Papers by Keyword: Damage Assessment

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Authors: Paola Antonaci, Pietro G. Bocca, Davide Masera, Nicola Maria Pugno, Marco Scalerandi, Fabrizio Sellone
Abstract: The results of an experimental research on plain concrete are presented. The non-linear behavior of both virgin and damaged samples is investigated by means of ultrasonic tests: recent theoretical models, indeed, have pointed out that mono-frequency ultrasonic excitations bring to light such phenomena as harmonic generation and sidebands production, which are essentially due to the material classical or hysteretic non-linearity. The estimation of the harmonic components parameters (amplitudes and phases) is achieved through a signal processing technique based on MUltiple SIgnal Classification (MUSIC) system, which reveals to be optimal for the specific signal model here considered. The experiments described in this paper show that the material non-linear features increase with increasing level of internal micro-cracking, thus suggesting the possibility to use the ultrasonic signal analysis in the frequency domain as a valuable tool for damage assessment.
Authors: Rhys Pullin, Karen M. Holford, R.J. Lark, P. Beck
Authors: Karen M. Holford
Abstract: Structural Health Monitoring (SHM) is of paramount importance in an increasing number of applications, not only to ensure safety and reliability, but also to reduce NDT costs and to ensure timely maintenance of critical components. This paper overviews the modern applications of acoustic emission (AE), which has become established as a very powerful technique for monitoring damage in a variety of structures, and the new approaches that have enabled the successful application of the technique, leading to automated crack detection. Examples are drawn from a variety of industries to provide an insight into the current role of AE in structural health monitoring.
Authors: Robert Jankowski
Abstract: The reports after earthquakes indicate that earthquake-induced pounding between insufficiently separated structures, or their parts, may cause substantial damage or even lead to structural collapse. One of the most spectacular example of pounding-involved destruction resulted from interactions between the Olive View Hospital main building and one of its independently standing stairway towers during the San Fernando earthquake of 1971. The aim of the present paper is to assess the range and intensity of damage caused by collisions between these reinforced concrete structures based on the results of a detailed 3D non-linear FEM analysis of poundinginvolved response. In the study, reinforced concrete has been modelled as layered material with rebar elements embedded into concrete. The non-linear material behaviour, including stiffness degradation of concrete due to damage under cyclic loading, has been incorporated in the numerical model. The results of the study show that pounding may lead to the significant increase of the range and intensity of damage at the base of the stairway tower, as a lighter structure, as well as may cause substantial damage at the points of contact. On the other hand, the intensity of damage induced in the heavier main building has been found to be nearly unaffected by structural interactions.
Authors: Onder Altuntas, Ekici Selcuk, Gorkem Yalin, T. Hikmet Karakoc
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.
Authors: Peter Avitabile, Eric Harvey, Justin Ruddoc
Abstract: Measured data from operating systems are often acquired to predict structural health of a system. With only a few measurement sensors, very limited understanding of the system can be obtained. Utilizing some recent novel expansion results, full field information can be obtained to identify a more complete strain description for the system. Using these results in conjunction with an analytical prediction of the expected strains, comparisons and differences can be identified using time response data. The expected full field stress-strain from the analytical model is compared to the predicted full field dynamic stress strain from limited sets of measured locations due to either operating or imposed loading on the structure. Differences in strain distributions at many time increments can provide indications of regions of possible damage in the structure. The work presented in this paper identifies the methodology as well as some results to illustrate the usefulness of the approach.
Authors: E. H. Hegazy, Ahmed Kh. Mehanna, Mohamed Y. Omar, Heba Elkilani, Amr A. Hassan
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.
Authors: Zhong Long Li, Hong Lin Wu, Zhen Yu Liu, De Jian Xu, Xiao Di Zhu, Hong Jiang Gu
Abstract: Fire effects cause one span of a frame underpass bridge in Harbin large area of different levels burning. Among them, some parts burned seriously; many adjacent beams turn black at bottom of roofs; parts of railings burned out of shape; parts decoration of side wall fractured, which blocked traffic towards Harbin. In order to make safety, repair on time, recovery traffic as soon as possible, satisfy the rules of original design and save money, this paper uses high strength non-shrinkage grouting material to repair stiffness of crack and damage concrete and carbon fiber to improve structure carrying capacity. Also, it uses middle support technique to reinforce the underpass bridge when repairing. Through a comparative analysis before and after reinforcement, paper confirms the feasibility and reliability of this repair design.
Authors: Rhys Pullin, D.C. Carter, Karen M. Holford
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