Seismic retrofit of low-ductile columns through concrete jacketing with inoxydable reinforcement

Retrofit of structures often is an inevitable task especially when buildings are not designed for seismic actions or their design has followed older design codes. Many retrofit strategies have been proposed and practiced by previous researchers. Usage of fiber reinforced polymer [FRP], steel jacketi...

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Main Author:	Vahed, Yousef Karimi
Format:	Thesis
Language:	English
Published:	2017
Subjects:	TA Engineering (General) Civil engineering (General)
Online Access:	http://eprints.utm.my/id/eprint/79595/1/YousefKarimiVahedPFKM2017.pdf
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spelling	my-utm-ep.795952018-10-31T13:00:26Z Seismic retrofit of low-ductile columns through concrete jacketing with inoxydable reinforcement 2017 Vahed, Yousef Karimi TA Engineering (General). Civil engineering (General) Retrofit of structures often is an inevitable task especially when buildings are not designed for seismic actions or their design has followed older design codes. Many retrofit strategies have been proposed and practiced by previous researchers. Usage of fiber reinforced polymer [FRP], steel jacketing and reinforcement jacketing are among the most common retrofitting methods. For reinforcement jacketing, carbon steel has been widely employed by engineers, however, only a few applications of inoxydable reinforcements can be found in the literature. Moreover, when it comes to reinforcement jacketing, connection between the interface of original column and the jacket plays an important role and has attracted the attention of many researchers. Load transfer mechanism between original column and jacket is another field of study which has not been addressed in previous research. In this study application of inoxydable rebars for seismic retrofit of Reinforced Concrete (RC) columns was investigated. Two new connectors were used to increase the integrity between the original column and jacket. Load transfer mechanism between original column and jacket is another topic addressed in this research. This study included experimental and numerical analysis. For experimental study, 8 full scale RC columns were constructed and retrofitted with different reinforcement jacketing configurations. Numerical studies investigated the effect of different axial forces on the obtained results from experimental test. Results indicated that regardless of the employed retrofit configurations, the retrofitted columns have higher initial stiffness and ultimate strength compared to un-retrofitted columns. However, the retrofitted columns showed significantly lower ductility ratio when compared with un-retrofitted columns. All the retrofitted columns displayed a brittle failure mode in which spalling of concrete at the base of columns occurred without yield or buckling of reinforcements. Results indicated that confined jackets have higher ultimate strength and stiffness compared to un-confined jackets. However, they showed a lower ductility ratio when compared with un-confined jackets. It was observed that, when internal angle connection was used for retrofit, the highest ultimate strength, post-yield stiffness and effective stiffness were achieved. Monitoring the strain distribution between jackets and original columns revealed that confinement in jackets reduced the strain in the longitudinal reinforcement of original columns more than un-confined jackets. Strain values in the stirrups of confined jackets were significantly smaller than that of un-confined jackets. Strain ratios on the surface of concrete of confined jackets were larger than that of un-confined jackets. It is concluded that the proposed connectors have improved the ultimate strength of retrofitted columns as compared to conventionally retrofitted column, as they were unable to elevate the ultimate strengths to the level of a monolithic column. 2017 Thesis http://eprints.utm.my/id/eprint/79595/ http://eprints.utm.my/id/eprint/79595/1/YousefKarimiVahedPFKM2017.pdf application/pdf en public phd doctoral Universiti Teknologi Malaysia, Faculty of Civil Engineering Faculty of Civil Engineering
institution	Universiti Teknologi Malaysia
collection	UTM Institutional Repository
language	English
topic	TA Engineering (General) Civil engineering (General)
spellingShingle	TA Engineering (General) Civil engineering (General) Vahed, Yousef Karimi Seismic retrofit of low-ductile columns through concrete jacketing with inoxydable reinforcement
description	Retrofit of structures often is an inevitable task especially when buildings are not designed for seismic actions or their design has followed older design codes. Many retrofit strategies have been proposed and practiced by previous researchers. Usage of fiber reinforced polymer [FRP], steel jacketing and reinforcement jacketing are among the most common retrofitting methods. For reinforcement jacketing, carbon steel has been widely employed by engineers, however, only a few applications of inoxydable reinforcements can be found in the literature. Moreover, when it comes to reinforcement jacketing, connection between the interface of original column and the jacket plays an important role and has attracted the attention of many researchers. Load transfer mechanism between original column and jacket is another field of study which has not been addressed in previous research. In this study application of inoxydable rebars for seismic retrofit of Reinforced Concrete (RC) columns was investigated. Two new connectors were used to increase the integrity between the original column and jacket. Load transfer mechanism between original column and jacket is another topic addressed in this research. This study included experimental and numerical analysis. For experimental study, 8 full scale RC columns were constructed and retrofitted with different reinforcement jacketing configurations. Numerical studies investigated the effect of different axial forces on the obtained results from experimental test. Results indicated that regardless of the employed retrofit configurations, the retrofitted columns have higher initial stiffness and ultimate strength compared to un-retrofitted columns. However, the retrofitted columns showed significantly lower ductility ratio when compared with un-retrofitted columns. All the retrofitted columns displayed a brittle failure mode in which spalling of concrete at the base of columns occurred without yield or buckling of reinforcements. Results indicated that confined jackets have higher ultimate strength and stiffness compared to un-confined jackets. However, they showed a lower ductility ratio when compared with un-confined jackets. It was observed that, when internal angle connection was used for retrofit, the highest ultimate strength, post-yield stiffness and effective stiffness were achieved. Monitoring the strain distribution between jackets and original columns revealed that confinement in jackets reduced the strain in the longitudinal reinforcement of original columns more than un-confined jackets. Strain values in the stirrups of confined jackets were significantly smaller than that of un-confined jackets. Strain ratios on the surface of concrete of confined jackets were larger than that of un-confined jackets. It is concluded that the proposed connectors have improved the ultimate strength of retrofitted columns as compared to conventionally retrofitted column, as they were unable to elevate the ultimate strengths to the level of a monolithic column.
format	Thesis
qualification_name	Doctor of Philosophy (PhD.)
qualification_level	Doctorate
author	Vahed, Yousef Karimi
author_facet	Vahed, Yousef Karimi
author_sort	Vahed, Yousef Karimi
title	Seismic retrofit of low-ductile columns through concrete jacketing with inoxydable reinforcement
title_short	Seismic retrofit of low-ductile columns through concrete jacketing with inoxydable reinforcement
title_full	Seismic retrofit of low-ductile columns through concrete jacketing with inoxydable reinforcement
title_fullStr	Seismic retrofit of low-ductile columns through concrete jacketing with inoxydable reinforcement
title_full_unstemmed	Seismic retrofit of low-ductile columns through concrete jacketing with inoxydable reinforcement
title_sort	seismic retrofit of low-ductile columns through concrete jacketing with inoxydable reinforcement
granting_institution	Universiti Teknologi Malaysia, Faculty of Civil Engineering
granting_department	Faculty of Civil Engineering
publishDate	2017
url	http://eprints.utm.my/id/eprint/79595/1/YousefKarimiVahedPFKM2017.pdf
_version_	1747818264826740736

Seismic retrofit of low-ductile columns through concrete jacketing with inoxydable reinforcement

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