Pedestrian Loading Research Articles

Dynamic response and vibration suitability analysis of the large-span double-connected structure under coupled wind and pedestrian loads

Modern buildings increasingly utilize lightweight, high-strength materials and feature high-rise, large-span structural designs. These structures often exhibit low natural frequencies and are susceptible to resonance from low-frequency dynamic loads such as wind and pedestrian loads. This paper focuses on a large-span double-connected structure and analyzes its dynamic response under the combined effects of wind and pedestrian loads. First, a finite element model of the structure was created using ANSYS, and model validity verification and modal analysis were performed. Second, a Fourier-based pedestrian model was used to simulate pedestrian loads and generate time-range data. The pulsating wind speed was generated from the Davenport spectrum using the harmonic superposition method. Wind load time-range data were calculated for different heights using Bernoulli’s theorem. Finally, the solution yields information about the dynamic response of the structure. The study revealed maximum vertical comfort ratings in the connecting corridor were achieved when crowd density did not exceed 0.3 persons/m2. The connecting corridor’s most unfavorable horizontal comfort level was evaluated as a medium, except for the 0-degree wind angle condition. This paper provides experience in studying the dynamic response and vibration suitability assessment of the large-span double-connected structure under wind and pedestrian loads.

Evaluation of Cognitive Load Differences between Elderly and Young Pedestrians at the Signalised Intersection

The pedestrian cognitive load has an important effect on the pedestrian crossing decision making. Compared with young adults, old people are characterised by declining physical function and slower reaction ability, which makes them prone to traffic accidents when crossing the street. This study aims to compare the visual information-mental load correlation between elderly and young adults waiting at the signalised intersections and evaluate their cognitive load conditions. Therefore, two signalised intersections with different traffic scenes in the Nan’an District, Chongqing, China were selected. The eye-tracking, electrocardiographic and electrodermal activity data of young and old pedestrians were collected using eye-tracking and physiological instruments. The visual indexes (the total duration of fixations, the number of fixations, the average pupil diameter changing rate, the number of saccades, the average peak speed of saccades, the average amplitude of saccades and the total amplitude of saccades) and physiological indicators (the average growth rate of heart rate, the time-domain analysis indicator of HRV and HRV frequency domain analysis indicators, electrodermal response amplitude and rise time of the EDR amp.) were taken as inputs and outputs parameters, respectively. Then, the comprehensive cognitive load evaluation model for pedestrians was constructed when waiting to cross the street based on the data envelopment analysis method. And the cognitive load characteristic differences between the young adults and the elderly were compared. The results show that in the same crossing scene, compared with the young pedestrian, the elder pedestrian exhibited lower overall perceptual efficiency, lower fixation durations and higher cognitive loads. These results can provide certain references on improving the street crossing safety for the elderly pedestrian.

Analytical Investigation of the Effects of Additional Load Mass on the Fundamental Frequency of Pedestrian Beam Bridges

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.

Optimization of tuned mass dampers – minimization of potential energy of elastic deformation

A tuned mass damper (TMD) optimization can be performed under various assumptions and objectives. All the variables of the optimization, such as structural model, performance index and load type affect the optimal parameters of the TMD. This paper presents a new optimization method that implements straightforward performance index and allows taking load spectral characteristics into account. Thanks to the usage of modal coordinates, the method allows fast numerical optimization of TMD attached to large or complicated structures with numerous degrees of freedom. One of the complicated tasks while optimizing TMD is the choice of a performance index. In this paper, the mean value of potential energy stored in the elastic deformation of a structure under periodic load serves as a performance index, which leads to a low numerical complexity task if the optimization is performed in the frequency domain. The new method also allows a simple inclusion of load spectral characteristics and permits TMD optimization for any loading spectral range. When applied to a structure with a single degree of freedom, this method leads to H2 optimization in the case of white noise excitation. However, it is applicable to multiple degrees of freedom structures with single or multiple TMDs and any given load. The paper also presents several examples of numerical optimization of the TMD attached to both single and multiple degrees of freedom structures under various loads, including white noise excitation, pedestrian load, and earthquake strong motion.

Modelling Human-Structure Interaction in Pedestrian Bridges Using a Three-Dimensional Biomechanical Approach

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.

Structural Performance and Stress Contour Analysis of Multi Utility Tunnels Using LISA V.8 Finite Element Analysis

The growing complexity of urban infrastructure necessitates efficient management of utilities like electricity, water, and telecommunications. Multi Utility Tunnels (MUTs) provide a consolidated approach to housing these utilities, reducing surface disruption and enhancing maintenance efficiency. This study assesses the structural performance and stress distribution within MUTs using Finite Element Analysis (FEA) through LISA FEA V.8 software. The analysis involved detailed geometric modeling of the MUT, considering initial conditions and potential subsidence. Material properties for steel, concrete, wood, backfill soil, and the top surface layer were defined, focusing on their Young's modulus, density, and Poisson's ratio. The MUT was subjected to a uniform line pressure of 86.49 kN/m, representing vehicular traffic and pedestrian loads. Results showed that the applied stresses and observed deflections were within safe limits, with a tensile strength of 3.4 MPa and current stress at 3046 kN/m², indicating no risk of cracking. The observed deflection of 3.9 mm was significantly below the allowable limit of 10 mm, affirming structural stability. The reinforcing steel also exhibited stress levels well within its allowable limit, demonstrating the design's adequacy and ensuring the structure's safety and efficiency under the specified load conditions

Uncertain pedestrian load modeling for structural vibration assessment in footbridge design

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.

Probabilistic assessment of the dynamic response of floors under multi-pedestrian walking loads

The dynamic behavior of floors under multi-pedestrian walking loads affects the safety, serviceability, and comfort of floor occupants. The complexity of pedestrian-induced dynamic loads necessitates a probabilistic approach to understand and predict the performance of floors under such conditions. This paper investigates the dynamic response of floors subjected to multiple-pedestrian walking loads, taking into account the randomness of the walking path and walking load. The research focuses on probabilistic multi-pedestrian walking load scenarios and utilizes Monte Carlo simulations to analyze the modal loading. An analytical equivalent Power Spectral Density (PSD) function for the modal force, based on an existing model introduced for footbridges, is proposed. Furthermore, a formula is developed to estimate the mean value of the peak acceleration response of floors. The findings of this study contribute to the advancement of simplified methods for predicting the dynamic response of floors under multiple pedestrian walking loads. These methods can enhance the accuracy and reliability of vibration serviceability assessment for floor structures.

A Review of Evaluation Methods of Standards for Structural Vibration Serviceability under Crowd Walking

Structures such as long-span footbridges, floors, and long cantilevers are vulnerable to vibration serviceability problems under crowd walking, which should be taken into consideration during the structural design, operation, and maintenance stages. Standards have been developed to enable designers to assess the vibration serviceability of structures using simplified load models that simulate crowd-induced loading. To facilitate engineers in quickly selecting appropriate standards for vibration serviceability design, ten current standards were collected which deal with the assessment of structural vibration serviceability under walking loads, including the French “Assessment of vibrational behavior of footbridges under pedestrian loading” (2006), the German “Design of footbridges guideline” (2007), the Chinese “Technical standard for human comfort of the floor vibration” (2019), etc. The ten standards were reviewed and evaluated from three aspects including the crowd loading model, structural response calculation method, and vibration serviceability evaluation standard in this paper. Through summary and comparison between standards, three directions for future improvement and perfection of the standards were proposed: the challenges of the improvement of the standards focus on the establishment of the refined stochastic load model, the analysis of the crowd–structure coupling system, and the modelling of multifactor coupling serviceability evaluation indexes.

