Plastic Rotations in Continuous Encased Beams

Reported are test results of rotation capacities of 11 two-span continuous encased beams. Composite beams consisting of steel-joists of variable moments of inertia, encased in concrete, were tested under single and two-point loadings. Beams of both rectangular and T-cross sections were tested. A method of computing the magnitude of plastic rotation at the hinge sections and the redistribution of ments is proposed.The total measured rotations over the plastic lengths corresponding to different hinge sections of the beams, compared well with the theoretical rotations. Consequently,a close agreement has been noticed for the degree of redistribution of moments obtained in tests and that predicted on the basis of the proposed moment-curvature relationship.