Load tests of bridges are widely performed in a large number of countries.
Deterministic comparis... more Load tests of bridges are widely performed in a large number of countries. Deterministic comparison of measurement results to the theoretical, FEM-based outcomes with possible further calibration is mostly applied. Sometimes the data collected in the tests are also used to calibrate the reliability factors of bridge structures or their components. This work proposes to complement the stage of the load test design with the use of probabilistic tools. This approach is intended to provide a reliable and trustworthy limit range of measured values (e.g. displacements) instead of restrictive single values, streamlining the performance of in-situ tests. The proposed procedure is supported by an arch bridge example with the following uncertainty sources: random imperfections of the arch girder, random stiffness of the deck and random total weight of the applied load trucks. The presented calculations refer to global structural stiffness assessment. Both Point Estimate Method (PEM) and Response Surface Method (RSM) are applied here. It has been shown that the proposed procedure effectively supplements the deterministic approach, thus the suggested extension of application of probabilistic tools to bridge load test design is innovative and justified.
This paper is a review of selected problems that occur during installation of tendon sheaths and ... more This paper is a review of selected problems that occur during installation of tendon sheaths and strands in post-tensioned, concrete bridges. The main focus is on highlighting the dangers associated with different types of errors. Advice and suggestions on how to eliminate or minimize the risk of their occurrence are also included.
Post-tensioned concrete bridges are currently often constructed engineering structures. In this t... more Post-tensioned concrete bridges are currently often constructed engineering structures. In this type of bridges it is crucial that geometrical layout of prestressing system complies with the design requirements. Unfortunately, major errors still occur during assembly of tendon routes. This has often negative effects. In a local aspect, it may cause a local damage, such as spalling of concrete cover. In a global aspect, prestressing may produce distribution of forces in the bridge structure different from the expected. That is why numerous methods have been developed to control the accuracy of executed tendon routs. Some of them, e.g. geodetic measurements with levelers, require direct access to tendon sheaths. Other methods, which can be used after casting of concrete (mainly NDT methods) have a series of resolution, efficiency and accessibility limitations. Hence, the paper presents a proposal of an alternative method for control of tendons routing using a special probe with Micro Electro-Mechanical Systems capacitive accelerometer. The paper presents a concept of tests performed with the probe, evaluation of the probe application in the view of a random process and finally assessment of the results obtained with the use of the constructed measurement system in trial laboratory conditions.
Zwrócono uwagę na potrzebę umiejętnej oceny stanu technicznego istniejących mostów sprężonych, sz... more Zwrócono uwagę na potrzebę umiejętnej oceny stanu technicznego istniejących mostów sprężonych, szczególnie na aspekt identyfikacji sprężenia. Zamieszczono wybrane aspekty ekspertyzy technicznej mostu w Kobiernicach, gdzie zastosowano badania niszczące. Przedstawiono zarys badań dwóch mostów sprężonych, z wykorzystaniem między innymi georadaru do wykrycia kabli sprężających. Uwypuklono potrzebę reprezentacji efektu sprężenia w ustrojach statycznie niewyznaczalnych już na etapie modelowania. Zaprezentowano wybrane metody reprezentacji sprężenia. Zauważono, że badania nieniszczące georadarem w celu uzupełnienia informacji o geometrii sprężenia, wraz ze wspomnianymi metodami jego reprezentacji w modelu mogą pomóc w próbie oceny nośności istniejących obiektów.
Streszczenie: W referacie przedstawiono podstawy teoretyczne, złożonego stanu naprężeń w strefie ... more Streszczenie: W referacie przedstawiono podstawy teoretyczne, złożonego stanu naprężeń w strefie zakotwień. Wymieniono wybrane zagrożenia i odpowiadające im sposoby na wyznaczenie zbrojenia zabezpieczającego. Pokazano przykładowy rysunek ze oznaczeniem rodzajów zbrojenia. Zaprezentowano przypadki uszkodzeń w strefie zakotwień opatrując je sugestiami, które mogą pomóc w zmniejszeniu ryzyka ich wystąpienia.
13th SGEM GeoConference on SCIENCE AND TECHNOLOGIES IN GEOLOGY, EXPLORATION AND MINING, 2013
The paper presents results of tendons and reinforcement identification in several test areas in e... more The paper presents results of tendons and reinforcement identification in several test areas in examined multiple-span bridge located in Gliwice (Poland), using ground penetrating radar (GPR). Rules and requirements for correct installation of the reinforcement and tendons imposed upon contractors are very precise. Nevertheless, in practice, occasionally, the geometry of the reinforcement and prestressing system does not correspond adequately with design drawings. Moreover, especially in older objects, sometimes, there is no design documentation. For this, non-destructive techniques in particular GPR can be used. The papers main objective is to present the capabilities and limitations of GPR technique for identification of reinforcement and tendons in various areas of the box girder. Tested object is a five span prestressed bridge. The one-cellular box girder is pre-stressed with two types of tendons: internal, centric tendons and eccentric tendons. Both types were objects of GPR identification. The measurements were carried out from the inner and external side of the box girder. Test areas include chosen areas of: bridge deck, bottom slab, mid-span deviator (investigated from inner side) and anchorage zone, sidewalk slab (investigated from external side of the box girder). For the inspection a 1.0 GHz radar antenna were used. Results in given test area, are shown as the B-scans (echograms) and compared with the design drawings. In most cases reinforcement bars were properly detected. Accurate information about the localization of tendons was not achieved. The reason for this, is concentration of reinforcement above the tendons and some geometrical limitations of GPR technique.
In the introduction, some problems that can be caused by the anchorage zone were outlined and a p... more In the introduction, some problems that can be caused by the anchorage zone were outlined and a potential usefulness of NDT method in this area was demonstrated. Example of damage in anchorage zone is presented. The initial results of tendons identification in anchorage zone are also shown. The object of investigation was a post-tensioned bridge erected with incremental launching method while investigation was done using ground penetrating radar with high frequencies antennas.
The article presents the results of non-destructive testing, which was carried out on the concret... more The article presents the results of non-destructive testing, which was carried out on the concrete pillar with an unusual, trapezoidal shape and densely spaced reinforcement. After stripping the formwork, some surface voids became visible, which suggested that the existence of subsurface voids was also probable. The GPR method was used to state whether these voids are formed and possibly to determine their approximate location. This paper discusses the adopted methodology of measurements, analysis and the GPR data processing. The interpretation of the echograms was based on a comparison of recorded GPR data with the modelling results MRS (FD) of electromagnetic wave propagation with the known geometry of the tested pillar. The results of detection are shown mainly in the form of the echograms (B-SCAN) and are collected as a cumulative sketch (C-SCAN). In order to assess the impact of the identified voids on the bearing capacity of the structure, the shell model of the pillar was built with the use of FEM. It shows stress distribution differences in the pillar with a continuous internal structure and in the pillar with the modelled voids. The obtained results were used for checking the bearing capacity of damaged pillar and during the preparation of the effective repair program.
Load tests of bridges are widely performed in a large number of countries.
Deterministic comparis... more Load tests of bridges are widely performed in a large number of countries. Deterministic comparison of measurement results to the theoretical, FEM-based outcomes with possible further calibration is mostly applied. Sometimes the data collected in the tests are also used to calibrate the reliability factors of bridge structures or their components. This work proposes to complement the stage of the load test design with the use of probabilistic tools. This approach is intended to provide a reliable and trustworthy limit range of measured values (e.g. displacements) instead of restrictive single values, streamlining the performance of in-situ tests. The proposed procedure is supported by an arch bridge example with the following uncertainty sources: random imperfections of the arch girder, random stiffness of the deck and random total weight of the applied load trucks. The presented calculations refer to global structural stiffness assessment. Both Point Estimate Method (PEM) and Response Surface Method (RSM) are applied here. It has been shown that the proposed procedure effectively supplements the deterministic approach, thus the suggested extension of application of probabilistic tools to bridge load test design is innovative and justified.
This paper is a review of selected problems that occur during installation of tendon sheaths and ... more This paper is a review of selected problems that occur during installation of tendon sheaths and strands in post-tensioned, concrete bridges. The main focus is on highlighting the dangers associated with different types of errors. Advice and suggestions on how to eliminate or minimize the risk of their occurrence are also included.
Post-tensioned concrete bridges are currently often constructed engineering structures. In this t... more Post-tensioned concrete bridges are currently often constructed engineering structures. In this type of bridges it is crucial that geometrical layout of prestressing system complies with the design requirements. Unfortunately, major errors still occur during assembly of tendon routes. This has often negative effects. In a local aspect, it may cause a local damage, such as spalling of concrete cover. In a global aspect, prestressing may produce distribution of forces in the bridge structure different from the expected. That is why numerous methods have been developed to control the accuracy of executed tendon routs. Some of them, e.g. geodetic measurements with levelers, require direct access to tendon sheaths. Other methods, which can be used after casting of concrete (mainly NDT methods) have a series of resolution, efficiency and accessibility limitations. Hence, the paper presents a proposal of an alternative method for control of tendons routing using a special probe with Micro Electro-Mechanical Systems capacitive accelerometer. The paper presents a concept of tests performed with the probe, evaluation of the probe application in the view of a random process and finally assessment of the results obtained with the use of the constructed measurement system in trial laboratory conditions.
Zwrócono uwagę na potrzebę umiejętnej oceny stanu technicznego istniejących mostów sprężonych, sz... more Zwrócono uwagę na potrzebę umiejętnej oceny stanu technicznego istniejących mostów sprężonych, szczególnie na aspekt identyfikacji sprężenia. Zamieszczono wybrane aspekty ekspertyzy technicznej mostu w Kobiernicach, gdzie zastosowano badania niszczące. Przedstawiono zarys badań dwóch mostów sprężonych, z wykorzystaniem między innymi georadaru do wykrycia kabli sprężających. Uwypuklono potrzebę reprezentacji efektu sprężenia w ustrojach statycznie niewyznaczalnych już na etapie modelowania. Zaprezentowano wybrane metody reprezentacji sprężenia. Zauważono, że badania nieniszczące georadarem w celu uzupełnienia informacji o geometrii sprężenia, wraz ze wspomnianymi metodami jego reprezentacji w modelu mogą pomóc w próbie oceny nośności istniejących obiektów.
Streszczenie: W referacie przedstawiono podstawy teoretyczne, złożonego stanu naprężeń w strefie ... more Streszczenie: W referacie przedstawiono podstawy teoretyczne, złożonego stanu naprężeń w strefie zakotwień. Wymieniono wybrane zagrożenia i odpowiadające im sposoby na wyznaczenie zbrojenia zabezpieczającego. Pokazano przykładowy rysunek ze oznaczeniem rodzajów zbrojenia. Zaprezentowano przypadki uszkodzeń w strefie zakotwień opatrując je sugestiami, które mogą pomóc w zmniejszeniu ryzyka ich wystąpienia.
13th SGEM GeoConference on SCIENCE AND TECHNOLOGIES IN GEOLOGY, EXPLORATION AND MINING, 2013
The paper presents results of tendons and reinforcement identification in several test areas in e... more The paper presents results of tendons and reinforcement identification in several test areas in examined multiple-span bridge located in Gliwice (Poland), using ground penetrating radar (GPR). Rules and requirements for correct installation of the reinforcement and tendons imposed upon contractors are very precise. Nevertheless, in practice, occasionally, the geometry of the reinforcement and prestressing system does not correspond adequately with design drawings. Moreover, especially in older objects, sometimes, there is no design documentation. For this, non-destructive techniques in particular GPR can be used. The papers main objective is to present the capabilities and limitations of GPR technique for identification of reinforcement and tendons in various areas of the box girder. Tested object is a five span prestressed bridge. The one-cellular box girder is pre-stressed with two types of tendons: internal, centric tendons and eccentric tendons. Both types were objects of GPR identification. The measurements were carried out from the inner and external side of the box girder. Test areas include chosen areas of: bridge deck, bottom slab, mid-span deviator (investigated from inner side) and anchorage zone, sidewalk slab (investigated from external side of the box girder). For the inspection a 1.0 GHz radar antenna were used. Results in given test area, are shown as the B-scans (echograms) and compared with the design drawings. In most cases reinforcement bars were properly detected. Accurate information about the localization of tendons was not achieved. The reason for this, is concentration of reinforcement above the tendons and some geometrical limitations of GPR technique.
In the introduction, some problems that can be caused by the anchorage zone were outlined and a p... more In the introduction, some problems that can be caused by the anchorage zone were outlined and a potential usefulness of NDT method in this area was demonstrated. Example of damage in anchorage zone is presented. The initial results of tendons identification in anchorage zone are also shown. The object of investigation was a post-tensioned bridge erected with incremental launching method while investigation was done using ground penetrating radar with high frequencies antennas.
The article presents the results of non-destructive testing, which was carried out on the concret... more The article presents the results of non-destructive testing, which was carried out on the concrete pillar with an unusual, trapezoidal shape and densely spaced reinforcement. After stripping the formwork, some surface voids became visible, which suggested that the existence of subsurface voids was also probable. The GPR method was used to state whether these voids are formed and possibly to determine their approximate location. This paper discusses the adopted methodology of measurements, analysis and the GPR data processing. The interpretation of the echograms was based on a comparison of recorded GPR data with the modelling results MRS (FD) of electromagnetic wave propagation with the known geometry of the tested pillar. The results of detection are shown mainly in the form of the echograms (B-SCAN) and are collected as a cumulative sketch (C-SCAN). In order to assess the impact of the identified voids on the bearing capacity of the structure, the shell model of the pillar was built with the use of FEM. It shows stress distribution differences in the pillar with a continuous internal structure and in the pillar with the modelled voids. The obtained results were used for checking the bearing capacity of damaged pillar and during the preparation of the effective repair program.
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Papers by Piotr Owerko
Deterministic comparison of measurement results to the theoretical, FEM-based
outcomes with possible further calibration is mostly applied. Sometimes the data
collected in the tests are also used to calibrate the reliability factors of bridge
structures or their components. This work proposes to complement the stage of
the load test design with the use of probabilistic tools. This approach is intended
to provide a reliable and trustworthy limit range of measured values (e.g.
displacements) instead of restrictive single values, streamlining the performance
of in-situ tests. The proposed procedure is supported by an arch bridge example
with the following uncertainty sources: random imperfections of the arch girder,
random stiffness of the deck and random total weight of the applied load trucks.
The presented calculations refer to global structural stiffness assessment. Both
Point Estimate Method (PEM) and Response Surface Method (RSM) are applied
here. It has been shown that the proposed procedure effectively supplements the
deterministic approach, thus the suggested extension of application of
probabilistic tools to bridge load test design is innovative and justified.
prestressing may produce distribution of forces in the bridge structure different from the expected. That is
why numerous methods have been developed to control the accuracy of executed tendon routs. Some of them, e.g. geodetic measurements with levelers, require direct access to tendon sheaths. Other methods,
which can be used after casting of concrete (mainly NDT methods) have a series of resolution, efficiency and accessibility limitations. Hence, the paper presents a proposal of an alternative method for control of
tendons routing using a special probe with Micro Electro-Mechanical Systems capacitive accelerometer. The paper presents a concept of tests performed with the probe, evaluation of the probe application in the
view of a random process and finally assessment of the results obtained with the use of the constructed measurement system in trial laboratory conditions.
Deterministic comparison of measurement results to the theoretical, FEM-based
outcomes with possible further calibration is mostly applied. Sometimes the data
collected in the tests are also used to calibrate the reliability factors of bridge
structures or their components. This work proposes to complement the stage of
the load test design with the use of probabilistic tools. This approach is intended
to provide a reliable and trustworthy limit range of measured values (e.g.
displacements) instead of restrictive single values, streamlining the performance
of in-situ tests. The proposed procedure is supported by an arch bridge example
with the following uncertainty sources: random imperfections of the arch girder,
random stiffness of the deck and random total weight of the applied load trucks.
The presented calculations refer to global structural stiffness assessment. Both
Point Estimate Method (PEM) and Response Surface Method (RSM) are applied
here. It has been shown that the proposed procedure effectively supplements the
deterministic approach, thus the suggested extension of application of
probabilistic tools to bridge load test design is innovative and justified.
prestressing may produce distribution of forces in the bridge structure different from the expected. That is
why numerous methods have been developed to control the accuracy of executed tendon routs. Some of them, e.g. geodetic measurements with levelers, require direct access to tendon sheaths. Other methods,
which can be used after casting of concrete (mainly NDT methods) have a series of resolution, efficiency and accessibility limitations. Hence, the paper presents a proposal of an alternative method for control of
tendons routing using a special probe with Micro Electro-Mechanical Systems capacitive accelerometer. The paper presents a concept of tests performed with the probe, evaluation of the probe application in the
view of a random process and finally assessment of the results obtained with the use of the constructed measurement system in trial laboratory conditions.