Out-of-plane cyclic behavior of URM walls retrofitted with fiber composites

Persistent Link:
http://hdl.handle.net/10150/282734
Title:
Out-of-plane cyclic behavior of URM walls retrofitted with fiber composites
Author:
Velazquez-Dimas, Juan Ignacio, 1960-
Issue Date:
1998
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
The vulnerability of unreinforced masonry buildings (URM) to earthquakes is a major concern among the earthquake engineering community. One of the most dangerous failure in URM buildings is that caused by out-of-plane loading. The main objective of this study was to understand the flexural behavior of URM masonry walls retrofitted with fiber composite strips. Seven half-scale brick masonry walls were constructed with solid clay brick tied with a Type N mortar. Six specimens were constructed in single wythe and one in double wythe. The specimens were retrofitted with vertical E-glass fabric composite strips bonded with a two component epoxy resin. All walls were subjected to a standard pattern of static cyclic out-of-plane loading applied with an air-bag system. The specimens were classified according to their height to thickness ratio (h/t) i.e. short walls having h/t = 14 and slender walls having h/t = 28. The main investigated parameter was the amount of reinforcement. This varied from 0.2 to 0.75 times the corresponding balanced condition for the short walls and from 0.5 to 3.0 times the balanced condition for the slender ones. The collected experimental data consisted of; out-of-plane deflections, tensile longitudinal strains in composite strips, and rotations along the wall sides. It was found that the strength and ductility of the walls were enhanced significantly. The walls were capable to deflect a height drift of 2 to 5% and to support pressures in excess of thirty times their own weight. Although many failures occurred such as tensile of composite strips, compression of brickwork, and in-plane shear failure, the delamination process controlled the behavior of the tested specimens. The experimental results were compared with respect to predictions given by beam theory using ultimate strength and linear elastic approaches. Three main stages of behavior corresponding to the first visible bed-joint crack, the first delamination and the ultimate load were investigated. It was concluded that the ultimate strength method overestimates the flexure capacity of the walls. The best predictions were obtained using linear elastic analysis. Preliminary design recommendations are also proposed for tensile strain in the composite, maximum deflection, and maximum reinforcement ratio.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Engineering, Civil.; Engineering, Materials Science.; Plastics Technology.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Civil Engineering and Engineering Mechanics
Degree Grantor:
University of Arizona
Advisor:
Ehssani, Mohammad R.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titleOut-of-plane cyclic behavior of URM walls retrofitted with fiber compositesen_US
dc.creatorVelazquez-Dimas, Juan Ignacio, 1960-en_US
dc.contributor.authorVelazquez-Dimas, Juan Ignacio, 1960-en_US
dc.date.issued1998en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractThe vulnerability of unreinforced masonry buildings (URM) to earthquakes is a major concern among the earthquake engineering community. One of the most dangerous failure in URM buildings is that caused by out-of-plane loading. The main objective of this study was to understand the flexural behavior of URM masonry walls retrofitted with fiber composite strips. Seven half-scale brick masonry walls were constructed with solid clay brick tied with a Type N mortar. Six specimens were constructed in single wythe and one in double wythe. The specimens were retrofitted with vertical E-glass fabric composite strips bonded with a two component epoxy resin. All walls were subjected to a standard pattern of static cyclic out-of-plane loading applied with an air-bag system. The specimens were classified according to their height to thickness ratio (h/t) i.e. short walls having h/t = 14 and slender walls having h/t = 28. The main investigated parameter was the amount of reinforcement. This varied from 0.2 to 0.75 times the corresponding balanced condition for the short walls and from 0.5 to 3.0 times the balanced condition for the slender ones. The collected experimental data consisted of; out-of-plane deflections, tensile longitudinal strains in composite strips, and rotations along the wall sides. It was found that the strength and ductility of the walls were enhanced significantly. The walls were capable to deflect a height drift of 2 to 5% and to support pressures in excess of thirty times their own weight. Although many failures occurred such as tensile of composite strips, compression of brickwork, and in-plane shear failure, the delamination process controlled the behavior of the tested specimens. The experimental results were compared with respect to predictions given by beam theory using ultimate strength and linear elastic approaches. Three main stages of behavior corresponding to the first visible bed-joint crack, the first delamination and the ultimate load were investigated. It was concluded that the ultimate strength method overestimates the flexure capacity of the walls. The best predictions were obtained using linear elastic analysis. Preliminary design recommendations are also proposed for tensile strain in the composite, maximum deflection, and maximum reinforcement ratio.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectEngineering, Civil.en_US
dc.subjectEngineering, Materials Science.en_US
dc.subjectPlastics Technology.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineCivil Engineering and Engineering Mechanicsen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorEhssani, Mohammad R.en_US
dc.identifier.proquest9901718en_US
dc.identifier.bibrecord.b38838138en_US
All Items in UA Campus Repository are protected by copyright, with all rights reserved, unless otherwise indicated.