POSSIBLE SKYSCRAPER PERMANENT MONITORING SYSTEM APPLICATION ON THE TERRITORY OF THE REPUBLIC OF SERBIA
MILOŠ BASARIĆ Military Geographical Institute - ‘‘General Stevan Bosković’’, Belgrade, [email protected]
IVAN GARIĆ Military Geographical Institute - ‘‘General Stevan Bosković’’, Belgrade, [email protected]
Abstract: Permanent monitoring system for high rise buildings is a system for control and monitoring. The paper presents two examples of high rise buildings in the world, and then gives a proposal for the locations and types of sensors that would be used for permanent monitoring of the Belgrade Tower. The first example is the Burj Khalifa, a business and hotel center built in Dubai in 2010. Another facility that has an integrated system for permanent monitoring is the Shanghai Tower, which is far more robust. In the proposal of permanent monitoring of the Belgrade Tower, the basic calculation of possible costs of sensor procurement was performed. The calculation of costs does not include the software, installation or the maintenance of the system. Keywords: permanent monitoring, Belgrade Towe,r
1. INTRODUCTION 2. CONCEPT OF THE PERMANENT Shifting the boundaries of the modern construction and MONITORING SYSTEM architecture beyond the concept of conventional building Sensor networks are the basis of the facilities permanent structures is especially visible in the case of tall buildings monitoring concept. The sensor network is a distributed that are becoming lighter, more flexible and with greater system made up of a different type of the sensor group height, which leads to measures having to be taken as a interconnected by a communication network. The data result of their structural sensitivity and interaction with from the sensor output are divisible and represent the the urban environment. Those construction requires input of the distributed system which performs the data complete monitoring that would provide feedback of their evaluation (estimation). The task of this system is to microdynamics. extract the most probable information about the ‘‘Advances in other technical disciplines in the last phenomenon being monitored, depending on the sensor decade of the 19. century, primarily electronics, have type, based on the available data from the sensor. The made the availability of high technologies in the case of basic elements of the network are individual building construction in order to improve it and open new multifunctional sensor nodes (which include sensor units) possibilities. This resulted in the creation of a new which connected to the communication network form a discipline in civil engineering and surveying, structural sensor network. When the monitored phenomena reach condition monitoring (Structural Health Monitoring - by values that exceed the limit values, then the feedback analogy with human health control)’’[1]. information is provided in the central system which is the main assumption of the system intent. ‘‘These and other technologies have resulted in higher demands for equipment and systems for testing various Different types of geotechnical and surveying sensors structures, which has resulted in the commercialization of within the sensor nodes from different interest areas for high technologies in the field of sensors, data acquisition the building structural condition are installed, and they are and analysis for the experimental construction design placed on the characteristic points of the object from verification. In this way, the conditions were created for where the measurements of characteristic values are the significant improvements of the possibilities for the performed. In the case of the application of optical building structures testing and brought new technologies surveying instruments, optical prisms are placed on the available for wider application’’[1]. object structure as the passive elements. Some of these values may relate to the climate conditions, wind The paper presents a conceptual solution for the pressure, horizontal and vertical accelerations, force, permanent monitoring system of a building under vector displacements, inclination relative to the horizontal construction, Belgrade Tower, in the form of a suggestion or vertical plane, and groundwater pressure. for the spatial arrangement of sensors and communication solutions. Suggested system structure financial costs are Measurements are performed automatically and analyzed in Chapter 5. periodically in relation to the current state of the object,
POSSIBLE SKYSCRAPER PERMANENT MONITORING SYSTEM APPLICATION ON THE TERRITORY OF THE REPUBLIC OF SERBIA OTEH 2020 after which the results are collected within a single user flexible in terms of positioning, relocating and interface where the analysis is performed, often based on modularity. the internet geoportal solution. In newer monitoring systems, communication is usually done via wireless internet connection. In the case of results obtained outside the range of set (expected) values, an automatic alarm is performed in the central system, which informs the system user about the current state of the facility. Based on these measurements, decisions are made regarding the maintenance and rehabilitation of the monitored facility. The basis for the standardized realization of the permanent monitoring process is the OGC Sensor Web Enablement (SWE) standard.
3. EXAMPLES OF PERMANENT Figure 1. Overview of the transverse and longitudinal MONITORING SYSTEM APPLICATION profile of the Burj Khalifa IN THE WORLD ‘‘The first application of the SmartSync system took place during the construction of the Burj Khalifa in 2008. In the next part of the paper, permanent monitoring Two accelerometers were placed on the 137th floor with system examples of the two buildings that occupy a very meteorological sensors and sensors for measuring noticeable place on the list of the tallest skyscrapers in the displacement (global displacement modules) that relied on world will be presented. GPS technology. As a reference point, such module for ‘‘Changing the trend in construction entails a change in measuring displacement is placed at the foot of the technological solutions when it comes to monitoring. building. The sampling values for these sensors were: Monitoring of conventional buildings was based on a accelerometers - 20 hertz, meteorological sensors - 1 hertz centralized network of sensors with a wired connection. and displacement sensors - 10 hertz. This setting provided The wired system has encountered the problem of feedback on the buildings dynamics during the synchronization and data loss in transmission, but also construction phase as well as the verification of concept from the technical point of view regarding the installation for the system in a given environment’’[2]. of the cable connection vertically. Although more ‘‘In 2010, 9 more accelerometers were added to this complex, the wireless connection system gives greater system, installed at 7 different locations, and the original reliability of synchronization and there is no loss of data setting was moved from the 137th floor to the 160th floor. in the transmission’’[2]. Such a setting was followed by two servers where one In accordance with these needs, the SmartSync was based on the processing of GPS data obtained from monitoring system was created, which is used for the displacement tracking sensors to determine the current purposes of the Burj Khalifa’s permanent monitoring. The position of building elements, while the other was internet connection replaced the cables that connected the synchronized according to the flow of new data’’[3]. sensors to the control panel located in the building itself. During the year of 2016, the existing setup was expanded Modular sensors, which can measure the values of by 5 biaxial, high-precision tiltmeters set at different acceleration, displacement of the building, meteorological heights to improve performance in real-time location data, within this system can be installed at any location in estimation. The obtained slope values were converted into the building where a network connection and power displacement values in accordance with the height where supply can be provided. In this way, flexibility in the the sensor was placed. Additional unification of this placement, expansion and relocation of sensor elements monitoring system will be achieved after the expansion of over time is achieved. As the sampling rate and sensor the Internet environment for visualization and data density fit the capabilities of the local internet connection, management that will allow authorized users to assess at a this type of access is fully practicable for data flow that higher level both the data in real time situation and monitoring requires. archived data from previous observations for comparison. The Burj Khalifa is hotel and business center in Dubai ‘‘This system is a trigger-based system, which means that built in 2010 as the tallest building in the world with a not all data is stored. The collected and processed data is height of 828 meters with 163 floors. The building is Y- stored for 10 minutes in the database. If due to certain shaped and consists of 3 wings and each wing is circumstances or natural phenomena (wind or seismic connected to the hexagonal base of the building. In this event) it is established that the values of the measured way, the construction of the building has a torsionally- quantities exceeded the defined zone of expected values curved aesthetic structure (Figure 1). for the next 50 minutes, the data are stored as a one-hour history cycle in the database’’[2]. This process continues As the monitoring system was set up in the later stages of until the measured values fall into the expected value construction and then evolved into a permanent zone in a ten-minute cycle. This approach minimizes the monitoring system, such a system was required to be data management process and clearly indicates the
POSSIBLE SKYSCRAPER PERMANENT MONITORING SYSTEM APPLICATION ON THE TERRITORY OF THE REPUBLIC OF SERBIA OTEH 2020 periods in which deeper data analysis should be that environment, time chronicles and history of performed. measurements, statistical processing, sudden jumps of measured quantities as well as many other secondary Figure 2 shows the environment in the web interface for analyzes can be followed. insight and overview of the monitoring system. Within
Figure 2. Inspection of sensors by parts of the building [3] This monitoring system includes over 400 sensors that are located in the structure elements of the building, as well as on the building itself. ‘‘The key things of this monitoring system are [4]: simultaneous installation of sensors and construction of the object itself, in order to collect the initial values of parameters, measurement of structural displacements and subsidence during different phases of the construction, direct measurement of wind influence on the structure using 27 sensors for measuring wind pressure and measuring the inclination angles of an object at the different heights with the help of 40 Figure 3. Overview of the transverse and longitudinal inclinometers’’ [4]. profile of the Shanghai Tower ‘‘The monitoring system consists of 4 modules: sensor China’s approach to permanent monitoring has a far more system, communication and data collection module, complex structure. The Shanghai Tower is a building 632 processing and control module and risk assessment meters high. It represents the tallest building in China and module’’ [4]. the second tallest building in the world. It was built in the The sensor system is responsible for collecting raw data period from 2008 to 2014. It houses office and hotel from different types of sensors. The sensor system facilities, and some parts of the building are used for includes 11 different types of sensors with a total number cultural and other commercial purposes. ‘‘The triangular of over 400 sensor units, as shown in Table 1. ‘‘These outer facade covers the entire building, gradually twisting o sensors are arranged to monitor three parameters: load in a clockwise direction by about 120 to the entire height (wind pressure, earthquakes, structure temperature), of the building (Figure 3)’’ [5]. The building is divided structural responses of the object - object behavior into 9 height zones on the basis of the eight reinforced (subsidence, inclination, displacement or torsion) and floors, in accordance with which the monitoring solution effects of the internal environment (air flow and was implemented. temperature)’’ [4].
