This paper proposes a prediction method of maximum in-plane response of flexible floor in single-story elastic structures with eccentricity. The relative lateral displacement between parallel plane frames and the in-plane shear force sustained by the floor are targeted as requirements for the floor against earthquake using a six-degree of freedom model considering masses distributed on the floor. It is revealed that the predicted results well correspond with the results of time history response analysis, and also the effect of eccentricity on in-plane response is negligibly small.