Experimental study on fundamental frequency and human‐induced vibration characteristics of light steel foam concrete composite floor

SummaryIn order to study the dynamic characteristics and human‐induced vibration response of light steel foamed concrete composite floor (LCSF), the vibration characteristics of 4.2 m × 5 m LCSF model were tested under the condition of opposite side support, and the natural vibration frequency of LCSF was obtained. The orthogonal anisotropic elastic plate and the simulated beam element were used, respectively, to compute the natural vibration frequency of the LCSF, and the estimated findings were compared with those obtained from measurements. The discrepancy between the calculated results and the measured results of the approximate beam element using the natural vibration frequency calculation technique is around 13%, but the error for the plate element using the calculated results and the tested results is about 23%. To examine the floor's vibration response under the factors of step frequency, walking path, pedestrian density, and load distribution, the LCSF underwent a human‐induced vibration test. The test results show that the fundamental frequency of the LCSF specimen is about 11 Hz, which can meet the requirements of the specification. However, the vibration response of the LCSF specimen under different conditions of pedestrian load is significantly different. With the acceleration of step frequency and the increase and concentration of load, the floor's vibration response becomes more visible. In the route test, it is established that LCSF has the attribute of a unidirectional plate. The natural vibration frequency of similar floor slab can be calculated by the method of simulating the natural vibration frequency of beam element. The findings can serve as a guide for LCSF research and implementation.

Comparative Analysis of the Dynamic Behaviors of Steel Pedestrian Bridges with Circular Tubular Girders

The dynamic behavior of two circular tubular steel pedestrian bridges, namely an end cut-off girder bridge and a concrete-filled girder bridge, were examined in this study. The former is proposed in this study as a solution to the construction problems associated with the latter. The numerical models of the two bridges, which were developed and analyzed using the ABAQUS program, were subjected to pedestrian-induced vibrations and seismic excitations to evaluate the acceleration and stress response of the bridge and bridge girders, respectively. The results demonstrate that the two bridge types exhibit similar serviceability performance under a given dynamic load. Specifically, the acceleration response under pedestrian loading differed marginally between the two by approximately 5%. In contrast, the maximum stress in the end cut-off bridge under the seismic excitations was 45% higher than that in the concrete-filled bridge. However, the stress levels observed in both bridge types were within the seismic performance limit.

Human-induced vibrations of floors: A probabilistic approach

The current design guidelines for assessing floor vibration performance rely on a simplified approach that considers a single pedestrian as a fixed load with multiple harmonic components applied to the anti-nodes of the floor mode shapes. However, these guidelines do not account for the influence of variability in the walking path on the dynamic response of floors. Moreover, the deterministic approaches used in these guidelines may yield unreliable estimates of vibration response due to the stochastic nature of pedestrian walking force. The aim of this paper is to investigate the dynamic response of floors under a single pedestrian walking load while considering the randomness of the walking path and the walking load itself. A probabilistic perspective is adopted to analyze the dynamic response under different random loading scenarios. Furthermore, the effectiveness of the current guidelines in predicting the dynamic response of floors is critically assessed. The importance of incorporating probabilistic approaches is emphasized to achieve a more comprehensive understanding of the vibration serviceability of floors and to enhance design practices in this context.

Research on comfort analysis method and optimization design of pedestrian bridge

In this paper, the characteristics and modes of pedestrian load are summarized, and the norms of pedestrian load in different countries are compared. At the same time, the pedestrian excitation load is briefly introduced .Then, combining the three conditions of single, double and three-person pedestrian load with the above four common pedestrian load conditions, 12 groups of different load conditions are formed, and the case study is carried out, and the conclusion is drawn as follows: Under the condition of slow walking, the vertical peak acceleration response of the structure under inconsistent stride length slightly increases, but the impact on the pedestrian comfort of the bridge is not significant. When walking slowly and at the same pace, the vertical peak acceleration of the structure increases significantly, which has a significant impact on the pedestrian comfort of the bridge. The common vibration control measures are also introduced. Through the comparison of relevant regulations, combined with case studies and common vibration control measures, it is hoped that it will be helpful to improve the comfort of pedestrian Bridges in the future, and the relevant regulations in China will be revised.

Analysis of human-induced vibration response in elevated waiting hall of Beijing Fengtai High-Speed Railway Station

This study applies the IABSE specification model, the Chen Jun model, and two types of load models developed in this paper to analyze the human-induced vibration response of the Fengtai Station waiting hall project. Three different analysis scenarios were selected, and the load curves, acceleration response curves, Fourier amplitude spectra curves, and acceleration contour maps of the four load models were compared under the same scenario. It was found that the load model with a 75% probability established in this paper is similar to the Chen Jun model, while there are some differences between the load model with a 95% probability in this paper and the IABSE specification model. This research provides a reference for establishing pedestrian load models based on the walking habits of Chinese people and analyzing the differences between these models and existing pedestrian load models in engineering applications.

Dynamic identification and vibration serviceability assessment of a wooden cable‐stayed footbridge

AbstractThis paper discusses the dynamic characterization of a 3 spans wooden cable‐stayed footbridge newly built in Italy. The footbridge is 235 m long and consists of a 2‐girder wooden deck. The edge spans are simply supported, while the mid one (about 150 m long) is sustained by 16 stays linked to 2 pillars. Ambient vibration tests and operational modal analyses are performed to identify the global dynamic behaviour of the structure and 17 stable vibration modes are identified in the frequency range 0‐6 Hz. Moreover, the vibration serviceability is assessed performing in situ pedestrian load tests following the load protocols provided by Hivoss and Sètra technical guidelines, and verifying the recorded accelerations with the maximum ones suggested by codes (fib bulletin 32 and EN1990:2002).

Human-Induced Vibration Analysis and Reduction Design for Super Long Span Pedestrian Arch Bridges with Tuned Mass Dampers

With the increasing demands on span length, aesthetics, and urban landscapes of pedestrian bridges, the fundamental frequency of pedestrian bridges is continuing to decrease, and their vibration and walking comfort issues are becoming increasingly prominent. The pedestrian load model of the pedestrian bridge was introduced here referencing current design specifications, and a spatial finite element model was established to study the dynamic characteristics of the case of a long-span pedestrian arch bridge. The comfort of the bridge under human-induced vibration was analyzed using the time history analysis method. According to the optimal damper parameter expression, the design parameters of the damper were obtained. In addition, the vibration reduction effects of different generalized mass ratios were analyzed, and the damping effects of setting the tuned mass damper (TMD) at different positions were compared. The results indicated that setting the TMD on the bridge can enhance the damping effect, and the transverse vibration can be suppressed by setting TMDs on both the arch ribs and the bridge deck. The research content could provide recommended parameters for the vibration reduction design of long-span pedestrian arch bridges.

A new quasi-static friction model for the spherical hinge bearing in structural engineering

For most frictional issues in structural engineering, the classical friction law named after Coulomb is a reliable and convenient tool, but it cannot be used to predict a slippage-related quasi-static process due to the lack of relevant items. In this paper, based on some commonly used dynamic friction models, a new rate-independent friction model is proposed to describe a quasi-static frictional process in structural field, e.g., the motion of a spherical hinge bearing in a pedestrian bridge under reciprocal pedestrian and temperature loads. Most quasi-static processes happen at the pre-sliding regime when a friction contact tends to slide slightly before the Coulomb friction is reached. The well-known Dahl model, LuGre model, and other test-based dynamic models are surveyed, and their shortcomings in engineering use are summarized subsequently. The new model, the same as the Dahl model, is rate-independent, but adopts a more engineering-oriented form. On the basis, it can be easily applied on a finite element analysis by adjusting a built-in ideal elastoplastic model. Meanwhile, the accuracy has no obvious decrease according to a test-based comparison between the Dahl model and the new. The coefficient of stiffness deviation, defined as the deviation of the pre-sliding friction stiffness from the initial friction stiffness, is introduced into the new model, which makes the model possible to predict the energy dissipation at the pre-sliding regime and can be well explained by the asperity-based theory at microscopic level. The impacts from the curvature and the coverage of a contact on the coefficient of static friction are assessed by the finite element method. It is shown that the curvature has very few impacts while the coverage is highly positively related to the observed coefficient of friction. A friction test of a spherical hinge is then carried out to verify the new model. By data regression, the coefficient of stiffness deviation for the proposed model and the exponent for the Dahl model are identified as 0.492 and 2.272, respectively. A comparison of friction torque-slippage hysteresis loops shows both the Dahl model and the proposed model have good predication as the normal force is large enough and the proposed one is even better in some load cases. Finally, a brief application on a pedestrian bridge of the new model is introduced. It indicates that there will be some mechanical residuals when a spherical hinge is applied with a reciprocating load, but the residuals tend to be limited.

