| In our multi-layered, high-rise and even super tall reinforced concrete structure has been widely used in various industrial and civil buildings, but the infrastructure to meet the public in fire safety can not keep up the pace of social development, fire-resistant design of the structure is still in the member level and lack of theoretical basis. Therefore, to carry out full-scale all edges simply supported reinforced concrete composite plastic box hollow web girder floor fire resistance test analysis, will help to establish a scientific and reliable design methods, it will also contribute to the building structure after fire the repair and reinforcement.Based on the series of experiments and analysis of mentors, using ANS YS software to simulate fire experiment analysis, the main contents are:1, through the three-dimensional thermal solid element SOLID70, simulated hollow floor heating in ISO834 standard curve effect change at the temperature field. In order to facilitate comparative analysis, the heating surface temperature by fitting the temperature curve, the temperature degree of freedom constraint definitions node temperature, given the overall temperature contours mold box hollow floor, cross-sectional contours and along the rib Beam direction at different heights the temperature-time curve. Finally, select the key moments of the experiment is consistent comparative analysis;2, during the indirect heat-stress coupled analysis when the node was solved by the temperature in the structural analysis as a bulk load, the temperature will be applied to the results of a structural unit, analyze mold box hollow floor in temperature and uniformly distributed load together deformation of action, given the floor plane displacement contours, displacement at the center of the plate-time curve and the board across 1/4 of the displacement-time curve. Finally, select the key moments of the experiment is consistent comparative analysis;3, Envelope thinking, the damaged portion of the base unit completely kill analyze its complete failure in the floor overall hollow floor flat in the case of external deformation, given the displacement plane using-when time curve, the actual design facilitates conservative analysis;Through the above work, mainly the following conclusions:1) the use of three-dimensional thermal solid element SOLID70, can simulate analyze temperature distribution in case of fire concrete composite plastic cartridge. Temperatures at different heights through the rib Beam-time curve experiments and numerical simulation comparison analysis, simulation curve shape of the curve with the experimental data and trends coincide. The reason to consider a slight deviation has two effects:First, the finite element simulation itself, for the continuity of space meshes will reduce the temperature value of the result of its calculation. Second, the analysis ignores the evaporation of moisture in concrete heat loss, thermal parameters of materials, there is a difference between the mechanical parameters and the test piece is not completely burn real value and impact of the composite bottom panel on the temperature field. Comprehensive calculation error that in the current meshing fineness computer capacity constraints under the calculated temperature field results meet the requirements.(2) from the floor section temperature contours and temperature-time curve analysis, reinforced concrete floor by the fire temperature gradient phenomenon is very obvious. Due to the presence of temperature stress, due to the presence of the upper floor of the tensile stress and cracks.(3) Based on the deflection-time curve analysis can be drawn:the factors that affect the dynamic change in the elastic modulus of the structural member at a high temperature, the yield strength, the fire on the floor redistribution of internal forces and deformation of the structure is very clear, far beyond the relevant Scope of the normal design specifications 1/200 span. Through vertical displacement value compared with the bottom portion of the unit after killing, the combination shows relatively ribbed plastic box girder floor under high temperature resistance (fire) deflection advantage.In the model analysis in this article is based on an isotropic on the basis of concrete, reinforced concrete and did not consider the result of differences in each direction, so there are some differences between the actual results and the material itself. While the simulation internal reinforcement, using as an additional dispersion reinforced monolithic approach and did not consider the bond between steel and concrete-slip influence. Integral Methods error exists between the results with the experimental value of the future can be further optimized from a separate model, reinforced concrete units were modeled using the element nodes share, resolved in good convergence of stress analysis problems, although the amount of calculation have The increase, but it can visually acquire steel stress, to further improve the accuracy.Analysis in the next hollow slabs subjected to fire test studies may be based on the literature [69] of "lightweight concrete at below 500? unchanged compressive strength," this feature,We recommend the use of lightweight concrete instead of ordinary concrete, make the structure to reduce weight, which will help the earthquake, along with a good anti-fire performance to play a greater economic and social benefits in the floor. Fire behavior can be carried out in future lightweight concrete analysis, the analysis between the temperature field and deflection and ordinary concrete. While there are special considerations for fire protection needs of architectural space, a combination of plastic boxes backplane fireproof paint coating with the use of lightweight concrete construction and to improve the overall anti-fire time building. By comparative tests with ordinary concrete building fire resistance performance analysis, will help to some extent in structural fire resistance performance of the design. |
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