The Temperature Analysis Of Concrete Composite Box(Concealed Box Type)Net Joint Floor Based On ANSYS

In recent years, a new forms of floor-Concrete Composite Box Net Joint Floor which is suitable for large span, large space and withstand heavy loads has been widely used in various projects. Since the fire area and damage of the floor as the horizontal load-bearing elements are large, so it is very necessary to carry out the research of fire behavior about floor. On the basis of fire test and analysis of concrete composite box (concealed box type) net joint floor, by using the technology of "element birth and death" of the finite element software ANSYS to make3-d solid model for the heat transfer process of the floor. By finite element analysis, the overall temperature distribution contours、cross-sectional temperature distribution contours and the temperature-time curve of the cross section is obtained at the crucial moment. It is concluded as follows:(1) Using the ANSYS finite element analysis software is a good method for the temperature distribution of concrete composite box (concealed box type) net joint floor in the fire.(2) The heat transfer process of the floor after burn through is obtained from the overall temperature distribution contours of the floor which visually confirms the presence of water in the test.(3) Because of a larger size of the side beam and the thermal inertia of the concrete, therefore, the temperature gradient and temperature stresses of the edge beam section is comparatively large; as the temperature increased, the side beam produce a lot of cracks which are consistent with the experimental phenomenon duo to torsion.(4) After the composite box generation blowout, the beam is in three face state by fire, but it is different from the ordinary T-beam. Because the heating curve of the cavity and ISO834standard temperature curve have the big difference, and composite box side plate for ribbed beam has a certain protective function, eventually lead to a large temperature gradient at the bottom of the ribbed, but steadily up(5) Duo to the assumption that does not consider the loss of part of the heat generated by the evaporation of water in the concrete, so the temperature-time curve along the ribbed section through the ANSYS simulation is not a straight section, and analog value is slightly higher than the experimental values.(6) The size of the residual portion and burn holes is significant to the heat transfer.