CRACKING IN RC BENT CAPS

This final project report documents the findings of a Texas Department of Transportation sponsored research program to determine the causes of unexpected cracking in reinforced concrete bent caps at outside column locations (cantilevered regions) during service load conditions. Sixteen full-scale bent cap specimens were constructed and tested under quasi-static monotonic loading up to service level loading and through failure. Researchers considered and evaluated the following bent cap parameters in regard to their influence on cracking: longitudinal reinforcement stress, size, and spacing; embedment of longitudinal reinforcement near the discontinuous end of the cap; transverse reinforcement detailing and shear strength; critical section for flexure; and skin reinforcement. Researchers measured and recorded cracks from initial cracking through failure, and reinforcement strain data were recorded continuously throughout the loading history for each specimen. The experimental program confirmed that the observed flexural cracking during service load conditions is directly proportional to the level of stress in the flexural reinforcement. In addition, enhancing the shear strength of the bent cap leads to a reduction in inclined flexure-shear cracks during service and ultimate load conditions.

[1]  Edward G. Nawy,et al.  Crack Control in Reinforced ConcreteStructures , 1968 .

[2]  Michael D. Kotsovos,et al.  Structural Concrete: Finite-element Analysis for Limit-state Design , 1995 .

[3]  E. P. Warnke,et al.  CONSTITUTIVE MODEL FOR THE TRIAXIAL BEHAVIOR OF CONCRETE , 1975 .

[4]  E Hognestad,et al.  High strength bars as concrete reinforcement, part 6: fatigue tests , 1964 .

[5]  Young Mook Yun.  NONLINEAR STRUT-TIE MODEL APPROACH FOR STRUCTURAL CONCRETE , 2000 .

[6]  De Ngo.  A network-topological approach to the finite element analysis of progressive crack growth in concrete members , 1975 .

[7]  Peter Gergely,et al.  Maximum Crack Width in Reinforced Concrete Flexural Members , 1968 .

[8]  D. Ngo,et al.  Finite Element Analysis of Reinforced Concrete Beams , 1967 .

[9]  James R. Clifton,et al.  State-of-the-art report , 1995 .

[10]  T. Paulay,et al.  Reinforced Concrete Structures , 1975 .

[11]  Bengt B. Broms,et al.  Crack Width and Crack Spacing In Reinforced Concrete Members , 1965 .

[12]  J E Breen,et al.  CONTROL OF CRACKING ON THE SIDE FACES OF LARGE REINFORCED CONCRETE BEAMS , 1978 .

[13]  James G. MacGregor,et al.  Reinforced Concrete: Mechanics and Design , 1996 .

[14]  William C. Schnobrich,et al.  Nonlinear Layered Analysis of RC Plates and Shells , 1973 .

[15]  Robert J. Frosch,et al.  Another Look at Cracking and Crack Control in Reinforced Concrete , 1999 .

[16]  Arthur P. Clark.  Cracking in Reinforced Concrete Flexural Members , 1956 .

[17]  J. Mander,et al.  Theoretical stress strain model for confined concrete , 1988 .

[18]  Perry Adebar,et al.  Side-Face Reinforcement for Flexural and Diagonal Cracking in Large Concrete Beams , 1999 .

[19]  Wai-Fah Chen,et al.  Constitutive equations for engineering materials , 1994 .