TY - CONF A1 - Liao, Chun-Man A1 - Petryna, Y. T1 - Damage assessment of civil structures using wave propagation analysis and transmissibility functions N2 - This presentation shows the applicaiton of seismic interferometry to vibration recordings. The Normalized-Input-Output-Minimization (NIOM) method to reconstruct the virtual impulse wave propagation is introduced. We obtain wave velocities and transmissibility functions and consider them as reference values for the damage detection method. At the end, the evaluation results are presented by two examples: a 14-story RC building and a 64 m long pedestrian bridge. T2 - EVACES2021 9th International Conference on Experimental Vibration Analysis for Civil Engineering Structures CY - Online meeting DA - 14.09.2021 KW - Damage detection KW - Damage indices KW - Normalized-Input-Output-Minimization KW - Transmissibility function KW - Wave propagation PY - 2021 AN - OPUS4-53437 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hicke, Konstantin A1 - Liao, Chun-Man A1 - Chruscicki, Sebastian A1 - Breithaupt, Mathias T1 - Vibration Monitoring of Large-Scale Bridge Model using Distributed Acoustic Sensing N2 - Results of DAS measurements along a large-scale concrete bridge model are presented. The improvement of measurable dynamic strain range is demonstrated. Vibration modes obtained by DAS correspond well to those determined from broadband seismometer measurements. T2 - 27th International Conference on Optical Fiber Sensors (OFS-27) CY - Alexandria, VA, USA DA - 29.08.2022 KW - Distributed acoustic sensing KW - Vibration modes KW - Bridge monitoring KW - WS-COTDR KW - Fiber-optic vibration monitoring PY - 2022 SP - 1 EP - 4 PB - Optica CY - Washington D.C., USA AN - OPUS4-56082 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Liao, Chun-Man A1 - Petryna, Y. T1 - Damage Assessment of Civil Structures Using Wave Propagation Analysis and Transmissibility Functions N2 - A common damage detection method in civil engineering is to monitor dynamic characteristics such as natural frequencies and modal shapes, which are directly related to the structural stiffness. However, the discrepancy in measured natural frequencies may result from environmental changes, the soil-structure interaction or effects caused by earthquakes. This makes it difficult to decide whether the local change in structural properties is caused by damage or other factors. To address this challenge and thus improve the current damage detection method, the wave propagation analysis method and the transmissibility relationship were considered. In our study, the wave propagation field in structures was reconstructed by applying the Normalized-Input-Output-Minimization (NIOM) method to vibration recordings. Wave velocities and transmissibility functions were considered as reference values for the damage indicators. This paper demonstrates the evaluation of local property changes in two examples of large-scale structures: a 14-story RC building and a 64 m long pedestrian bridge. The proposed damage indicators show a clear correspondence to structural changes. T2 - EVACES2021 9th International Conference on Experimental Vibration Analysis for Civil Engineering Structures CY - Online meeting DA - 14.09.2021 KW - Damage detection KW - Damage indices KW - Normalized-Input-Output-Minimization KW - Transmissibility function KW - Wave propagation PY - 2022 SN - 978-3-030-93235-0 SN - 978-3-030-93236-7 DO - https://doi.org/10.1007/978-3-030-93236-7_2 SP - 3 EP - 13 PB - Springer CY - Cham AN - OPUS4-55565 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Liao, Chun-Man A1 - Hille, Falk A1 - Fontoura Barroso, Daniel A1 - Niederleithinger, Ernst T1 - Monitoring of a prestressed bridge model by ultrasonic measurement and vibration recordings N2 - Nowadays, civil engineers have applied prestressing technique to long span bridges to enhance the structural strength and to improve the structural performance in their life time. However, it‘s not easy to avoid prestress loss during the construction or in service time. This problem will influence the function of the structures and worse make our life in danger. Therefore, it‘s important to focus on the topic „bridge monitoring“ to make sure the structural property is "health". This presentation introduces the work which fulfills the research goal - birdge monitoring. A large-scale prestressed concrete bridge model was considered in this work. We obteined various damaged condition due to the different prestressed levels which we can change every time in the experiment. The experimental measurement in two scales were demonstrated by ultrasonics and natural vibration of the bridge. T2 - COMPDYN 2021 8th ECCOMAS Thematic Conference on Computational Methods in Structural Dynamics and Earthquake Engineering CY - Online meeting DA - 28.06.2021 KW - Bridge monitoring KW - Prestressed concrete bridge KW - Ultrasonic KW - Natural vibration PY - 2021 AN - OPUS4-52955 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Liao, Chun-Man A1 - Hille, Falk A1 - Fontoura Barroso, Daniel A1 - Niederleithinger, Ernst ED - Papadrakakis, M. ED - Fragiadakis, M. T1 - Monitoring of a prestressed bridge model byultrasonic measurement and vibration recordings N2 - The aim of this work is to improve the current structural health monitoring (SHM) methods for civil structures. A field experiment was carried out on a two-span bridge with a built-in un-bonded prestressing system. The bridge is a 24-metre long concrete beam resting on three bear-ings. Cracks were formed subsequently when a prestressing force of 350 kN was changed to 200 kN, so that different structural states could be demonstrated. The structural assessment of this reference bridge was accomplished by the non-destructive testing using ultrasonic devices and vibration measurements. The ultrasonic velocity variations were investigated by using the coda wave interferometry method. The seismic interferometry technique was applied to the vi-bration recordings to reconstruct the wave propagation field in the bridge. This investigation shows that the wave velocity is sensitive to the current structural state and can be considered as the damage indicator. Overall, the implementation of coda cave interferometry and seismic interferometry technique facilitates structural health monitoring (SHM) in civil engineering. T2 - COMPDYN 2021 8th ECCOMAS Thematic Conference on Computational Methods in Structural Dynamics and Earthquake Engineering CY - Online meeting DA - 28.06.2021 KW - Structural health monitoring KW - Non-destructive testing KW - Coda wave interferometry KW - Seismic interferometry KW - Ultrasonic measurement KW - Prestress PY - 2021 SP - 1 EP - 9 PB - European Community on Computational Methods in Applied Sciences (ECCOMAS) AN - OPUS4-52957 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Liao, Chun-Man A1 - Mehrkens, F. A1 - Hadziioannou, C. A1 - Niederleithinger, Ernst T1 - Investigation of ambient noise seismological methods on a bridge model N2 - This presentation is to introduce the research work in the GIOTTO project funded by Federal Ministry of Education and Research (BMBF) in the frame of “early warning of earthquakes” program. The aim of this work is to investigate the application of seismological noise-based monitoring for bridge structures. A large-scale two-span concrete bridge model with a build-in post-tensioning system, which is exposed to environmental conditions, is chosen as our experimental test structure. Ambient seismic noise measurements were carried out under different pre-stressed conditions. Using the seismic interferometry technique, which is applied to the measurement data in the frequency domain, we reconstruct waveforms that relate to wave propagation in the structure. The coda wave interferometry technique is then implemented by comparing two waveforms recorded in two pre-stress states. Any relative seismic velocity changes are identified by determining the correlation coefficients and reveal the influence of the pre-stressing force. The decrease of the wave propagation velocity indicates the loss of the pre-stress and weakening stiffness due to opening or event extension of cracks. We conclude that the seismological methods used to estimate velocity change can be a promising tool for structural health monitoring of civil structures. T2 - EGU General Assembly 2021 CY - Online meeting DA - 19.04.2021 KW - Ambient seismic noise measurements KW - Pre-stress loss KW - Coda wave interferometry PY - 2021 DO - https://doi.org/10.5194/egusphere-egu21-2773 AN - OPUS4-52578 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Liao, Chun-Man A1 - Mehrkens, F. A1 - Hadziioannou, C. A1 - Niederleithinger, Ernst T1 - Investigation of ambient noise seismological methods on a bridge model N2 - This poster is to introduce the research work in the GIOTTO project funded by Federal Ministry of Education and Research (BMBF) in the frame of “early warning of earthquakes” program. The aim of this work is to investigate the application of seismological noise-based monitoring for bridge structures. A large-scale two-span concrete bridge model with a build-in post-tensioning system, which is exposed to environmental conditions, is chosen as our experimental test structure. Ambient seismic noise measurements were carried out under different pre-stressed conditions. Using the seismic interferometry technique, which is applied to the measurement data in the frequency domain, we reconstruct waveforms that relate to wave propagation in the structure. The coda wave interferometry technique is then implemented by comparing two waveforms recorded in two pre-stress states. Any relative seismic velocity changes are identified by determining the correlation coefficients and reveal the influence of the pre-stressing force. The decrease of the wave propagation velocity indicates the loss of the pre-stress and weakening stiffness due to opening or event extension of cracks. We conclude that the seismological methods used to estimate velocity change can be a promising tool for structural health monitoring of civil structures. T2 - EGU General Assembly 2021 CY - Online meeting DA - 19.04.2021 KW - Ambient seismic noise measurements KW - Coda wave interferometry KW - Pre-stress loss PY - 2021 DO - https://doi.org/10.5194/egusphere-egu21-2773 AN - OPUS4-52584 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Liao, Chun-Man T1 - Investigation of ambient noise seismological methods on a bridge model N2 - Structural health monitoring is a big issue of the prevention measure for civil structures in the seismic hazard region. The GIOTTO project aims to develop of the real time monitoring in civil engineering by use of the 6 DOFs sensors. This presented work is part of the GIOTTO Project. BAM offered the idea test structure BLEIB bridge for experiment. This prestressed concrete bridge model benefits us to have the various structural condition with different pre-stress. The passive and active monitoring were carried out. The seismic interferometry technique was considered to extract the virtual wave propagation in the structure comparable to the real impulse response excited by the hammer impact. Meanwhile the ultrasonic measurement was performed during the monitoring. The coda wave interferometry (CWI) was applied to investigate the wave velocity variation in two kinds of scale recordings at different prestressed states. The experimental result approves that the seismological noise- based methods are the appropriate evaluation tool for the measurement data. T2 - Seminar WP 2.2 Special Topics in Seismology CY - Online meeting DA - 04.05.2021 KW - Real time monitoring KW - Seismological noise-based methods KW - Coda wave interferometry PY - 2021 AN - OPUS4-52572 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Liao, Chun-Man A1 - Fontoura Barroso, Daniel T1 - Investigation of temperature effects on ultrasonic velocity in a prestressed concrete bridge model N2 - Ultrasonic measurements have recently been applied in the context of structural health monitoring in civil engineering. The ultrasonic method is very sensitive to environmental conditions and material property changes, which might be caused by prestress losses and loading effects on the bridge. However, it remains a challenge to identify the damage mechanisms causing structural property changes from the above mentioned factors influencing ultrasonics. The focus of this contribution is to investigate the correlation between ultrasonic velocities and temperature by the coda wave interferometry (CWI) analysis. Long-term monitoring of a prestressed concrete bridge model under field conditions was carried out to observe the effect of temperature. The homogeneous change in concrete caused by temperature was revealed by applying the CWI method. The threshold value of the best correlation coefficients for the linear regression of temperature and ultrasonic velocity changes was also studied. Experimental assessment will provide a ratio for temperature correction to evaluate the pre-stressing force decrease and its consequences on crack opening or extension. T2 - Tagung EWSHM2022 CY - Palermo, Italy DA - 04.07.2022 KW - Ultrasonic Velocity KW - Coda Wave Interferometry KW - Temperature Correction KW - Prestressing Force KW - Bridge Monitoring PY - 2022 SN - 978-3-031-07257-4 SN - 978-3-031-07258-1 DO - https://doi.org/10.1007/978-3-031-07258-1_82 VL - 2 SP - 813 EP - 823 PB - Springer Nature AN - OPUS4-55289 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Liao, Chun-Man T1 - Investigation of temperature effects on ultrasonic velocity in a prestressed concrete bridge model N2 - Ultrasonic measurements have recently been applied in the context of structural health monitoring in civil engineering. The ultrasonic method is very sensitive to environmental conditions and material property changes, which might be caused by prestress losses and loading effects on the bridge. However, it remains a challenge to identify the damage mechanisms causing structural property changes from the above-mentioned factors influencing ultrasonics. The focus of this contribution is to investigate the correlation between ultrasonic velocities and temperature by the coda wave interferometry (CWI) analysis. Long-term monitoring of a prestressed concrete bridge model under field conditions was carried out to observe the effect of temperature. The homogeneous change in concrete caused by temperature was revealed by applying the CWI method. The threshold value of the best correlation coefficients for the linear regression of temperature and ultrasonic velocity changes was also studied. Experimental assessment will provide a ratio for temperature correction to evaluate the prestressing force decrease and its consequences on crack opening or extension. T2 - Tagung EWSHM2022 CY - Palermo, Italy DA - 04.07.2022 KW - Ultrasonic velocity KW - Coda wave interferometry KW - Temperature correction KW - Prestressing force KW - Bridge monitoring PY - 2022 AN - OPUS4-55290 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -