The vibration frequency of box gird is usually calculated by the elementary beam theory, but it will lead to a large error because of the existence of shear lag effect and shear deformation.
由于剪力滞效应及剪切变形的存在，箱梁的弯曲振动频率按照初等梁理论计算往往存在较大的误差。
2
Three general analysis methods are discussed: amplitude, time and frequency analysis, which are the most elementary methods.
幅域分析法、时域分析法以及频域分析法。
3
The elementary studies show that insect species can be accurately distinguished through the sound-frequency characteristics of insect activity in grain.