B.H .• Spacing of Cracks in Reinforced Concrete

ABSTRACT: The spacing and width of cracks in a parallel crack system is ap-proximately analyzed using the energy.cnt.eno ~ of fracture mechamcs as well as the strength criterion. The energy cntenon indicates that the crack spacing is a function of the axial strain of the bars and also depends on bar spacing, bar diameter, fracture energy of concrete, and its elastic modulus. Both the energy and strength criteria yield a minimum strain ~ecessary to "roduce any cracks. The energy criterion and the bond slip conditions further Yield a lower bound on possible spacing of continuous cracks. The rules for the formatIOn of shorter, partial length, cracks are also set up. Ap!:'roxlmate ex!:'resslons for the crack width at, and dway, from the bdrs are denved. Numencal compan-sons indicate satisfactory agreement with existing test data, and lend theoretical support to one aspect of the empirical Gergely-Lutz f~rmula obtamed by sta-tistical regression analysis of test data. Finally,. formation of skew cracks In a biaxially stressed and biaxially reinforced plate IS analyzed and a crack spacing formula is derived for one typical case