Ambient vibration testing and seismic performance of precast I beam bridges on a high-speed railway line

Burak Toydemir,Ali Koçak,Barış Sevim,Basak Zengin 국제구조공학회 2017 Steel and Composite Structures, An International J Vol.23 No.5

In this study, the seismic performance levels of four bridges are determined using finite element modeling based on ambient vibration testing. The study includes finite element modeling, analytical modal analyses, ambient vibration testing and earthquake analyses of the bridges. For the purpose, four prestressed precast I beam bridges that were constructed for the Ankara-Sivas high speed railway line are selected for analytical and experimental studies. In the study, firstly a literature review related to the dynamic behavior of bridges especially precast beam bridges is given and then the formulation part related to ambient vibration testing and structural performance according to Turkish Seismic Code (2007) is presented. Next, 3D finite element models of the bridge are described and modeled using LARSA 4D software, and analytical dynamic characteristics are obtained. Then ambient vibration testing conducted on the bridges under natural excitations and experimental natural frequencies are estimated. Lastly, time history analyses of the bridges under the 1999 Kocaeli, 1992 Erzincan, and 1999 Düzce Earthquakes are performed and seismic performance levels according to TSC2007 are determined. The results show that the damage on the bridges is all under the minimum damage limit which is in the minimum damage region under all three earthquakes.

철근콘크리트조 4층 골조건물의 강제진동실험

유은종 한국지진공학회 2007 한국지진공학회논문집 Vol.11 No.2

노스리지 지진에 의해 손상을 받은4층 철근콘크리트조 골조건물을 대상으로 선형가진기 및 대용량의 편심가진기를 이용한 강제진동실험과 상시미진동 측정을 실시하였다. 미진동 가속도데이터 및 선형가진기에 의한 백색잡음 실험시의 가속도데이터로부터 구조물식별을 수행하여 7차모드까지의 고유진동수 및 모드감쇠비를 얻었다. 두대의 대용량 편심가진기를 사용하여 얻은 큰 진폭의 조화 진동하에서는 가속도데이터를 사용하여 각 방향 1차모드를 식별하였으며 변위계와 변형게이지를 이용하여 층간변위각, 기둥과 슬래브와 같은 구조부재의 곡률분포를 측정하였다. 각 경우 고유진동수는 진동의 크기가 클수록 낮아졌다. 즉, 편심가진기가력시 고유진동수는 상시미진동시에 비해 70{\sim}75%, 선형가진시가력시에 비해 92{\sim}93% 정도로 낮게 나타났다. 이러한 진동수의 감소폭은 지진에 의해 큰 손상을 받았던 건물의 남북방향에서 크게 나타났다. A series of forced vibration tests and ambient vibration measurement was conducted on a four-story reinforced concrete building damaged in the 1994 Northridge earthquake. Both low amplitude broadband and moderate amplitude harmonic excitation were applied using a linear shaker and two eccentric mass shakers, respectively, and ambient vibrations were measured before and after each forced vibration test. Accelerations, interstory displacements, and curvature distributions were monitored using accelerometers, LVDTs and concrete strain gauges. Natural frequencies and the associated mode shapes fur the first 7 modes were identified. Fundamental frequencies determined from the eccentric mass shaker tests were 70% to 75% of the values determined using ambient vibration data, and 92% to 93% of the values determined using the linear shaker test data. Larger frequency drops were observed in the NS direction of the building, apparently due to damage that was induced during the Northridge earthquake.

흥인지문의 진동특성 및 상반성 분석

최재성(Jae-Sung Choi),이성경(Sung-Kyung Lee),민경원(Kyung-Won Min),윤원규(Weon-Kyu Yoon),김덕문(Derk-Moon Kim) 한국소음진동공학회 2010 한국소음진동공학회 논문집 Vol.20 No.4

Heunginjimun designated as a Treasure No.1 is a two-story wooden structure with 5 bay and 2 bay in its front and side views, respectively. This paper presents an investigation on vibration characteristics of Heunginjimun through both ambient vibration and impact hammer tests. Ambient vibration test was performed to identify the natural frequency of Heunginjimun from the spectrum analysis of time history. Impact hammer test was undertaken to find the frequency of Heunginjimun which is affected by the surrounding traffics and to verify the reciprocal principle for the wooden structural system. Ambient vibration test results of Heunginjimun showed that the natural frequencies in two principal axes 1.5 Hz and 1.1 Hz, respectively. It was confirmed from impact hammer tests for a ground that the frequency of 4.2 Hz is caused by the traffics surrounding Heunginjimun. It was also observed that from the impact hammer test results between two locations in Heunginjimun that the transfer functions measured from two corresponding locations coincided well with each other. This result shows that the wooden structural system is globally linear, and the reciprocal principle is established.

