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1、山东建筑大学毕业设计外文文献及译文外文文献：Materials and StructuresRILEM201010.1617/s11527-010-9700-yOriginal ArticleImpact of crack width on bond: confined and unconfined rebar DavidW.Law1, DengleiTang2, ThomasK.C.Molyneaux3 and RebeccaGravina3(1)School of the Built Environment, Heriot Watt University, Edinburgh, EH14
2、4AS, UK(2)VicRoads, Melbourne, VIC, Australia(3)School of Civil, Environmental and Chemical Engineering, RMIT University, Melbourne, VIC, 3000, AustraliaDavidW.LawEmail: D.W.Lawhw.ac.ukReceived: 14January2010Accepted: 14December2010Published online: 23December2010 AbstractThis paper reports the resu
3、lts of a research project comparing the effect of surface crack width and degree of corrosion on the bond strength of confined and unconfined deformed 12 and 16mm mild steel reinforcing bars. The corrosion was induced by chloride contamination of the concrete and an applied DC current. The principal
4、 parameters investigated were confinement of the reinforcement, the cover depth, bar diameter, degree of corrosion and the surface crack width. The results indicated that potential relationship between the crack width and the bond strength. The results also showed an increase in bond strength at the
5、 point where initial surface cracking was observed for bars with confining stirrups. No such increase was observed with unconfined specimens.Keywords:bond;corrosion;rebar;cover;crack width;concrete 1 IntroductionThe corrosion of steel reinforcement is a major cause of the deterioration of reinforced
6、 concrete structures throughout the world. In uncorroded structures the bond between the steel reinforcement and the concrete ensures that reinforced concrete acts in a composite manner. However, when corrosion of the steel occurs this composite performance is adversely affected. This is due to the
7、formation of corrosion products on the steel surface, which affect the bond between the steel and the concrete. The deterioration of reinforced concrete is characterized by a general or localized loss of section on the reinforcing bars and the formation of expansive corrosion products. This deterior
8、ation can affect structures in a number of ways; the production of expansive products creates tensile stresses within the concrete, which can result in cracking and spalling of the concrete cover. This cracking can lead to accelerated ingress of the aggressive agents causing further corrosion. It ca
9、n also result in a loss of strength and stiffness of the concrete cover. The corrosion products can also affect the bond strength between the concrete and the reinforcing steel. Finally the corrosion reduces the cross section of the reinforcing steel, which can affect the ductility of the steel and
10、the load bearing capacity, which can ultimately impact upon the serviceability of the structure and the structural capacity 12, 25. Previous research has investigated the impact of corrosion on bond 25, 7, 12, 20, 2325, 27, 29, with a number of models being proposed 4, 6, 9, 10, 18, 19, 24, 29. The
11、majority of this research has focused on the relationship between the level of corrosion (mass loss of steel) or the current density degree (corrosion current applied in accelerated testing) and crack width, or on the relationship between bond strength and level of corrosion. Other research has inve
12、stigated the mechanical behaviour of corroded steel 1, 11 and the friction characteristics 13. However, little research has focused on the relationship between crack width and bond 23, 26, 28, a parameter that can be measured with relative ease on actual structures. The corrosion of the reinforcing
13、steel results in the formation of iron oxides which occupy a larger volume than that of the parent metal. This expansion creates tensile stresses within the surrounding concrete, eventually leading to cracking of the cover concrete. Once cracking occurs there is a loss of confining force from the co
14、ncrete. This suggests that the loss of bond capacity could be related to the longitudinal crack width 12. However, the use of confinement within the concrete can counteract this loss of bond capacity to a certain degree. Research to date has primarily involved specimens with confinement. This paper
15、reports a study comparing the loss of bond of specimens with and without confinement. 2 Experimental investigation 2.1 Specimens Beam end specimens 28 were selected for this study. This type of eccentric pullout or beam end type specimen uses a bonded length representative of the anchorage zone of a
16、 typical simply supported beam. Specimens of rectangular cross section were cast with a longitudinal reinforcing bar in each corner, Fig.1. An 80mm plastic tube was provided at the bar underneath the transverse reaction to ensure that the bond strength was not enhanced due to a (transverse) compressive force acting on the bar over this
