Construction Technology And Vibration Analysis For Large Space Prestressed Structures

Long-span flat slabs supported by columns are widely used for floors in offices, shopping centres and airport terminals. The use of this type of structure can lead to a serviceability problem due to vibrations produced by people walking and this should be considered in design. According to practical engineering, the thesis introduced the construction scheme for the prestressed frame beam, and determined the static testing scheme of prestressed beam and the vibration measurement scheme. Based on the comparison between the numerical results and the corresponding measurements, the most appropriate model was determined for studying the dynamic behaviour of long-span prestressed floors. The main contents are as follows:1,Through comprehensive analysis of the practical engineering, the construction scheme and the static testing scheme for the long-span prestressed frame beam. The testing methods, including the measuring of effective prestress of prestressed reinforcement, inverted arch in the prestressing phase and the temperature of the concrete in the prestressed beam, was given. It provided a reliable reference for the construction and static tests of long-span prestressed concrete structures.2,The thesis introduced two finite element methods for the calculation of floor vibration, mode decomposition method and Ritz vector superposition method. The calculation model of the two methods was introduced, and the element stiffness matrix and element mass matrix was given, and then the global stiffness matrix and global mass matrix was obtained by coordinate transformation, and finally the calculation formula for free vibration and forced vibration were given.3,The measurement scheme and results of the long-span floor vertical vibration were given. Through the results obtained from Shenyang Olympic gymnasium, the first two order of the floor vertical vibration natural frequencies and the corresponding damping ratio was 4.919Hz,1.32% and 8.507Hz,0.97%, respectively.4,Three different FE models were established to simulate the floor vertical vibration. The consideration of the effect of regular reinforcement and prestressed reinforcement in the concrete structure is equivalent to enlarging the Young's modulus of concrete. The natural frequency of vibration of the three floor modals were calculated by the mode decomposition method. Based on the comparison between the numerical predictions and the corresponding measurements, it is concluded that the floor-column model gives the most appropriate representation of the actual structure for studying the dynamic behaviour of long-span prestressed floors.