Study On Design Theory And Comfortable Degree Under Walking Loads About Cast-in-situ Reinforced Concrete Hollow Floor

The cast-in-situ reinforced concrete hollow floor is a new form of floor,it combines many advantages on using function, structural performance, economic performance and so on.It becomes a major technological innovation in the field of building structure in China. Now many scholars have done a lot of theory and experimental research about its properties under limit state, due to the different methods of theoretical analysis and experimental research be used, the results of the research have great limitations in the engineering application. So by the engineering viewpoint, giving a simple and practical design method becomes the primary problem.In this paper, based on the elastic theory method, we analysis the internal force and deformation about cast-in-situ reinforced concrete hollow floor, which simply supported on four sides. From this we get the calculation formulas of internal force and deflection. In addition, we also analysis the torsion of edge beam and comfortable degree of concrete hollow floor under walking loads, and use numerical simulations to verify the theoretical results. Main contents as follows:1. The numerical analysis results indicate that, concrete hollow floor is very similar to solid slab, the stress distribution and crack development have certain rules, and the phenomena of producing yield-line occur just like solid slab. Because of light weight, big stiffness and small deformation of concrete hollow floor, it is better than solid slab.2. Based on the small deflection theory of the elastic thin plates, considering the structure of concrete hollow floor and amplifying coefficients of bending stiffness and torsional stifness, we get the calculation formulas of internal force and deflection. Actual calculation example shows that, compared with ANSYS numerical analysis results, the formulas are effective and efficient.3. Considering the torsion bending of secondary beam, the rotation of frame joint that caused by out of plane moment and the relative torsion of edge beam, we get the torque calculation formulas of edge beam. Actual calculation example shows that, compared with ANSYS numerical analysis results, the formulas are effective and efficient.4. In this paper, three methods are adopted to simulate walking loads. The method of fourier fixed-point loading is over-conservative, the simulation result shows that continuous and impulsive loading on the central point of the floor is unfavorable to comfortable degree.The result of individual footstep loading is similar to the loading that considering frequency changing, but considering frequency changing is likely more consistent with the reality of human walking. In addition, the comfortable degree for many people walking is also numerically simulated, and compared it with the limit value of specification, the result shows that the comfortable degree of concrete hollow floor is fine.