On-site vibration test of the servicing rigsubstructure is made, and the frequency response function curve and preceding 10 modes frequency are obtained.
对现役钻机底座做了现场振动测试，得到频响函数曲线及前10阶模态频率。
2
Thus, it's necessary to improve the design of rigsubstructure or better the dynamic characteristic of substructure that is being used by dynamic modification.
所以改进钻机底座的设计或对现役钻机底座进行动力修改以改善其动态特性，很有必要。
3
It is at the same elevation as the rig floor, usually cantilevered out from the main substructure supporting the rig.