1,721,200 research outputs found
Value of information of static and modal data for a concrete bridge exposed to reinforcement corrosion
No full textA lot of infrastructure is ageing and reaching the anticipated service life. Measurements or inspections performed on ageing bridges can provide information on the actual degradation state and hence the remaining capacity of these structures. Nevertheless, these measurements or inspections also come at a cost, whereas the budgets for maintenance and repair are often limited. Based on pre-posterior analyses, the Value of Information (VoI) of these measurements or inspections can be determined on beforehand and the most optimal measuring/inspection strategy can be chosen. However, applying these VoI analyses to real-world structures, considering the time-dependent and spatial character of degradation, can be challenging. In this work, a case study is considered where the VoI analysis is applied to a reinforced concrete girder bridge subjected to corrosion. Different monitoring strategies are considered, and different times of performing the measurements or inspections are evaluated. The influence of some parameters, such as the failure cost and the threshold for performing an action based on the measurement or inspection outcomes, has been investigated. The VoI is evaluated for two cases: one with low exposure (corrosion due to carbonation) and one with high exposure (corrosion due to chlorides). In the first case, the degradation rate is very low, and no repairs are required within the considered time span. Monitoring does not induce an intervention and hence will lead to a negative VoI. In the case of chloride-induced corrosion, a positive VoI is found for some time steps and the VoI reaches a maximum in the considered time span. This could be ascribed to the fact that monitoring triggers an intervention for this situation. In this case, changing the threshold that triggers the intervention will affect the VoI and, consequently, the most optimal measuring/inspection strategy
Assessment of the corrosion degree of beams subjected to accelerated corrosion based on indirect data
No full textAssessment of the corrosion degree of beams subjected to accelerated corrosion based on indirect data
No full textIn the view of circular construction, there should also be a focus on the assessment of existing structures.
Their remaining strength and capacity should be determined, taking into account the degradation over
their life-time. Often, only indirect measurement data is available to assess the level of degradation.
Previous studies have illustrated how strain data from proof-loading and modal data from vibration
tests can be used to estimate the corrosion level of reinforced concrete structures. However, most of
these studies are based on virtual measurement data, and the use of real-case data will often be accompanied
with additional challenges. To get a better insight in the challenges of real-case data, an experimental
campaign has been performed in the Magnel-Vandepitte laboratory at Ghent University. Different
real-size reinforced concrete beams have been subjected to accelerated corrosion. They have been
subjected to 4-point bending tests and vibration tests. Afterwards, the actual corrosion degree was determined
based on the mass loss of the reinforcement. The influence of the corrosion degree on the
measurement data has been investigated and a Bayesian inference framework has been adopted to estimate
the corrosion degree of these beams from the test results. From these analyses, important conclusions
can be drawn towards the use of Bayesian inference for assessment of the corrosion degree on
real-case structures
Assessment of the corrosion degree of beams subjected to accelerated corrosion based on indirect data
No full textIn the view of circular construction, there should also be a focus on the assessment of existing struc-tures. Their remaining strength and capacity should be determined, taking into account the degradation over their life-time. Often, only indirect measurement data is available to assess the level of degradation. Previous studies have illustrated how strain data from proof-loading and modal data from vibration tests can be used to estimate the corrosion level of reinforced concrete structures. However, most of these studies are based on virtual measurement data, and the use of real-case data will often be accompanied with additional challenges. To get a better insight in the challenges of real-case data, an experimental campaign has been performed in the Magnel-Vandepitte laboratory at Ghent University. Different real-size reinforced concrete beams have been subjected to accelerated corrosion. They have been subjected to 4-point bending tests and vibration tests. Afterwards, the actual corrosion degree was determined based on the mass loss of the reinforcement. The influence of the corrosion degree on the measurement data has been investigated and a Bayesian inference framework has been adopted to estimate the corro-sion degree of these beams from the test results. From these analyses, important conclusions can be drawn towards the use of Bayesian inference for assessment of the corrosion degree on real-case struc-tures
Investigation on the effect of corrosion on testing data of reinforced concrete beams
No full textIn light of circular construction, there is a rising need for effective methods to assess the remaining structural capacity of reinforced concrete structures, accounting for degradation mechanisms such as corrosion. Different studies, mostly based on simulations, have illustrated how data from static and dynamic tests can be used to estimate the corrosion level of existing reinforced concrete structures. To get a better insight in the effect of corrosion on real-case data, an experimental campaign has been performed at the Magnel-Vandepitte Laboratory of Ghent University. Different real-size reinforced concrete beams have been subjected to accelerated corrosion, 4-point bending tests and vibration tests. After loading the beams to failure, the actual corrosion degree was determined and the influence of the corrosion degree on the measurement data has been investigated
Unsteady Reynolds averaged Navier-Stokes simulation of the post-critical flow around a closely spaced group of silos
No full textDuring a storm in October 2002, wind induced ovalling oscillations were observed on several empty silos of a closely spaced group of 8 by 5 silos in the port of Antwerp (Belgium). Present day standards describe only basic wind load cases, unable to explain this ovalling phenomenon. In order to improve the design of engineering structures with cylinders placed in groups, a thorough understanding of the fluid flow around such groups is required. 2D unsteady Reynolds averaged Navier-Stokes (URANS) equations using Menter's shear stress transport turbulence model were performed, considering the wind flow around the rectangular group for a range of angles of incidence (0° < a < 90°). The 2D highly turbulent post-critical flow (Re = 1.24 × 107) around a single cylinder was computed to elucidate the influence of the applied turbulence model and to validate the spatial and temporal discretization. Similarities of the flow regime around and within the present silo group and the flow around rectangular cylinders and the flow within tube arrays (e.g. heat exchangers) respectively are discussed to qualitatively assess the results of the simulations. Static and dynamic pressure loadings on separate silos of the group are studied to explain the existence and location of wind induced vibrations in closely spaced silo groups. It is found that ovalling oscillations in the third and fourth ovalling eigenmodes can be excited by dynamic pressure fluctuations at the lee side of the group, corresponding with the visually observed vibrations in 2002.status: Publishe
Identification of Damage in Truss and Beam Structures Based on Flexibility Matrix
No full textIn this work, we propose a numerical strategy to detect damages in truss and beam structures exploiting lowest frequencies and mode shapes that are employed to calculate the flexibility matrix. In particular, for truss structures, the modal strain difference between damaged and healthy structures is used to identify the element characterized by the highest value of strain change, which corresponds to the most likely damaged element in the structure. Conversely, for beam structures, the highest value of modal curvature change is used as an index of element damage. Both procedures are validated using pseudo-experimental data accounting for noise pollution in mode shapes components
Minimax optimization of Tuned Mass Dampers under seismic excitation
Full text linkThe present paper concerns the optimal tuning of the free parameters of passive Tuned Mass Damper (TMD) devices, added to benchmark frame structures taken from the literature and subjected to a given deterministic seismic excitation. The tuning procedure is achieved through a numerical optimization approach, namely a Minimax algorithm implemented in a MATLAB environment. Different objective functions have been considered, from both kinematic and energy response indicators of the primary structure. The optimization process is carried-out in time domain, whereby the dynamic response is evaluated numerically by a step-by-step integration based on Newmark’s average acceleration method. In order to assess the efficiency of the proposed methodology and investigate the effectiveness of the so-conceived TMD, several numerical tests on both single- and multi-degree-of-freedom frame structures endowed with a TMD are performed. The salient numerical results are presented in plots and tables. Plots of the optimal TMD parameters (frequency ratio and damping ratio) as a function of mass ratio are reported and graphs showing the seismic response reduction in terms of top-floor displacement are provided. Tables gathering the optimal TMD parameters and the seismic response reduction at assumed given values of the mass ratio are outlined. Comparisons to results obtained from well-known tuning formulas are provided. The achieved output demonstrates the reliability of the proposed method and shows that, in principle, the design of an optimal TMD device for a specific seismic event is possible. This should have important implications in the framework of adaptive, semi-active and active TMD devices
Soil vibration and auralisation software tools for application in railways
No full textThe main objective of the SILVARSTAR Shift2Rail project is to develop validated software tools for application in the field of ground vibration and auralisation in the railway sector. The first project work stream focuses on the prediction of ground vibration through the development and validation of a hybrid approach, combining numerical prediction with experimental results. The general framework adopted expresses the vibration level in a building as the product of terms describing the source, the propagation through the soil and the receiver. For each term, a database of both measured and pre-computed data is provided, allowing rapid calculations to be performed. In the upcoming project phase, this ground vibration software will be integrated in an industrial noise mapping software (IMMI). This will result in a unique software platform that will allow engineers to perform noise and vibration environmental impact studies within the same software environment, on a large scale. In the second work stream, auralisation and Virtual Reality (VR) software tools are developed based on physical models to synthesise railway noise in high quality. The novel auralisation and VR tools enable perception-based evaluation of noise mitigation technologies and an effective demonstration of different noise scenarios, including noise mitigation measures and vehicle design variants. This will support decision-making and facilitate communication with stakeholders through VR prior to project delivery. The new software tools will be made available to the industry at the end of 2022
Demonstration and validation of a hybrid vibration prediction tool for railway induced vibration
No full textAlthough rail is a sustainable and climate-friendly mode of transport, noise and vibration remain particular environmental concerns. Within SILVARSTAR, a two-year collaborative project funded under the Shift2Rail Joint Undertaking in Horizon 2020, the aim is to develop validated software tools to assess the noise and vibration environmental impact of new railway lines or the extension of existing lines. One of two major objectives is the development of a hybrid vibration prediction tool for railway induced vibration incorporating widely accepted solution methods and standards. In order to keep the computational effort low, the soil impedance and track-soil transfer functions are pre-computed for a large number of cases and stored in a numerical database. Additionally, the vibration velocity level is predicted using a low speed approximation, which disregards the Doppler effect. Incoherent axle loads are also assumed. This paper demonstrates the use of the vibration prediction tool for tracks at grade and in tunnels; results are validated with state-of-the-art numerical models
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