The Research Of Hollow Floor Of Thin-walled Square Box About Sound And Vibration Performance

Currently, hollow floor of thin-walled square boxes are widely used in various types of large-span and large load on the floor, such as buildings, bridges, ports, terminals and underground project, it can reduce the amount of steel, cement, concrete and high energy consumption. Because of their different structure, the solid floor and hollow floor have big difference in terms of the sound effect. There are little published literature and relevant standard about the sound vibration of hollow floor especially haven’t the solid sound(bump sound). In this paper, according to sound and vibration performance of the hollow floor of the thin-walled square box combined with acoustic theory, the theory of structural dynamics and elasticity theory, we can study hollow floor in sound vibration if we impose the mechanical vibration force on the floor. Finally, we will study the hollow floor of thin-walled square boxes in sound vibration and compare to the solid floor in the same span condition through finite element program. The contents of this paper is as follows:1、Hollow plate is vibrated by mechanical vibration force. we will establish the dynamic equations of beam and floor respectively. We can translate the beam equation into the cavity rib force applied to board through the Fourier transformation and delta function feature. Therefore, the problem of solid board can be simplified and we will obtain the dynamic equations of the sound spectrum with regard to hollow plate. That is model of mechanics.2、We can solve the equation by semi-numerical and semi-analytical method and transform the dynamic equations into the matrix form, Then, it can be solved by MATLAB program and get the spectral displacement.3、We can establish the relationship between the flow field of sound pressure and acoustic spectrum of displacement by Helmholtz equation and the condition of sommerfeld acoustic radiation, then, we will calculate the value of the sound pressure level in space according to spectral displacement obtained.4、The theoretical calculations of hollow floor about sound vibration can be verified through finite element method and compared to acoustic calculation of solid plate.According to the above research, we have verified the sound pressure level of hollow floor of thin-walled square boxes by semi-numerical and semi-analytical method and analyzed the relation of spectral displacement and vibration frequency and the SPL change, The issue of the sound vibration of hollow floor can be translated into vibration of board and beam. At the same time, We have utilized the software of finite element to analyze the sound and vibration performance of hollow floor and solid plate imposed the mechanical vibration force under the condition of the same span, At last, we can compare the sound insulation of hollow floor with the solid floor.