Elastoplasticity Analysis On Cast-In-Situhollow Reinforced Concrete Floor System

Cast-in-situ hollow reinforced concrete floor system (CHRCF) is a new system of cast-in-situ reinforced concrete floor come after ordinary beam slab floor, waffle floor prestressed concrete without adhesion floor, which integrate merits of precast core slab, flat slab floor, beram and girder floor, put performance good in stress of I-shape beam and honeycomb structure characteristic into floor structure. Because it satisfies the people's higher request to building store height, big space, flexible in comparting and so on, therefore it is accepted by the more and more construction units.Compares with the ordinary plate beamless roof, CHRCF has three prominent diversities: First, buries the hollow circular pipe in the floor to form the hollow floor in advance; secondly, equipped with thin-walled beam between the frame column; finaly, thicker than the common beamless roof. Because of the low tensile strength of concrete material and the relationship between stress and strain is non-linearity etc, the reinforced concrete floor may cracks in the small load situation, the non-linear distortion obtains development, which lead to more complex structure analysis and the design. Although the research of concrite slab and floor started early, and already proposed many analysis and design method, but, because of the core slab beamless roof own characteristic, the explanations to core slab beamless roof stress performance is different, especially stress performance under the elastoplasticity condition is not very clear. This article based on the CHRCF's characteristic, analyzes its basic mechanics performance and explores the reasonable computation pattern and design method, which has the extremely vital significance to design, safeguard structure's safe using and further promoting its application.Firstly, this article began from the reinforced concrete material elastoplasticity's constitutive relation, discuss the concrete destruction criterion as well as all kinds of destruction model. Next, based on finite element software ANSYS, did analysis and discussion to each kind of unit which appeared in the nonlinear analysis of the concrete reinforced concrete structure, established core slab model conforme to the actual situation, did deadweight simulation to single span core slab beamless floor and its material non-linear finite element computation from adds load, crazes, submits until destroyed. Obtained the core slab's dehiscence load, destruction load, the displacement and the stress distributed rule under vertical load. Obtained some conclusions which gives certain reference value to improve the CHRCF's structure, after analysis to the finite element computed result. Through the theoretical analysis and the finite element computation, this article thought that the ratio of vertical hole direction rigidity and along the hole direction rigidity may take 0.8 in the CHRCF. Above research results have the practical significance and application value to the actual project, can be the reference to engineering.