POSSIBLE SKYSCRAPER PERMANENT MONITORING SYSTEM APPLICATION ON THE TERRITORY OF THE REPUBLIC OF SERBIA OTEH 2020
Table 1. Types and number of sensor units for 4. CONCEPTUAL SUGGESTION FOR permanentmonitoring of the Shanghai Tower [4] THE PERMANENT MONITORING The purpose of the SYSTEM OF THE BELGRADE TOWER Sensor type Number sensor BUILDING earthquake movement The permanent monitoring system is in use on the 1 seismograph 2 detector territory of the Republic of Serbia at the Avala Tower, but considering its importance and position, it is clear that the wind speed and absence of such a system would be unacceptable. 2 anemometer 1 direction However, the application of permanent monitoring in Serbia is not present on the facilities of commercial wind pressure importance such as skyscrapers. In order to initiate the 3 wind pressure 27 sensor application on commercial facilities, the conceptual solution will be based on one of such examples. 4 accelerometer speed up 71 Based on the analyzed examples of permanent 5 inclinometer deviation by axes 40 monitoring, the conceptual solution will be given below temperature 6 thermometer 75 as a proposal for permanent monitoring of the Belgrade measurement Tower skyscraper, still under construction. The displacement 7 extensometers 209 conceptual solution is not based on the conditions of measurement economic profitability, but on the functionality of the 8 GPS displacement vector 3 monitoring application in accordance with the character 9 total station spatial displacement 2 of the construction site location, but economic factors will be discussed separately in the next chapter. 10 level instrument vertical displacement 1 Belgrade Tower is a 42-storey skyscraper under construction 11 video camera spatial displacement 1 within the Belgrade Waterfront project. The planned height In total 432 of the building is 168 meters and as such, upon completion of construction, it will be the tallest building in Serbia. The All these sensors were chosen to provide important characteristics of its location are that it is located in the information related to the static and dynamic properties of immediate vicinity of the right bank of the Sava River in the the observed object. The sensors are placed in specific part of Belgrade better known as Savamala. The purpose of places based on research studies. ‘‘The accuracy of the the building is business and hotel space as well as separate data obtained for a specific structural deformation can be residential units (Figure 4). Construction of the building improved by combining several different types of sensors. began in 2016. For example: the camera, total station and GPS are set up to give feedback on the horizontal movement of the top of the object in different phases of construction. The combination of GPS, accelerometer and inclinometer provides reliable information on the static and dynamic movement of the object’’ [5]. Communication and data collection consists of 11 separate substations, which are located at different heights of the building to communicate with other sensors. In real time, data is transferred from the substations to the main monitoring station. ‘‘During construction, a wireless form of communication between stations and sensors was used. After the completion of the facility construction, it was switched to wired communication, which provides longer life than wireless transmission’’ [4]. The data processing and control module consists of high- performance computers and data processing software. This computer is located in the central monitoring room, to control the operation of the subsystems. The risk assessment module consists of a facility performance assessment system and a safety assessment system. The system for evaluating the performance of an object works on the basis of a combination of static and dynamic measurements, adopted models and predefined critical values of parameters. Figure 4. Perspective view of the Belgrade Tower
POSSIBLE SKYSCRAPER PERMANENT MONITORING SYSTEM APPLICATION ON THE TERRITORY OF THE REPUBLIC OF SERBIA OTEH 2020
In accordance with the given examples of skyscrapers at meteorological sensors, i.e. thermometers and wind the world level, the idea of setting up a geosensor network pressure sensors, as well as accelerometers that can be for monitoring purposes for this facility will be presented placed in the central part of the building. When it comes below. to measuring displacement vectors, GPS sensors can be placed at the top of the building where these In considering the previous examples, it can be noticed displacements are most impressive along with reference how the structure of the monitoring elements can be sensors of this type at the base. Also, by placing optical divided into three parts. These are elements that are prism for the use of total station measurement on the top grouped in the base, top or upper part and body of the of the building, optical visibility would be provided in building. The connection between the sensor settings for numerous places in the immediate vicinity, considering the base and the roof of the building can be considered in that this building will dominate the Savamala region with particular, but it is noticeable that their role is cohesive its height. Additional corroboration of this data can be work in order to provide GPS control while measuring the achieved by placing a biaxial tilmeter on top of the displacement vectors, while the body of the building is building. Given the proximity of the river as well as the characterized by sensors setup that measure soil problems that appeared during the construction, meteorological conditions and wind pressure. setting up a piezometer to measure groundwater pressure The location of this building is near the river Sava. As a is very important. In that way, it would be possible to problem with groundwater in the area of the construction monitor underground activities and react in a timely site appeared during the construction, in the analysis of manner. For all other additional movements, the monitoring system setting, attention will be paid to the accelerometers can be placed in the central part of the groundwater prevention by installing piezometer sensors. building, as well as at the foot of the building due to The location of the building foundation in relation to the possible soil dynamics. The scheme of the sensors river in the initial phase of construction is shown in placement within the building is presented in Figure 6. Figure 5.
