**5. Conclusions**

The vibration-based SHM techniques and related ISO standards and national codes have been reviewed. The advantages and drawbacks of each method as well as the applicability of each standard or code have been presented. For different types of structure, different vibration-based SHM techniques should be selected. There is no universal approach for all types of structures and all kinds of damages. Although the standards, codes, and regulations have provide basic requirements and principles of a SHM system, it is still difficult for engineers to answer questions such as what types of sensors are to be used, where to install them, and how to use the monitored data to evaluate the structure health condition and predict the remaining life for a given structure. Therefore, it is necessary to develop such a code of SHM system construction that can be applied to real civil engineering structures.

**Author Contributions:** Conceptualization, Y.Y.; methodology, Y.Y. and Y.Z.; draft writing, Y.Z. and X.K.T.; final writing, Y.Z. and Y.Y. All authors have read and agreed to the published version of the manuscript.

**Funding:** We are grateful to the following agencies for their supports in this study: The National Key Research and Development Program of China(Grant No. 2020YFF0217802), National Natural Science Foundation of China (Grant No. 51778090, 51911530244), Science and technology plan project of Chongqing Science and Technology Bure (Grant No. cstc2020jscx-msxm0907), Graduate Research and Innovation Foundation of Chongqing, China (Grant No. CYS19004, CYS20022), Science and Technology Project of China Power Construction Co., Ltd. (Grant No. KJ-2020-117).

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Conflicts of Interest:** The authors declare no conflict of interest.
