Damage Identification on Steel Torsional Bracings Based on Dynamic Monitoring (original) (raw)
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Bridges are ageing and traffic is growing, which creates a demand for accurate fatigue life assessment. The Europabrücke – a well known Austrian steel bridge near Innsbruck, opened in 1963 - is one of the main alpine north-south routes for urban and freight traffic. It represents a bridge generation, where bridge designers acted on a maxim of building material economisation. A long-term preoccupation of VCE with BRIMOSâ (BRIdge MOnitoring System) on the Europabrücke (since 1997) with regard to fatigue problems and possible damage led to the installation of a permanent monitoring system in 2003. Since that time a lot of investigations and additional special measurements were devoted to innovative, mainly monitoring-based fatigue assessment as the emphasis is to replace the standard’s premises – referring to loading - by measurements. In the course of these investigations - and parallel to visual inspections - the steel bridge’s torsional bracings and their joints turned out to be the...
PERFORMANCE PREDICTION OF TORSIONAL BRACINGS using strictly in-situ based loading impact
Bridges are ageing and traffic is growing, which creates a demand for accurate fatigue life assessment. The Europabrücke – a well known Austrian steel bridge near Innsbruck, opened in 1963 - is one of the main alpine north-south routes for urban and freight traffic. It represents a bridge generation, where bridge designers acted on a maxim of building material economisation. A long-term preoccupation of VCE with BRIMOSâ (BRIdge MOnitoring System) on the Europabrücke (since 1997) led to the installation of a permanent monitoring system in 2003. Since that time a lot of investigations and additional special measurements were devoted to innovative, mainly monitoring-based fatigue assessment as the emphasis is to replace the standard’s premises – referring to loading - by measurements. In the course of these investigations - and parallel to visual inspections - the steel bridge’s torsional bracings and their joints turned out to be the main subject of interest, as their response is most...
Structural control & health monitoring, 2015
One of the most important issues in engineering is the detection of structural damages. During its life cycle, a building, besides the exposure to operational and environmental forces, can be subjected to earthquakes or to other non-ordinary loads. These events may have a deep impact on the building safety, and thus, a continuous monitoring of the structure health conditions becomes desirable or even necessary in many cases. In this context, the usage of vibration-based structural health monitoring (SHM) systems is spreading from big infrastructures applications, like bridges, dams or skyscrapers, to the historical heritage and to public or residential buildings. The aim of this work is to propose a combined experimental and numerical methodology to perform the SHM of structures of the civil engineering lying in seismic hazard zones. A relatively low cost SHM prototype system based on this approach is developed. The data acquired by the system are provided to a finite element method (FEM) numerical model to detect the appearing, the rise and the distribution of local damages and to estimate a global damage level. The system has been tested and calibrated on a three-storey prototype model. The procedure for the estimation of the damage level is calibrated by comparing the experimental quantities measured during cyclic failure tests with the FEM model predictions.
State of the Art Review on Bridges Structural Health Monitoring (Model Testing)
The International Conference on Civil and Architecture Engineering
Most structural health monitoring methods focus on using dynamic responses to detect and locate damage (i.e. items I and II above) because they are global methods that can provide rapid inspection of large structural systems. These dynamic-based methods can be divided into four groups: (1) spatial-domain methods, (2) modal-domain methods, (3) time-domain methods, and (4) frequency-domain methods. Spatial-domain methods use changes of mass, damping, and stiffness matrices to detect and locate damage. Modal-domain methods use changes of natural frequencies, modal damping ratios, and mode shapes to detect damage.
The article analyses the problems of local influences in structural details of bridges as the critical locations, whose damages or excessive force may directly affect the safety of users. These analyses are shown on selected examples. Presented is the example of local changes in the forms of proper vibrations in the node of the truss bridge that can be used in expert issues concerning the causes of damages. The second example are the changes in stresses in the stay cable anchorage element including the nonlinear material models. Models of this type can be successfully used by engineers as they allow for analysis of selected structural details without the need for detailed mapping of the entire structure, but only a selected section. W artykule podjęto problematykę analizy lokalnych wpływów w szczegółach konstrukcyjnych mostów, jako miejscach newralgicznych, których uszkodzenia lub nadmierne wytężenie może bezpośrednio wpłynąć na bezpieczeństwo użytkowania. Możliwość takich analiz po...
Assessment of a multiple-span bridge by dynamic testing, in-situ monitoring and numerical modeling.