CONCEPT DESIGN FOR BUILDING OF PRESCHOOL

The modern task of architectural and structural design is the use of «green» building technologies. However, the problems of their practical implementation at this stage of development of urban planning in Russian cities have been studied insufficiently. In order to develop «green» building technologies a set of issues of providing green spaces for kindergarten buildings, including design proposals in terms of architectural, space-planning, structural and techno-logical solutions for the arrangement of built-in and built in group playgrounds, placed on the «green» roofs, are con-sidered. Options for the organization of blocks of group playgrounds for a separately standing on a separate land plot building of a preschool educational organization of general type (educational organization which carries out as the main purpose of its activities educational activities under educational programs of preschool education, supervision and care of children; implementing a general developmental and (or) combined educational program for all groups) are proposed for discussion. Two variants of group occupancy - 10 and 25 children - are under consideration. Vari-ants of design-projects of «green» roofs for playgrounds for groups of children under three years old and for groups of children from three to seven years old have been developed. Monolithic reinforced concrete slab cover is designed and calculated for the pedestrian load, taking into account the play and sports equipment, as well as stationary greenery of intensive and semi-intensive types. In the field of «green» construction technologies there is a need to develop both individual typical solutions and design solutions of buildings of repeated application. It is reasonable to develop re-use buildings in the wall and frame construction schemes.

Experimental Tests and Numerical Analyses for the Dynamic Characterization of a Steel and Wooden Cable-Stayed Footbridge

Vibrations are an issue of increasing importance in current footbridge design practice. More sophisticated footbridges with increasing spans and more effective construction materials result in lightweight structures and a high ratio of live load to dead load. As a result of this trend, many footbridges have become more susceptible to vibrations when subjected to dynamic loads. The most common dynamic loads on footbridges, other than wind loading, are pedestrian-induced footfall forces due to the movement of people. This paper concerns the experimental and numerical dynamic characterization of a newly built steel and wooden cable-stayed footbridge. The footbridge was dynamically tested in situ under ambient vibration, and the results allowed the real dynamic behavior of the footbridge to be captured. The dynamic response under pedestrian dynamic loads was also investigated and compared with the limitations provided by the main international codes and guidelines for footbridge serviceability assessment. A numerical model of the footbridge was also developed and updated based on the experimental outcomes. Then, the calibrated model was used to numerically assess the footbridge’s serviceability following the guideline prescriptions for pedestrian load simulation, and the design accuracy was also validated. This paper aims to increase the state-of-the-art knowledge about footbridge dynamic testing so as to support the design of new and futuristic structures as well as prove the effectiveness of using the requirements of codes and guidelines for footbridge serviceability assessment by adopting a calibrated numerical model.

Implementation of damped bipedal inverted pendulum model of pedestrian into FE environment for prediction of vertical structural vibration

Motivated by the limited availability of tools for vibration serviceability assessment of civil engineering structures under pedestrian excitation in finite element (FE) environment, this study proposes a strategy for transferring a damped bipedal inverted pendulum (DBIP) model for a pedestrian from the analytical to the numerical domain. The strategy is implemented in FE-software ANSYS to addresses the key challenge of pedestrian alternating between the left and right stance leg. This is achieved by using COMBIN14 element in conjunction with employing element birth and death techniques to model temporary nature of the foot-structure contact. The implementation in FE environment has been verified against the analytical results of the DBIP model. The proposed method successfully transfers the pedestrian load modelling approach from biomechanics to FE modelling environment typical of civil engineering projects enabling efficient vibration serviceability assessment.