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Full-Text Articles in Civil and Environmental Engineering
A Review Of Probabilistic Methods Of Assessment Of Load Effects In Bridges, Eugene J. Obrien, F Schmidt, Donya Hajializadeh, X-Y Zhou, Bernard Enright, Colin C. Caprani, Simon Wilson, Emma Sheils
A Review Of Probabilistic Methods Of Assessment Of Load Effects In Bridges, Eugene J. Obrien, F Schmidt, Donya Hajializadeh, X-Y Zhou, Bernard Enright, Colin C. Caprani, Simon Wilson, Emma Sheils
Articles
This paper reviews a range of statistical approaches to illustrate the influence of data quality and quantity on the probabilistic modelling of traffic load effects. It also aims to demonstrate the importance of long-run simulations in calculating characteristic traffic load effects. The popular methods of Peaks Over Threshold and Generalized Extreme Value are considered but also other methods including the Box-Cox approach, fitting to a Normal distribution and the Rice formula. For these five methods, curves are fitted to the tails of the daily maximum data. Bayesian Updating and Predictive Likelihood are also assessed, which require the entire data for …
Nonlinear Analysis Of Isotropic Slab Bridges Under Extreme Traffic Loading, Donya Hajializadeh, A. Salam Al-Sabah, Eugene J. Obrien, Debra F. Laefer, Bernard Enright
Nonlinear Analysis Of Isotropic Slab Bridges Under Extreme Traffic Loading, Donya Hajializadeh, A. Salam Al-Sabah, Eugene J. Obrien, Debra F. Laefer, Bernard Enright
Articles
Probabilistic analysis of traffic loading on a bridge traditionally involves an extrapolation from measured or simulated load effects to a characteristic maximum value. In recent years, Long Run Simulation, whereby thousands of years of traffic are simulated, has allowed researchers to gain new insights into the nature of the traffic scenarios that govern at the limit state. For example, mobile cranes and low-loaders, sometimes accompanied by a common articulated truck, have been shown to govern in most cases. In this paper, the extreme loading scenarios identified in the Long Run Simulation are applied to a non-linear, two-dimensional (2D) plate finite …
Spatial Time-Dependent Reliability Analysis Of Reinforced Concrete Slab Bridges Subject To Realistic Traffic Loading, Donya Hajializadeh, Mark Stewart, Bernard Enright, Eugene J. Obrien
Spatial Time-Dependent Reliability Analysis Of Reinforced Concrete Slab Bridges Subject To Realistic Traffic Loading, Donya Hajializadeh, Mark Stewart, Bernard Enright, Eugene J. Obrien
Articles
Resistance and loads are often correlated in time and space. The paper assesses the influence of these correlations on structural reliability/probability of failure for a typical two-lane RC slab bridge under realistic traffic loading. Spatial variables for structural resistance are cover and concrete compressive strength, which in turn affect the strength and chloride-induced corrosion of RC elements. Random variables include pit depth and model error. Correlation of weights between trucks in adjacent lanes and inter-vehicle gaps are also included and are calibrated against Weigh-In-Motion (WIM) data. Reliability analysis of deteriorating bridges needs to incorporate uncertainties associated with parameters governing the …
A Review Of The Hl-93 Bridge Traffic Load Model Using An Extensive Wim Database, Cathal Leahy, Eugene J. Obrien, Bernard Enright, Donya Hajializadeh
A Review Of The Hl-93 Bridge Traffic Load Model Using An Extensive Wim Database, Cathal Leahy, Eugene J. Obrien, Bernard Enright, Donya Hajializadeh
Articles
HL-93, the current bridge traffic load model used in the United States, is examined here. Weigh-in-motion from 17 sites in 16 states, and containing 74 million truck records, is used to assess the level of consistency in the characteristic load effects implied by the HL-93 model. The load effects of bending moment and shear force are considered on single-lane and two-lane same-direction slab and girder bridges with a range of spans. It is found that the ratio of WIM-implied to HL-93 load effect varies considerably from one load effect to another. An alternative model is proposed which achieves improvements in …
