טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentMadah Hazem
SubjectStrengthening of Masonry Walls Subjected to Dynamic
Out-of-Plane Loads with Composite Materials:
Experimental Study and a Tailored Finite
Element
DepartmentDepartment of Civil and Environmental Engineering
Supervisor Professor Oded Rabinovitch
Full Thesis text - in Hebrew Full thesis text - Hebrew Version


Abstract

The thesis studies the dynamic response of one-way masonry walls strengthened to resist dynamic out-of-plane loads with externally bonded Fiber Reinforced Plastic (FRP) strips. The study combines a derivation of a specially tailored finite element (FE) for the one-way dynamic response of the strengthened wall with full-scale shake table experiments. The derivation of the special FE aims to develop a simple and computationally efficient numerical model for the nonlinear dynamic analysis of the strengthened one-way wall under out-of-plane loads. The experimental phase aims to characterize the dynamic response of the strengthened wall and to provide experimental benchmarks for the numerical model. The comparison between the two and the comparison between the responses of the strengthened wall and an un-strengthened one throw light on the dynamic behavior of the unique structural element.

The study opens with a literature survey and a derivation of a special finite element for the dynamically loaded FRP strengthened unidirectional masonry wall. The derivation is based on variational principles, geometrically nonlinear kinematics, a high-order theory, and nonlinear constitutive laws for the mortar joints. This law, which is calibrated experimentally, is brittle under tension, nonlinear under compression, and it includes the effects of unloading and reloading. The unique behavior of the masonry construction and the high order stress and deformation fields in the layered structure are implemented in a variational formulation, which is then converted into a finite element form. The analytical part of the work is supported by static, eigenvalue, and dynamic convergence studies, and by comparison with the results of the experimental phase. This phase include two series of shake-table experiments on full-scale one-way walls. First, an unstrengthened masonry wall is dynamically tested. Then, an FRP strengthened wall is tested. The analysis and the experiments focus on the global and localized dynamic response and they highlight the impact of a broad range of aspects. These include the in-plane and out-of-plane coupling, the boundary conditions, the cracking of the joints, the arching and rocking effects, the geometrical nonlinearity, the temporal variation of the axial compressive force, and the localized variation of the strains near the joints. The study highlights the ability of a simple and fast strengthening procedure to contribute to the resilience of the dynamically loaded masonry wall and presents a computationally efficient tool for its analysis. Both aspects contribute to the effective design and the safe use of FRP strengthened masonry walls.