Date of Award

Spring 1993

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Civil Engineering - (Ph.D.)

Department

Civil and Environmental Engineering

First Advisor

M. Ala Saadeghvaziri

Second Advisor

William R. Spillers

Third Advisor

C.T. Thomas Hsu

Fourth Advisor

Edward G. Dauenheimer

Fifth Advisor

Rajesh N. Dave

Abstract

Unreinforced masonry (URM) structures have been a common type of construction in the past and are still used in regions of low seismicity. Retrofitting of these structures is necessary because of two reasons: Firstly, observed damage after earthquakes reveals that URM construction is one of the most hazardous constructions even in the region of low seismicity; secondly, reclassification of seismic zones would require retrofitting of existing structures to comply with new guidelines for earthquake design.

Retrofitting measures require that the response of original and new structural systems as well as their interaction be considered. It is therefore important to correctly understand and predict the response of URM structures before implementing any strengthening scheme. Special techniques for analysis of URM structures are necessary because mortar joints act as planes of weakness.

In this thesis a new approach for analytical modeling of URM structures is presented with a special emphasis on nonlinear behavior of mortar joints. This approach is included in a general purpose finite element software so that various options of the software can be effectively utilized for linear and nonlinear analysis of different structural systems under static and dynamic loading conditions.

The analytical scheme is verified at element as well as structure level by comparison with available experimental and analytical results. Two rehabilitation schemes commonly used to strengthen existing URM structures are analyzed and their effectiveness in increasing strength and stiffness is discussed. Finally, nonlinear dynamic analysis is performed to study the effect of ground motion on URM walls and rehabilitation schemes.

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