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.
Bridge structures are the important part of lifeline engineering, which are easy to lose their traffic function when subjected to strong earthquakes. Seismic resilient bridge structures are that do ...not require repair or can be restored to normal operating condition with minor repair after an earthquake, which are mainly characterized by self-centering capacity, damage control capacity and easy repair. Therefore, the bridge structures with seismic resilience have become one of the research hotspots in bridge engineering due to the excellent characteristics. This paper firstly reviews the development of bridge seismic design theory, and then highlights the current status of research on bridge structures with seismic resilience. The seismic resilient bridge structures are divided into rocking bridges, bridges with replaceable members and bridges with high-performance materials, according to the method to achieve the performance recovery of bridge structures. Then the research status of these three kinds of seismic resilient bridge structures is reviewed and summarized systematically. A large number of experimental studies and numerical simulations have presented that the seismic resilient bridge structures have excellent performance recovery capability. In addition, this paper also summarizes the current research status of performance evaluation and design methods of seismic resilient bridge structures, and presents practical engineering applications of typical seismic resilient bridge structures. Finally, the future research directions and development trends of seismic resilient bridge structures are prospected.
This study investigates the impact of cyclic tunnel blasting on adjacent bridge structures under construction. Monitoring vibration velocities of the bridge deck, piers, and middle column adjacent to ...the Zhanma Tian Tunnel, a three-dimensional numerical model was developed using FLAC3D software, utilizing blasting vibration test data from the Zhanma Tian Tunnel project in Guizhou. Results show that, as the distance between the bridge and tunnel increases, vibration velocity at the bridge deck decreases more rapidly compared to the base of the pier. Peak vibration velocities recorded were 0.235 cm/s for the bridge deck, 0.081 cm/s for the pier base, and a predicted 0.209 cm/s for the middle column. The impact order from blasting vibrations on the bridge structure is: pier base, middle column, bridge deck. Peak vibration velocity induced by blasting ranged between 0.05 and 0.25 cm/s, within safe limits of bridge material strength. Eight daily blasting cycles do not compromise the safety of bridge structures located 43 m away.
Introduction: Despite the fact that, in recent years, the construction of long-span bridges has been extensively developed, cases of bridge structures buckling in wind still occur, but the issue of ...their interaction with wind has not been sufficiently studied. Purpose of the study: We aimed to improve the structural integrity and operational safety of long-span bridge structures by conducting a computational and experimental study on the effect of various designs of aerodynamic dampers on the aerodynamic stability of such structures. Methods: The study was performed in two stages. At the first stage, preliminary two-dimensional numerical modeling was conducted to study the effect of various designs of aerodynamic dampers on the wind flow over selected bridge spans. Based on the results of the preliminary two-dimensional numerical modeling, we chose the most effective designs of aerodynamic dampers and made their models to conduct experimental studies on aerodynamic stability on a special test bench. Results: Based on the obtained computational and experimental results, we analyzed the effectiveness of various designs of aerodynamic deflectors and fairings used to improve the aerodynamic stability of the standard bridge structure under consideration. Discussion: For a span with one main girder, we determined the deflector design that reduces the vibration amplitude at high wind velocities.
Along the long service life of the approximately 65,000 bridges in Germany of more than 50 years, it requires the execution of many meetings under the participation of many different parties. These ...meetings are still location‐bound and run very manually using analog inventory documentation. For an optimization, further digitization as well as dissolution of the location dependency at the structure, immersive technologies can be used in connection with digital twins of bridge structures.
This article presents an approach for a location‐independent meeting at the bridge structure under the integration and possibility of interaction of all actors and linking of the digital and physical world. A digital building model of the bridge serves as the data basis and immersive technologies such as augmented and virtual reality as the output and interaction technology. In the first section, the status quo is elaborated based on a literature review. This is followed by the presentation of the theoretical concept. In the next step, the concept is implemented and validated by using a real bridge demonstrator. Finally, further development possibilities as well as still existing challenges are derived.
The result of the article shows a concept and the first feasibility of location‐independent meetings in the maintenance management of a bridge by merging the following elements.
Cable force identification is crucial for ensuring the safety and operational performance of in-service long-span bridge structures. Besides the commonly-used frequency measurements for calculating ...cable forces using frequency-cable force relationship formulas, more efficient and straightforward identification could be achieved by directly utilizing frequency response functions (FRFs). This study presents a novel approach that employs neural networks to model the relationship between the FRFs and cable forces, resulting in a more streamlined method for identifying cable forces on long-span bridges. Firstly, the working mechanism of an auto-encoder is merged with the unique characteristics of the FRFs, giving the cross signature assurance criterion. This criterion is then integrated into the loss function as a constraint to account for the poor interpretability of pure data-driven methodology in solving engineering problems, leading to a grey-box data-driven paradigm. Following this paradigm, a physics-informed auto-encoder (PIAE) network is employed to reduce the dimensionality of the FRF data during extracting key features. The reduced FRF data are paired with the cable forces to form training samples. The PIAE network is then trained directly on these samples for the purpose of cable force identification. Finally, the validation of the proposed method was conducted on the actual monitoring data from a cable-stayed bridge and a concrete-filled steel tubular arch bridge. Results indicate that the proposed method achieves not only high prediction accuracy, but also a good fit between the predicted and actual developmental trends of cable forces, and is well-suited for the different types of bridges.
Fiber reinforced elastomeric isolators (FREI) possess unique characteristics relative to traditional steel reinforced elastomeric isolators (SREI). FREI can be classified as either bonded or unbonded ...according to the connection type employed. An understanding of the behavior of FREI under these loading configurations is needed in order to extend the application of FREI to bridges. The objective of this study is to investigate the response of FREI when vertical and rotational deformations are applied separately as well as in combination. Finite element modeling is carried out on five FREI having the same material properties but possessing different geometrical properties. The mean vertical pressure values employed in this studied are 1, 4.5, 7 and 10MPa, which represent the specified upper and lower limits presented in CAN/CSA-S6 and AASHTO-LRFD. The behavior of the isolators under different angles of rotation is investigated up to a maximum value of 0.05 radians. Results obtained from the finite element model study and values obtained from available closed-form analytical solutions are found to be in excellent agreement. In addition, results show that U-FREI experience lower normal stresses and shear strains in the elastomer and lower strains in the reinforcement relative to B-FREI.
