|Ph.D Student||Hamed Ehab|
|Subject||Dynamic Behavior of Concrete and Masonry Structures|
Strengthened with Composite Materials
|Department||Department of Civil and Environmental Engineering||Supervisor||Professor Oded Rabinovitch|
|Full Thesis text|
The dissertation studies the dynamic behavior of reinforced concrete (RC) and masonry elements strengthened with externally bonded composite materials. In particular, RC beams subjected to dynamic loads and masonry walls under static and dynamic out-of-plane loading are examined. An analytical approach for the dynamic analysis of these structural members is developed. The analytical approach is based on variational principles, dynamic equilibrium, compatibility of deformations, and on the concepts of higher order theory. The governing dynamic equations of the strengthened member are formulated. The constitutive relations of the materials involved, which in many cases are strongly nonlinear, and the high order stress and deformations field of the adhesive are also developed. Procedures for the solution of the governing partial differential equations, which in most cases are nonlinear due to the geometrical and physical nonlinearities are developed, presented, and discussed.
The capabilities of the theoretical approaches developed in this work are numerically demonstrated. The numerical study reveals and quantifies the major phenomena that govern the dynamic response of the strengthened beam and the out-of-plane static and dynamic response of strengthened masonry walls. A special chapter is devoted to the modeling and analysis of the viscoelastic and damping effects. The model developed for the analysis of strengthened masonry walls accounts for the cracking and the nonlinear material behavior of the mortar joints, the nonlinear breathing of the flexural cracks, the formation of debonded regions, the nonlinear destabilizing effects of the arching action, the rocking phenomena, the coupled in-plane:out-of-plane dynamic response, and the local buckling/wrinkling of the compressed FRP strip. Parametric studies that examine and explain the role of the various parameters and their influence on the response of the strengthened wall are also presented.
An experimental program that includes loading to failure of six full-scale strengthened masonry walls and three full-scale control walls is also conducted. In addition, a series of tests for the characterization of the mechanical properties of the materials involved is conducted. The results of the static analysis and tests reveal and explain the unique physical phenomena that characterize the response of the strengthened wall, and quantify its failure mechanism.
The theoretical approaches developed in this dissertation enhance the fundamental understanding and provide insight into the dynamic behavior of RC beams and the out-of-plane dynamic behavior of masonry walls strengthened with composite materials. Hence, they take another meaningful step towards the effective strengthening of structural members to resist dynamic loads.