This article presents a sophisticated approach to updating the finite element model of two historical arch masonry bridges located in the challenging terrain of Kalka Shimla mountain railway, using ...vibration testing results. To estimate the dynamic characteristics of the bridges, ambient vibration testing was carried out. Next, initial finite element models of the bridges were developed based on geometrical survey data. Sensitivity analysis was used to determine which parameters needed to be modified for the bridges. The response surface method and global optimization techniques were employed to identify the optimal values of structural parameters that would result in a satisfactory agreement between the numerical and measured natural frequencies of the heritage bridges. Ultimately, the methodology provided a surrogate mathematical model to represent the relationship between structural parameters and dynamic response, and could predict the damage status of the historical bridges.
Highway bridges stand as paramount elements within transportation infrastructure systems. The ability to ensure swift recovery after extreme events, such as earthquakes, is a fundamental trait of ...resilient communities. Consequently, expediting the recovery process necessitates near real-time diagnosis of structural damage to provide dependable information. In this study, a data-driven approach for damage detection and assessment is investigated, focusing on bridge columns-the pivotal supporting elements of bridge systems-based on simulations derived from nonlinear time history analysis. This research introduces a set of cumulative intensity-based damage features, whose efficacy is demonstrated through unsupervised learning techniques. Leveraging the support vector machine, a prominent pattern recognition algorithm in supervised learning, alongside Bayesian optimization with a Gaussian process, seismic damage detection and assessment are explored. Encouragingly, the methodology yields high estimation accuracies for both binary outcomes (indicating the presence of damage or the occurrence of collapse) and multi-class classifications (indicating the severity of damage). This breakthrough opens avenues for the practical implementation of on-board sensor computing, enabling near real-time damage detection and assessment in bridge structures.
For several years, the use of the BIM method has been mandatory for public new construction and replacement projects of the transport infrastructure in the Federal Republic of Germany. As a result, ...about 20 use cases (UC) for the application of digital models have been defined. Most of them focus on the planning and execution phase. Despite the importance and long duration of the operational phase, there are isolated definitions for use case for operational phase and therefore underrepresented in the overall context. Moreover, none of the published use cases so far consider the specifics of bridge structures. For this reason, a further definition of specific BIM use cases for the operation of bridge structures is needed. In this article, BIM use cases for the use of digital models of bridge structures in the operation and maintenance phase are defined based on a qualitative empirical study. First, the current state of the art is elaborated by means of a literature analysis. Based on this, a expert interviews are conducted and systematically evaluated. The BIM use cases for operation are derived from the results. In addition, requirements and artifacts are defined. This results in a further specification of the use of BIM models in the operational phase of bridge structures and promotes the digitalization of maintenance management.
There are about 65,000 bridge structures in the infrastructure network of the Federal Republic of Germany. Due to the long operating phase of bridges, they have an influence on sustainability. To ...evaluate the sustainability of bridges in the operational phase, digital building models can serve as a consistent and structured database to increase the efficiency and transparency.
In this article, an innovative evaluation system for measuring and assessing the sustainability of a bridge structure in the operational phase based on a digital bridge twin is developed. First, the workflow is presented in a process model and the necessary requirements for the digital twin of the bridge structure are defined. In addition, the semi‐automatic sustainability assessment system is described and the linkage via an interoperable interface to the digital twin is designed. The approach is tested and validated using a real demonstrator. The result of the paper shows an approach to use digital twins for a novel and semi‐automatic sustainability assessment in the operation of bridge structures.
In this paper, the behavior of short-circuit (SC) caused by incorrect gate signals in bridge structures is analyzed in detail by semiconductor device theory, experimentations, and physics-based ...simulations, which has rarely been studied before. The voltage redistribution phenomenon and the associated dynamic avalanche failures are discovered. An experimental platform is designed and built to reproduce the SC conditions in bridge structures. Both theory and experimental results reveal that the bus voltage V SC will be redistributed between the high-side and low-side IGBT devices, and the voltages of the devices will be reversed in the initial phase of the SC event. This paper derives the formula of the voltage difference Δ V CE between the high-side and low-side IGBT devices at the SC steady state and proposes the corresponding parameter extraction method. The SC experiments at different load currents I Load and bus voltages are performed to verify the formula. In addition, both experimental and simulation results show that when I Load is large, the Δ V CE will be close to the V SC, and the device subjected to a low voltage will be in the saturation state. And the dynamic avalanche occurs during turn-off transient where the SC current is shut down by the device bearing a low voltage. The associated failure cases and their relationship with SC time are discussed. And a targeted SC protection scheme is proposed.
•Seismic responses of bridge structures with segmental columns are numerically investigated.•Seismic responses of bridge structures supported by segmental columns and monolithic columns are ...compared.•The influences of pounding, frequency ratio and gap size are systematically investigated.
Recently, extensive experimental and numerical studies have been carried out to understand the seismic behaviors of segmental columns. Very limited studies, however, focused on the seismic performances of a whole bridge system with precast segmental columns. This paper carries out numerical studies on the seismic responses of bridge structures with precast segmental columns. For comparison, the seismic responses of the bridge with conventional monolithic columns are also calculated. The two-dimensional (2D) finite element (FE) models of these two bridge types are developed by using the FE code OpenSEES. The segmental column and monolithic column are simulated by the simplified lumped-mass model and fiber-based model respectively and validated by the previous experimental studies. The calibrated column models are then incorporated into the whole bridge structures to calculate the structural responses. The influences of pounding, frequency ratio and gap size on the structural responses are investigated and discussed. Numerical results show that the bridges supported by the segmental columns or monolithic columns have very different seismic responses.
Abstract
Die Eisenbahninfrastruktur besitzt eine hohe Signifikanz für Wirtschaft und Gesellschaft. Das Durchschnittsalter der Eisenbahnbrücken in Deutschland liegt bei etwa 75 Jahren. Entsprechend ...ist auch die Bestandsdokumentation der Bauwerke historisch bzw. veraltet. Für den Anlagenbetreiber stellt die Inventarisierung, Aktualisierung und Bereitstellung von mehr als 4,6 Millionen Bestandsplänen eine enorme Herausforderung dar. Zudem benötigt die Generation von digitalen Modellen der Brückenbauwerke viele Ressourcen. Diese Faktoren stellen ein gravierendes Problem für ein qualitatives und effizientes Erhaltungsmanagement dar. Im Rahmen des Forschungsprojekts mdfBIM wird eine teilautomatisierte Methode zur Erstellung objektbasierter digitaler Modelle von Bestandsbrücken mittels Multi‐Datenfusion entwickelt. Für diese Methode wird ein ganzheitliches Prozessmodell erarbeitet und die Möglichkeiten einer teilautomatisierten Datenaufnahme und ‐verarbeitung hin zu einem BIM‐Modell als zentrale Datenbasis eruiert. Die Validierung des Ansatzes erfolgt anschließend an einem realen Demonstrator. Der Beitrag zeigt, wie ein teilautomatisierter Ansatz zur Digitalisierung von Bestandsbrückenbauwerken und die Schaffung einer einheitlichen Datengrundlage für das Instandhaltungsmanagement erfolgreich umgesetzt worden sind.
Translation abstract
Digitization of critical infrastructure structures using multi‐data fusion
The rail infrastructure is highly significant for the economy and society in the Federal Republic of Germany and the European Union. On average, rail infrastructure bridges are around 75 years old. Accordingly, the inventory documentation of the structures is also historical or outdated. For Deutsche Bahn AG, the inventory, updating and provision of more than 4.6 million as‐built plans represents an enormous challenge. Furthermore, the as‐built documents are managed decentralised and in heterogeneous data formats at the plant operator. This poses a serious problem for a qualitative and efficient maintenance management. Within the research project mdfBIM, a holistic, semi‐automated method for the creation of object‐based, digital models of as‐built bridges by means of multi‐data fusion is being developed. For this method, a holistic process model is developed and the possibilities of a semi‐automated data acquisition and processing towards a BIM model as a central data basis are explored. The approach was subsequently validated on a real demonstrator. The article successfully demonstrates a partially automated approach using laser scanning, artificial intelligence and digital building models to digitize bridge structures and create a consistent database for maintenance management.
Subspace-based system identification algorithms have been developed as an advanced technique for performing modal analysis. We introduce a novel tensor subspace-based algorithm to identify the ...time-varying modal parameters of bridge structures. A new time dimension is introduced in the traditional Hankel matrix, and a mathematical model of tensor subspace decomposition is established. Combined with the stabilization diagram, tensor parallel factor decomposition is used to estimate the frequencies, mode shapes, and modal damping ratios. The effectiveness of the proposed algorithm is validated by comparing it with the classical sliding-window–based stochastic subspace algorithm on a model cable-stayed bridge dynamic test. The proposed algorithm is further applied to process the dynamic responses of a real bridge health monitoring system to identify its time-varying modal frequencies. Our results demonstrated that the proposed algorithm significantly reduces computational efforts and extends the range of solution ideas for future out-only time-varying system identification problems.
Highway bridges are critical components of the lifeline transport infrastructure in urban areas. They are designed with the expectation of not sustaining significant structural/non‐structural damage ...after major earthquake‐induced ground shaking. However, in the current structural performance‐based assessment practice, the effects of a pre‐damaged state during ground‐motion sequences are often neglected. Additionally, environmentally induced deterioration mechanisms (e.g., steel rebar corrosion) may exacerbate the consequences of such ground‐motion sequences on the seismic structural performance during the bridge design lifetime; yet such effects are commonly overlooked. This study proposes a computational methodology to derive state‐dependent fragility and vulnerability relationships (i.e., explicitly depending on the damage state achieved by the bridge structure during a first shock) for bridge structures subjected to chloride‐induced corrosion deterioration and ground‐motion sequences. The methodology is demonstrated for a case‐study ordinary bridge structure (representing a typical bridge vulnerability class in southern California) under seismic sequences assembled from the CyberShake 15.12 (hybrid) simulated ground‐motion database. In the proposed approach, parameterised (i.e., dependent on the corrosion deterioration level) vector‐valued probabilistic seismic demand models are developed for the bridge components (i.e., columns and shear keys). These models, calibrated through sequential cloud‐based nonlinear time‐history analyses, relate the dissipated hysteretic energy in the ground‐motion sequence to a deformation‐based engineering demand parameter induced by the first shock and a ground‐motion intensity measure of the second shock for a given corrosion deterioration level. Fragility relationships are first derived for a single ground motion at the component‐level; state‐dependent fragility relationships are then derived by considering the additional damage induced by a second ground motion within the simulated sequence (structure‐specific damage states are considered). Furthermore, a component‐based simulation approach accounting for the correlations across the components’ response is utilised to derive fragility relationships at the system level (i.e., for the bridge structure). Finally, appropriate damage‐to‐loss models for ordinary bridges are used to derive state‐dependent vulnerability relationships. The results demonstrate the significant impact of earthquake‐induced ground‐motion sequences and environmentally‐induced corrosion deterioration, emphasising the necessity of accounting for this multi‐hazard threat in the structural performance‐based assessment of bridges. Relative variations up to 120% can be found in the system‐level state‐dependent fragility median values comparing the results for the bridge in pristine and deteriorated conditions.