Microsimulation Evaluation Of Eurocode Load Model For American Long-Span Bridges, Bernard Enright, Colm Carey, Colin Caprani
Microsimulation Evaluation Of Eurocode Load Model For American Long-Span Bridges, Bernard Enright, Colm Carey, Colin Caprani
Articles
The ability to accurately predict traffic loading is essential for cost-effective bridge maintenance and repair programs. The traffic load model currently used in the United States for the design of long-span bridges was developed over three decades ago. In the meantime vehicle characteristics and traffic patterns have changed. The Eurocode for traffic loading is more recent, but was calibrated only for bridges up to 200 m long. In this work, Weigh-In-Motion traffic records from 11 different sites across Alabama are used to establish congested traffic loading. Traffic microsimulation is used to generate the congestion, based on the real traffic data. …
Estimating Characteristic Bridge Loads On A Non-Primary Road Network, Eugene J. Obrien, Bernard Enright, Brendan Williams, Cathal Leahy
Estimating Characteristic Bridge Loads On A Non-Primary Road Network, Eugene J. Obrien, Bernard Enright, Brendan Williams, Cathal Leahy
Conference papers
When collecting truck loading data on a primary road network a common approach is to install a large network of permanent pavement-based Weigh-In-Motion systems. An alternative to this approach would be to use one or more portable Bridge Weigh-In-Motion systems which could be moved between bridges at regular intervals to determine the traffic loading throughout the network. A data collection strategy is needed to put such a system to best use. This paper details the data collection strategies which were examined for the National Roads Authority in Ireland. The use of urban economic concepts including Central Place Theory are discussed …
Portable Bridge Wim Data Collection Strategy For Secondary Roads, Bernard Enright, Cathal Leahy, Eugene J. Obrien, Jennifer Keenahan
Portable Bridge Wim Data Collection Strategy For Secondary Roads, Bernard Enright, Cathal Leahy, Eugene J. Obrien, Jennifer Keenahan
Conference papers
A common method of collecting traffic loading data across a large road network is to use a network of permanent pavement-based WIM systems. An alternative is to use one or more portable Bridge Weigh-In-Motion systems which are moved periodically between bridges on the network. To make optimum use of such a system, a suitable data collection strategy is needed to choose locations for the system. This paper describes a number of possible strategies which the authors have investigated for the National Roads Authority in Ireland. The different strategies are examined and their advantages and disadvantages compared. Their effectiveness at detecting …
Modeling Extreme Traffic Loading On Bridges Using Kernel Density Estimators, Cathal Leahy, Eugene J. Obrien, Bernard Enright
Modeling Extreme Traffic Loading On Bridges Using Kernel Density Estimators, Cathal Leahy, Eugene J. Obrien, Bernard Enright
Conference papers
Kernel density estimators are a non-parametric method of estimating the probability density function of sample data. In this paper, the method is applied to find characteristic maximum daily truck weights on highway bridges. The results are then compared with the conventional approach
Simulation Of Traffic Loading On Highway Bridges, Bernard Enright
Simulation Of Traffic Loading On Highway Bridges, Bernard Enright
Other resources
This work is based on weigh-in-motion measurements for approximately three million trucks obtained from sites in five European countries. Techniques have been developed, supported by photographic evidence, for filtering the measurements to identify and remove unreliable values, and for the classification of extremely heavy vehicles. The collected measurements have been used as the basis for building and calibrating a Monte Carlo simulation model for bridge loading. Two-lane traffic is simulated – either two lanes in the same direction or one lane in each direction. The model allows for vehicles that are both heavier and have more axles than in the …
