SHM: Structural Health Monitoring

Ping-An Finance Center (PAFC), with a total height of 600 m, is the fourth tallest building in the world. An integrated structural health monitoring (SHM) system with total number of 553 sensors, which was designed based on the modular design methodology, is being installed in PAFC to monitor its structural performance and external excitations during both construction and service stages. This paper first gives a brief introduction of the architecture of the SHM system, followed by detailed descriptions on its 7 subsystems, including the components, functions, and interrelationship corresponding to each subsystem. The modular design of the SHM system ensures highly effective operation of the comprehensive monitoring system, and such an extensible system allows the subsystems to be deployed and augmented easily to meet the evolving monitoring needs. The second part of this paper introduces the research activities and selected results from the SHM system equipped in PAFC, including monitoring of vertical deformations of various structural components, verification of effectiveness of active tuned mass damper systems, and verification of numerous damage identification methods. Finally, representative monitoring results from the SHM system in PAFC during a typhoon are presented and discussed. This paper aims to provide useful information for the SHM, construction, and design of super-tall buildings.

Ending. 

BENCHMARK PROBLEM STUDIES OF THE SHM SYSTEM

It is of great significance to establish a SHM benchmark regarding a full-scale structure with field measurements, which enables involved researchers to testify their SHM techniques using the measured data from a full-scale structure. Given this situation, a SHM benchmark platform for super-tall buildings is developed by taking PAFC as a test platform, in which a wide range of tasks are included and introduced below:

VERTICAL DEFORMATION OF SUPER-TALL BUILDINGS

It has been well recognized that reinforced concrete buildings are subject to vertical deformations (axial shortenings), including elastic deformations caused by short-term service loads and inelastic deformations due to concrete rheology (creep and shrinkage). Moreover, the differential axial shortenings between gravity load-bearing elements in structural systems with different stiffness could also result in adverse effects, such as unacceptable cracking and unexpected distortions of floor plates, which not only cause the damages of facade and finishes but also lead to difficulties in mechanical and plumbing installations and elevator operation. [25] Under such circumstance, a strategy named as “elevation reservation” was adopted at the design stage of PAFC, in which certain lengths for vertical structural components of the super-tall building were reserved from the beginning of the construction of each floor (Figure 9), which attempt to compensate for the axial shortenings of vertical load bearing elements. The lengths of reserved elevations, as determined by numerical analysis at the design stage of PAFC, took into account of the effects of shrinkage and creep of concrete, construction sequence and various loads on vertical structural members, and so forth. It was expected that the length of reserved elevation for a vertical load bearing element equals to the corresponding accumulative vertical deformation after the first service year. In other words, the floor elevations of PAFC could reach the designed heights at the time after the building is in-service for 1 year. The schematic diagram of the ith floor elevation reservation is shown in Figure 10. [26] The construction monitoring system that is a part of the SHM system established in PAFC was deployed to monitor the structural performance during the construction process of PAFC, and field measurements at various construction stages were used to validate numerical analysis results. In particular, the surface-type and embedded fiber Bragg grating (FBG) sensors were used to assess the vertical deformations of the vertical structural members of PAFC. The effectiveness of the elevation reservation strategy can therefore be validated by means of a comparison between the field measurements and numerical predictions of the axial shortenings of vertical load bearing components.

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AUTHORS: QIUSHENG LI, DEPARTMENT OF ARCHITECTURE AND CIVIL ENGINEERING, CITY UNIVERSITY OF HONG KONG, KOWLOON TONG, HONG KONG, ARCHITECTURE AND CIVIL ENGINEERING RESEARCH CENTRE, SHENZHEN RESEARCH INSTITUTE, CITY UNIVERSITY OF HONG KONG, SHENZHEN, CHINA, YINGHOU HE, ARCHITECTURE AND CIVIL ENGINEERING RESEARCH CENTRE, SHENZHEN RESEARCH INSTITUTE, CITY UNIVERSITY OF HONG KONG, SHENZHEN, CHINA, SCHOOL OF CIVIL ENGINEERING AND MECHANICS, HUAZHONG UNIVERSITY OF SCIENCE AND TECHNOLOGY, WUHAN, CHINA, KANG ZHOU, ARCHITECTURE AND CIVIL ENGINEERING RESEARCH CENTRE, SHENZHEN RESEARCH INSTITUTE, CITY UNIVERSITY OF HONG KONG, SHENZHEN, CHINA, XULIANG HAN, ARCHITECTURE AND CIVIL ENGINEERING RESEARCH CENTRE, SHENZHEN RESEARCH INSTITUTE, CITY UNIVERSITY OF HONG KONG, SHENZHEN, CHINA, YUNCHENG HE, DEPARTMENT OF ARCHITECTURE AND CIVIL ENGINEERING, CITY UNIVERSITY OF HONG KONG, KOWLOON TONG, HONG KONG, ZHENRU SHU, DEPARTMENT OF ARCHITECTURE AND CIVIL ENGINEERING, CITY UNIVERSITY OF HONG KONG, KOWLOON TONG, HONG KONG.