טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentElmalich Dvir
SubjectDynamics of Masonry Walls Upgraded with Externally Bonded
Composite Materials
DepartmentDepartment of Civil and Environmental Engineering
Supervisor Professor Oded Rabinovitch
Full Thesis textFull thesis text - English Version


Abstract

This dissertation studies the dynamic behavior of masonry walls strengthened with externally bonded composite materials. Masonry walls are found in many modern as well as old structures. In order to meet the modern demands, strengthening and retrofitting of existing walls is often required. One leading modern approach for the strengthening and upgrading of walls uses external bonding of fiber reinforced plastics (FRP) composite materials. This dissertation studies, characterizes, and explains the 3D dynamic behavior of such FRP strengthened walls. The study establishes a theoretical, analytical, numerical and experimental approach to the dynamic behavior of the FRP strengthened wall and looks into the range of scales that govern the behavior of the strengthened wall.

The analytical/numerical methodology, which is developed in this dissertation, combines a high-order theory with the finite element concept and develops a high-order specially tailored finite element for the analysis of FRP strengthened walls. The study addresses the coupling of the strengthened wall with other structural components and, at the same time, gains insight into the localized effects that critically affect the 3D dynamic behavior. The latter are addressed using a super-element approach. By means of that concept, the localized displacement and stress fields that evolve near irregular points and their sensitivity to a range of geometrical and elastic parameters are studied. The experimental phase of the study focuses on dynamic (shake table) testes of autoclave aerated concrete wall specimen, provides a basis for the validation of the analytical phase, and throw light on the physical problem at hand. Finally, motivated by the experimental observations on the evolution of delaminated regions and the evolution of compressive stresses in the FRP layer, the analytical/numerical model is augmented to include the geometrically nonlinear effects. This family of FE models combines fully bonded and delaminated regions for the modeling of strengthened but delaminated wall and studies its response to in-plane normal and in-plane shear loadings.

This dissertation establishes a platform for the dynamic analysis of walls strengthened with composite materials. The analytical framework combines the advantages of a high order layered plate approach and the finite element method and together with the experimental findings, they look into a broad spectrum of physical phenomena. The research contributes to the widening of the theoretical, analytical, computational, and experimental basis for the handling of this modern branch of structures and thus to a safer and more effective use of the modern strengthening technique.