FEM Analysis and Experimental Study on Monolayer Cable Net for Glass Facades: Dynamic Properties

摘要

Study of the dynamic properties of a monolayer cable net is described in this part II of the paper. The linear vibration properties of a cable net are analyzed in the form of a lumped-mass system based on the assumption of small-amplitude vibration. The respective influence of two vital factors: geometric shape and cable pretension on the dynamic properties of cable nets at different deflected positions under load is especially focused upon. Results show that when the geometric shape has a small displacement, the displacement influence on frequencies of vibration is almost the same as that of pre-tension, otherwise, the influence of geometric shape is far greater than that of pre-tension. Dynamic tests on the cable net model mentioned in Part I were also carried out at each pre-stretching stage. The results of experiments agree well with those of finite element analysis (FEA). In addition, a modified method called "MML" based on Rayleigh's approach for the calculation of fundamental frequency is put forward in this paper, since it was found that Rayleigh's approach may sometimes introduce large errors. The nonlinear dynamic properties of the cable net were also analyzed. Different from the linear vibration case, nonlinear cases are to some extent amplitude-dependent. Thus explicitly approximate formulae for the first and second nonlinear modal frequencies are derived from continuous theory assuming the cable net to act as a continuous membrane. Transient dynamic analysis using the finite element software ANSYS was carried out to validate the formulae. The results given by the formulae and those via numerical analysis agree with each other well.