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This paper aims to provide a novel insight into the influence of uncertainties in system- and pedestrian-induced load parameters on the vibration response of footbridges. The study begins with a sensitivity analysis for the vertical vibration response of a representative footbridge to two loading cases: a single pedestrian and a crowd. Two methods are utilized: the Sobol'-based global sensitivity analysis method and the local sensitivity analysis method. Uncertainties in all model parameters (which include bridge and human body dynamics in a walking posture, as well as dynamic force generated by humans) are considered in stochastic response estimation. Parametric analysis is then performed to investigate the influence of the variation of the mean values of the bridge modal mass, damping ratio, and natural frequency on the results of global and local sensitivity analysis. Systematic comparison of the results of global and local sensitivity analysis is performed to identify their similarities and differences. It has been found that the sensitive parameters and their importance ranking strongly depend on bridge modal properties and loading scenarios (i.e., a single pedestrian or a crowd crossing). The damping ratio and natural frequency of the human body are found to be the only two insensitive parameters. Therefore, they could be treated as deterministic parameters in the stochastic estimation of human-induced vibration. Global sensitivity analysis is recommended as a choice for the sensitivity analysis of pedestrian-induced vibration of footbridges as it leads to more reliable results, owing to the advantage of characterizing model sensitivity over the entire input spaces. [ABSTRACT FROM AUTHOR]

One of the objectives of structural health monitoring (SHM) is to maximize the information while keeping the number of sensors, and consequently the cost of the sensor system, to a minimum. Besides, the sensor configurations must be robust in the sense that the feasibility of small errors inherent to the process must not lead to large variations in the final results. This paper presents novelties regarding the robustness evaluation to model and measurement errors of four of the most influential optimal sensor placement (OSP) methods: the modal kinetic energy (MKE) method; the effective independence (EFI) method; the information entropy index (IEI) method; and the MinMAC method. The four OSP methods were implemented on the Streicker Bridge, a footbridge located on the Princeton University Campus, to identify five mode shapes of the bridge. The mode shapes, obtained in a FE model's modal analysis, were used as input data for the OSP analyses. The study indicates that the MKE method seems to be the most suitable method to estimate the optimal sensor positions: it provides a relatively large amount of information with the lowest computational time, and it outperforms the other three methods in terms of robustness in the usual range of number of sensors. [ABSTRACT FROM AUTHOR]

Trough bridge over the river Broye – a pedestrian and cycling bridge made of weathering steel with laser‐cut webs The pedestrian and cycling bridge over the river Broye (Switzerland) connects the new residential area Rives de la Broye to the nearby town Payerne. The superstructure of the 36 m span trough bridge is made of 26 t of weathering steel. Due to the trough cross‐section, the full superstructure is above flood level. Webs and upper flanges do not only have structural purpose but also function as railings and handrails. The webs have a perforated pattern, which was generated computer‐aided and CNC‐laser cut. The pattern was chosen according to the stress distribution in the webs. The remaining material follows the stress trajectories and the seizes of the perforations depend on the local stresses. The pattern does not only make the superstructure look more transparent and lighter, but also reduces the total weight and saves material. The bridge superstructure was completely prefabricated and installed within hours using a mobile crane. At the abutments a restraining effect is achieved by a combination of a tension and a compression bearing, which positively affect the maximum deflection in mid‐span and the dynamic bahaviour. The bearings can move at bearing level to allow for temperature differences. [ABSTRACT FROM AUTHOR]

Resource and emission efficiency in bridge construction using the example of the Leverkusen campus bridge The construction industry is a major contributor to the global emissions of climate‐affecting CO2. Solutions on the track to carbon‐neutral construction and operation can only be achieved through a holistic approach that includes the use of resources. The approach spans from questions about the necessity and size of a building (build less), through a planned re‐use of components and the reduction of material in the design process (build clever), to the selection of materials based on their specific grey emissions (build efficiently) in a tight circulation system (minimise waste). A uniform assessment of the efficiency of resources and emissions for bridge structures is currently not possible due to the lack of internationally coordinated regulations. Using the example of the Campusbrücke in Opladen, Leverkusen, a footbridge built in 2013, the paper explores the different practical approaches that have contributed to a reduction of emissions and used resources. Using a Life Cycle Analysis method (LCA), the selected structure is compared to an alternative design. [ABSTRACT FROM AUTHOR]

Pedestrians face difficulties when trying to cross a road in the urban environment since they are exposed to vehicular traffic. One of the measures to overcome the problems in the case of multilane roads with high traffic volumes is the construction of footbridges. However, pedestrians are not always in favor of footbridges for various reasons (e.g., excessive effort to use the footbridge, deviation from their scheduled route etc.). Thus, pedestrians often face a dilemma, whether to use the footbridge or the signalized crossing. In the framework of this paper an attempt has been made to examine the factors that influence the use of footbridges in the urban environment and the factors that influence the use of signalized crossings in the near area of the footbridge. The case study refers to a major arterial road with heavy traffic volumes in the city of Thessaloniki, Greece. A statistical model was developed, quantifying the impact of quantitative and qualitative factors, as well as pedestrians' social characteristics on the frequency of using the footbridge. The study area included two signalized crossings and the footbridge. Pedestrians can choose either the footbridge or the signalized intersections to cross the road. Counts were made concerning traffic volume, vehicle speed and pedestrian flow. A questionnaire- based survey including 130 interviewees was conducted among pedestrians referring to the three ways of crossing the road (2 level crossings and the footbridge). Almost half of the pedestrians (49%) stated that they never use the footbridge. Most of the responders (87%) consider the footbridge very safe even though they do not use it. In the analysis made in this paper, an ordinal regression model was developed that utilizes questionnaire survey data and field measurements. The aim of the ordinal regression model is to investigate the variables affecting the operation of the footbridge through measuring the frequency of choosing the footbridge to cross the road. The model indicated that pedestrians aged between 25-39 years old have less possibilities to cross using the footbridge. The odds ratio calculation revealed that interviewees who state that the footbridge is very easy to use are more likely to use the footbridge frequently compared to those who state that the footbridge is not at all or almost at all easy to use. The ordinal regression model predicted 0,2 times higher possibility to use the footbridge seldom when interviewees say that their distance from the footbridge affects a little or a lot their crossing point decision. Finally, amongst other important outcomes, the model revealed that interviewees spotted on the footbridge are more likely to use it regularly, thus using the footbridge is more a habit than a random act. Statistical models of this type may help researchers understand pedestrians' attitudes better and potentially contribute to a far better design of new infrastructures or better management of existing infrastructures, considering the user's point of view.

With the advancement in civil engineering, the applications of lightweight and high-strength materials, and large-span, low-damping structural systems, are increasing. One important structural system for such applications is the corridor pedestrian bridge structure. The vibration frequency of the corridor pedestrian bridge structure is often in the same range as the step frequency of pedestrians, and it is easy to cause the appearance of the corridor structure. The vibration frequency of the corridor pedestrian bridge structure is often in the same range as the step frequency of pedestrians, and it is easy to cause the appearance of the corridor structure. Vibration comfort issues even affect the safe use of the corridor. Vibration comfort issues even affect the safe use of the corridor. Regarding the vertical vibration caused by pedestrians on the steel structure corridor footbridge, using a tuned mass damper (TMD) system can reduce the vibration effect. After the TMD vibration reduction test of the steel structure corridor footbridge, it can be found that the vibration reduction rate of the footbridge has reached 62.56%. The results show that vibration reduction by TMD system is a safe and effective method for pedestrian bridge vibration reduction, improving the structural performance and pedestrian comfort of the structural corridor pedestrian bridge.

Copyright of Tecnura is the property of Tecnura and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Studia Universitatis Babes-Bolyai, Philologia is the property of Babes-Bolyai University, Cluj-Napoca, Romania and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Current codes and guidelines for the dynamic design of footbridges often only specify the pedestrian-induced excitations. However, earthquakes may occur during the passing stage of pedestrians in earthquake-prone regions. In addition, modern footbridges tend to be slender and are sensitive to vertical ground motions. Therefore, we investigate the effects of vertical ground motion on pedestrian-induced vibrations of footbridges. A total of 138 footbridges with different materials, dimensions, and structural types are considered as the target structures. The classical social force model combined with the pedestrian-induced load is used to simulate crowd loads for the scenarios with six typical pedestrian densities. Furthermore, 59 vertical ground motions with four seismic intensities are taken as the seismic inputs. An amplification factor is introduced to quantify the amplification effects of vertical ground motion on human-induced vibrations of footbridges. Four machine learning (ML) algorithms are used to predict the amplification factor. The feature importance indicates that the scaled peak ground acceleration, the pedestrian density, and the bridge span are the three most important parameters influencing the amplification factor. Finally, the vibration serviceability of the footbridge subjected to both crowd load and vertical ground motion is assessed.

