Bond Strength of Lap-Spliced Bars

The performance of reinforced concrete structures depends on adequate bond strength between concrete and reinforcing steel. This article reports on a study of the bond strength of lap-spliced bars. The authors note that calculation methods to evaluate the strength of tension lap splices are based primarily on nonlinear regression analysis of test results. However, the results from these analyses may not be generalizable to situations beyond the domain of the data. In this study, the authors developed an expression for the calculation of bond strength based on a physical model of tension cracking of concrete in the lap-spliced region. Two different types of failure modes are considered: horizontal splitting that develops at the level of the bars (side-splitting failure), and vertical splitting that develops along the bar on the face cover (face-splitting failure). The developed expression was verified using results from 203 unconfined and 278 confined beam tests where the splice region was subjected to constant moment. Results showed that the relation between splice strength and splice length is not linear. The use of the fourth root of the concrete strength provides an improved estimate regarding the behavior of lapped splices as compared with the square root. In addition, the effect of the thickness of the concrete cover surrounding the bar is not linear.

[1]  Douglas Cleary,et al.  Performance of Concrete Bridge Decks and Slabs Reinforced with Epoxy-Coated Steel Under Repeated Loading , 1996, SP-180: Bond and Development of Reinforcement - A Tribute to Dr. Peter Gergely.

[2]  John E. Breen,et al.  THE STRENGTH OF ANCHOR BARS: A REEVALUATION OF TEST DATA ON DEVELOPMENT LENGTH AND SPLICES , 1977 .

[3]  David Darwin,et al.  Bond of Epoxy-Coated Reinforcement: Splices , 1993 .

[4]  Yukimasa Goto,et al.  CRACKS FORMED IN CONCRETE AROUND DEFORMED TENSION BARS , 1971 .

[5]  S. J. Chamberlin,et al.  Spacing of Spliced Bars in Beams , 1958 .

[6]  Atorod Azizinamini,et al.  Behavior of Lap-Spliced Reinforcing Bars Embedded in High-Strength Concrete , 1999 .

[7]  David Darwin,et al.  BOND OF EPOXY-COATED REINFORCEMENT: BAR PARAMETERS , 1991 .

[8]  J. Zuo,et al.  Splice Strength of Conventional and High Relative Rib Area Bars in Normal and High-Strength Concrete , 2000 .

[9]  David Darwin,et al.  SPLICE STRENGTH OF HIGH RELATIVE RIB AREA REINFORCING BARS , 1996 .

[10]  Shyh Jiann Hwang,et al.  EFFECT OF SILICA FUME ON THE SPLICE STRENGTH OF DEFORMED BARS OF HIGH-PERFORMANCE CONCRETE , 1994 .

[11]  David Darwin,et al.  DEVELOPMENT LENGTH CRITERIA FOR CONVENTIONAL AND HIGH RELATIVE RIB AREA REINFORCING BARS , 1996 .

[12]  Ralejs Tepfers,et al.  Cracking of concrete cover along anchored deformed reinforcing bars , 1979 .

[13]  T. Rezansoff,et al.  Confinement limits for tension lap slices under static loading , 1992 .

[14]  Tel Rezansoff,et al.  TENSILE LAP SPLICES UNDER STATIC LAODING: A REVIEW OF THE PROPOSED ACI 318 CODE PROVISIONS , 1993 .

[15]  B. Hamad,et al.  Effect of transverse reinforcement on bond strength of reinforcing bars in silica fume concrete , 1999 .

[16]  John E. Breen,et al.  BEHAVIOR OF MULTIPLE LAP SPLICES IN WIDE SECTIONS. , 1975 .

[17]  James O. Jirsa,et al.  Bond Strength of Epoxy-Coated Reinforcing Bars , 1989 .

[18]  Ralejs Tepfers.  Lapped Tensile Reinforcement Splices , 1982 .

[19]  Atorod Azizinamini,et al.  Tension development length of reinforcing bars embedded in high-strength concrete , 1995 .

[20]  Bilal S. Hamad,et al.  BOND STRENGTH OF REINFORCEMENT IN HIGH-PERFORMANCE CONCRETE: THE ROLE OF SILICA FUME, CASTING POSITION, AND SUPERPLASTICIZER DOSAGE , 1998 .

[21]  Bilal S. Hamad,et al.  Bond strength of noncontact tension lap splices , 1996 .

[22]  Atorod Azizinamini,et al.  Bond Performance of Reinforcing Bars Embedded in High-Strength Concrete , 1993 .

[23]  James O. Jirsa,et al.  Rationale for Suggested Development, Splice, and Standard Hook Provisions for Deformed Bars in Tension , 1979 .

[24]  Douglas Cleary,et al.  Bond Strength of Epoxy-Coated Reinforcement , 1991 .