A New Congested Traffic Load Model For Highway Bridges, Colin C. Caprani, Colm Carey, Bernard Enright
A New Congested Traffic Load Model For Highway Bridges, Colin C. Caprani, Colm Carey, Bernard Enright
Conference papers
Long span highway bridges are critical components of any nation’s infrastructure. Therefore accurate assessment of highway bridge loading is essential, and it is well known that congested traffic governs load effect for such bridges. Current congestion models use conservative assumptions about traffic and inter-vehicle gaps. This research investigates congested traffic flow through the use of traffic microsimulation which has the ability to reproduce complex traffic phenomena based on driver interactions. A time series model has been developed to produce a speed time-series similar to the results of the microsimulation. The speed time-series from the new model, combined with the established …
Importance Of The Tail In Truck Weight Modeling For Bridge Assessment, Eugene J. Obrien, Bernard Enright, Abraham Getachew
Importance Of The Tail In Truck Weight Modeling For Bridge Assessment, Eugene J. Obrien, Bernard Enright, Abraham Getachew
Articles
To predict characteristic extreme traffic load effects, simulations are sometimes performed of bridge loading events. To generalize the truck weight data, statistical distributions are fitted to histograms of weight measurements. This paper is based on extensive WIM measurements from two European sites and shows the sensitivity of the characteristic traffic load effects to the fitting process. A semi-parametric fitting procedure is proposed: direct use of the measured histogram where there are sufficient data for this to be reliable and parametric fitting to a statistical distribution in the tail region where there are less data. Calculated characteristic load effects are shown …
Highway Bridge Assessment For Dynamic Interaction With Critical Vehicles, Daniel Cantero, Eugene J. Obrien, Arturo González, Bernard Enright, Cillian Rowley
Highway Bridge Assessment For Dynamic Interaction With Critical Vehicles, Daniel Cantero, Eugene J. Obrien, Arturo González, Bernard Enright, Cillian Rowley
Conference papers
Dynamic vehicle-bridge interaction is often considered for the most common classes of vehicle such as the 5-axle articulated truck. However, the dynamic response of bridges to this type of trucks is quite different to the response to the vehicles more likely to feature in maximum-in-lifetime traffic loading events. This paper focuses on large (>100 tonne) cranes and crane-type vehicles that have been recorded at Weigh-in-Motion sites in Europe. This paper analyses the total bending moment due to these vehicles on short to medium span bridges and compare them to 5- axle articulated trucks. To account for the variability in …
The Structural Reliability Of Bridges Subject To Time-Dependent Deterioration, Colin C. Caprani, C. Mcnally, E. J. O'Brien, A. Bordallo-Ruiz
The Structural Reliability Of Bridges Subject To Time-Dependent Deterioration, Colin C. Caprani, C. Mcnally, E. J. O'Brien, A. Bordallo-Ruiz
Conference papers
The reliability of the structural performance of any given structure is affected by both in-service loading and material deterioration due to environmental attack. They must be evaluated at any given time in order to compute lifetime probability of failure. This paper presents an innovative methodology to derive the structure lifetime load effect due to existing traffic using a statistical tool known as Predictive Likelihood. Loss of resistance due to corrosion originated by chloride ingression is also taken into account. Finally the lifetime probability of failure is evaluated via the application of a time-discretization strategy.
