טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentUri Wexler
SubjectEffect of Steel Fibers and Concrete Strength on the Bond
of Deformed Reinforcing Steel Bars
DepartmentDepartment of Civil and Environmental Engineering
Supervisors Professor Dancygier Avraham
Full Professor Katz Amnon


Abstract

In the world today there is a growing use of High Strength Concrete (HSC), which has different mechanical properties than Normal Strength Concrete (NSC).  Hence the need to study its mechanical properties and the structural behavior of members made of this material. One of the ways to improve the mechanical performance of HSC is to add steel fibers to the mixture. However, although there are references to the use of HSC with steel fiber, there are still no international standards that include design provisions for this type of mixtures. 


This study deals with the bond of ribbed steel bars in HSC. Its objective is to investigate the influence of concrete strength and of the inclusion of steel fibers in the concrete mixture on its bond to ribbed steel bars. The research is based on an extensive literature survey together with laboratory experiments, which were aimed at testing the bond in direct pull-out experiments without cracking or splitting of the specimen.

The cylindrical specimens were made of NSC and HSC with cubic strengths of 35 and 115 MPa, respectively.


Analysis of the test results yield conclusions regarding the effect of concrete strength, steel fibers, as well as bar diameter and relative rib area (fR) on the bond strength and on the bond-slip behavior. Test results (bond strengths) were also compared with their pertinent and extrapolated values in the Israeli and European codes for design of reinforced concrete.