Figure 6. Spatial arrangement of sensors within the Belgrade Tower building Figure 5. Location of the Belgrade Tower building foundations 5. CALCULATION OF POSSIBLE COSTS The communication solution of the hardware elements of Geodetic, geotechnical and other sensors represent the the Belgrade Tower monitoring, considering the height of core of the system for monitoring of high rise buildings. the building, should be via the Internet. In this way, the In addition to the costs of the sensors themselves, the minimization of data loss could be ensured. On the other costs of setting up and initializing should also be taken hand, the data management process should be based on into account. Table 2 presents the estimated costs of the server application. individual sensors and the total cost of procuring the required sensors. In that case, other facilities that are an integral part of the Belgrade Waterfront project could be incorporated into In addition of the cost of the sensor themselves, real-time the monitoring process, so we could talk about centralized monitoring requires appropriate software. There are permanent monitoring system of the entire group of ready-made licensed solution, such as Leica GeoMos or facilities in the immediate vicinity within the same Trimble 4D. In addition to these licensed solutions, there internet network. are also free open source solutions. Both solutions have their advantages and disadvantages. As the proposed As there are no seismic activities on the territory of communication solution is via wireless connection, open Belgrade city, the emphasis can be placed on source solutions could not meet these requirements. The
POSSIBLE SKYSCRAPER PERMANENT MONITORING SYSTEM APPLICATION ON THE TERRITORY OF THE REPUBLIC OF SERBIA OTEH 2020 use of Leica GeoMos software is recommended. The References price of one license of this software is around 24 000 €. [1] Mišković, Z., Milovanović, G. 2009. Structural Table 2.Types of sensors with cost for permanent Monitoring Of Rebuilt Telecomunication Tower monitoring system of Belgrade Tower [8, 9, 10, 11, 12] “Avala’’, Izgradnja, 63 (7-8), pp. 373-378 [2] Kijewski-Correa, T., Kwon, D., Kareem, A., sensor type cost [€] quantity ∑ Bartolini, A., and Abdelrazaq, A., 2013. Implementation of the SmartSync Concept on the 1 total station 42 700 1 42 700 Burj Khalifa: An Application of Structural Identification for Tall Buildings. Collection of SHM 2 piezometer 350 1 350 Case Studies by ASCE SEI Methods of Monitoring Committee. 3 GPS 16 000 2 32 000 [3] Kijewski-Correa, T., Kwon, D., Kareem, A., Bentz, 4 accelerometer 1 300 2 2 600 A., Guo, Y., Bobby, S. and Abdelrazaq, A., 2013. wind pressure 5 1 200 1 1 200 SmartSync: An Integrated Real-Time Structural sensor Health Monitoring and Structural Identification 6 biaxial tilmeter 1 300 1 1 300 System for Tall Buildings. Journal of Structural 7 thermometer 180 1 180 Engineering, 139(10), pp.1675-1687. [4] Su, J., Xia, Y., Chen, L., Zhao, X., Zhang, Q., Xu, Y., ∑ 80 330 . . . Chen, A. 2013. Long-term structural performance monitoring system for the Shanghai 6. CONCLUSION Tower. Journal of Civil Structural Health Monitoring, 3(1), 49-61. doi:10.1007/s13349-012- The application of permanent monitoring undoubtedly 0034-z provides a new approach in terms of maintenance, control and monitoring of the behavior of buildings, weather it is [5] Annamdas, V., Bhalla, S. and Soh, C., 2016. a high rise building, tower, bridge, for commercial or Applications of structural health monitoring noncommercial use. The benefits of obtained through the technology in Asia. Structural Health Monitoring: application of permanent monitoring cannot be measured An International Journal, 16(3), pp. 324-346. with the cost of establishing it. The data obtained from [6] Li, Q., He, Y., Zhou, K., Han, X., He, Y. and Shu, Z., monitoring system are very important. It is possible to 2018. Structural health monitoring for a 600 m high monitor certain changes in real time and react in time in skyscraper. The Structural Design of Tall and case of possible deformations or catastrophes. With the Special Buildings, 27(12), p.e1490. help of the history of measurements, it is possible to find [7] Gradnja. 2020. Beograd Na Vodi. [online] out the behavior of the object on various environmental Availablepat: