6.0 earthquake occurred in Changning County, Sichuan Province, China. Considerable highway subgrades were damaged in this earthquake. By investigating seismic damage of these subgrades, a systematical analysis of influence factors and failure mode of the damages on highway subgrade have been given. There is a close relationship between the damaged degree of subgrade and the distance of epicenter, fault distance, and structure type of subgrade. The seismic hazard investigation shows that the seismic damage of the cut-and-fill subgrade was more severe than that of the fill subgrade. Taking the Changning earthquake ground motion record as input, 3D dynamic finite element analyses were performed. The seismic damage mechanisms of cut-and-fill subgrade and fill subgrade were revealed. The numerical simulation confirmed that the cut-and-fill subgrade was more easily damaged by earthquakes compared with the fill subgrade. The fill-and-cut interface of the cut-and-fill subgrade had a notable plastic strain band after the earthquake, and the permanent displacement of the slope top was significant. In this manner, the numerical results are consistent with seismic investigation data. Considering the seismic investigation data for highway subgrades are rare, this paper may provide effective references for aseismic design and deformation control of highway subgrades.
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Dar, RooufUnNabi, S. M. Anas e Mehtab Alam. "Effect of Skew Angle on the Dynamic Response of a Reinforced Concrete Bridge under Blast Loading". Proceedings of the 12th Structural Engineering Convention, SEC 2022: Themes 1-2 1, n. 1 (19 dicembre 2022): 555–61. http://dx.doi.org/10.38208/acp.v1.548.
Testo completoAbstract (sommario):
Accidental explosions and subversive blasts are on rise. The recent devastating Beirut explosion witnesses this fact. Performance of the structures such as bridges in cities and strategic boarder areas is of paramount importance. With this concern the effect of skew angle on the performance of a single span reinforced concrete (RC) bridge deck supported on three symmetrically placed RC girders under blast loading generated by1000kgTNT charge located above and below the mid-section of the central girder at a standoff distance of 0.5 m has been investigated using ABAQUS/CAE. Analyses have been performed at different skew angles i.e. 0º, 10º, 20º, 30º, 40º, and 50º. Several empirical relations from the literature have been used to estimate the blast parameters such as peak overpressure, positive phase duration, the arrival time of blast wave, and decay coefficient. Blast pressure P(t), has been modeled using modified Friedlander’s equation. Distributions of damages have been evaluated with a mesh size of 300 mm using concrete damage plasticity (CDP) model. Maximum displacements have been computed and are compared with those obtained from the provisions of AASHTO: Load Resistance and Factor Design (LRFD) - Bridge Design Specifications (2014). It has been found that the midspan displacement and the stresses of the deck increase for 10º skew angle but decrease for subsequent increase in skew angle for the explosive charge loaded above the mid-section of the central girder. However, tensile as well as compressive damages in girders increase with increase of skew angle irrespective of the location of the blast. Side girders suffer more damage with increase in skew angle than uniform damage for ‘under the deck’ location of explosive charge.
41
Roccheggiani, Matteo, Daniela Piacentini, Emanuela Tirincanti, Daniele Perissin e Marco Menichetti. "Detection and Monitoring of Tunneling Induced Ground Movements Using Sentinel-1 SAR Interferometry". Remote Sensing 11, n. 6 (15 marzo 2019): 639. http://dx.doi.org/10.3390/rs11060639.
Testo completoAbstract (sommario):
SAR interferometry is a powerful tool to obtain millimeter accuracy measurements of surface displacements. The Sentinel-1 satellite mission nowadays provides extensive spatial coverage, regular acquisitions and open availability. In this paper, we present an MT-InSAR analysis showing the spatial and temporal evolution of ground displacements arising from the construction of a 3.71 km overflow tunnel in Genoa, Italy. Underground tunneling can often modify the hydrological regime around an excavated area and might induce generalized surface subsidence phenomena due to pore pressure variations, especially under buildings. The tunnel was excavated beneath a densely urbanized area lying on upper Cretaceous marly limestone and Pliocene clays. Significant cumulative displacements up to 30 mm in the Line of Sight (LOS) direction were detected during the tunnel excavation. No displacements were recorded before until the middle of 2016. The Persistent Scatterers Interferometry (PSI) analysis reveals in high detail the areal subsidence, especially where the subsurface is characterized by clay and alluvial deposits as well as there is the presence of large building complexes. The time-series and the displacement rate cross-sections highlight a clear relation with the tunnel face advancement, responsible for the subsidence phenomena, which proceeded northward starting from the middle of 2016 to the end of 2017. The stabilization occurred in a range of five-six months from the beginning of each displacement phase. Due to the low subsidence ratio the ground settlements did not cause severe damages to the buildings.
42
Tao, Shilin, Xueqi Cen, Xiaocong Yu, Junqing Hu e Changbin Kan. "Study on Critical Parameters of Nitrogen Injection during In Situ Modification in Oil Shale". Energies 15, n. 21 (28 ottobre 2022): 8034. http://dx.doi.org/10.3390/en15218034.
Testo completoAbstract (sommario):
During in situ modification, inappropriate thermal insulation measures applied in annulus of injection wells will cause injection technical problems such as tremendous heat loss, wellhead lifting, serious casing damages, and corrosion. Continuous nitrogen injection into annulus is an effective measure to realize thermal insulation of injection wells. The critical displacement parameters of nitrogen injection in annulus are a key factor in the process of continuous nitrogen injection. However, the critical nitrogen injection rate under various working conditions, such as different well types, different wellhead steam parameters, and insulation pipe parameters, was not fully considered and studied. In this paper, the annular critical nitrogen injection displacement model was established based on the completion structure of injection well by applying the basic principles of heat transfer and fluid mechanics comprehensively. The influencing factors of critical nitrogen injection displacement were calculated and analyzed. The results show that the annular thermal resistance of horizontal wells is larger than that of directional wells for different well types, and the critical nitrogen injection displacement required is higher. The parameter sensitivity analysis shows that with the increase of pressure, steam displacement, and steam dryness, the required critical nitrogen injection displacement rate increases nearly quadratically. However, with the increase of the length and thermal conductivity of insulation pipe, the critical nitrogen injection displacement decreases cubically. The critical nitrogen injection can be reduced by reducing the annular area of the casing annulus and lowering the string deeply. The research results can provide key basic theoretical guidance for improving the heat utilization efficiency of in situ modified wells and reducing the casing damage rate for hot injection wells.
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DECANINI, L. D., L. LIBERATORE e F. MOLLAIOLI. "DAMAGE POTENTIAL OF THE 2009 L'AQUILA, ITALY, EARTHQUAKE". Journal of Earthquake and Tsunami 06, n. 03 (settembre 2012): 1250032. http://dx.doi.org/10.1142/s1793431112500327.
Testo completoAbstract (sommario):
On April 6, 2009 (1:32 UTC) an earthquake of magnitude MW 6.3, caused by a normal fault rupture, shook the Abruzzo Region of Central Italy causing 309 deaths, hundreds injured and thousands homeless. L'Aquila city, which is located very close to the causative fault in hanging wall position, was severely damaged by the event. In this work, after a description of the damages observed in reinforced concrete (RC) buildings, a study on the characterization of damage potential of strong ground motions recorded during the main shock and the strongest aftershocks is presented. Elastic and inelastic spectral demands, in terms of displacement, forces, and energy are estimated and different parameters related to the "ground motion records destructiveness" are calculated. Moreover, the demand imposed on multi degree of freedom systems is estimated by means of nonlinear dynamic analyses and compared to the single degree of freedom systems demand.
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Liu, Yang, Kai Ling Li, Yu Ming Men, Guang Yuan Weng e Hong Jia Liu. "Study on Interaction between Soil and U-Shaped Subway Tunnel in the Environment of Ground Fissures". Advanced Materials Research 250-253 (maggio 2011): 2342–45. http://dx.doi.org/10.4028/www.scientific.net/amr.250-253.2342.
Testo completoAbstract (sommario):
The interaction mechanism, between soil and U-shaped Subway tunnel, is studied by numerical simulation in the environment of ground fissures. The Subway Line 2 through the ground fissures in Xi’an. The analysis results show that the soil mass influenced by the relative displacement and the vertical displacement gradually increases with the relative displacement increasing of ground fissures movement. The deformation area of tunnel lies in the two sides of presupposed ground fissure, and the area enlarge with vertical relative displacement increasing. The tunnel structure damages at the ground fissures when the relative displacement reaches to 100mm. The footwall part is in tension and the hanging wall part is under pressure on the top of tunnel structure at the ground fissure. The footwall part is under pressure and the hanging wall part is in tension on the bottom of tunnel structure at the ground fissure. In the practical projects, the sectional type tunnel should be employed when the Subway tunnel through the ground fissures.
45
Ma, Hua, Xinyu Luan, Zhenbao Li, Haijian Cui, Wenjing Wang e Jia Song. "Seismic Performance of Damaged Dovetail Joints with Different Damaged Degrees in Timber Frames". Advances in Civil Engineering 2019 (21 agosto 2019): 1–17. http://dx.doi.org/10.1155/2019/7238217.
Testo completoAbstract (sommario):
The mortise and tenon joints are the main connection forms used in ancient timber buildings, and damaged joints have a critical effect on the safety of a timber structure. There are three main damaged cases of dovetail joints which are pulling, contraction, and mixing damages. In this study, using a theoretical analysis of the stress distribution in a mortise and tenon joint resulted from the pullout damage, a theoretical equation for the resisting moment of the joint was proposed. A finite element model was used to simulate the cyclic displacement loading of a frame with intact joints and with different levels of pulling and contraction damaged joints. The results show that the moment capacities both for the test and the simulation were in good agreement with each other. The simulation results also indicated that there are no changes in the capacity and energy dissipation of the pulling damaged joint compared to that of the intact joint, and good seismic performance still was provided when the pulling damage was less than 2/5 of the joint length. However, the capacity of the contraction damaged joint was significantly reduced, and its seismic performance was tolerably lost. The seismic performance of a mixing damaged tenon with the same degree of pulling damage was between that of the pulling damaged tenon and the contraction damaged tenon, and generally, it was controlled by the contraction damage. The friction between the tenon and the mortise is the main source of resisting moment and energy dissipation ability.
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Sieira, Ana C., e Alberto S. Sayão. "Experimental Investigation of Mechanical Damage in Geogrids". Soils and Rocks 32, n. 1 (1 gennaio 2009): 19–30. http://dx.doi.org/10.28927/sr.321019.
Testo completoAbstract (sommario):
This paper presents the results of a comprehensive experimental program for investigating the influence of mechanical damage on the load-displacement behavior of geogrids. Unconfined tension tests, pullout and direct shear tests were carried out on intact and damaged specimens. Natural or artificial damages were produced either by imposing heavy compaction procedures in the laboratory or by simply cutting one or more geogrid elements. It is concluded that natural damage in the geogrid may be more pronounced when aggressive compaction methods are used with coarse grained soils. Fine grained soils did not show a significant strength reduction even when subjected to heavy compaction in the laboratory. Under pullout loading, artificial damage was also noted to be of little significance for fine soil (silty clay). Rupture of the geogrid’s transverse elements led to a significant pullout strength reduction. These transverse elements are responsible for anchoring the geogrid within the soil mass. However, under unconfined tensile load, these transverse elements are responsible only for the grid’s geometrical configuration and their rupture did not induce a significant strength loss. In direct shear, the position of the geogrid relative to the potential failure surface was shown to be an important factor.
47
Irwansyah, Muhammad, Johannes Tarigan e Zulfazly Putra. "The Structural Performance Analysis of Base-Isolated Hospital Buildings with Analysis Modal (Case Study: General Hospital in Labuhan Batu Utara Regency Area)". Simetrikal: Journal of Engineering and Technology 1, n. 2 (28 settembre 2019): 63–78. http://dx.doi.org/10.32734/jet.v1i2.736.
Testo completoAbstract (sommario):
The development of earthquake analysis towards structures is required to prevent damages and loss in buildings due to earthquakes. The base isolation system is a simple design approach for earthquake-resistant buildings to protect the structures and components from the risk of earthquake damages by using the concept of reducing earthquake forces. This research aims to analyze the performance of a general hospital building in Labura Regency area in order to know the safety of the building in terms of period, frequency, base shear force, displacement and earthquake force, used the base isolators and without the base isolators. The method used is response-spectrum dynamic analysis by ETABS v2016 program. From the calculation of structural analysis, the application of base isolation is able to build up the period of the structure, therefore, the maximum acceleration of earthquakes can be reduced at certain period. There is an average increase by 48.21% of the structural period compared to non-isolated base structure, and the frequency that occurs in structures using base isolators is smaller than without base isolators. The friction force obtained is smaller compared to the structures without dampers. Base-isolated building structures observed have bigger displacement than non-base isolated structures. The average rise of the building displacement is 27.14% at x and 2.74% at y directions. In base-isolated structures, earthquake forces are reduced averagely by 57.51% at x and 82.73% at y directions. The analysis of structural performance, General Hospital in Labura Regency is categorized to Immediate Occupancy (IO) in which the building structures are safe with no significant risk of fatalities due to structural failures, there are no any significant damages and the building can be used and functioned/operated again immediately.
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Shehu, Rafael. "Implementation of Pushover Analysis for Seismic Assessment of Masonry Towers: Issues and Practical Recommendations". Buildings 11, n. 2 (16 febbraio 2021): 71. http://dx.doi.org/10.3390/buildings11020071.
Testo completoAbstract (sommario):
Seismic assessment is a paramount issue and a valuable instrument towards the conservation of vulnerable structures in seismic prone regions. The past seismic events have highlighted the vulnerability of masonry towers that is exhibited by severe structural and nonstructural damages or even collapses. The preservation of existing structures, mainly focused on the built heritage, is emerging and imposing substantial enhancements of numerical methods, including pushover analysis approaches. The accuracy of the estimated seismic capacity for these structures is correlated with the assumed strategies and approximations made during the numerical modeling. The present paper concerns those aspects by exploring the limitations and possibilities of conceiving pushover analysis in the finite element method environment. The most crucial target is tracing in a pushover capacity curve the corresponding initiation of structural damages, maximum load-bearing capacity, and the ultimate displacement capacity. Different recommendations for achieving this target have been proposed and illustrated for practical utilization. Three representative geometrical towers, adopting three different materials and five different load patterns, are investigated in this study. The load pattern’s role and necessity of the displacement-like control approach for the pushover analysis are exploited. This paper highlights the load-bearing capacity overestimation when the force-controlled are implemented. The material model influences the achievement of softening branch with a distinguishable displacement capacity.
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Ruan, Zhi-Gang, e Zu-Guang Ying. "Comparative Study of Structural Anomaly Diagnosis Based on ANN Model Using Random Displacement and Acceleration Responses with Incomplete Measurements". Sensors 22, n. 11 (29 maggio 2022): 4128. http://dx.doi.org/10.3390/s22114128.
Testo completoAbstract (sommario):
Structural anomaly diagnosis, such as damage identification, is a continuously interesting issue. Artificial neural networks have an excellent ability to model complex structure dynamics. In this paper, an artificial neural network model is used to describe the relationship between structural responses and anomalies such as stiffness reduction due to damages. Random acceleration and displacement responses as generally measured data are used as the input to the artificial neural network, and the output of the artificial neural network is the anomaly severity. The artificial neural network model is set up by training and then validated using random vibration responses with different structural anomalies. The structural anomaly diagnosis method based on the artificial neural network model using random acceleration and displacement responses is applied to a five-story building structure under random base excitations (seismic loading). Anomalies in the structure are denoted by stiffness reduction. Structural anomaly diagnosis using random acceleration responses is compared with that using random displacement responses. The numerical results show the effects of different random vibration responses used on the accuracy of predicting stiffness reduction. The actual incomplete measurements include intensive noise, finite sampling time length, and limited measurement points. The effects of the incomplete measurements on the accuracy of predicting results are also discussed.
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Sanabria, M. P., C. Guardiola-Albert, R. Tomás, G. Herrera, A. Prieto, H. Sánchez e S. Tessitore. "Subsidence activity maps derived from DInSAR data: Orihuela case study". Natural Hazards and Earth System Sciences Discussions 1, n. 5 (8 ottobre 2013): 5365–402. http://dx.doi.org/10.5194/nhessd-1-5365-2013.
Testo completoAbstract (sommario):
Abstract. A new methodology is proposed to produce subsidence activity maps based on the geostatistical analysis of persistent scatterer interferometry (PSI) data. PSI displacement measurements are interpolated based on Conditional Gaussian Simulation (CGS) to calculate multiple equiprobable realizations of subsidence. The result from this process is a series of interpolated subsidence values, with an estimation of the spatial uncertainty and a confidence level on the interpolation. These maps complement the PSI displacement map, improving the identification of wide subsiding areas at regional scale. At local scale, they can be used to identify buildings susceptible to suffer subsidence related damages. In order to do so, it is necessary to calculate the maximum differential settlement and the maximum angular distortion for each building of the study area. Based on PSI derived parameters those buildings in which serviceability limit state has been exceeded, and where in situ forensic analysis should be made, can be automatically identified. This methodology has been tested in Orihuela City (SE Spain) for the study of historical buildings, damaged during the last two decades by subsidence due to aquifer overexploitation.