*3.4. National Codes*

Several national codes on SHM have been published in the past two decades. In North America, Intelligent Sensing for Innovative Structures of Canada published the first guideline for SHM, "Guidelines for Structural Health Monitoring" [129] in 2001, in which the techniques of both static and dynamic structural testing, periodic regular inspection, and continuous monitoring were presented and summarized. The Federal Highway Administration, U.S., published guidelines for SHM of bridges and tunnels, "Development of a Model Health Monitoring Guide for Major Bridges" [130] and "Tunnel Operations, Maintenance, Inspection, and Evaluation Manual" [131], where the regular visual inspection is the most important method. The International Federation for Structural Concrete also published "Monitoring and Safety Evaluation of Existing Concrete Structures" as a guideline for SHM of existing concrete structures [132], whereas the vibration-based SHM methods are less important than the quality and durability evaluation of concrete.

In Europe, the Structural Assessment, Monitoring and Control of European Union developed "Guideline for Structural Health Monitoring" [133] in 2006 to present the basic regulations and procedures of SHM, including determination of actions, structural condition analysis, design and operation of monitoring, numerical analysis and general damage identification. It is comprehensive and provides a framework for the following standards and codes. The Russian Federation also published its national code, GOSTR 53778-2010, "Building and structures, technical inspections and monitoring regulations" [134], where regular visual inspections, modal testing methods, condition classification, and grading system were presented. Similar to the Federal Highway Administration, U.S., the German administration also published the codes for SHM of bridges and tunnels, "Quality assurance for structural maintenance, surveillance, checking and assessment of bridges and tunnels, monitoring of bridges and other engineering structures", [135] where checking

procedures and methods were presented. However, it was drafted in German, so it is not so easy for engineers in other countries to understand.

In Asia, "GB50982-2014 Technical Code for Monitoring of Buildings and Bridge Structures" [136], was published by Ministry of Housing and Urban-Rural Development of China. It has nine chapters and covers the basic requirements for SHM systems and general monitoring methods, and specific methods for high rise buildings, long-span spatial building, bridge structures, and other structures. For each type of structure, the requirements of SHM system for both construction stage and operation stage are provided. The monitored data are mostly vibration related, in addition to temperature and humidity. This is a comprehensive technical code on SHM, and its supplementary codes "Application and Analysis of Technical Code for Monitoring of Buildings and Bridge Structures" has also been published. However, it should be admitted that it can be improved by including more advanced vibration-based SHM techniques reviewed in Section 2 and more details about the sensor selection and arrangement.
