两铰抛物线拱的在初始条件下

说明：  % 本程序为第八章的第二个算例，采用平面梁单元计算两铰抛物线拱的在初始条件下 % 自由振动，并对时程曲线结果进行FFT变换，求得的频率可与exam8_1.m的结果进行 % 比较，以验证本程序的可靠性
(This procedure for the eighth chapter of the second examples, calculation of plane beam element with two hinged parabolic arch free vibration in the initial conditions, and the results of time curve of FFT transform, the frequency can be compared with the results of exam8_1.m, which verifies the reliability of the program)