Determination of the natural frequencies of a prestressed cable RC truss floor system

The finite element method (FEM) and the analytical formula were used to study the vertical vibration of a prestressed cable RC truss (PCT) floor system. Three element types were compared for estimating the natural frequencies of this floor system. Extensive sensitivity studies using ABAQUS were conducted considering: (a) live load; (b) the number of web members; (c) opening ratio; (d) span; (e) rise-span ratio; (f) span to spacing ratio. Detailed derivation using the energy method for the natural frequencies of an orthotropic floor with four built-in edges is described. The unified formula for the PCT floor system was then developed for the first time based on the orthotropic plate theory to calculate the natural frequencies. The results obtained by the formula were compared with those from the field test and FEM. The comparison shows that the results are generally in a good agreement, indicating that the derived formula for natural frequencies is reasonably accurate and suitable for the vibrational analysis and design of the PCT floor system.