The Garrison Crossing project in Toronto project includes the North-American's first two pedestrian bridges using duplex stainless steel on the entire structure. The structure has an extended life cycle, is more corrosion-resistant and requires less maintenance, reducing its overall life-cycle cost. Each bridge is supported by a single arch rib inclining at 18° to provide a slender, transparent, and elegant impression. The two arches tilt in opposite directions that result in a dynamic expression. The stainless steel provides premium aesthetics and a safe and durable asset for the City of Toronto. [ABSTRACT FROM AUTHOR]

The pedestrian-induced lateral vibration of footbridges is essentially classified as a nonlinear stochastic vibration. Accordingly, bridge vibration stability falls within the field of nonlinear stochastic vibration stability. At present, the Lyapunov method is mainly used to analyze such stability. However, this method is qualitative, and it cannot quantitatively analyze the vibration stability probability. In this study, a new analytical method based on a comparison of the input energy and the variation of intrinsic energy (IEVIE) is used to analyze the nonlinear stochastic vibration stability of the lateral vibration of the footbridge. The improved Nakamura model is used to describe the lateral nonlinear stochastic vibration of the footbridge. A combination of the IEVIE method and the probability density evolution (PDE) method is then proposed, in which the IEVIE method is utilized to determine vibration stability. The PDE method is used to obtain the reliability of vibration stability. The proposed method is successfully applied to the Millennium Bridge, and its effectiveness is verified by comparing the Monte Carlo and Lyapunov methods. The proposed method can obtain the dynamic probability of the vibration as stable or instable and provide a reference for quantitative analysis of lateral nonlinear stochastic vibration stability of footbridges. [ABSTRACT FROM AUTHOR]

Purpose: In the assessment of footbridge lateral vibrations, the modeling of human-structure interaction requires representation of the dynamics of the human body and the forces induced by people walking, and additionally, consideration of the effects of the crowd. This way, this paper presents a single degree of freedom biodynamic model to represent the action of a walking pedestrian in the lateral direction. Methods: The biodynamic parameters of mass, stiffness and damping, as well as the dynamic load factor were determined from the measured acceleration of people's center of mass. Before the identification of the parameters in the lateral direction, an initial experimental campaign was carried out to identify and characterize the corporal movements of the pedestrians, define a procedure to process the acquired signals and observe the effect of the crowd on such corporal movements, specifically on acceleration and rotation of the pedestrian's pelvis. A second campaign was carried with people walking alone and later in crowd. In the first stage, each participant walked alone with their normal (free) pacing frequency and metronome-controlled pacing frequencies. Subsequently, each individual walked in group with two crowd density conditions. Results: Comparison between biodynamic parameters of people walking individually and in a crowd allowed the identification of the influence caused by the crowd. Also, regression expressions were obtained by relating the biodynamic parameters to the walking lateral frequency and body mass of the pedestrian, for both free walking and walking in crowd conditions. Conclusion: The values of the parameters obtained and the regressions expressions of the biodynamic model in the lateral direction can be used in the study of the human-structure interaction in footbridges. [ABSTRACT FROM AUTHOR]

The request of material savings in bridge constructions leads to the development towards slender and lightweight structures, which are more sensitive to human-induced vibrations caused by walking pedestrians. The resulting accelerations do not endanger the structural safety, but can be perceived as unpleasant for the user and must therefore be restricted within the limit state of serviceability. For this purpose, the guidelines define acceleration intervals, called as "comfort levels" (CL), which evaluate the comfort of the pedestrians, given the maximum acceleration of the bridge. The model for human-induced loads in the design guideline is based on conservative and deterministic simplifications. In particular, the uncertainties in the human gait parameters are neglected. The main objective of this paper is to develop an uncertain load model for walking pedestrians based on Fourier series. The aleatory and epistemic uncertainties in the human gait parameters are quantified with appropriate uncertainty models relying on available data. In a dynamical finite element analysis, the model is used to simulate groups of pedestrians randomly walking over a bridge to calculate the resulting acceleration amplitudes. The approach is applied to a single span beam and to a real world footbridge using a 3D finite element model. The results are then evaluated within the CLs, enabling new assessment methods. • Uncertainty quantification for human-induced loads. • Introduction of a Fuzzy Fourier load model for walking pedestrians. • Simulation of human-induced vibrations of a real world footbridge with polymorphic uncertain data. • New assessment methods for the footbridges comfort level. [ABSTRACT FROM AUTHOR]

Failures of civil structures, such as bridges, due to natural events or anthropic loads can generate significant social and economic impacts. As an alternative for the identification of damage in these structures, dynamic structural health monitoring has been proposed. This paper presents the experimental evaluation of three damage identification techniques on a full-scale footbridge. One of the evaluated techniques is based on damage localization vectors; a second technique is based on changes in the curvature of the modal shapes, while the third technique uses a numerical model and artificial neural networks for locating the damaged section. Five scenarios of controlled damage were induced in the footbridge. Output-only ambient vibration tests were performed at each damage state and the results of the identification techniques were analyzed. The three implemented techniques showed promising results for the numerical simulations, and two of these techniques produced satisfactory results in the experimental evaluation.

Research on the lateral vibrational stability of footbridges has attracted increasing attention in recent years. However, this stability contains a series of complex mechanisms, such as nonlinear vibration, random excitation, and random stability. The Lyapunov method is regarded as an effective tool for analyzing random vibrational stability; however, it is a qualitative method and can only provide a binary judgment for stability. This study proposes a new method, IEVIE-SA, which combines the energy method based on the comparison between the input energy and the variation of intrinsic energy (IEVIE) and the stochastic averaging (SA) method. The improved Nakamura model was used to describe the lateral nonlinear stochastic vibration of a footbridge, whereby the IEVIE method was used to establish the criteria for judging the lateral vibrational stability. Additionally, the SA method was used to deduce the corresponding backward Kolmogorov equation. Subsequently, the backward Kolmogorov equation was combined with the stability criterion established by the IEVIEmethod to analyze the first passage stability. The proposed method is a semi-analytical, quantitative method that only requires a small calculation. By applying the proposed method to the Millennium Bridge, method effectiveness was verified by comparing it with the Monte Carlo and traditional Lyapunov methods. [ABSTRACT FROM AUTHOR]

Summary: This paper presents an overview of the structural performance monitoring system for a butterfly‐shaped arch footbridge located at The Hong Kong Polytechnic University. The system is the product of a multidisciplinary academic collaboration of the pooling expertise of four academic departments, namely, structural engineering, traffic engineering, surveying, and optical communication engineering. This system consists of 88 sensors of 13 types, including an advanced Brillouin optical time‐domain analysis technology, an optical fiber Bragg grating technology, a global navigation satellite system (GNSS), and high‐performance video cameras. The paper summarizes the modular design, subsystem framework, and advanced features of the monitoring system. Preliminary monitoring results, such as high spatial resolution distributed temperature/strain measurement, global heat‐transfer analysis, pedestrian traffic analysis, dynamic characteristics, and GNSS measurements, are introduced. A fire accident is employed to demonstrate the function and value of the monitoring system and provided a rare opportunity to detect damages in a real structure. The monitoring system not only monitors the performance of the bridge in real‐time but also provides a multifunctional platform, including an Internet‐based software for research and teaching and a touchscreen visualization platform for public education. [ABSTRACT FROM AUTHOR]

This paper aims to provide a novel insight into the influence of uncertainties in system- and pedestrian-induced load parameters on the vibration response of footbridges. The study begins with a sensitivity analysis for the vertical vibration response of a representative footbridge to two loading cases: a single pedestrian and a crowd. Two methods are utilized: the Sobol’-based global sensitivity analysis method and the local sensitivity analysis method. Uncertainties in all model parameters (which include bridge and human body dynamics in a walking posture, as well as dynamic force generated by humans) are considered in stochastic response estimation. Parametric analysis is then performed to investigate the influence of the variation of the mean values of the bridge modal mass, damping ratio, and natural frequency on the results of global and local sensitivity analysis. Systematic comparison of the results of global and local sensitivity analysis is performed to identify their similarities and differences. It has been found that the sensitive parameters and their importance ranking strongly depend on bridge modal properties and loading scenarios (i.e., a single pedestrian or a crowd crossing). The damping ratio and natural frequency of the human body are found to be the only two insensitive parameters. Therefore, they could be treated as deterministic parameters in the stochastic estimation of human-induced vibration. Global sensitivity analysis is recommended as a choice for the sensitivity analysis of pedestrian-induced vibration of footbridges as it leads to more reliable results, owing to the advantage of characterizing model sensitivity over the entire input spaces.

Copyright of Journal of Heilongjiang University of Science & Technology is the property of Journal of Heilongjiang University of Science & Technology Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract For the range of medium spans, around 30 to 40m, composite footbridges are getting popular in Brazil. This kind of structure consists on longitudinal steel truss beams providing support for a concrete deck usually made of precast elements. Typical examples of these structures may be found in many cities in Brazil, especially in Brasilia where a large number of highways demanded a significant set of footbridges. Due to the amount of this kind of composite footbridges in Brazil, studies concerning their mechanical behavior are required in order to ensure pedestrian’s safety. For this end, in this paper, a typical Brazilian composite footbridge located in Brasilia is analyzed by means of experimental tests and computational modeling. The focus is the determination of natural frequencies and mode shapes. Strategies to correctly obtain the vertical modes are also discussed since vertical vibration is the main vibration problem expected for the tested footbridge. The obtained results showed that structural balance between stiffness and mass leads to natural frequencies out of the critical frequency range excited by pedestrians in normal use, although the idea was not to measure how these parameters, mass or stiffness, could influence the model. Moreover, Finite Element models were evaluated comparing complexity versus accuracy to predict modal parameters.

Abstract In systems of suspended cable bridges, the cable-stayed bridges have been widely used because of its capacity to overcome large spans and not require large areas of support during their execution, minimizing interference with existing vehicle flow or overcoming large spans in rivers and channels that require space to the passage of vessels. In addition to this structural advantages, they are aesthetically well accepted by society, valuing the urban space and often making it a landmark. This paper aims to describe the influence of unilateral suspension of decks on the behavior of cable-stayed bridges with curved decks through structural models in order to evaluate whether structural gains or losses are relevant to project considerations. Results indicated that stresses variation in the deck depends not only on the position of the cables and their forces (which depends on the stiffness of the deck), but also on the cable itself and the central pylon.

Featured Application: Improvement of procedures for the vibration serviceability of footbridges in the vertical direction by taking into account the presence of pedestrians as part of the dynamics of the system. The vibration serviceability of footbridges has evolved from the adoption of a single pedestrian crossing in the resonance condition to load cases in which several pedestrians cross the structure simultaneously. However, in spite of this improvement, pedestrians continue to be considered as applied loads in codes of practice. Recent research has pointed out that modeling pedestrians as dynamic systems is a step further in the search for a more realistic design approach. This is explored in this paper, focusing on the case of vertical vibration. A two-span cable-stayed test structure was selected, and accelerations were measured from single and group crossings, both at the structure and at a pedestrian's waist. Numerical simulations considering the pedestrians modeled as loads only and also as dynamic systems were implemented, and numerical and experimental time response vibration signatures were compared. Reductions of up to 25% and 20% in peak and RMS acceleration, respectively, were obtained when pedestrians were modeled as dynamic systems, in comparison with the less realistic model of pedestrians as loads only. Such reductions were shown to depend on the number of pedestrians involved in the group. The results, thus, highlight that pedestrian–structure interaction is an asset for the vibration serviceability design of footbridges. [ABSTRACT FROM AUTHOR]

It is essential to reliably predict the human-induced vibrations in serviceability design of footbridges to ensure the vibration levels to be within the acceptable comfort limits. The human-induced structural responses are dependent on the dynamic properties of structures and human-induced excitations. For concrete footbridges, the elastic modulus of concrete is a vital parameter for determining the dynamic structural properties. To this end, a two-stage machine learning (ML)-based method is first proposed for modeling the elastic modulus of concrete. At the first stage, the ensemble algorithm, i.e. the gradient boosting regression tree (GBRT), is used to predict the compressive strength by selecting eight parameters, including concrete ingredients and curing time, as the inputs. At the second stage, the elastic modulus of concrete is modeled by using the GBRT method with the compressive strength as the input. Pedestrian crowd-induced load is the most common and crucial design load for footbridges. To consider the inter- and intra-subject variability in walking parameters and induced forces among persons in a crowd, a load model is developed by associating a modified social force model with a walking force model. By integrating the two submodels of structure and excitation, an intelligent analysis method for human-induced vibration is finally developed. A concrete footbridge with typical box cross-section subjected to human-induced excitation is analysed to illustrate the application of the proposed method. [ABSTRACT FROM AUTHOR]

Copyright of Revista Sul-Americana de Engenharia Estrutural is the property of Revista Sul-Americana de Engenharia Estrutural and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper, Laplacian smoothing, which is an algorithm originally used to smooth polygon meshes in computer graphics (CG), is applied to solve a structural form-finding problem with the proof that the result of such algorithm is equivalent to force density method. Such CG algorithm is used on the design of a new-built suspension footbridge in Shaoxing, China and the algorithm works well. Since Laplacian smoothing is a pure geometric algorithm without any mechanical concept, the algorithm shows the inner relationship between force and shape, more structural applicable CG algorithms are expected to be found in the future. [ABSTRACT FROM AUTHOR]

Pedestrians face difficulties when trying to cross a road in the urban environment since they are exposed to vehicular traffic. One of the measures to overcome the problems in the case of multilane roads with high traffic volumes is the construction of footbridges. However, pedestrians are not always in favor of footbridges for various reasons (e.g., excessive effort to use the footbridge, deviation from their scheduled route etc.). Thus, pedestrians often face a dilemma, whether to use the footbridge or the signalized crossing. In the framework of this paper an attempt has been made to examine the factors that influence the use of footbridges in the urban environment and the factors that influence the use of signalized crossings in the near area of the footbridge. The case study refers to a major arterial road with heavy traffic volumes in the city of Thessaloniki, Greece. A statistical model was developed, quantifying the impact of quantitative and qualitative factors, as well as pedestrians' social characteristics on the frequency of using the footbridge. The study area included two signalized crossings and the footbridge. Pedestrians can choose either the footbridge or the signalized intersections to cross the road. Counts were made concerning traffic volume, vehicle speed and pedestrian flow. A questionnaire- based survey including 130 interviewees was conducted among pedestrians referring to the three ways of crossing the road (2 level crossings and the footbridge). Almost half of the pedestrians (49%) stated that they never use the footbridge. Most of the responders (87%) consider the footbridge very safe even though they do not use it. In the analysis made in this paper, an ordinal regression model was developed that utilizes questionnaire survey data and field measurements. The aim of the ordinal regression model is to investigate the variables affecting the operation of the footbridge through measuring the frequency of choosing the footbridge to cross the road. The model indicated that pedestrians aged between 25-39 years old have less possibilities to cross using the footbridge. The odds ratio calculation revealed that interviewees who state that the footbridge is very easy to use are more likely to use the footbridge frequently compared to those who state that the footbridge is not at all or almost at all easy to use. The ordinal regression model predicted 0,2 times higher possibility to use the footbridge seldom when interviewees say that their distance from the footbridge affects a little or a lot their crossing point decision. Finally, amongst other important outcomes, the model revealed that interviewees spotted on the footbridge are more likely to use it regularly, thus using the footbridge is more a habit than a random act. Statistical models of this type may help researchers understand pedestrians' attitudes better and potentially contribute to a far better design of new infrastructures or better management of existing infrastructures, considering the user's point of view. [ABSTRACT FROM AUTHOR]

• Optimal use of footbridges in low- and middle-income countries (LMICs) is a challenge. • Pedestrians uncomfortable with the footbridge height are less likely to utilise it. • Tiredness when climbing the stairs will lower the likelihood of using the footbridge. • Non-users of the footbridge will change their behaviour if an escalator is installed. Road safety of vulnerable road users in low- and middle-income countries (LMICs) is a major concern. Footbridges or overpasses are pieces of infrastructure designed to allow pedestrians to cross safely. Although there is tension over whether footbridges are the most inclusive and sustainable way to support safe road crossing for vulnerable road users, footbridges are still a predominant piece of infrastructure in LMICs. Therefore, research aimed at optimising the use of footbridges could have an impact on the safety of vulnerable road users. The objective of the present study is to understand the motivational factors influencing pedestrian crossing decisions to use a footbridge in Malaysia. Additionally, the present study investigates the effectiveness of some proposed interventions to change the crossing behaviour of footbridge non-users. An intercept study was conducted in five major cities in Malaysia. Pedestrians answered questions regarding their perceptions about footbridges and previous walking experiences. The analysis was divided into two parts: Firstly, a decision tree analysis was conducted to study the relationship between the observed decision to use or not a footbridge and pedestrians' perceptions about footbridges and experiences. Secondly, a decision tree analysis was used to identify the effectiveness of proposed countermeasures in increasing the footbridge usage among non-users. The findings showed that the footbridge height and the frequency of using it were associated with a decrease in the likelihood of utilising this structure. Being in a hurry was highly associated with crossing at the street level. In addition, footbridge non-users might change their behaviour if escalators or fences are provided as interventions. The results indicated that safety messages delivered through posters to alert footbridge non-users have the potential to sustain safe mobility. A user-centred approach is necessary to increase the usability of footbridges in LMICs. [ABSTRACT FROM AUTHOR]

Copyright of Revista Sul-Americana de Engenharia Estrutural is the property of Revista Sul-Americana de Engenharia Estrutural and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A new class of tensegrity footbridges based on ring modules has been proposed and studied in the recent years. This article restudies the tensegrity footbridge and puts emphasis on some issues that are questionable or need further clarification in the previous studies. New cross-sectional sizes that satisfy the given internal space requirement are used for the tensegrity ring modules. The integral feasible prestresses of the tensegrity ring modules are determined and a new classification on the groups of members is proposed. A parametric study on the effects of cross-sectional areas of members and the level of prestress on the behavior of the tensegrity footbridge is carried out. The dominated parameters on the behavior of the tensegrity footbridge are identified. An improved structural efficiency index is proposed to evaluate the efficiency of the tensegrity footbridge. The effect of the number of modules on the structural efficiency index of the system is investigated. The reliability of the new index is verified through a comparison with the index proposed by a previous study. This article provides a more comprehensive understanding on the tensegrity footbridges based on ring modules. [ABSTRACT FROM AUTHOR]

This paper introduces a novel approach that focuses on application of cooperative game theory model for automated finite element model updating. The approach involves transforming the conventional single-objective optimization finite element model updating problem into a game theory problem. Among the different alternatives, a cooperative game model is considered to solve the transformed updating problem. This new approach overcomes the limitations of the conventional single-objective optimization formulation, which include challenges related to selecting appropriate weighting factor of residuals and analysing their influence on optimization results. To demonstrate the effectiveness of the proposed approach, an ultralight fibre reinforced polymer footbridge is considered. The numerical model of the footbridge is updated using the experimentally determined inherent properties (natural frequencies and mode shapes) using the proposed approach. A comparison with the conventional sensitivity-based weighted single objective method reveals that the inclusion of the weighting factor in the optimization process under the cooperative game model method allows for more efficient solution of the single-objective updating optimization problem, while maintaining accuracy and quality in the updated model. [ABSTRACT FROM AUTHOR]

Modern architecture leads to design subtle bridge structures that are more sensitive to increased dynamic loading than the massive ones. This phenomenon can be especially observed on lightweight steel structures such as suspended footbridges. As a result, it is necessary to know precisely its dynamic characteristics, such as natural frequencies, natural shapes and damping of construction. This information can be used for further analysis such as damage detection, system identification, health monitoring, etc. or also for the design of new types of construction. For this purpose, classical modal analysis using trigger load or harmonic vibration exciter in combination with acceleration sensors is used in practice. However, there are many situations where it is not possible to stop the traffic or operation of the bridge. The article presents an experimental measurement of the dynamic parameters of the structure at the operating load using the operational modal analysis.

The study presents a numerical analysis of the arched footbridge designed in two variants, made of steel and aluminium. The first part presents the criteria for evaluation of the comfort of using the footbridges. The study examined the footbridge with arched design with span in the axis of 24 m and width of 1.4 m. Arch geometry was made as a part of the circle with radius of r = 20 m cut off with a chord with length equal to the calculation length of the girders. The model of the analysed footbridge was subjected to the dynamic effect of wind and the pedestrian traffic with variable flexibility. The analyses used Robot Structural Analysis software.

The paper presents proposals for the use of glass fiber reinforced polymer composites for the construction of engineering objects, known and commonly used in the shipbuilding industry. An example of a pedestrian footbridge was used in this case, which, despite the considerable thickness of the structural material, was made using infusion technology in one production cycle. The designed and produced footbridge span is durable, dynamically resistant, incombustible, easy to install and maintain, resistant to weather conditions and also aesthetically interesting. For footbridge production environmentally friendly PET foam core may be used. It may come from recycling of used plastic packages and which is produced with less energy consumption process and much less CO2 emission. The load bearing part of the structure (skin) is made of polymer laminate reinforced with glass fabrics (GFRP).

The paper analyses possible causes of failure of the rotating footbridge over the Ustka port channel. In July, 2015, strange behaviour of this object was observed in the form of excessive vibrations of bridge platform suspension rods, with the accompanying acoustic effects. A preliminary geotechnical analysis has revealed that this destructive effect was caused by the nearby construction works, namely construction of a fishing basin and communication routes in the area close to the bridge, which affected the bridge lashing rod foundation settings. Ground vibrations generated by certain construction activities were likely to have direct impact on decreasing the bearing capacity of these rods and increasing the susceptibility od the piles to extraction. After detecting the above problems in bridge operation, its geodetic monitoring was started. The data recorded during this monitoring, along with the results of force measurements in the rods, have made the basis for a series of numerical simulations, performed in the Finite Element Method (FEM) formalism. The bridge structure was analysed in the conditions defined as the emergency state. Extreme efforts of bridge elements and its dynamic characteristics were examined. A possible source of strange behaviour of the footbridge during its operation which was recognised during these simulations was the coincidence of the global natural frequency of the entire bridge structure with local vibrations of suspension rods, at the frequency approximately equal to 1 Hz. This situation was likely to lead to the appearance of the so-called internal resonance phenomenon. As a final conclusion of the research, recommendations were formulated on possible object oriented corrective actions.

Vibration serviceability of footbridges is important in terms of fitness for purpose. Human-induced dynamic loading is the primary excitation of footbridges and has been researched with traditional sensors, such as inertial sensors and force plates. Along with the development of computer hardware and algorithms, e.g., machine learning, especially deep learning, computer vision technology improves rapidly and has potential application to the problem. High precision pedestrian detection can be realized with various computer vision methods, corresponding to different situations or demands. In this paper, two widely recognized computer vision approaches are used for detecting body center of mass and ankle movement, to explore the potential of these methods on human-induced vibration research. Consumer-grade cameras are used without artificial markers, to take videos for further processing and wearable inertial sensors were used to validate and evaluate the computer vision measurements.

Based on the pedestrian lateral force hybrid Van der Pol/Rayleigh model, this study investigates the interaction dynamic model of a pedestrian-flexible footbridge lateral coupling system. A multi scale method is adopted to decouple the equation. The paper also studies the nonlinear dynamic response of the pedestrian-footbridge coupling system as well as the relationship between the lateral displacement of pedestrians and flexible footbridges, and the lateral interaction of the two variables. The results show that with the same frequency tuning parameters, when the mass ratio of pedestrians and footbridges is very small, the larger the mass ratio is, the larger the lateral response amplitude of pedestrians becomes. Conversely, when the mass ratio of pedestrians and footbridges is much larger, the larger the mass ratio is, the smaller the response amplitude becomes. When the natural frequency of a footbridge is larger, its Phase Angle becomes larger. As the lateral amplitude of pedestrians increases, the Phase Angle approaches zero. Moreover, regarding the variation of the Phase Angle between the interaction force and footbridge lateral vibration speed based on the lateral relative displacement of pedestrians, of which the variation range is (0, π), as the pedestrians' lateral amplitude increases, the Phase Angle approaches − π / 2 . The dynamic load coefficient varies linearly with the lateral amplitude of pedestrian vibrations. [ABSTRACT FROM AUTHOR]