장대교량의 건전도 모니터링을 위한 FE 모델 개선 기법의 연구

허광희 ( Heo Gwanghee ),이진옥 ( Lee Chin Ok ),전준룡 ( Jeon Joonryong ),이규 ( Lee Giu ) 한국구조물진단유지관리공학회 2005 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.9 No.1

This paper proposes an effective unite element model updating method for steel plate girder bridges subjected ambient vibration excitations such as winds and traffic loads. Updating FE model is necessary to secure structural integrity for heath monitoring, and is made possible by using the correlation between the experimental and analytical results. In this research, experimental testing adopts ambient vibration under normal traffic loads because forced vibration is inappropriate for long-term measuring and real-time monitoring. For our FE analysis, a 3-dimensional model with beam and shell element is employed for precision. Also, updating involves direct matrix and error matrix method to increase applicability. The efficiency of the proposed FE model updating method is evaluated by MAC(Modal assurance criteria) value and difference of natural frequencies each before and after updating. All such comparisons prove the effectiveness of FE model updating for structural health monitoring using ambient vibration. Therefore, the updating techniques proposed in this paper prove to be applicable in the real structure by applying the ambient vibration techniques under the normal traffic loads.

Seismic safety assessment of eynel highway steel bridge using ambient vibration measurements

Ahmet Can Altuni sik,Alemdar Bayraktar,Hasan Özdemir 국제구조공학회 2012 Smart Structures and Systems, An International Jou Vol.10 No.2

In this paper, it is aimed to determine the seismic behaviour of highway bridges by nondestructive testing using ambient vibration measurements. Eynel Highway Bridge which has arch type structural system with a total length of 216 m and located in the Ayvaclk county of Samsun, Turkey is selected as an application. The bridge connects the villages which are separated with Suat U urlu Dam Lake. A three dimensional finite element model is first established for a highway bridge using project drawings and an analytical modal analysis is then performed to generate natural frequencies and mode shapes in the three orthogonal directions. The ambient vibration measurements are carried out on the bridge deck under natural excitation such as traffic, human walking and wind loads using Operational Modal Analysis. Sensitive seismic accelerometers are used to collect signals obtained from the experimental tests. To obtain experimental dynamic characteristics, two output-only system identification techniques are employed namely, Enhanced Frequency Domain Decomposition technique in the frequency domain and Stochastic Subspace Identification technique in time domain. Analytical and experimental dynamic characteristic are compared with each other and finite element model of the bridge is updated by changing of boundary conditions to reduce the differences between the results. It is demonstrated that the ambient vibration measurements are enough to identify the most significant modes of highway bridges. After finite element model updating, maximum differences between the natural frequencies are reduced averagely from 23% to 3%. The updated finite element model reflects the dynamic characteristics of the bridge better, and it can be used to predict the dynamic response under complex external forces. It is also helpful for further damage identification and health condition monitoring. Analytical model of the bridge before and after model updating is analyzed using 1992 Erzincan earthquake record to determine the seismic behaviour. It can be seen from the analysis results that displacements increase by the height of bridge columns and along to middle point of the deck and main arches. Bending moments have an increasing trend along to first and last 50 m and have a decreasing trend long to the middle of the main arches.

Seismic safety assessment of eynel highway steel bridge using ambient vibration measurements

Altunisik, Ahmet Can,Bayraktar, Alemdar,Ozdemir, Hasan Techno-Press 2012 Smart Structures and Systems, An International Jou Vol.10 No.2

In this paper, it is aimed to determine the seismic behaviour of highway bridges by nondestructive testing using ambient vibration measurements. Eynel Highway Bridge which has arch type structural system with a total length of 216 m and located in the Ayvaclk county of Samsun, Turkey is selected as an application. The bridge connects the villages which are separated with Suat U$\breve{g}$urlu Dam Lake. A three dimensional finite element model is first established for a highway bridge using project drawings and an analytical modal analysis is then performed to generate natural frequencies and mode shapes in the three orthogonal directions. The ambient vibration measurements are carried out on the bridge deck under natural excitation such as traffic, human walking and wind loads using Operational Modal Analysis. Sensitive seismic accelerometers are used to collect signals obtained from the experimental tests. To obtain experimental dynamic characteristics, two output-only system identification techniques are employed namely, Enhanced Frequency Domain Decomposition technique in the frequency domain and Stochastic Subspace Identification technique in time domain. Analytical and experimental dynamic characteristic are compared with each other and finite element model of the bridge is updated by changing of boundary conditions to reduce the differences between the results. It is demonstrated that the ambient vibration measurements are enough to identify the most significant modes of highway bridges. After finite element model updating, maximum differences between the natural frequencies are reduced averagely from 23% to 3%. The updated finite element model reflects the dynamic characteristics of the bridge better, and it can be used to predict the dynamic response under complex external forces. It is also helpful for further damage identification and health condition monitoring. Analytical model of the bridge before and after model updating is analyzed using 1992 Erzincan earthquake record to determine the seismic behaviour. It can be seen from the analysis results that displacements increase by the height of bridge columns and along to middle point of the deck and main arches. Bending moments have an increasing trend along to first and last 50 m and have a decreasing trend long to the middle of the main arches.

Time Dependent Changing of Dynamic Characteristics of Laboratory Arch Dam Model

Ahmet Can Altuni ik,Bar Sev m,Alemdar Bayraktar,Süleyman Adanur,Murat Günaydin 대한토목학회 2015 KSCE JOURNAL OF CIVIL ENGINEERING Vol.19 No.4

This paper investigates the time dependent changing of dynamic characteristics of laboratory arch dam models using ambient vibration test. For this aim, a prototype arch dam-reservoir-foundation model is constructed in laboratory conditions. The first experimental measurement tests are performed after the poured concrete aged for 10 months for some damage scenarios such as undamaged, minor-damaged and severely damaged of dam body in November 2009. To extract the experimental dynamic characteristics such as natural frequencies, mode shapes and damping ratios, a small impact effect is used as a source of ambient vibrations. Experimental measurements tests are repeated using same excitations considering severely damaged conditions with and without reservoir water in February 2014, and the dynamic characteristics are obtained, experimentally. Enhanced Frequency Domain Decomposition Method in the frequency domain is used to extract the experimental dynamic characteristics. At the end of the study, experimentally identified dynamic characteristics are compared with each other and time effects are investigated in detail. Maximum differences between the natural frequencies obtained as 15.36% and 14.38% in the third mode for empty and full reservoir conditions, respectively. It is thought that the increase of the natural frequencies is resulted from gaining of rigidity of the concrete, ageing, temperature and different environmental effects.

풍동실험결과와 풍응답 계측결과의 비교

김지영(Kim Ji-Young),김대영(Kim Dae-Young),김상대(Kim Sang-Dae) 대한건축학회 2007 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.27 No.1

Basically, the wind tunnel tests are performed based on several assumptions due to some restrictions in the wind tunnel tests. In general, the reliability of a newly developed analytical method of a structural system is verified by a series of structural tests. The accuracy of the suggested method could be directly demonstrated by comparing the expected behaviours with the test results. In case of the wind tunnel studies, the reliability of the wind tunnel studies couldn't be verified by the laboratory tests. Not only the actual structures but also the dynamic wind loads couldn't be modelled in laboratory scale. As the development in measurement technology, it could be possible to measure wind-induced responses of large scale structures such as tall buildings. In order to verify the reliability of the wind tunnel test, the acceleration responses were measured for a tall residential building. The measured accelerations were compared with the wind tunnel test results. It was suggested based on the comparison results to improve the reliability and accuracy of the wind tunnel tests.

An Overview: The Application of Vibration‑Based Techniques in Bridge Structural Health Monitoring

Siti Shahirah Saidin,Adiza Jamadin,Sakhiah Abdul Kudus,Norliyati Mohd Amin,Muhamad Azhan Anuar 한국콘크리트학회 2023 International Journal of Concrete Structures and M Vol.17 No.2

Dynamic Characteristics of Megami Cable-stayed Bridge- A Comparison of Experimental and Analytical Results-

Qingxiong Wu,Yuichi Kitahara,Kazuo Takahashi,Baochun Chen 한국강구조학회 2008 International Journal of Steel Structures Vol.8 No.1

The Megami Bridge, with a main span of 480 m, is the 6th longest cable-stayed bridge in Japan. A comparison of experimental and analytical modal analysis is performed to determine the dynamic characteristic of this bridge. The ambient vibration test is carried out using very few accelerometers. Parameter identification is carried out using the stochastic subspacebased identification (SSI) method in the time-domain as proposed by Katayama. The SSI method used in this paper can be used for estimating the modal properties of a long span cable-stayed bridge by comparing with the maximum entropy method(MEM). Furthermore, the effectiveness of the tuned mass dampers (TMDs) used in the bridge is evaluated through a human excitation test. Logarithmic damping is about 0.030 when the TMD is activated, a little higher than the design value 0.026, so proving that the TMDs are effective. Finally, the analytical eigenvalues obtained from finite element analysis agree well with the experimental values, thus verifying the analytical model.