Papers by Keyword: Damage Assessment

Abstract: The dynamic behaviour and the seismic vulnerability of different masonry “Apennine Churches”, dramatically damaged by the last shocks sequence of 2016 that occurred in Central Italy, have been studied in this paper by means of advanced 3D numerical analyses with the Discrete Element Method (DEM). Thus, a discontinuous approach has been used to assess the dynamic properties and the vulnerability of the masonry structure, through large deformations regulated by the Signorini’s law, concerning the impenetrability between the rigid bodies, and by the Coulomb’s law, regarding the dry-friction model. The major purpose of this study is to highlight that relevant data on the real structural behaviour of historical masonry can be provided through advanced numerical analyses. The comparison between the results of the numerical simulation and the survey of the existing crack pattern of the churches permitted to validate the used approach. Finally, from the results and conclusions of these cases study, it is possible to affirm that the used methodology can be applied to a wide variety of historical masonry structure in Europe.

Abstract: Buckling Restrained Braces (BRBs) are effective energy dissipation devices. The key advantages of BRB are its comparable tensile and compressive behavior and stable energy dissipation capacity. In this paper, low-cycle fatigue performance of domestic BRBs is obtained based on collected experimental data under constant and variable amplitude loadings. The results show that the relationship between fatigue life and strain amplitude satisfies the Mason-Coffin equation. By adopting theory of structural reliability, this paper presents several allowable fatigue life curves with different confidential levels. Besides, Palmgren-Miner method was used for calculating BRB cumulative damages. An allowable damage factor with 95% confidential level is put forward for assessing damage under variable amplitude fatigue. In addition, this paper presents an empirical criterion with rain flow algorithm, which may be used to predict the fracture of BRBs under severe earthquakes and provide theory and method for their engineering application. Finally, the conclusions of the paper were vilified through precise yet conservative prediction of the fatigue failure of BRB.

Abstract: The Port Bridge across Danube in Bratislava is about 461 m long with 4 spans. The bridge was designed for both a highway and simultaneously for two railway tracks. Nowadays the construction is overloaded and that is why the structural health monitoring of the bridge is being developed. The test setup consists of two measuring polygons. This setup needed an original LabVIEW program, which has been developed in cooperation with experts – electrical engineers and experts on structural mechanics. Main problem was to achieve a synchronization of both measuring polygons connected by Wi-Fi antennas. Except of software difficulties there were complications during in-situ measurement, like cable connection between highway and railway level and especially the time synchronization of the traffic video and measurement. The measurement has been done and some eigenmodes have been identified from ambient data.

Abstract: This work proposes a simple and efficient approach to locating the storeys whose stiffness change in the life cycle of a structure. The storeys that may be damaged are determined by comparing the unitary stiffness matrix in different stages in the life cycle of a building. An appropriate ARX (autoregressive with exogenous input) model of structure in established from the structural dynamic responses in terms of acceleration or velocity. The parameters in an ARX model are identified through the short time Fourier transform, and the natural frequency and damping ratio of structure are estimated directly through these identified parameters. The effectiveness of the proposed procedure is verified using the numerically simulated earthquake acceleration responses of a six-storey structure that is damaged at one or two storeys. The proposed scheme is compared to the DLV approach (flexibility-based damage locating vector approach) in identifying damage storeys.

Abstract: In this study, the Auxiliary Power Unit (APU) and the Ground Power Unit (GPU) that are required meet the energy demand in ground operations of aircraft were compared in terms of their damages –human health (disability adjusted life years- DALYs), ecosystem quality (PDF.m².yr) and resources (MJ Surplus). These damages were calculated with gate-to-gate method of Life Cycle Assessment (LCA). This assessment was held on three main stages; capital investment, operation and maintenance. SimaPro 7.2.4 was used for this calculation. Human Health Damages (HHDs) of APU were found to be (0.0557 -disability adjusted life years- DALYs) 20.34 days/year while HHDs of GPU were calculated as (0.0411 -disability adjusted life years-DALYs) 15 days/year. While Ecosystem Quality Damages (EQDs) of APU were calculated as 103366.37 PDF.m².yr, EQDs of GPU were found to be 82651.23 PDF.m².yr. In other words, although the use of APU gives rise to loss of 0.1 species –1 year, 1 square kilometer area, the use of GPU gives rise to loss of 0.083 species. With regards to Resources Damages (RDs), 62125 MJ surplus energy needed for future extractions of minerals and fossil fuel considering APU, one the other hand 36002 MJ surplus energy needed for future considering GPU. As a result, the use of APU effects on human health, ecosystem quality and resources was determined greater than the use of GPU for 30 minute. The use of GPU has less impact on human health, ecosystem quality and resources in ground operations.

