Nonlinear Finite Element Analysis of Concrete Structures

- 18 -
(1965, 1974) and of Cedolin et al. (1977) both involve singular
points, i.e. corners. In addition, the trace of the latter proposal
is concave along the tensile meridian. As will appear
later this concavity has large consequences. The proposal of
Willam and Warnke (1974) and of the writer (1977) both correspond
to smooth convex curves.
Great importance is attached to plane stress states, and fig. 4
a) shows a comparison for all criteria, except that of Cedolin
et al. (1977) with the experimental results of Kupfer et al.
(1969, 1973). All criteria in fig. 4 a) show good agreement with
the experimental data especially those of Willam and Warnke
(1974) and Ottosen (1977) even when tensile stresses occur. Comal
Willam and Warnke (1974)
Reimann-Janda (1965.1974)
Ottosen (1977)
Chen and Chen (1975)
• KupferetaL (1969.1973),