Two types of tests on pin detailed connections and braced frame with concrete slab were carried out in order to investigate the effect of concrete slab on the structural behavior. From the result of connection tests, the evaluation method of structural behavior of the connection with slab was established. In the braced frame tests, the increase in stiffness and strength of the beam-column assembly was observed. Consequently, it was enabled to evaluate the structural behavior of braced frame by using the model obtained from connection tests and considering the presence of concrete slab to steel beam.