Abstract: Coral reefs are the most biological systems productive and versatile on the surface of the planet earth, which is a source with economic and social, returns great for the country that God-given this natural wealth. Egypt is home to some of the most spectacular coral reefs and associated marine life in the world. Egypt has enacted laws and takes effective measures for the protection and management of coral reefs and associated ecosystems in the Red Sea and its Gulf to characterize these areas of the richness and diversity of coral reef environment is scarce to be repeated elsewhere in the world. The largest sub-sector for the Egyptian tourism market is the coastal tourism. Coastal tourism depends largely on intact reefs, and this is also one of the most important causes of reef degradation in Egypt. Over the last two decades live coral cover has declined in Egypt. Egyptian Environmental Affairs Agency (EEAA) implements its own methodology to estimate the coral reefs impacts as a result of the destruction of coral reefs due to ship aground or anchorage. This paper focuses on and presents the modelling of the destruction of coral reefs as a result of the collision and the ship ground damage assessment in case of oil spills in Egyptian coastal water referring to the EEAA methodology applied in Egypt.

Abstract: In this paper, the network architecture of wireless network systems survivability, the ideas based on intrusion tolerance, redundancy and diversity of technology will be combined, using threshold cryptography, presents a viable network server security architecture. This proposal implements key features of the system security and robustness, the database system to meet the survivability requirements for building a wireless network server architecture has important reference value.

Abstract: Due to the fire effect, a frame underpass bridge had suffered a huge damage in Changjiang road in Harbin in the direction to Acheng. One span of the bridge was burned in large area, parts of which were burned badly. Many adjacent beams turned black at bottom of roofs; parts decoration of side wall were damaged to some extent. As a result, both directions of the traffic were disrupted, causing traffic jams. To make sure of repairing and restoring the traffic during the shortest period, Harbin municipal committee established the Changjiang road rescue headquarters. Under the precondition of utmost to save money and ensure that the repaired underpasses technology standards meet the design requirements, the research group were about to use steel plate or carbon fiber sheet as the reinforcing material, after detecting and identifying the bridge damage. Through a comprehensive consideration for the ascension of normal section bearing capacity of two reinforcing materials, pasting carbon fiber sheet was adopted to complete repair reinforcement scheme.

Abstract: Marine oil spill does cause huge economic losses and brings serious damages to the marine ecological environment. Therefore, how to claim compensation for oil spill damages has become very crucial for the environmental restoration. In recent years, many researchers have designed various kinds of assessment models for evaluating oil spill damages. This paper analyzes these assessment models, discusses the legal claim and technology claim, finally the suggestions for further research of oil spill damage assessment is proposed, and then the application of fuzzy neural network in technology assessment is also recommended.

Abstract: Cross-entropy optimization has recently been applied to the damage detection in structures subject to static loading. The optimization procedure minimizes the error between the measured deflection data and theoretical deflection data obtained from artificially generated finite element models based on assumed statistical distributions of stiffness for each discretized element. Following a number of iterations, the finite element model with stiffness properties producing deflections closer to reality is established as the mathematical model closest to the true structure. However, while previous testing of the algorithm has been relatively successful, it has been limited to theoretical simulations. Therefore, this paper conducts lab experiments on a beam loaded statically to test the accuracy of the algorithm. Deflections are measured for beam scenarios under different loading levels. The accuracy of the results is discussed and recommendations are made to improve the performance of the algorithm when implemented in practice.