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The human body, composed of interconnected subsystems with complex dynamic behavior, is often oversimplified or neglected by structural designers and building codes. Human-induced loads, whether passive (e.g., standing, sitting) or active (e.g., walking, dancing, jumping), considerably impact the dynamic response of structures such as grandstands, slender slabs, and pedestrian bridges, highlighting the necessity for their consideration in design. This study introduces three closed-loop control models to represent the human-structure interaction (HSI) effect: a Proportional Integral (PI) controller, the Pole Placement control algorithm (PP), and the Linear Quadratic Regulator with an Observer (LQR + L). While well-established in robotics and automation engineering, these control algorithms represent a novel and transformative approach when applied to HSI. They offer an intuitive and effective framework for modeling the dynamic feedback mechanisms inherent in HSI. The model parameters are obtained using global optimization and curve fitting methods, followed by experimental validation on a test structure. The results of this study indicate that feedback controllers accurately predict the experimental structural response for different subjects. These findings highlight the importance of incorporating HSI effects into structural design, promising the design of safer and more comfortable structures in human-occupied environments. [ABSTRACT FROM AUTHOR]

A routine for damage detection based on multiple damage modelling and artificial neural networks (ANNs) is presented in this article. The routine aims to identify the existence and location of damage, along with the most damaged elements. The first step in the routine is to define 'critical' regions based on stresses and deformations of the updated numerical model of the structure, as well as the probable order of occurrence in the case of multiple damage by simulating different scenarios. The second step is to train the ANN using the natural frequencies of intact and damaged numerical models as input data, with vectors indicating the position and magnitude of the damage as the expected output. A feed-forward back-propagation ANN was adopted. The approach was used to evaluate a cable-stayed footbridge. A new dynamic test was performed and a vector composed of the identified frequencies was input into the network, which indicated the existence of possible damage. The provided damage scenario was applied to the updated model, along with the experimentally obtained prestressing forces of the stays. The maximum difference between the frequencies of the updated and damaged numerical model with the damage vector provided by the network and the frequencies experimentally identified in the new test was 1.80%. [ABSTRACT FROM AUTHOR]

The dynamic response of light bridges to moving loads presents significant challenges in controlling vibrations that can impact on the structural integrity and the user comfort. This study investigates the effectiveness of nonlinear semi-active absorbers in mitigating these vibrations on light bridges that are particularly susceptible to human-induced vibrations, due to their inherent low damping and flexibility, especially under near-resonance conditions. Traditional passive vibration control methods, such as dynamic vibration absorbers (DVAs), may not be entirely adequate for mitigating vibrations, as they require adjustments in damping and stiffness when operating conditions change over time. Therefore, suitable strategies are needed to dynamically adapt DVA parameters and ensure optimal performance. This paper explores the effectiveness of linear and nonlinear DVAs in reducing vertical vibrations of lightweight beams subjected to moving loads. Using the Bubnov-Galerkin method, the governing partial differential equations are reduced to a set of ordinary differential equations and a novel nonlinear DVA with a variable damping dashpot is investigated, showing better performances compared to traditional constant-parameter DVAs. The nonlinear viscous damping device enables real-time adjustments, making the DVA semi-active and more effective. A footbridge case study demonstrates significant vibration reductions using optimized nonlinear DVAs for lightweight bridges, showing broader frequency effectiveness than linear ones. The quadratic nonlinear DVA is the most efficient, achieving a 92% deflection reduction in the 1.5–2.5 Hz range, and under running and jumping reduces deflection by 42%. [ABSTRACT FROM AUTHOR]

This review paper investigates the current state of research on structure-to-human interaction (S2HI) in the monitoring and control of cyclo-pedestrian footbridges, focusing specifically on the biodynamic effects of oscillations on pedestrians. Its aim is, therefore, twofold: In the first half, it examines the limited but evolving understanding of human gait responses to vertical and horizontal vibrations at frequencies and amplitudes characteristic of footbridge dynamics. The second half includes a detailed analysis of various modelling strategies for simulating pedestrian and crowd dynamics, emphasising the movements and stationary behaviours induced by structural vibrations. The aim is to highlight the strengths and limitations of these modelling approaches, particularly their capability to incorporate biomechanical factors in pedestrian responses. The research findings indicate that existing studies predominantly focus on human-to-structure interaction (HSI), often neglecting the reciprocal effects of S2HI, with many results in the literature failing to adequately address the biomechanics of single pedestrians or crowds experiencing structural vibrations on cyclo-pedestrian bridges. This gap underscores the need for more precise and comprehensive studies in the field to improve the understanding of dynamic interactions between single or multiple walking individuals and footbridge vibrations, especially for vulnerable and elderly people with limited mobility. Furthermore, considerations regarding the impact of Structural Control and Health Monitoring to alleviate these issues are briefly discussed, highlighting the potential to optimise footbridge performance in terms of pedestrian comfort. [ABSTRACT FROM AUTHOR]

This study employed an enhanced social force model to investigate the impact of bidirectional crowd load on the vertical vibration characteristics of pedestrian bridges. The research incorporated a two-step prejudgment approach to optimize agents' transcendental behavior and introduced a fan-shaped pedestrian perception area for bidirectional crowd movement simulation based on the social force model. The structural vibration response resulting from the evolution of these behaviors was numerically simulated and analyzed. Vertical crowd–structure coupling models were established using a pedestrian moving dynamics model with spring, mass, and damping. A real-time solution method for the structural acceleration response, varying with the moving pedestrian load entering the footbridge deck, was implemented in a numerical environment. Subsequently, the structural response under crowd load, considering multiple behavioral factors, was investigated on an interior steel footbridge. The results demonstrated that bidirectional crowd load generates a higher vertical acceleration response than unidirectional crowd load under the same pedestrian density conditions. The vertical peak acceleration reached its maximum when the number of left- and right-oriented pedestrians was the same, while the peak acceleration of the structure decreased as the difference between the left- and right-oriented pedestrian numbers increased, both in steady-state and transient-state conditions. Bidirectional crowd load poses a higher risk of inducing severe potential vertical resonance of the structure due to synchronization issues, highlighting its significance in the operation of the footbridge. [ABSTRACT FROM AUTHOR]

Progress in quantifying and codifying pedestrian–structure interaction with a vertical structural vibration and the effects on both human beings and structures has been slow, primarily owing to a lack of experimental facilities that can simulate a wide range of vibration conditions. To accelerate the progress of pedestrian–structure interaction research, a new experimental facility (the UNIOVI footbridge) has been developed at the University of Oviedo, Gijón, Spain, and is presented in this paper. The UNIOVI footbridge is a unique laboratory structure, whose fundamental vertical vibration mode can be finely tuned in the frequency range between 1.6 and 9.3 Hz by altering its mass or stiffness. The clear separation of the first vibration mode from higher vibration modes and a low damping ratio make the structure ideal for interaction studies. The paper describes unique features of the facility and provides analytical expressions for modeling its dynamics. Time-domain procedures based on free decay response data are proposed to identify the dynamic parameters of both the structure and the human body in stationary postures. The use of the facility was successfully demonstrated by identifying body dynamics for six test subjects in three passive postures: one standing posture and two instantaneous postures extracted from the walking gait. The next task is to employ the facility in studying walking, for which the facility was primarily designed. [ABSTRACT FROM AUTHOR]

Since the occurrence of pedestrian-induced large lateral vibration of the London Millennium Bridge in 2000, scholars have realized the complexity of pedestrian-induced lateral vibrations. Despite extensive research spanning over two decades, the underlying mechanisms between pedestrians and footbridges remain incompletely understood. Currently, there are two main popular models for explaining the pedestrian-induced lateral vibration of the footbridge: the synchronization lock-in model and the self-excited force model. Among existing studies, the inverted pendulum model (IPM) essentially belongs to the self-excited force model, has gradually gained recognition. This model assumes that pedestrians maintain a constant step frequency and suggests that footbridge lateral vibration divergence can occur through pedestrian-bridge interaction without synchronization. Although the IPM theoretically elucidates the mechanism by which pedestrian-bridge interaction leads to self-excited forces, it still has its shortcomings: it overestimates the critical number of pedestrians required for triggering vibration divergence of the footbridge. The underlying cause of this problem stems from the inverted pendulum model’s inherent limitation as a single-mechanism framework, which fails to consider the adjustments of pedestrian’s step frequency and instead solely relies on the adjustments of pedestrian’s step width. Consequently, this results in an underestimation of the virtual equivalent damping coefficient that is in phase with the vibration velocity of the footbridge. This study proposes a generalized-inverted pendulum model (G-IPM), in which the pedestrian walking phase evolution is effectively combined with the IPM, thereby the adjustments of pedestrian’s step frequency and step width can be considered simultaneously. Compared to the single-mechanism-based IPM, the numerical simulation results indicate that the proposed dual-mechanism-based G-IPM requires fewer pedestrians to trigger the bridge vibration divergence, which is closer to the actual results. Additionally, parameter analysis reveals that varying pedestrian characteristic parameters exert different impacts on the vibration response of bridge. The proposed model pioneers the use of a dual-mechanism-based model, which is of significant theoretical importance in revealing the underlying mechanism of pedestrian-induced lateral vibrations of the footbridge. [ABSTRACT FROM AUTHOR]

Translation abstract 73‐metre‐long integral timber‐carbon‐reinforced concrete composite bridge – Concrete details of the pedestrian and cycle bridge over the Seeblickweg in StuttgartThe construction of the ‘Bridge over the Seeblickweg’ is characterised by the use of innovative construction methods and unconventional materials. The two‐span pedestrian and cycle bridge combines a timber‐concrete composite cross‐section in the span areas with a carbon concrete T‐beam in the support area and at the abutments. By using non‐metallic reinforcement, the concrete cover can be reduced and there is no need for an additional protective layer. In this paper, the details of carbon concrete technology are presented. The design was based on the draft of the now published guideline ‘Concrete components with non‐metallic reinforcement’. Crack widths were measured in a bending test and the permissible stresses of the longitudinal carbon fibre reinforcement were determined. This was sanded for improved composite behaviour. The shear force reinforcement combines stirrups made of carbon and glass fibre reinforced polymer. The challenges in dealing with the innovative building materials during the construction of the bridge are described. Initial results from crack monitoring using fibre optic measuring strands are also presented. [ABSTRACT FROM AUTHOR]

UHPC has been developed in the Czech republic for about 15 years. The paper shows some of the new footbridges with the deck made of UHPC and then focuses on repair and strengthening of existing structures. Extensive experimental work was carried out as a basis for applications. Different loading situations were examined so that the structural performance in serviceability and in ultimate limit states was investigated. Experience from the construction of structures made of UHPC, from extensive experimental campaign, and from literature resulted in development of the Technical conditions for production of UHPC, design and execution and for reconstruction of structures with UHPC, which were approved by the Ministry of Transport in 2024. The document provides a possibility to apply UHPC also in structures of the transport infrastructure. Finally, example of application of UHPC in repair of a heavily loaded road bridge is introduced. Now, the fourth stage of the repair is under construction. Experience from earlier stages led to minor modifications of the original technology. [ABSTRACT FROM AUTHOR]

Bracklinn Falls is situated in a gorge surrounded by ancient woodland within the Loch Lomond and the Trossachs National Park. The park authority required a replacement footbridge to cross the gorge and to provide views of the falls. However, access for construction plant and materials was extremely difficult, with the sole access by way of a steep and sharp-cornered path. The construction and access constraints drove the development of a new modular system and governed the structural and aesthetic design for the new footbridge. The resulting structure consists of perforated panels, formed from single sheets of weathering steel folded into a z-shape. These panels were bolted to cross-frames and assembled to create a half-through beam that spans 21.4 m. The scheme achieved an A+ rating under the 'structural carbon for bridges' (SCORBs) system (Archer and Green, 2021). The structure was assembled bay by bay and push launched along a set of temporary rails, then jacked onto the permanent bearings. By using a folding process, the modular system minimised welding and hence fabrication time. The system is in the process of being developed for repeated use at other locations, and forms an attractive 'flat-packed' modular alternative for difficult to access locations. [ABSTRACT FROM AUTHOR]

Stockbridge dampers are widely used to mitigate the vibrations of cable-stayed bridges and of many other cable-suspended or cable structures exposed to the action of pedestrians, traffic or wind load. Within the current research work, one of the most effective and likely used damper types, the Stockbridge damper, was investigated to support its design and application within the daily engineering praxis. The Stockbridge damper has a relatively simple structural layout, which ensures its modular design allows it to easily adapt the damper to cables having different dynamic properties (eigenfrequencies, mass, etc.). This paper focuses on two main research areas: (i) to understand the static and dynamic behaviour of the damper and the stay cable interaction to investigate the effectiveness of its damping; (ii) to study the sensitivity of the natural frequencies of the damper to the design parameters. The final aim of the research is to develop a simple design method that is easy to apply in engineering practice and allows the efficient adaptation of the Stockbridge damper to different cable-stayed bridges. Key findings include the recommendation to position the damper at approximately 20% of the cable length for optimal attenuation, the importance of detuning to maintain effectiveness under varying cable forces, and the observation that increasing the damper mass improves efficiency, particularly for detuned elements. [ABSTRACT FROM AUTHOR]

This paper presents an analysis of the designs of selected pedestrian footbridges, which serve as important connections that integrate housing environments and are attractive elements of public spaces. The presence of a footbridge enhances pedestrian accessibility to areas and uses by linking different urban regions. Unlike other types of bridge structures, pedestrian footbridges offer the opportunity for direct interaction with the structure and materials, which necessitates higher finishing and aesthetic standards compared to regular bridges. The analysis covered sixteen European projects, varying in scale, form, structure, and the role they play in cities. The main objective of this research was to identify the features that contribute to their significance in enhancing the quality of public spaces and housing environments. The research was based on the assumption that the role of contemporary pedestrian footbridges extends beyond transport and circulation to include the creation of attractive spaces. Based on the study, the characteristics that pedestrian footbridges should possess to serve as attractive elements in the integration of housing environments were identified. [ABSTRACT FROM AUTHOR]

In the design of cantilever method bridge anti-overturning structures, the appropriate gap between the supporting foot and the lower rotating table is a crucial factor. It affects the distribution of the upper load and the friction force of the rotating structure, playing a key role in stability control. Currently, a reasonably defined range for this gap based on engineering practice has not been established. This study, set against the backdrop of practical engineering for large-tonnage rotational bridges, analyzes potential overturning instability forms during rotation. It provides a detailed examination of the stability performance of bridges in unbalanced states under single-side joint support configurations and analyzes the mechanical performance and stability under different gaps and impact velocities during rotation. The result is that the impact acceleration, angular acceleration of rotation, and tilt angle (gap) increase displacement and stress in the support system, posing a significant safety risk. The present research demonstrates the safety and rationality of the proposed unbalanced rotation and provides control limits for tilt angle and rotation acceleration during the rotation process. These results demonstrate that the proposed support mode ensures safety requirements during unbalanced rotation, offering insights for the design and construction of large-tonnage rotational bridges. [ABSTRACT FROM AUTHOR]

• Performance of different loading models is compared in reproducing the observed results of typical real-world footbridges. • SMD model with (inconsistent) parameters may result in significant differences in response predictions. • This paper modifies the SMD model and proposes a pedestrian synchronization ratio formula. • Modified SMD can reliably and conveniently reproduce lateral responses as the real-world data. The pedestrian-induced lateral vibration of footbridges has attracted much attention since the London Millennium Bridge incident. Significant investigations were mainly performed by external-excited force models and self-excited force models. The first type models consider pedestrians as harmonic forces and/or spring-mass-damping (SMD) systems. The second type consider the self-excited forces of pedestrians that initialize the instability of footbridges by e.g. applying the inverted pendulum (IP) model. This study compares performance of different models in reproducing the observed results of typical living footbridges: the London Millennium Bridge (UK), T-bridge (Japan) and Pedro e Inês footbridge (Portugal). With varying step frequencies and pedestrian numbers, both the acceleration time history and the discrepancy between the input work and consumed work exhibit a consistent trend for the harmonic force (HF) model and SMD model, yet a notable difference for the IP model. The HF model and SMD model are better suited for assuming synchronization, making them convenient for estimating the serviceability of pedestrian-induced lateral vibration. On the other hand, the IP model is more appropriate for incorporating random step frequencies and can better capture observed instability phenomena realistically. Because the SMD model with (inconsistent) parameters from literature may result in significant differences in predicting the acceleration amplitudes, this paper modifies the SMD model and proposes a pedestrian synchronization ratio formula as an exponential function of the maximum lateral acceleration. It is validated by comparing the analytical and numerical results for the three footbridges. Furthermore, by the modified SMD model, the lateral lock-in phenomenon of footbridges is simulated reliably and conveniently. This work contributes to analyze pedestrian-induced lateral vibration of footbridges. [ABSTRACT FROM AUTHOR]

Studies of the cables of the Lover's pedestrian bridge in the city of Tyumen were conducted using the previously developed method, which takes into account the bending stiffness of steel cables during their transverse vibrations. The obtained values of tension forces and bending stiffness were in the expected range. The high variability in the values of bending stiffness prompted attention to the accuracy of the initial cable length values, which were obtained from a photograph. To refine the cable length, a method of recording nodal harmonics was proposed, but the results obtained by this method turned out to be higher than those obtained from the photograph. The error analysis of the measurements could not explain this overestimation, leading to the need to reconsider the solution of the differential equation for transverse vibrations. It was found that only its particular solution, assuming a hinged support for the cable, had been considered earlier, while in reality, it is cantilevered and has a bending response. Accounting for this feature by introducing an additional boundary condition allowed the improvement of the calculation model and explained the overestimation of the cable length in the nodal harmonics method. Taking into account the type of cable attachment allowed the introduction of a generalized parameter that takes a value of zero for a rigid cantilever attachment and a value of one for a hinged attachment. In this case, a reduction in stiffness within the attachment manifests itself as an increase in the parameter , which can be detected through the vibration spectrum recording results. [ABSTRACT FROM AUTHOR]

Urban pedestrian bridges should contribute to the improvement of the overall image and function of the place where the footbridge is located. In order to establish a complete pedestrian access area of a Green Belt Park, an elegant pedestrian landscape bridge with Y -shaped piers and mixed decks was designed and built, providing an open and diverse viewing experience. Accelerated bridge construction technologies were adopted to build the footbridge. Finite-element models, including the full bridge model and local model, were established and a continuous rigid frame and continuous girder composite bridge system was proposed after scheme comparison. Preliminary statics and dynamics analysis, as well as detailed calculations for the local stresses of Y -shaped piers and the shear lag effect of the deck, were carried out aiming to demonstrate its safety and suitability. [ABSTRACT FROM AUTHOR]

In the development of a sustainable city, it is essential to create pedestrian pathways and bridges that are both friendly and comfortable. A city requires pedestrian bridges that offer a safe way for pedestrians to crossroads. However, in practice, many pedestrian bridges are rarely used. This study aims to analyze the stair elevation of pedestrian bridges by examining the physiological workload involved in climbing the stairs and how this workload varies with the age of pedestrians. The research measured the energy expended by pedestrians in relation to their available capacity. The study was conducted on the stairs of a pedestrian bridge with a 27-degree slope. It was found that adult pedestrians aged between 25 and 45 years expend moderate to high levels of energy when climbing these stairs. The presence of stairs in public facilities encourages individuals to increase their physical activity for health purposes, making it important that the design of the stairs' slope considers both safety and comfort for routine use. The linear equation for cardiovascular load (%CVL) while climbing stairs is expressed as y = 0.999 x + 8.733, where x represents age. This equation indicates that pedestrians over the age of 41 will expend more than 50% of their capacity. The 27-degree slope of the pedestrian bridge may be inconvenient for some users. Therefore, lowering the slope of the stairs should be considered in the design to enhance safety, comfort, and encourage increased use of the stairs. [ABSTRACT FROM AUTHOR]

In this study, multiple tuned mass dampers (MTMDs) were studied to understand their impact on the human-induced vibration response and comfort level of a pedestrian cable-supported suspension bridge. A spatial finite element model based on a specific engineering case was established. The dynamic characteristics of the bridge under human-induced loads were investigated, and its comfort level under human-induced vibrations was analyzed using the time-history method. Then, this study adjusted the design parameters of the dampers based on various optimal damper parameter expressions. Furthermore, the damping effectiveness of MTMD under different mass ratios ( μ ) was evaluated, and it was found that increasing the mass ratio significantly impacts damping performance. Finally, determinant-TMD (TMDD) was introduced, and a comparison between the damping effect, robustness, and performance of TMDD and MTMD was conducted. The results indicate that while increasing the mass ratio does not linearly affect maximum vibration acceleration, the damping effect increases initially and then stabilizes, with a damping rate converging at approximately 55%. However, with the TMDD approach, the maximum damping rate can reach approximately 70%, enhancing comfort levels from the "minimum CL3" achieved with MTMD to the "medium CL2" level. Additionally, while TMDD's robustness is slightly inferior to MTMD at lower mass ratios, it demonstrates superior robustness at higher mass ratios. [ABSTRACT FROM AUTHOR]

The remarkable lateral oscillatory occurrences observed in renowned footbridges, such as the Solferino Bridge in France, the Millennium Bridge in the UK, and the Oda Bridge in Japan, have garnered widespread attention. The intricate nature of pedestrian-induced lateral vibrations necessitates a comprehensive investigation into their underlying mechanisms, with the crux lying in the identification of the lateral excitation model. Presently, most prevailing detection approaches predominantly rely on contact-based equipment, such as force sensors and displacement sensors. However, these approaches suffer from two main drawbacks. Firstly, contact measurement necessitate a substantial number of sensors and entail higher experimental costs. Secondly, when extending contact-based measurements to accommodate multiple individuals, complications arise, including cumbersome installation, heightened technical complexity, and escalated experimental costs. Therefore, we present a novel approach, based on visual technology, to expeditiously recognize the lateral excitation induced by pedestrians. Termed the Dual Perspective of Mediapipe (DPM), this method harnesses the power of Mediapipe, coupled with dual camera models, to precisely unravel pedestrian gait particulars and lateral forces. The efficacy of the proposed approach is validated through a comparative analysis with existing pedestrian gait data. It is noteworthy that this approach offers significant advantages: non-contact with the test pedestrians, thereby ensuring the accuracy of gait information; convenient and straightforward arrangement of measurement equipment; and low experimental costs. [ABSTRACT FROM AUTHOR]

This paper presents a maintenance prioritisation framework for Taiwan's 1268 pedestrian bridges. It aims to standardise their inspection and maintenance, as Taiwan's current bridge management specifications and manuals only apply to its highway and railway bridge infrastructure. It is designed to assess the structural safety and serviceability of six pedestrian bridge types by visual inspection. To assign weight factors to the structural safety and serviceability components of the identified bridge types, two rounds of Delphi method interviews with bridge experts were conducted. The framework is centred on a weighted average condition assessment method that integrates expert-determined weight factors with visual inspection results to calculate a condition index (PBCI). Pedestrian bridges are ranked and classified based on their PBCIs to set appropriate inspection frequency and scope, and to inform maintenance resource allocation. The application of the framework to five pedestrian bridges in Taoyuan City demonstrated its practicality and value for bridge authorities tasked with managing large inventories of pedestrian bridges. [ABSTRACT FROM AUTHOR]

Footbridges are analyzed in terms of dynamic response for pedestrian comfort. This problem is solved mainly on light and at the same time rigid constructions, which are easily oscillated by pedestrian load. It is often solved on steel footbridges, but with the technological development of UHPC, we are capable nowadays to build relatively light and long span concrete footbridges. Behaviour of a thin concrete cross-section with its geometry is closer to steel structures, but at the same time we have to deal with rheological effects such as creep and shrinkage. There are many influences on the structure that can affect the dynamic behavior of the structure, including the non-linear behavior of the cable system. This paper presents an initial entry into the computational issues of more complex constructions that have more input influences. [ABSTRACT FROM AUTHOR]

The text of this submitted paper is devoted to the experimental dynamic analysis of the newly designed footbridge across the Jizera River in Mladá Boleslav. Theoretical modal analysis has shown potential risk that some of the natural frequencies of the bridge deck will belong to the range which is typical for pacing frequencies induced by pedestrians. The resonance behaviour of this structure should be reduced by Tuned Mass Dampers (TMD), which would be tuned for separate natural frequencies of this structure. Therefore, the experimental dynamic analysis was performed on the footbridge in order to assess the effectiveness of installed TMDs. The experiment was divided into two stages, the first one was realized at the footbridge when TMDs were not yet installed, and the second one was carried out on the footbridge with installed and activated TMDs. Moreover, the authors have performed an experimental modal analysis in order to verify the aptness of the computational model and its results. [ABSTRACT FROM AUTHOR]

The vibration serviceability problems induced by the coupling vibration of lightweight footbridges is a research focus. Much research has been conducted in recent years, yet the attenuation of the coupling vibration subjected to a low-density crowd is still challenging. To investigate the coupling vibration between a moving crowd and aluminum alloy footbridge due to synchronous excitation, orthogonal crowd load tests were carried out on a simply supported aluminum alloy footbridge with a span of 34.8 m. Load tests with different numbers of pedestrians and step frequencies were conducted to obtain vibration frequency and peak acceleration of the footbridge. The comparative analysis reveals that vibration serviceability under certain conditions of synchronous excitation was not in accordance with German footbridges guidelines or British standards. Synchronous excitation of low-density crowds may lead to a marked decline in pedestrian comfort. A two degrees of freedom (TDOF) human dynamic model with a supporting mass of human body was applied to establish a crowd-footbridge coupling system. The numerical results are in agreement with experimental data, which validates the finite element model of the footbridge. Further numerical analysis was conducted to investigate the coupling vibration response of the footbridge subjected to low-density crowd below 1 person/m2. The results show that the coupling effect is minor when the mass ratio is 0.12–0.3. When the mass ratio is 0.3–0.46, the coupling vibration is significant. Therefore, the coupling vibration of lightweight aluminum alloy footbridge deserves attention in design when subjected to low-density crowds. The evaluation of vibration serviceability is advised to be conducted according to the requirements of peak acceleration given in footbridge specifications. [ABSTRACT FROM AUTHOR]

This study evaluates the dynamic performance of a reference footbridge under human–structure interaction (HSI) effects using real-time hybrid simulation (RTHS). The footbridge, designed with precise multi-axial dynamic sensitivity, is tested under pedestrian gait velocities of 1.20, 1.50, and 1.80 m · s − 1 . The RTHS framework involves an analytical continuous model of the footbridge as a numerical substructure and real human gait loads as the experimental substructure. The results reveal significant dynamic coupling between pedestrian-induced loads and the responses of the structure. Lateral vibrations exhibit a fundamental frequency of approximately 1.0 Hz, whereas vertical vibrations peaked near 2.0 Hz. Dynamic synchronization, particularly at higher gait velocities, amplified the structural vibrations, with lateral loading increasing by up to 300% in the middle span. Vertical loads show substantial amplification and attenuation depending on gait velocity and footbridge location. Lateral accelerations display a dispersion of approximately 15.0%, whereas vertical accelerations showed higher variability, with dispersions reaching up to 20%. The RTHS technique demonstrates high fidelity and accuracy, with global errors below 2.95% and delays of less than 2.10 ms across all evaluated directions. These results emphasize the critical importance of accounting for HSI effects in the design of pedestrian footbridges because human-induced vibrations can significantly impact structural serviceability and user comfort. This study offers important insights into optimizing footbridge design to mitigate the risks of excessive vibrations and ensure both safety and functionality under typical pedestrian loads. [ABSTRACT FROM AUTHOR]

Purpose: This study identifies basic characteristics and vibration-serviceability-related properties of recent footbridges in China. Also, it characterizes relations between vibration-serviceability-related properties and basic characteristics. Methods: A database is constructed for recent footbridges in China based on systematic literature survey. For each footbridge, it collects basic information (name, function, province, location, service year), structural information (girder cross-section type, main span length, width, bridge type, girder material, deck material, first lateral and vertical natural frequencies, first lateral and vertical damping ratios), response information (crowd density, acceleration responses, mitigation measures), etc. Results: Data analysis shows natural frequencies decrease with increasing bridge span. Estimation relations are proposed to quantitatively express fundamental natural frequencies and main spans in vertical and lateral directions. Damping ratios vary from 0.0015 to 0.0325, indicating the low damping capacity of the footbridges. Footbridges with non-solid cross-section are more vulnerable to human-induced excitations. Most footbridges apply mitigation measures, with mitigation efficiency from 18% to 70%. Conclusion: This study provides designers with first judgements on feasibility of footbridges' design scheme, for instance, a first estimation of natural frequency. Also, the reported information may guide them towards right directions of better design scheme, for example, by adjusting structural information. [ABSTRACT FROM AUTHOR]

Bayesian model updating has received considerable attention and has been extensively used in structural damage detection. It provides a rigorous statistical framework for realizing structural system identification and characterizing uncertainties associated with modeling and measurements. The Markov Chain Monte Carlo (MCMC) is a promising tool for inferring the posterior distribution of model parameters to avoid the intractable evaluation of multi-dimensional integration. However, the efficacy of most MCMC techniques suffers from the curse of parameter dimension, which restricts the application of Bayesian model updating to the damage detection of large-scale systems. In addition, there are several MCMC techniques that require users to properly choose application-specific models, based on the understanding of algorithm mechanisms and limitations. As seen in the literature, there is a lack of comprehensive work that investigates the performances of various MCMC algorithms in their application of structural damage detection. In this study, the Differential Evolutionary Adaptive Metropolis (DREAM), a multi-chain MCMC, is explored and adapted to Bayesian model updating. This paper illustrates how DREAM is used for model updating with many uncertainty parameters (i.e., 40 parameters). Furthermore, the study provides a tutorial to users who may be less experienced with Bayesian model updating and MCMC. Two advanced single-chain MCMC algorithms, namely, the Delayed Rejection Adaptive Metropolis (DRAM) and Transitional Markov Chain Monte Carlo (TMCMC), and DREAM are elaborately introduced to allow practitioners to understand better the concepts and practical implementations. Their performances in model updating and damage detection are compared through three different engineering applications with increased complexity, e.g., a forty-story shear building, a two-span continuous steel beam, and a large-scale steel pedestrian bridge. [ABSTRACT FROM AUTHOR]

Human–Structure Interaction (HSI) can significantly influence the dynamic characteristics of pedestrian footbridges, particularly those distinguished by their lightness and slenderness. This study examines the performance of Tuned Mass Dampers (TMD) and Semi-Active Tuned Mass Dampers (STMD) on pedestrian footbridges when their modal parameters change due to the influence of HSI. For this purpose, a 30 m long simply-supported footbridge with linear mass values ranging from 200kg/m to 2000kg/m and a fundamental frequency varying from 1Hz to 5Hz has been considered. In addition, several pedestrian streams with different pedestrian densities have been used to assess the structural dynamic response. The analysis highlights that structural lightness and slenderness are critical factors in determining whether the incorporation of an HSI model is relevant to accurately predict the dynamic performance of the structure. The findings indicate that while TMDs can become ineffective due to shifts in natural frequencies caused by HSI, resulting in a degradation of vibration reduction from 70–75% to 40–45%, STMDs demonstrate a robust capability to adjust and cope with these frequency changes, maintaining a higher average vibration reduction of around 55–60%. Consequently, STMDs emerge as a necessary solution for very slender structures where HSI significantly alters the global frequency response. This study highlights the importance of considering HSI in the design and implementation of damping solutions to ensure optimal functionality and user comfort on lightweight pedestrian bridges. [ABSTRACT FROM AUTHOR]

To accurately predict the vibration response of large-span floor under crowd walking, the random crowd load model was established according to the relationship among variable step size, variable step frequency and variable step speed during pedestrian walking. Based on the thin plate vibration theory, the crowd-large-span floor coupling dynamic equation considering human-structure interaction was deduced, and the variation rule of dynamic characteristic parameters and acceleration response of large- span floor under random crowd action was calculated and analyzed. The results show that under the random crowd walking, the instantaneous frequency of the large-span floor is decreased with latter increasing, and the instantaneous damping ratio is increased with latter decreasing. With the increasing of the number of people walking, the minimum instantaneous frequency of the structure is decreased significantly, and the maximum instantaneous damping ratio is increased significantly, while the instantaneous acceleration and root mean square acceleration of the large-span floor show the trend of increasing with latter decreasing. Under the different number of people walking, the acceleration response of the structure with and without pedestrian randomness is significantly different. The maximum difference rate of instantaneous acceleration can reach 53.90%, and the maximum difference rate of root mean square acceleration can reach 61.57%. [ABSTRACT FROM AUTHOR]

Sky Bridge 721 was opened on 13 May 2022. It is located in the area of the Kralicky Sneznik mountain massif in the area of the Dolni Morava Mountain Resort. It was built in two years and spans the valley between the two ridges Slamnik and Chlum with a length of 721 metres. It has become a new landmark of the region, although in reality it is almost invisible when viewed from a distance. It winds like a thin thread below the horizon of the mountain ridge, suspended between the sky and the ground, so that it does not interfere with the view of the surrounding countryside. It was a real challenge to bridge such a wide valley at a height of nearly 100 metres and to achieve a subtle line of the footbridge that would not disturb the silhouette of the mountain massif. This is the story of the whole process, from the design to the statics, construction, design and implementation, that the TAROS NOVA a.s. team had to overcome during the implementation of the footbridge. [ABSTRACT FROM AUTHOR]

Once constructed, the Baku White City pedestrian bridge will be a landmark for the newly developed White City district in the east of the Capital. Designed by UNStudio, the bridge crosses the highway of 8th November Avenue and connects the newly build city to the seaside, forming a wide promenade. Due to the pending construction of the mall as future bridge support, the bridge had to be redesigned. A cantilevering viewing platform will highlight the bridge's ending. This paper covers the structural design of the architecturally shaped cable stayed bridge, supported through a 46 m high A‐shaped, slightly curved pylon. Based on 3‐D modelling in Rhino® and Grasshopper®, the FE‐software SOFISTIK® is used both for cable force finding and bridge design. The structural system, steel structure's specific detail for cable connection and its design approach have been documented. [ABSTRACT FROM AUTHOR]

'Robinson' Bridge was built as part of the National Athletic Centre project in Budapest, Hungary. The 168 m long cable‐stayed pedestrian bridge has a 65 m tall inclined pylon standing on a small island. The 12,72 m wide main girder is suspended to a monopylon with a two‐plane fan‐shaped FLC stay cable system. The landmark bridge's stunning appearance was achieved with hybrid structures. Both the pylon and parts of the slender stiffening girder were made of S460 steel tubes filled with concrete to enhance their load‐bearing and dynamic characteristics. Due to very limited construction area, a special erection process was used for the pylon involving a 200t floating crane. The stiffening girder was built with incremental launching. Cable tensioning with a curved deck proposed special design challenges. Large displacements had to be accurately predicted. To meet the strictest requirements for pedestrian comfort, TMDs were applied and dynamic load tests carried out to prove the results. [ABSTRACT FROM AUTHOR]

Footbridges with prestressed concrete deck, which are suspended on steel arch ribs, are described in terms of the structural arrangement, static function and erection. These bridges create stiff structural systems which guarantee the bridges' favourable dynamic response. While steel arch ribs allow easy erections, the concrete deck guarantees structural integrity. The footbridges are structurally efficient, they are light and transparent, corresponds to the scale of the landscape and all structural members have human dimensions. They were erected with a minimum impact on the environment. Their structural arrangement is illustrated on examples of four bridges. [ABSTRACT FROM AUTHOR]

Pedestrian comfort, subtle design, minimizing the number of fixed supports of the footbridge or material saving. These are the key arguments for integrating tuned mass dampers into the bridge project. The goal is to protect people and structure from vibrations and damage. The following paper presents findings from the design, production and tuning of mass dampers, their optimization possibilities and benefits for bridge engineering. The validity of damper design was verified on two footbridges in the Czech Republic and Slovakia. It concerns the footbridge over the Svitava River in Bílovice nad Svitavou and the footbridge over the high‐speed road in Banská Bystrica. Dynamic tests including measurement were carried out on both bridges before and after the installation of the dampers. The dynamic monitoring of the compliance of modal parameters was conducted using operational modal analysis (OMA). The evaluation of the dynamic tests also includes the response to pedestrian effects (comfort criteria) and the determination of the logarithmic decrement of the damping. [ABSTRACT FROM AUTHOR]

The new pedestrian and bicycle bridge in Castrop Rauxel is part of the "Emscherland" project, a nature and water experience park. "Emscherland" is a joint project of the Emschergenossenschaft with the adjacent municipalities of Castrop‐Rauxel, Recklinghausen, Herne and Herten. The total length of the bridge is 412 meters, and the usable width of the pedestrian and bike path is 2.50 meters. The weight of the steel structure is 900 tons. A highlight of the assembly work is the floating‐in of the bridge section (70 meters long and weighing 105 tons) over the Rhein‐Herne‐Canal. [ABSTRACT FROM AUTHOR]

The new pedestrian footbridge at Luxembourg Train Station is an integral component of the revamped platform canopies. Its unique undulating wave design, symbolic of motion, is mirrored in the canopies' roofs, creating asynchronous waves between platforms. As the footbridge aligns with the wave, it gracefully encompasses the translucent tube of the new structure. An integrated staircase fits beneath this architectural wave, with an elevator opposite for easy platform access. This translucent prism stands in stark contrast to the sweeping curves of the roofs and the footbridge itself. Prioritizing user comfort and safety, a translucent design was chosen, eliminating blind spots. The 100‐meter footbridge is constructed with an orthotropic steel deck, offering substantial spans with minimal height. The roof's central section serves to reduce sun exposure and conceal electrical wiring. The assembly process involved crane work during railway track closures over consecutive weekends, using a CC3800 crane with a maximum capacity of 650 tons [ABSTRACT FROM AUTHOR]

The proliferation of signal-free corridors in Karachi, Pakistan, has necessitated the construction of foot-over bridges to facilitate pedestrian road crossings. However, these structures have gradually deteriorated due to vandalism and social factors. Pedestrians perceive them as unsafe primarily due to their poor physical condition, including the absence of guardrails, and the presence of social hazards such as beggars, addicts, and stray dogs. This study aims to assess the safety rating of a foot-over bridge by pedestrians, considering various physical and social hazard factors. An in-person questionnaire-based survey was conducted at a foot-over bridge located near a major university in Karachi. Pedestrians were asked to rate the bridge's safety as safe or unsafe based on the factors they considered most hazardous while crossing it. These factors included the absence of guardrails, and the presence of beggars, addicts, and stray dogs. Pedestrians were also queried about the optimal time for crossing the bridge (morning, evening, or afternoon). Their age was recorded. A Binary Logistic Regression (BLR) model was developed to analyze the data, and odds ratios were calculated for each hazard factor. The results of the BLR model revealed that the gender of the pedestrian significantly influenced the safety rating of the bridge compared to other variables. Female pedestrians were five times more likely to rate the bridge as unsafe compared to males. Furthermore, younger pedestrians were 0.39 times more likely to perceive the bridge as unsafe compared to older ones. The absence of guardrails increased the likelihood of rating the bridge as unsafe by 1.1 times compared to other hazards, and pedestrians crossing the bridge during the afternoon were 1.7 times more likely to perceive it as unsafe compared to morning or evening crossings. In conclusion, female pedestrians perceive foot-over bridges in Karachi as more unsafe, with the absence of guardrails being identified as the primary physical hazard. These findings underscore the importance of addressing safety concerns and improving infrastructure to enhance pedestrian safety in urban environments. It is recommended that the guard rails of pedestrian bridges should be constructed with recycled sustainable materials to prevent them from theft and improve safety, thus, creating a more resilient infrastructure. [ABSTRACT FROM AUTHOR]

Cracks, common indicators of deterioration in bridge frameworks, frequently stem from wear and rust, leading to increased local flexibility and changes in the structure's dynamic behavior. This study examines how these cracks affect the dynamics of footbridges when subjected to loads generated by walking individuals. The pedestrian is modeled as a linear oscillator, while the cracked bridge is represented by a simply supported beam following Euler–Bernoulli's theory. The use of the Dirac delta function allows for the precise representation of the localized stiffness reduction at the crack location, facilitating the calculation of analytical expressions for the beam's vibration modes. The research suggests that the presence of cracks minimally affects the bridge's mid-span displacement. However, with a limited depth of cracks, the appearance of cracks notably amplifies the mid-span acceleration amplitude of the bridge, leading to a pronounced concentration of energy at the third natural frequency of the bridge in the acceleration spectrum. As the depth and number of cracks increase, the acceleration amplitude continues to decrease, but the corresponding spectrum remains almost unchanged. The study's outcomes enhance the comprehension of how cracks affect the performance of bridge structures when subjected to loads from pedestrians, offering insights for the monitoring and evaluation of the condition of cracked footbridges. [ABSTRACT FROM AUTHOR]

The use of pedestrian bridges is often ineffective as pedestrians tend to prefer crossing directly on the roadway, even though heavy traffic conditions increase the risk of accidents. This lowers the safety level of crossers and causes traffic problems. This study aims to evaluate the efficient use of pedestrian bridges and determine public perceptions of road crossing facilities. The research was conducted using geometric assessment and road performance evaluation methods that refer to the 2023 Indonesian Road Capacity Guidelines. In addition, crossing times were analyzed based on the traffic TCT distribution histogram, as well as pedestrian perceptions of crossing facilities. The evaluation results show that the effectiveness of road services falls into category A. Based on pedestrian perceptions, 60% of respondents prefer to cross directly on the roadway, with an average TCT of 1.2 m/sec. From the results of the CSI analysis, the level of respondents' satisfaction with the condition of the pedestrian bridge is 71.373%. Based on the results of the study, the use of pedestrian bridges will be effective in the next 15 years. Recommendations proposed to increase the effectiveness of the use of pedestrian bridges and the level of pedestrian safety is the use of guardrails. [ABSTRACT FROM AUTHOR]

Many modern pedestrian bridges exhibit flexibility and susceptibility to vibrations due to the use of lightweight and high‐strength materials, which can cause discomfort for pedestrians and affect their serviceability. Although gait biomechanics have been extensively studied and optimisation techniques for gait prediction on rigid surfaces have been previously employed, there is a paucity of studies investigating the effects of human‐structure interaction on pedestrian crossings over flexible structures. In this study, inverse dynamics and optimisation techniques were employed to predict human gait on a flexible structure in the sagittal plane. Gait was formulated as an optimal motor task subject to multiple constraints, with the performance criterion being the minimization of mechanical energy expenditure throughout a complete gait cycle. Segmental movements, pedestrian‐applied forces, and bridge vibrations were predicted based on parameters describing gait (such as gait speed, gait frequency, and double support duration), as well as physical and dynamic parameters characterizing the pedestrian bridge (including natural frequency, damping coefficient, and bridge length). [ABSTRACT FROM AUTHOR]

The aspect of resonant vibrations due to pedestrian movement is of great significance in engineering practice. Therefore, understanding the variations in the natural frequency of bridge structures under varying positions of additional mass is of particular interest. This paper presents a procedure for the straightforward determination of the natural frequencies of a beam pedestrian bridge for various positions of pedestrians or a service vehicle based on derived analytical solutions. The calculation takes into account the inertial effects of the additional load mass, modeled as either uniformly distributed or concentrated. The importance of additional load mass effects on the fundamental frequency of a beam pedestrian bridge and its dynamic response to a moving pedestrian load is demonstrated on a bridge example. The proposed solutions are also applicable to other girder system structures with uniform mass and stiffness along their span. [ABSTRACT FROM AUTHOR]

Pedestrian bridges, which are essential in urban and rural infrastructures, are vulnerable to vibrations induced by pedestrian traffic owing to their low mass, stiffness, and damping. This paper presents a novel predictive model of Human-Structure Interaction (HSI) that integrates a three-dimensional biomechanical model of the human body, and a pedestrian bridge represented as a simply supported Euler-Bernoulli beam. Using inverse dynamics, the human model accurately captures three-dimensional gait and its interaction with structural vibrations. The results show that this approach provides precise estimates of human gait kinematics and kinetics, as well as the bridge response under pedestrian loads. The incorporation of a three-dimensional human gait model reflects the changes induced by bridge vibrations, providing a robust tool for evaluating and improving the effect of structural vibrations on the properties and gait patterns. [ABSTRACT FROM AUTHOR]

The Silvertown Tunnel is a new twin‐bore road tunnel under the River Thames in the east of London that increases the river crossing capacity in this area and provides enough clearance for the zero‐emission double‐decker buses. It is being delivered by Riverlinx CJV on behalf on Transport for London (TfL). The overall project consists of tunnel approach ramps at both portals, cut and cover tunnels, and two 1.1 km‐long bored tunnel sections as well as highway connections including a new footbridge and service buildings for operating the tunnel from either end. In this article, the approach and challenges of mechanised tunnelling including the river crossing in a high‐density area, with a large‐diameter earth pressure balance (EPB) machine in mixed‐face conditions, are presented. The Tunnel Bori selection based on the geological and geotechnical information is evaluated and compared to the experience during execution of tunnelling. In detail, the actual EPB drive is evaluated by considering the face pressure support, predicted surface settlements and planned cutterhead maintenance. [ABSTRACT FROM AUTHOR]

This study presents a robot-assisted solution for the automated identification of bridge frequencies and high-spatial-resolution mode shapes using a minimal number of sensors. The proposed approach employs programmable wheeled robots, whose movement can be remotely controlled, as the mobile platform carrying accelerometers. The output-only frequency domain decomposition (FDD) algorithm is adopted for use with the proposed stop-and-go mobile sensing scheme, resulting in the identification of frequencies and high-resolution mode shapes. The solution was verified via two numerical case studies and was validated on a full-scale test of a footbridge. The results reveal that the frequencies and high-resolution shapes of the excited structural modes are identified successfully using only two accelerometers, confirming the satisfactory practicality and efficiency of the proposed solution. [ABSTRACT FROM AUTHOR]