טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentRabinovitch Oded
SubjectRetrofitting and Rehabilitation of Concrete Structures
with Composite Materials
DepartmentDepartment of Civil and Environmental Engineering
Supervisor Professor Emeritus Yeoshua Frostig


Abstract

The need for upgrading, strengthening, retrofitting, and rehabilitation of existing structures is one of the major problems that structural engineers are facing these days. The study deals with strengthening and retrofitting of existing reinforced concrete structures using composite materials externally bonded to the tensile face of the member. For this purpose, a systematic and general approach for the analysis of stresses, stress resultants, and deformations within a wide range of strengthened structural members is developed. In addition, an experimental study that examines the various aspects of the strengthening method is conducted. The field and governing equations of the analytical model, and their associated boundary and continuity conditions, are rigorously derived using the variational principle of virtual work following the concepts of the Closed-From High-Order theory. The model fulfills accurately all global and point equilibrium requirements, as well as compatibility of deformations and any combination of boundary and continuity conditions.

Various aspects of the strengthening method are examined and studied through the presented approach. These aspects include: the strengthening of different types of reinforced concrete beams; the stress concentrations that arise near the edge of the adhesive layer and the methods for the control and reduction of these stresses; the effect of the nonlinear behavior of the materials involved and its influence on the response of the member; the failure modes of the strengthened members and the development of a reliable failure criteria for such structures; and the strengthening of concrete slabs using circular patches made of laminated composite materials.

The analytical approach developed provides the analytical tool for the comprehensive investigation of the overall linear and nonlinear response of the strengthened members, as well as the inevitable localized effects that these structures are associated with. Moreover, the proposed approach presents a significant enhancement of the physical insight of the various aspects of the investigated method and provides the basis for an effective use and a safe design of the various strengthened, upgraded, and rehabilitated structural members.