Interface Behavior in Reinforced Concrete
- PDF / 284,638 Bytes
- 6 Pages / 420.48 x 639 pts Page_size
- 67 Downloads / 233 Views
INTERFACE BEHAVIOR IN REINFORCED CONCRETE S.K. MITAL, R.L. MULLEN, A.A. HUCKELBRIDGE, JR. Case Western Reserve University, Department of Civil Engineering Cleveland, Ohio 44106, U.S.A.
ABSTRACT The mechanism of bond transfer between steel and concrete in a reinforced concrete member is studied in the present work. It is seen that the behavior of the interface zone can be represented by a simple generalized Mohr-Coulomb model. It is also seen that the complex relationships between the local bond stress and local slip suggested by other researchers (cubic or higher order polynomials) may be due to the geometry of the specimen and nature of stress distribution along the bar rather than intrinsic interface behavior. Behavior predicted by a generalized Mohr-Coulomb model is compared to predictions and observed behavior previously reported.
INTRODUCTION It is well known that the shear stresses transferred across interfaces, such as crack surfaces and bond surfaces, have a significant influence on the behavior of concrete structures. Hence, many investigations to measure bond stress distribution and its effect on crack spacing and splitting have been carried out [1,2,3,4]. Since bond behavior is an interaction between the steel bar and surrounding concrete, it is a rather complex phenomenon. It is also essential to understand the bond phenomenon to understand the long term behavior of concrete structures. Most deterioration in concrete structures under cyclic loading is due to the loss of bond between the concrete and steel. Current design procedures assume perfect bond between steel and concrete. Since the load carrying capacity largely depends upon the bond interaction, understanding of the mechanism of bond transfer is of primary importance.
HISTORICAL REVIEW Ngo and Scordelis [5] first proposed linearly elastic bond links to model the bond behavior in reinforced concrete using finite element studies. Their work demonstrated the importance of bond-slip on the member behavior. This lead to many other studies to formulate such a relationship in a more realistic manner. Nilson [6] and Mirza and Houde [71 have conducted numerous experiments to measure the bond stress and bond slip at internal locations in concrete. Two testing methods have been emphasized in these investigations. In the so called ASTM "Pullout Tests" [8], a single reinforcing bar is embedded in a concrete specimen and pulled from one protruding end. In the other test called a "Beam Test", or a "Transfer Test", tensile force is applied at both ends of the protruding bar. Later types of tests were designed to simulate the conditions in the constant moment region of reinforced concrete beam between tensile cracks. It should be noted that the bond behavior of a deformed bar is different than a plain bar and depends mainly on the bearing of the steel ribs against the intervening concrete keys. The effects of discrete ribs and internal cracks are generally smeared in modeling, so as to simulate a continuous action along the bar. Local bond stress on the inter
Data Loading...
