A comprehensive traffic load model for bridge safety checking

doi:10.1016/S0167-4730(97)00016-7

Structural Safety

Volume 19, Issue 4, 1997, Pages 339-359

https://doi.org/10.1016/S0167-4730(97)00016-7 Get rights and content

Abstract

In this paper a new model for the global analysis of traffic actions on roadway bridges will be presented. It has been developed in the frame of Crespo-Minguillón, C., Reliability based methodology for the definition of the limit state of decompression in prestressed concrete bridges. Ph.D. thesis, Department of Civil Engineering, Technical University of Catalunya, Barcelona, 1996. In order to make it feasible for use in the verification of most important limit states, the model includes an algorithm for the simulation of a continuous flow of traffic and another for the extrapolation of maximum results in short periods to long return periods. The model for traffic flow simulation includes a statistical treatment of most significant variables involved, and some original techniques to account for the most important correlations found in actual traffic. At the end, an example of application is shown.

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Intelligent cognition of traffic loads on road bridges: From measurement to simulation – A review
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Traffic load is a crucial but complicated factor in determining the in-service performance and deterioration behavior of bridges. A better understanding of traffic loads in different traffic densities has become increasingly important in structure health monitoring. As a result, for the traffic load measurement, the relevant technologies had great progress in the past decades. Therefore, we focus on introducing the state-of-the-art approaches most relevant to the traffic load cognition on road bridges, including in-site measurement and data-driven simulation. General principles of the traffic load cognition are firstly presented by reviewing different statistical analysis techniques for determining the spatial-temporal factors of vehicles. Then, this paper reviews various measurement methods carried out for the essential data of traffic loads. The methods are roughly grouped into mechanical, optical and microwave sensor-based methods. Within each category, technical descriptions of the sensor types, properties and applications are discussed in terms of theoretical formulas and feasible scenarios. This paper also implements qualitative and comprehensive comparisons between multiple measurement sensors to show the efficiency of each method or technique. Base on in-site measurement, several kinds of simulation models can be established for traffic loads on road bridges, including the modelling of single vehicles and the overall traffic flow. Considering the significant contribution of statistics-based deterministic, direct probabilistic methods, and artificial intelligence to traffic load cognition, we carried out the investigation on them in vehicle modelling. For on-bridge traffic flow simulation, three representative microscopic models are reviewed, involving the car-following, hydrodynamic, and cellular automatic models. Overall, this study highlights the application of intelligent cognition methods in identifying and simulating traffic loads on road bridges, potentially providing support for digitalised design, operation, and maintenance.
Investigation of multiple-presence factor for traffic loads on road-rail bridges based on a novel extreme value analysis approach
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Multiple-presence factor (MPF) is an efficient measure for calculating traffic load effects on bridges with multiple lanes. It takes into account the probability of multiple heavy vehicles that simultaneously present in adjacent lanes. Though road-rail bridges carrying both road and rail traffic are common in modern cities, no sophisticated method is available to obtain the MPFs for the combined traffic loads. This study presents a novel extreme value analysis approach to predict the extreme load effects on road-rail bridges and investigate the corresponding MPFs. The core of the new approach is an unsupervised clustering algorithm based on a generalized extreme value mixture model (GEVMM), which can fit data with mixed distribution characteristics and can predict extreme values. The road-vehicle flow is represented by vehicle parameters and traffic parameters. The train flow is generated based on the distribution of passenger volume and train schedule. The 1000-day load effects on road-rail bridges with various spans are simulated and then used to predict the maximum load effects in 100 years based on the proposed method and the conventional generalized extreme value (GEV) approach, respectively. The comparison among the predicted maximum load effects and those obtained from the simulated 100-year road-rail traffic flow shows that the proposed approach is more reliable than the conventional GEV approach. Then the MPF values of the road-rail bridges are calculated from the predicted maximum load effects during a specified return period of 2000 years. The proposed method provides a valuable reference for the design and evaluation of road-rail bridges with various spans.
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Reliability design code calibrations typically involve the comparison of calculated levels of safety (β) of designs to a range of prospective partial safety factors with the minimum acceptable level of safety (β_T). When updating the calibration and the original β_T is unknown or undocumented, design-specific probability models and the code-implied level of safety are necessary. This study presents a methodology for updating capacity reduction factors ϕ for a suite of PSC bridge girder section designs for ultimate strength in bending for a design code for which β_T is unknown. In the methodology, the code-implied safety as inferred from the notional traffic design load, and the designed girder safety under actual traffic loading are computed. The method is applied to the suite of prestressed concrete Super-T girders designed to the Australian bridge standards AS 5100, in which the implicit β_T is not known. The results find both code-implied safety and designed girder safety far surpasses the usual recommendations for β_T for all designs and regardless of ϕ. As such, only through the relative comparison of code-implied safety and designed girder safety can recommendations be made on increasing ϕ in AS 5100 for Super-T girder ultimate strength in bending. Moreover, the comparison with code-implied safety is taken to indicate the desired degree of reserve capacity available for future traffic growth. The results inform on possible improvements for the next version of AS 5100. More significantly, the work illustrates a way to reliability-update partial factors of design codes when β_T is not known, and future-proofing structures is seen as necessary.

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A comprehensive traffic load model for bridge safety checking

Abstract

Journal of Structural Safety

Journal of Hydrology

Probabilistic Engineering Mechanics

Random response of highway bridges to vehicle loads

Journal of the Engineering Mechanics Division, ASCE

Extremes and first passage times with applications in civil engineering

Modeling extreme vehicle loads on highway bridges

Markov renewal model for maximum bridge loading

Journal of Engineering Mechanics, ASCE

Analisis probabilistica della sicurezza a fatica dei ponti

Giornali del Genio Civile

Modelisation des charges dues au trafic routier

Caracterización de las acciones del tráfico en puentes de carretera. Aplicación al caso español

Hormigón y Acero

Calcul des effets du trafic routier sur les ponts par le programme TRAFMUL

Bull. liaison Labo. P. et Ch.

Le calcul des effets produits par plusieurs voies de trafic routier sur un pont. Le logiciel TRAFMULTI

Bulletin de Liaison des Laboratories de Ponts et Chaussues

Un nouveau logiciel: le programme CASTOR pour le calcul des actions et sollicitations du trafic dans les ouvrages routiers

Bulletin de Liaison des Laboratories de Ponts et Chaussues

Trafic flow models

Studie zur Ermüdungsnachweis von Strassenbrücken

DYBES: Simulation program for the dynamic calculation of the crossing vehicles on road bridges