Structural Health Monitoring of High-Rise Structure Using Different

Dynamic Properties

Kivanc Taskin

, Kerem Peker

and Müge Çelik

Eskisehir Technical University, Engineering Faculty, Civil Engineering Department, İki Eylul Campus, Eskisehir, Turkey

Erdemli Engineering and Consulting, Vişnezade Mahallesi Babaefendi Sokak Ufuk Palas No:3/1-2-4-6 34357 Beşiktaş,

İstanbul, Turkey

Keywords: Accelerometer, Dynamic Behaviour, Structural Health Monitoring, High-Rise Building.

Abstract: In this study, while monitoring the structural health of a tall building, it covers and exemplifies how sensor

placements should be, updating the digital model, continuous tracking, and event-based tracking. Pre-

engineering of the structure was carried out, and the system was analyzed with ground accelerations at

different levels. According to the results of this analysis, by giving priority to the floors where the stiffness

changes are experienced, sensors were placed on the floors determined, and on-site readings were done. With

the data taken from the accelerometers, the structure was followed continuously, and the trend lines of the

structure were determined. The behavior of the building was observed under single events, and it was checked

whether the trigger levels given for the structure were exceeded with a sample earthquake. The performance

of a high structure created in the model was determined under possible earthquake records. In light of the

actual acceleration records obtained thanks to the accelerometers placed in this building, the structure was

constantly monitored, the structure behavior under the influence of the earthquake was recorded, and the

dynamic properties of the building were realistically reported.

1 INTRODUCTION

It is known that our country is on an active seismic

belt and is always at risk considering its building

stock. This situation shows the necessity of

determining the performances of the structures and

building them according to these performances. The

Turkish Building Earthquake Regulation, which

entered into force in 2018, made it necessary to

design according to the implementation of the

structures. It is essential to examine whether the

structure behaves as designed under the influence of

different forces and to conduct engineering studies of

the structure according to the determinations made.

Structures are exposed to various ambient

vibrations and effects such as temperature, strong

wind, heavy rains, and strong ground motion. A

building health monitoring system is used to gather

information about worn-out structures and to

understand their behavior. With the help of sensors

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placed on buildings in the building health monitoring

system, vibrations monitored in real-time and

numerical quantities such as acceleration, velocity,

and displacement can be obtained. If the data is used,

it is possible to determine the damage conditions and

control whether the trigger levels given for the

structure are exceeded. Based on the physical change

values recorded by pre-engineering studies,

interpretations can be made about the mechanical

behavior of the structure.

Many researchers have studied building a health

monitoring system for a long time. Considering the

studies on structural health monitoring, analytical

studies on existing structures and experimental

studies on shaking tables appear. 21st century The

developments in structural health monitoring and

technology in the early days caused significant

progress in both the number and content of real-world

applications related to structural health monitoring

Taskin, K., Peker, K. and Çelik, M.

Structural Health Monitoring of High-Rise Structure Using Different Dynamic Properties.

DOI: 10.5220/0012114100003680

In Proceedings of the 4th International Conference on Advanced Engineering and Technology (ICATECH 2023), pages 265-272

ISBN: 978-989-758-663-7; ISSN: 2975-948X

 2023 by SCITEPRESS – Science and Technology Publications, Lda. Under CC license (CC BY-NC-ND 4.0)

265

and brought laboratories to the real world (Tekdemir,

2020).

Kırkpınar (2010) monitored a twenty-six-story

high-rise built with a core shear wall system in

Istanbul with sixteen accelerometers and obtained the

natural oscillation frequencies and mode shapes of the

structure by system diagnostic method. The real-time

data obtained were compared with the finite element

model results, and time-history analyses were

performed under the earthquake records. The finite

element model update applied based on the mode

values defined in this study has played a significant

role in determining the earthquake load demand on

the building.

The data obtained from the shaking table tests

carried out with earthquake recorders were analyzed

using definition methods in the time and frequency

domain. Results were obtained in practical

application (Alçık & Beyen, 2015). In the

experiment, accelerometers were placed on the model

at floor levels, and various filters were applied to the

vibration data obtained.

When the numerical analysis results were

compared with the model, it was seen that the

experimental data were consistent (Durgun, 2013).

Thirty-six accelerometers were used to monitor the

vibrations of the cast-reinforced Green Building

located on the Massachusetts Institute of Technology

campus and to measure the building's translational,

torsion, and vertical responses. Comparisons were

made between seven field measurement data sets

taken from the building. This building has an

identifiable soil-structure interaction behavior, and

the ground motion had significant effects on the

building response (Sun & Büyüköztürk, 2017).

