Study On The Calculation Methods For The Large-span Concrete Slab With Low Ribs

The large-span slab with low ribs behaves as a dimensional object under lateral load. Its reaction to the external forces is more reasonable, thus its concrete reinforcement is less. It may be placed once to form on spot, so itsconstruction is convenient and its construction is short. It adapts to the large span residence building especially. Whether the large-span slab would be used widely in many projects, it is very important that the economic index is good or not. But it is not very well in some experiments current projects. Consequently, veracious calculation and design methods for it are necessary.At first, the actuality in theories research and actual applied about the large-spen slab is expatiated in this article. Then some methods are compared, such as orthotropic deck, crossing beams and the ANSYS beam-shell element methods. And the results will be contrasted with the experiments. Some reasons for the difference between these methods is found out. This provides a good reference for improving the design methods. At the same time, a formula is given for calculating the deflection under short-term load effect.Secondly, the yield line theory is applied for calculating the ultimate load of the large-span slab, and the result keeps consistency with the experiment. A function is gained for allocating steel bar in the slab.At last, some geometry parameters are analysed solely for the affection to the large-span slab, such as the thickness of upper board, height, width and distance of the ribs. Combining the structure optimization theory, a optimization programs are compiled. And the economical geometry parameters are gained under equal loads for simply supported square board.