To investigate the behavior of composite beams under lateral-torsional buckling, a numerical model with rotational and horizontal springs, which consider the restraint by concrete floor slab, at the top flange is often used. This paper studies the effects of the arrangement of headed studs on the rotational restraint to the top flange by the slab. First, a loading test of slab-beam subassemblies is conducted, and the test results regarding rotational stiffness and maximum strength are compared with calculations based on past methods. Second, new calculation methods are proposed to consider bearing deformation of the slab and validated through the test results and FEA results.