2 MODEL BUILDING AND

METHODOLOGY

2.1 High-Rise Building Model

Within the scope of the article, a forty-four-story high

building with an eleven-floor basement and thirty-

three floors above ground is examined. The structure

studied has a total height of 190.67 m, Figure 1.

2.2 Dynamic Behavior of the Building

with Pre-Engineering Studies

It is expected that the structure will be damaged at

various levels as a result of earthquakes. The

structural health monitoring system is more

concerned with the level of damage to the building

than the data it will provide on whether the damage

limits have been exceeded. In structural health

monitoring systems, it is necessary to monitor the

vibrations occurring in the structure in order to be

able to interpret what levels the structure reaches in

the region up to its elastic limits.

Figure 1: High-rise Building Model.

In this article, elastic analysis was performed by

simulating a single component of the Kobe

earthquake to the design spectrum at seven different

levels, from the earthquake level, which is very

difficult to be felt by people, to a certain percentage

of the design earthquake, in order to express the

ground movements at various levels, all of which,

except the design earthquake, are expected elastic

behavior in terms of the structure.

By using the scaling method in the frequency

domain, it is possible to obtain records that broadly

match the design spectrum (Özdemir, Fahjan. 2007).

By scaling the 0.32 g acceleration level frequency

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266

domain using the original earthquake record of the

Kobe earthquake, the acceleration spectrum for this

acceleration record and the design spectrum for the

0.32 g acceleration level according to TBDY 2018

was created (Figure 2, Figure 3)

Figure 2: Original and scaled earthquake recording for 0.32

g acceleration level.

Figure 3: Original acceleration spectrum, scaled

acceleration spectrum, and design acceleration spectrum for

0.32 g acceleration level.

The general characteristics of the structure can be

determined from small ground movements where it is

not damaged at all to large ground movements where

it is heavily damaged. For this reason, target-based

spectra were created considering different

acceleration levels. These spectra were designated as

trigger levels, and each was scaled similarly. The

acceleration spectra generated are given in Figure 4.

The acceleration-time graphs created for acceleration

levels other than the original acceleration level are

shown in Figure 5.

The displacement values found by the analyzes

for different acceleration levels are given in Figure 6

and Figure 7. When these data are examined,

gradually decreasing displacement values for all

floors have been obtained from the analyses made for

different acceleration levels from 0.1 g acceleration

level to 0.0005 g acceleration level.

Figure 4: All scaled acceleration and design spectra.

Figure 5: Scaled acceleration records.

In Figure 8 and Figure 9, acceleration values read

at all building floors for different acceleration levels

are given. For all acceleration levels, increasing

acceleration values are seen from the foundation to

the top of the structure.

-0,1000

-0,0500

0,0000

0,0500

0,1000

0,00 10,00 20,00 30,00

(g)

(sn)

0.1_İK

-0,0100

-0,0050

0,0000

0,0050

0,0100

0,00 10,00 20,00 30,00

(g)

(sn)

0.01_İK

-0,0010

-0,0005

0,0000

0,0005

0,0010

0,00 10,00 20,00 30,00

(g)

(sn)

0.001_İK

Structural Health Monitoring of High-Rise Structure Using Different Dynamic Properties

267

Figure 6: Floor displacements in the x-direction.

Figure 7: Floor displacements in the y-direction.

Figure 8: Acceleration in x-direction.

Figure 9: Acceleration in y-direction.

As a result of the analysis, the relative story drift

graphs of the building are presented in Figure 10 and

Figure 11. In these graphs, it is seen that there are

severe changes in some floors along the height of the

building. It is observed that the floors where these

value accumulations are experienced are the regions

where the ductile frame system consisting of columns

and beams undergoes profound rigidity changes. The

mass stiffness, wall thicknesses, or plan dimensions

change.

Figure 10: Drift ratios (mm) in the x-direction.

Figure 11: Drift ratios (mm) in the y-direction.

3 STRUCTURE SENSOR

LAYOUT

The building health monitoring system, which

provides data on the building, shows the changes and

ensures that the damage detection methods are

applicable and the technical characteristics of the

related hardware. The excellent planning of its

placement in the building provides reliable data from

the system.

Modern design and manufacturing regulations

have made it mandatory to place and properly

monitor this equipment for some particular building

types. For this reason, in parallel with TBDY 2018,

the Structural Health Monitoring System Directive

(YSIS Directive 2019) was prepared and put into

effect for the establishment, maintenance, continuous

monitoring, and reporting of structural health

monitoring systems for buildings classified as high-

rise buildings and defined by their unique conditions.