The structural condition assessment of highway bridges is largely based on the visual observations described by the subjective indices, and it is necessary to develop a methodology for accurate and reliable condition assessment of in-service bridges. In this paper, an approach to condition assessment of in-service bridges making use of dynamic testing, in-situ monitoring and analytical and/or numerical simulations is proposed and applied to the instrumented Newmarket Viaduct, a 12-span bridge located in Auckland, New Zealand. Both ambient dynamic tests in two states and structural health monitoring data measured on the Newmarket Viaduct are reported and analysed. A finite element model of the bridge is successfully verified by using the natural frequencies and mode shapes extracted from the measured data. In the future work, realize meaningful interpretation of monitoring data is aim at inferring the state of a structure. Also, the FE models for structures calibrated and refined using the various types of field testing and monitoring or measurements data will be used in structural analysis simulations, yielding more realistic results.
Bridge Assessment and Maintenance based on Finite Element Structural Models and Field Measurements
2008
Maintenance, upgrading, repair and replacement of existing bridges lead to high cost and considerable disruption of traffic. In current practice, condition assessment and the evaluation of existing bridges are mainly based on visual inspection. Since this practice can only disclose faults limited to the surface of the structure, conclusions concerning the underlying structural health are difficult, if not impossible to derive. For bridge evaluations through finite element (FE) analysis a sound numerical model is needed to guarantee the reliability and safety of existing structures. However, in a FE model, used for the design of structural systems, uncertain parameters, such as support conditions and interactions between structural members can have a significant effect on the results. In existing structures, deterioration, damaging events and incomplete blueprints lead to less certain assumptions. To determine the residual loadcarrying capacity and the need for strengthening, repair or replacement, a good approximation of the real behaviour of the structure is required. In this report a strategy for improved bridge management by means of advanced structural modelling in combination with on-site measurements is presented. Important aspects of finite element modelling, field testing and monitoring, and FE model updating are presented. Through FE model updating, on-site measurements are combined with an initial FE model to obtain new information about the structural behaviour. This make it possible to benefit from the on-site measurements in an optimal way. It leads to a more accurate FE model and allows determining uncertain structural parameters which can not be measured directly. The study was financed by the Swedish road Administration (Vägverket) and the Swedish railway Administration (Banverket).
Damage detection of steel girder railway bridges utilizing operational vibration response
Structural Control and Health Monitoring, 2019
In this paper, we develop a damage identification framework based on acceleration responses for railroad bridges. The methodology uses sensor-clusteringbased time series analysis of bridge acceleration responses to the motion of the train. The results are expressed in terms of damage features, and damage to the bridge is investigated by observing the magnitude of these damage features. The investigation demonstrates the damage features by comparing the fit ratios of locations of interest so that damage can be identified and located and the relative severity of the damage assessed. The damage cases considered are stiffness loss, moment capacity reduction, and change in boundary conditions. In this study, a finite element analysis of a railway bridge model is used to verify our methodology. Our findings show that the proposed damage detection framework is very promising for continuously assessing the condition of railway bridges and thus will facilitate early detection of potential structural damage. This will be valuable for infrastructure owners seeking to develop more economical and effective maintenance strategies. KEYWORDS damage detection, operational vibration data, sensor clustering, steel girder railway bridges, structural health monitoring, time series analysis 1 | INTRODUCTION Existing bridge infrastructure is subjected to various potential risks such as aging, fatigue, and corrosion and is also vulnerable to natural disasters such as hurricanes and earthquakes. In addition, modern bridges are also subjected to everincreasing heavy axle loads and operational frequency. These potential risks result in varying degrees of damage that may cause the failure or even collapse of the given infrastructure asset. There are more than 600,000 (highway and railway) bridges in the United States, and more than 30% of these bridges are on the wrong side of their 50-year design life. Almost 10% of these bridges are classified as structurally deficient, and 14% are functionally obsolete. 1,2 In Canada, the National Highway System includes nearly 8,000 bridges, with 60% of these being more than 30 years old. 3 About 4% of the bridges across Canada have been rated poor, and 80% require some sort of repair. 4,5 Meanwhile, more than 20,000 bridges across Canada are vital components of the railway transportation system, and many federal and provincial bridges in Canada have passed the halfway mark of their design life. 6 Railway bridge operation is hampered by irregularities that cause accidents or service interruptions. 7 Therefore, the need for better condition assessments of these structures has become paramount. 8 Our focus is to develop a structural health monitoring (SHM) methodology specifically for railway bridges.
Proceedings of the 1999 American Control Conference (Cat. No. 99CH36251), 1999
The primary objective of this paper, and its affiliated research, is to rigorously demonstrate that modal analysis and flexibility are valid and effective tools for the condition assessment of civil-engineered structures. The use of flexibility as a condition assessment/damage identification index is the fundamental concept. The modal test method of multi-reference impact testing is the experimental tool used to acquire the objective data through which flexibility is derived. Consequently, the fundamental question to be resolved scientifically through the analysis and synthesis of modal test data is: