ANALYSIS OF THE BOND-STRENGTH BETWEEN CONCRETE AND REINFORCEMENT IN REINFORCED CONCRETE STRUCTURES

Prijenos sila sa armaturnih prola na okolni beton unutar armiranobetonskih elemenata pod utjecajem je brojnih faktora, stoga je veza beton{celik temeljno svojstvo u armiranobetonskim konstrukcijama. Diplomski rad obraduje utjecaj pojave proklizavanja armaturnih prola na vezu izmedu celika i betona unutar armiranobetonskog elementa. Provedeno je ispitivanje jednoosnim izvlacenjem armaturnih prola, na glatkim i rebrastim prolima koristeci dvije mjesavine betona razlicitih cvrstoca. Ukupno je provedeno 36 testova jednoosnim izvlacenjem, obradom vlastitih ekperimentalnih rezultata prikazano je ponasanje svakog od uzoraka pomocu krivulje posmicno naprezanje{proklizavanje, te je dana usporedba ponasanja veze u slucaju koristenja glatkih i rebrastih armaturnih prola. Rezultati ispitivanja pokazali su znatno bolja svojstva veze pri koristenju rebraste armature. U sklopu diplomskog rada provedena je i numericka studija, kako bi se prikazalo na koji nacin pojava proklizavanja moze biti implementirana unutar numerickih modela koji opisuju ponasanje armirano{betonskih elemenata. Numericka studija je zasnovana na eksperimentalnim ispitivanjima jednog od stupova iz baze PEER Structural Performance Database. Za modeliranje i kalibraciju utjecaja proklizavanja armature pri jednoosnom izvlacenju koristen je programski paket OpenSees.The transfer of forces from reinforcing bars to surrounding concrete in reinforced concrete is influenced by many factors, so the steel{concrete bond is a fundamental property in reinforced concrete structures. This thesis focuses on the problems of the bond{strength between concrete and reinforcement, and denes how local slip at the interface of reinforcement and matrix of cement{based composite, aects the durability of the bond. The study experimentally evaluates the bond between smooth and ribbed steel bars and concrete of 20 and 37 MPa compressive strength. The method used for testing the bond{strength was uniaxial pull{out test. The main contribution of this study, based on the results obtained and the methodology used, is to present dierences of the steel{concrete bond in case of using smooth or ribbed steel bars. Experimental study herein described includes 36 pull{out tests. The slip values have been measured, throughout the performed pull{out tests, allowing the force slip curves to be obtained. Test result showed better bond durability when ribbed bars are used. Numerical study was also performed to show how can appearance of local slip be implemented in three dierent numerical models. Numerical study was based on experimental investigation of a column from the PEER Structural Performance Database. The calibration was carried out using nonlinear models in OpenSees (PEER, Berkley)