Concrete Sections Unoeb Biaxial Bending

The general cases of cracked reinforced or prestressed concrete sections under axial load and biaxial or uniaxial bending in the serviceability and ultimate limit states have been treated in four previous papers. This paper is limited to serviceability limit state analyses of cross sections without prestressing or axial load and with trapezoidal or triangular compression zones. The effect of shrinkage is not covered. The approach suggested in this paper is simpler and about 50 times faster than the general method. The analysis may be carried out without the aid of a programmable computer. However, such a computer facilitates the calculation considerably. The concrete on the tension side of the neutral axis is assumed to be unable to transfer stresses, so the shape of this part of the cross section has no influence on the analysis. The reinforcement can be distributed arbitrarily over the cross section.