Theory And Test On Nonlinear Vibration And Pretension Measurement Of Building Membrane Structure

With the progress of science and technology and the development of society, themembrane structure has been widely applied in many areas, especially in the buildingengineering area. The building membrane structure is a new structure system, which hasbeen rising during the recent several dozens of years. It is widely applied in large-scalestadium, exhibition center, casino, and so on. Because the building membranestructure’s dead weight is light and the rigidity is small, it is very sensitive under theimpact load and easy to engender vibration, thus results in engineering accident.Therefore, it is quite necessary to study the vibration characteristics of the buildingmembrane structure under impact loading (such as rainstorm, hail, the waste picked upby the wind, and so on) to obtain the general laws of them. These studies haveimportant significance for the reasonable design and construction of building membranestructure, thus to prevent or reduce the engineering accident of building membranestructure. In addition, applying the theoretical studies of nonlinear vibration of buildingmembrane structure into the studies of pretension measurement method of buildingmembrane structure has a great significance for engineering practice. We can use thestudied measurement method to measure the actual pretension, thus to control the actualpretension accord with the design pretension and guarantee the construction quality.Meanwhile, we can use this method to detect whether the pretension has changed in theworking process, thus to adopt effective measures to adjust the pretension to prevent orreduce engineering accident.This dissertation mainly studied the theory and application of the nonlinear freevibration of orthotropic rectangular membrane structure and its forced vibration underimpact loading. Firstly, analytical method was applied to study the large deflectiongeometrical nonlinear free and forced vibration problem of orthotropic rectangularmembrane structure and the general analytical solution was obtained. Then, we appliedthe theoretical studies into actual building membrane engineering to develop a newmethod—Ejection Method for monitoring the pretension of building membranestructure and the theoretical measurement formula was derived and obtained. Finally,the numerical analysis and ejection experiment were carried out for the EjectionMethod and the numerical and experiment results proved the Ejection Method is valid.The concrete study contents are as follows:①The partial differential governing equations of damped and undamped nonlinear free vibration of orthotropic rectangular membrane were established bycombining the Von Kármán’s large deflection theory with the D’Alembert’s principle.The undamped free vibration governing equations were solved by direct integrationmethod and L-P perturbation method, and the approximate analytical solution of thefrequency and deflection function were obtained. The damped free vibration governingequations were solved by t KBM perturbation method, and the approximate analyticalsolution of the frequency and deflection function were obtained.②Based on the studies of nonlinear free vibration of orthotropic rectangularmembrane structure, the governing equations of the damped and undamped forcedvibration of orthotropic rectangular membrane structure under concentrated impact loadwere established. The undamped forced vibration governing equations were solved byL-P perturbation method, and the approximate analytical solutions of the frequency anddeflection function of were obtained. The damped forced vibration governing equationswere solved by KBM perturbation method, and the approximate analytical solution ofthe frequency and deflection function were obtained. The ANSYS/LS-DYNA finiteelement analysis software was adopted to carry out the numerical analysis of the forcedvibration of orthotropic rectangular membrane structure under the impact load. Thecomparison and analysis of the theoretical and numerical results indicate that thetheoretical results coincide well with the numerical results.③Applying the theoretical studies of this dissertation into actual buildingmembrane engineering, a new method—Ejection Method was developed for monitoringthe pretension of building membrane structure. The theoretical model of this methodwas established, and the theoretical measurement formula was derived and obtainedaccording to the principle of conservation of energy. The finite element analysis modelof Ejection Method was established and the numerical computation was carried out bythe ANSYS/LS-DYNA finite element analysis software. The theoretical and thenumerical results were compared and analyzed and the compared results prove that useEjection Method to measure the pretension of building membrane structure is feasibleand valid.④The experimental scheme was constituted for measuring the pretension ofmembrane structure by Ejection Method according to the theoretical studies of EjectionMethod. According to the experimental scheme, the crisscross screw biaxial stretchingdevice was prepared for stretching the membrane test specimens. Three kinds ofmembrane material were selected to carry out the ejection experiment. The ejection experiments with equal loading and unequal loading in the warp and weft directionswere carried out and the experimental data was recorded. Put each group ofexperimental data into the theoretical measurement formula to obtain the experimentalcomputational pretensions, and compared the experimental computational pretensionsto the actual pretensions. The comparing analysis results indicate that the most ofexperimental computational pretensions tallied with the actual pretensions. This alsoproved that use Ejection Method to measure the pretension of building membranestructure is feasible and valid.