-11

-7

-3

0 20 40 60 80 100 120 140

Floor

0.10

0.05

0.01

0.005

0.001

-11

-7

-3

0 20 40 60 80 100 120 140 160

Floor

0.10

0.05

0.01

0.005

0.001

-11

-7

-3

0 1000 2000 3000 4000 5000

Floor

0.10

0.05

0.01

-11

-7

-3

0 1000 2000 3000 4000 5000 6000

Floor

0.10

0.05

0.01

-11

-7

-3

0,0000 0,0010 0,0020

Floor

0.10

0.05

0.01

-11

-7

-3

0,0000 0,0005 0,0010 0,0015 0,0020

Floor

0.10

0.05

0.01

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In buildings that are planned to be continuously

monitored in real-time, firstly performing numerical

analysis for the placement of the hardware and

considering the floors where there are changes in the

height of the building, which can be considered

necessary in terms of building dynamics, as

intermediate monitoring zones ensure healthy

monitoring of the building (Çelik, Taşkın, Peker and

Güneş, 2019).

The correct placement of sensors is related to the

parameters to be measured and monitored. The

parameters to be followed can be listed as translation

modes in the horizontal x and y directions, torsion

modes (around the vertical axis), rotations of the rigid

structure around the foundation (around the x and y

axis), vertex displacement, floor displacements, and

interstory translation ratios. The displacements at the

apex are critical for modal analysis due to their

contribution to higher-order modes, so sensors must

be placed on the structure's top floor. A uniaxial

sensor should be placed at one point on the mezzanine

floors where the critical stiffness changes. A biaxial

accelerometer should be placed at a second point,

leaving a specific opening. Accelerometers with

vertical axis should be placed on the basement floor

to follow the rigid structure's rotations around the

foundation (Dinçer, Aydın, & Gencer, 2015).

With the analyses made as a result of preliminary

engineering studies, It has been determined that the

floors where there are severe changes in building

dynamics along the building height are the floors

where damage or possible disturbances can be seen.

Considering Figure 10 and Figure 11 above,

accelerometer placements were made on the floors

where the stiffness changes and the value

accumulations of the building are experienced. An

example image of accelerometer placements is given

in Figure 12.

4 RESULTS

4.1 Model Update with Recorded

Acceleration Data

The model update process integrates the results

obtained by the correct definition of the building

behavior with the data obtained from the field most

consistently. While updating the structure, the

reference behavior data, the correct selection of the

parameters to be updated, and the model calibration

process affect the resulting model.

Figure 12: Locations of the sensors.

The vibration records taken from the structure are used

for updating the model. The numerical model of the

structure is arranged as closely as possible and the mass,

stiffness, and damping values are updated most realistically

by simulating many structure modes.

The structural stiffnesses and elasticity modules of this

structure continued to shift until the results received from

the numerical model and the values read on-site were in

agreement with one another. By paying attention to the

predominant frequencies, it was determined that it was

adequate for the difference in value before and after the

upgrade to fall within the percentage range of 5 to 10%.

(Beyen, 2017). Table 1 presents the frequency values that

were acquired following the update to the model and that

were read on-site.

Table 1: Model frequencies (Hz) read in situ and after the

model update.

Modes

In-situ

Records

After

Update

Difference

Mode 0.354 0.338 %4.50

Mode 0.354 0.341 %3.67

Mode 0.488 0.446 %8.60

Structural Health Monitoring of High-Rise Structure Using Different Dynamic Properties

269

4.2 Build Trend, Trigger Level, and

Reporting in Continuous Events

Continuous monitoring is a method that covers the

data obtained from the past to the present and

estimates the data that can be obtained in the future.

While the building's health is constantly monitored,

reports on dynamic properties such as displacement,

acceleration, and speed are made using the data taken

at specific intervals.

While structural health is constantly monitored,

changes in the dynamic properties of the structure and

changes in damping values are followed. In the

process, the trend line was created by following the

frequency value changes of the structure. This

trendline can have a horizontal or downward slope,

and a downward-sloping trend line indicates wear in

the structure. By estimating the change in that trend

line and determining whether it is acceptable, it is

possible to predict how long it will continue to follow

the structure.

Since the building has no experience, it starts to

experience seasonal changes and wear caused by

people and equipment. With the increase in long-term

use of the structure, its period becomes longer due to

increased damping or mass.

