Bending capacity of composite girders with Class 3 section

In this research, the flexural behaviour of composite girders under non-monotonic service loads and the bending capacity of composite girders with Class 3 section were studied through experimental work. Three specimens were fabricated and, through the 4-point flexural test, the stiffness and strength of the composite girder under hogging moments were observed. Test specimens were overhanging simple support beams, in total 6 m long. From the test results, the deflection, stiffness, moment-curvature relationship, and strain distribution of the composite girder section under service and ultimate loading were analyzed. The flexural behaviour under reloading-unloading cycles and tension stiffening effects on the mechanical behaviour of composite girders were discussed. The ultimate strength of composite girders with different Class flange sections and a same Class web section were also studied. Test results were analyzed by design equations in Eurocode 3 and 4 for flexural stiffness and sectional resistances. Also, a new simple design equation for the bending capacity of composite girders with Class 3 sections was suggested.