There are no clear design standards for the concealed beams or reinforcements under partitions in big and thick slabs which often appear in contemporary reinforcedconcrete residential buildings. Designers have to rely on engineering experiences to design such concealed beams or reinforcements. We built a local finite element method model of a real building in ANSYS. The model included shear walls, big slabs and partitions, and the underlying reinforcements. The element for reinforcement was Link8, and the others were solid elements. Specifically, the element for big slabs was solid65 which can asses the nonlinear behaviour of concretes. Based on analysis results, we discuss the internal forces of big slabs, partitions and reinforcements. We offer suggestions for the design of reinforcements and selection of partitions.