The structure was analyzed according to its

stiffness before wear, the section stiffness of the

structure with the model updated, and the cracked

section stiffnesses according to TEC 2018, and the

structure modes were obtained. As a result of the

analyzes made, the frequency values of the structure

are given in Table 2, Table 3, and Table 4 below.

Table 2: Model frequencies obtained before an earthquake.

Modes Frequencies (Hz)

Mode 0.314

Mode 0.388

Mode 0.414

Table 3: Model Frequencies of the Structure After Update

Modes

Frequencies (Hz)

Mode

0.338

Mode

0.341

Mode

0.446

Table 4: Model Frequencies According to TEC 2018

Cracked Section Stiffness of the Structure

Modes Frequencies (Hz)

Mode 0.185

Mode 0.235

Mode 0.240

Vibration recordings were taken every month

from June 2017 to September 2020 for both the X and

Y directions of the structure using accelerometers.

The records taken formed a trend line in the process.

The structure's frequency values and the modes'

changes during the recording period were examined.

It can be said that the structure behaves as predicted

if the values read and monitored are within limits set.

The trend may damage the frequency values' structure

outside the determined limit values. For this reason,

continuous monitoring is critical to determine the

structure's trend in the coming years.

According to Figure 13, the first mode start

frequency for our structure's X direction is 0.36, and

according to Figure 14, the second mode start

frequency for our structure's X direction is 0.50.

Examining the frequencies of these two modes

reveals that the structure is stable because the slope

connecting the peaks of the value changes occurs at a

level that is comparable to what is considered

appropriate. Variations in temperature throughout the

year and shifts in the building's mass are two potential

contributors to shifts in frequency values.

Subsequently can be seen that the third Mode

starting frequency for the X orientation of the

structure is 1.92, and it can also be seen that a trend

line with a downward slope is formed. Both of these

observations can be found in Figure 15. Because the

structure has not yet reached a conclusion regarding

the third mode, the tendency should be adhered to.It

can be seen in Figure 16 that the first mode start

frequency for our construction in the Y direction is

0.36, and it can be seen in Figure 17 that the second

mode start frequency for the Y direction is 0.53.

When the fluctuations in the frequency values are

taken into account, both the increases and the

reductions in value are stable.

Figure 13: Structural Frequency Values Read to the X

Direction Sensors for the first mode.

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270

Figure 14: Structural Frequency Values Read to the X

Direction Sensors for the 2

Mode.

Figure15: Structural Frequency Values Read to the X

Direction Sensors for the third mode.

Figure 18 illustrates that there has been a gradual

decline over time in the third mode frequency for the

Y orientation of the structure, with the slope falling

between 1.56 and 1.50. The third phase of the build

exhibits a moderately steep decline of 3% throughout

its progression.

Figure 16: Structural Frequency Values Read to the Y

Direction Sensors for the first mode.

Figure 17: Structural Frequency Values Read to the Y

Direction Sensors for the second mode.

Figure 18: Structural Frequency Values Read to the Y

Direction Sensors for the 3rd Mode.

5 CONCLUSIONS

In this study, pre-engineering studies of the structure

were made, and numerical analyzes of the structure

were made with ground accelerations at different

levels. According to the results of this analysis,

sensors were placed, and on-site readings were done

by giving priority to floors where stiffness changes

were experienced, wall thicknesses, or plan

dimensions were changed. The structure was

continuously monitored with the vibration data

obtained from the accelerometers, and trend lines

were determined. The changes in the frequency

values of the building during the recording period

were examined. It has been observed that the values

read and monitored are within the limits set, and the

structure behaves as predicted.

With the introduction of building health

monitoring into TBDY 2018, the use of this system in

the new building stock is expected to increase. As

time passes, it will be possible to establish and

Structural Health Monitoring of High-Rise Structure Using Different Dynamic Properties

271

implement the building health monitoring system in

high-rise buildings and all low-rise and specialty

buildings. Thus, it will be possible to evaluate the

behavior of the building through numerical data and

to have information about the damage status of the

building.

The technical equipment needed for building

health monitoring is being provided with lower costs

with the help of technological developments. Suppose

the preliminary engineering work of the building is

carried out. In that case, it is possible to make

comments that will not cause discussion, based on

healthier data about the state of the building, with a

minimum of building health monitoring sensors at the

top and ground point.

ACKNOWLEDGEMENTS

We thank Erdemli Engineering and Consulting firm

for allowing us to use the building data monitored for

structural health in this study.

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