Finding The Distribution Of Bridge Lifetime Load Effect By Predictive Likelihood, Colin C. Caprani, E. J. O'Brien
Finding The Distribution Of Bridge Lifetime Load Effect By Predictive Likelihood, Colin C. Caprani, E. J. O'Brien
Conference papers
To assess the safety of an existing bridge, the loads to which it may be subject in its lifetime are required. Statistical analysis is used to extrapolate a sample of load effect values from the simulation period to the required design period. Complex statistical methods are often used and the end result is usually a single value of characteristic load effect. Such a deterministic result is at odds with the underlying stochastic nature of the problem. In this paper, predictive likelihood is shown to be a method by which the distribution of the lifetime extreme load effect may be determined. …
Statistical Computation For Extreme Bridge Traffic Load Effects, Colin C. Caprani, E. J. O'Brien
Statistical Computation For Extreme Bridge Traffic Load Effects, Colin C. Caprani, E. J. O'Brien
Conference papers
The maintenance of highway infrastructure constitutes a major expenditure in many countries. This cost can be reduced significantly by minimizing the repair or replacement of highway bridges. In the assessment of existing bridges, the strength estimate tends to be more accurate than that of traffic loading, due to the more variable nature of loading. Recent advances in the statistical analysis of highway bridge traffic loading have resulted in more accurate forecasts of the actual loading to which a bridge is subject. While these advances require extensive numerical computation, they can significantly improve the accuracy of the calculation. This paper outlines …
Bridge Dynamics And Loading, Colin C. Caprani, Eugene O'Brien, Arturo Gonzalez, Yingyan Li, Paraic Rattigan, Niall Harris
Bridge Dynamics And Loading, Colin C. Caprani, Eugene O'Brien, Arturo Gonzalez, Yingyan Li, Paraic Rattigan, Niall Harris
Conference papers
Recent UCD research on dynamic bridge-truck interaction and bridge traffic loading in general is reported. The accuracy of bridge traffic load assessment has been significantly improved by identifying the differences in the sources of traffic loading on short- to medium-span bridges and treating them separately. It is shown that results can be significantly improved by treating 1-,2-,3- and 4-truck loading events separately. Gaps between trucks are also identified as a critical issue that strongly influences the frequency of key3-and 4-truck events. Trends in the dynamics of traffic loading are identified using simple force models on simply supported beams. It is …
Probalistic Analysis Of Highway Bridge Traffic Loading, Colin C. Caprani
Probalistic Analysis Of Highway Bridge Traffic Loading, Colin C. Caprani
Other resources
Many bridges of the world’s highway networks have been in service for decades and are subject to escalating volumes of traffic. Consequently, there is a growing need for the rehabilitation or replacement of bridges due to deterioration and increased loading. The assessment of the strength of the existing bridge is relatively well understood, whereas the traffic loading it is subject to, is not as well understood. Accurate assessment of the loading to which bridges may be subject, can result in significant savings for the highway maintenance budgets internationally. In recent years, a general approach has emerged in the research literature: …
Site-Specific Probabilistic Load Modelling For Bridge Reliability Analysis, Colin C. Caprani, A. Belay, A. J. O'Connor
Site-Specific Probabilistic Load Modelling For Bridge Reliability Analysis, Colin C. Caprani, A. Belay, A. J. O'Connor
Conference papers
Reliability assessment of a short span beam-slab reinforced concrete bridge in Vienna is proposed using site-specific traffic data recorded using the Slovenian Weigh in Motion (SiWIM) system. An initial evaluation of the bridge using a determinintic approach shows that the critical limit state is bending. This paper describes the statistical analysis of the SiWIM data and the traffic flow simulations performed to predict the characteristic extreme load effects to which the bridge may be subjected during its remaining lifetime. These values are compared to the magnitude obtained from a deterministic approach. The influence lines used in the simulations are the …
Critical Loading Events For The Assessment Of Medium Span Bridges, Colin C. Caprani, S. A. Grave, E. J. O'Brien, A. J. O'Connor
Critical Loading Events For The Assessment Of Medium Span Bridges, Colin C. Caprani, S. A. Grave, E. J. O'Brien, A. J. O'Connor
Conference papers
This paper describes the simulation of free-flowing traffic across bridges to predict the characteristic values for bridge load effects such as bending moment and shear force. The results of these simulations are then used to demonstrate that, in predicting the characteristic extreme load effects to which a bridge may be subjected, it is not sufficient to solely model one-or two-truck presence events. It is shown that loading events involving three or more trucks may need be included in the model for short to medium spans. The critical loading events for a particular load effect are strongly dependent on the span …