Damage Characterization in Building Structures due to Blast Actions
Damage Characterization in Building Structures due to Blast Actions
Type of document
diplomová prácemaster thesis
Author
Ahmed Bulbul
Supervisor
Dinu Florea
Opponent
Ungureanu Viorel
Field of study
Sustainable Constructions under Natural Hazards and Catastrophic EventsStudy program
Civil EngineeringInstitutions assigning rank
katedra ocelových a dřevěných konstrukcíDefended
2018-02-12Rights
A university thesis is a work protected by the Copyright Act. Extracts, copies and transcripts of the thesis are allowed for personal use only and at one?s own expense. The use of thesis should be in compliance with the Copyright Act http://www.mkcr.cz/assets/autorske-pravo/01-3982006.pdf and the citation ethics http://knihovny.cvut.cz/vychova/vskp.htmlVysokoškolská závěrečná práce je dílo chráněné autorským zákonem. Je možné pořizovat z něj na své náklady a pro svoji osobní potřebu výpisy, opisy a rozmnoženiny. Jeho využití musí být v souladu s autorským zákonem http://www.mkcr.cz/assets/autorske-pravo/01-3982006.pdf a citační etikou http://knihovny.cvut.cz/vychova/vskp.html
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Structural identification is a technique that can be used to assess/characterize the damage state through the variation in eigenfrequencies, damping ratios and modal shapes in a structure or element. It has recently received more attention for the practical implementation in several fields, including damage assessment for structures following blast or explosion events. At present, large infrastructure components, like civil engineering structures, are the most turning point for the consideration for structural identification. Structures can be moderately or severely deteriorated due to accidental or intentional blasts or explosions. The structural engineers but also other stakeholders, like rescue and emergency agencies, are more concerned about the design of structures, design life span, proper maintenance, repair and residual capacity of structural systems in many countries.This dissertation work focuses on the experimental and analytical modal analysis of a full-scale steel frame structure building aiming to develop coherent scenarios that combine the probability of the hazard event with the structural vulnerability in case of a close in detonation. The field tests were carried out by forced vibration testing under hammer excitations. First series of tests were done for the undamaged structure using classical experimental modal analysis. Then, in order to model a structural damage, a secondary beam was dismantled (thus a damage was created artificially) and the measurements were repeated. The change in structural behaviour was observed by identifying the changes in the stiffness and natural frequencies of the structure. The modal parameters measured from field test were used then to validate finite element models using SAP2000 program. They were corrected so that the numerical natural frequencies and mode shapes match the experimental data. Good agreement was obtained in identifying the frequencies for the three-dimensional finite element models for both damaged and undamaged structure. Then, using the calibrated numerical model, several blasts induced damages were used in a numerical study. For the internal damage or non-visible crack, four different damage scenarios were made by the FE model for internal and external blast actions. The modal parameters changed significantly for higher modes for higher reduction of stiffness at the column-beam and base connections. The results (experimental data, calibrated numerical model) will be used as reference values of the undamaged structure for further investigations after blast tests will be performed. This research is a part of FRAMEBLAST project supported by a grant of the Romanian National Authority for Scientific Research and Innovation, CNCS/CCCDI-UEFISCDI, project number PNIII-P2-2.1-PED-2016-0962, within PNCDI III. ?Experimental validation of the response of a full-scale frame building subjected to blast load?-FRAMEBLAST (2017-2018)?. Structural identification is a technique that can be used to assess/characterize the damage state through the variation in eigenfrequencies, damping ratios and modal shapes in a structure or element. It has recently received more attention for the practical implementation in several fields, including damage assessment for structures following blast or explosion events. At present, large infrastructure components, like civil engineering structures, are the most turning point for the consideration for structural identification. Structures can be moderately or severely deteriorated due to accidental or intentional blasts or explosions. The structural engineers but also other stakeholders, like rescue and emergency agencies, are more concerned about the design of structures, design life span, proper maintenance, repair and residual capacity of structural systems in many countries.This dissertation work focuses on the experimental and analytical modal analysis of a full-scale steel frame structure building aiming to develop coherent scenarios that combine the probability of the hazard event with the structural vulnerability in case of a close in detonation. The field tests were carried out by forced vibration testing under hammer excitations. First series of tests were done for the undamaged structure using classical experimental modal analysis. Then, in order to model a structural damage, a secondary beam was dismantled (thus a damage was created artificially) and the measurements were repeated. The change in structural behaviour was observed by identifying the changes in the stiffness and natural frequencies of the structure. The modal parameters measured from field test were used then to validate finite element models using SAP2000 program. They were corrected so that the numerical natural frequencies and mode shapes match the experimental data. Good agreement was obtained in identifying the frequencies for the three-dimensional finite element models for both damaged and undamaged structure. Then, using the calibrated numerical model, several blasts induced damages were used in a numerical study. For the internal damage or non-visible crack, four different damage scenarios were made by the FE model for internal and external blast actions. The modal parameters changed significantly for higher modes for higher reduction of stiffness at the column-beam and base connections. The results (experimental data, calibrated numerical model) will be used as reference values of the undamaged structure for further investigations after blast tests will be performed. This research is a part of FRAMEBLAST project supported by a grant of the Romanian National Authority for Scientific Research and Innovation, CNCS/CCCDI-UEFISCDI, project number PNIII-P2-2.1-PED-2016-0962, within PNCDI III. ?Experimental validation of the response of a full-scale frame building subjected to blast load?-FRAMEBLAST (2017-2018)?.
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