ABSTRACT
JohnsonTs linear interaction method is based solely upon the degree of interaction and does not take into account stud flexibility. From fig. 5 it can be seen that this method is conservative in predicting the stiffness of the test beam in the low load levels of the test. However, the method is based upon the design degree of interaction in the ultimate lpad case. The test degree of interaction was much higher and indicated that, at ultimate load the beam sustained 85% of its theoretical fully composite plastic moment. If this degree of interaction is used the method proves unconserv ative in the prediction of stiffness and it is, therefore, clear that stud flexibility plays an important role in the stiffness of the composite beam.
The analysis based upon the derivations of Newmark et al can be seen to be most conservative when predicting stiffness. There are two reasons for this.
