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Author: Jordan Michael Pelphrey
Publisher:
ISBN:
Category : Bridges
Languages : en
Pages : 326
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Book Description
The LRFR Manual, within commentary Article C6.4.4.2.3, contains provisions for development of site-specific live load factors. In Oregon, truck Weigh-in-Motion (WIM) data were used to develop live load factors for use on state-owned bridges. The factors were calibrated using the same statistical methods that were used in the original development of LRFR. This procedure maintains the nationally accepted structural reliability index for evaluation, even though the resulting state-specific live load factors were smaller than the national standard. The first part of this report describes the jurisdictional and enforcement characteristics in the state, the modifications used to described the alongside truck population based on the unique truck permitting conditions in the state, the WIM data filtering, sorting, and quality control, as well as the calibration process, and the computed live load factors. Large WIM data sets from four sites were used in the calibration and included different truck volumes, seasonal and directional variations, and WIM data collection windows. Finally, policy implementation for actual use of the factors and future provisions for maintenance of the factors are described. For bridge rating and evaluation, notional truck models are commonly used to simulate the load effects produced by the truck population. The recently developed Load Resistance and Factor Rating (LRFR) Bridge Evaluation Manual was calibrated based on the 3S2 truck configuration as the notional model. Using GVW as the parameter for establishing live load factors to reflect load effects may not necessarily provide consistent outcomes across all bridge span lengths, indeterminacies, or specific load effects. This is because the load effects are dependent on the distributions of the axle weights, the axle spacing, and the number of axles, in addition to the span geometry and support conditions. The Oregon Department of Transportation currently uses a suite of 13 rating vehicles for evaluation of their bridge inventory. The load effects for Oregon's bridge rating vehicles have also been calculated for various span lengths and support conditions in the second part of this report. These load effects, both unfactored and factored, were compared with load effects calculated using vehicles from large sets of WIM data. Further, because no established standard of time or quantity of WIM data has previously been recognized, a separate study was conducted in order to determine an acceptable window of WIM data. The objective of this analysis was to determine if the load effects and the live load factors developed for bridge rating produced by the suite of vehicles envelope load effects produced by an acceptable window of collected vehicle data for a variety of bridge span lengths and types. Observations and suggestions are made based on the results of these analyses.
Author: Jordan Michael Pelphrey
Publisher:
ISBN:
Category : Bridges
Languages : en
Pages : 326
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Book Description
The LRFR Manual, within commentary Article C6.4.4.2.3, contains provisions for development of site-specific live load factors. In Oregon, truck Weigh-in-Motion (WIM) data were used to develop live load factors for use on state-owned bridges. The factors were calibrated using the same statistical methods that were used in the original development of LRFR. This procedure maintains the nationally accepted structural reliability index for evaluation, even though the resulting state-specific live load factors were smaller than the national standard. The first part of this report describes the jurisdictional and enforcement characteristics in the state, the modifications used to described the alongside truck population based on the unique truck permitting conditions in the state, the WIM data filtering, sorting, and quality control, as well as the calibration process, and the computed live load factors. Large WIM data sets from four sites were used in the calibration and included different truck volumes, seasonal and directional variations, and WIM data collection windows. Finally, policy implementation for actual use of the factors and future provisions for maintenance of the factors are described. For bridge rating and evaluation, notional truck models are commonly used to simulate the load effects produced by the truck population. The recently developed Load Resistance and Factor Rating (LRFR) Bridge Evaluation Manual was calibrated based on the 3S2 truck configuration as the notional model. Using GVW as the parameter for establishing live load factors to reflect load effects may not necessarily provide consistent outcomes across all bridge span lengths, indeterminacies, or specific load effects. This is because the load effects are dependent on the distributions of the axle weights, the axle spacing, and the number of axles, in addition to the span geometry and support conditions. The Oregon Department of Transportation currently uses a suite of 13 rating vehicles for evaluation of their bridge inventory. The load effects for Oregon's bridge rating vehicles have also been calculated for various span lengths and support conditions in the second part of this report. These load effects, both unfactored and factored, were compared with load effects calculated using vehicles from large sets of WIM data. Further, because no established standard of time or quantity of WIM data has previously been recognized, a separate study was conducted in order to determine an acceptable window of WIM data. The objective of this analysis was to determine if the load effects and the live load factors developed for bridge rating produced by the suite of vehicles envelope load effects produced by an acceptable window of collected vehicle data for a variety of bridge span lengths and types. Observations and suggestions are made based on the results of these analyses.
Author:
Publisher:
ISBN:
Category : Bridges
Languages : en
Pages :
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Book Description
Author: Aleš Žnidarič
Publisher:
ISBN:
Category :
Languages : en
Pages : 222
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Book Description
The thesis is dealing with the influence of number and quality of weigh-in-motion (WIM) data to calculate load effects on bridges. Weighing in motion is the only method that provides continuous and unbiased information on traffic loads, but the data contains errors as a result of environmental influences and measurements that can not be constantly monitored. Presented are improvements of bridge WIM technology, which replaces the weighing sensors in the road surface with instrumented bridge superstructures. The system had many advantages, but also shortcomings that prevented its long-term installations. Proposed are a new installation procedure for the sensors that detect axles of the vehicles, a new way of calculating the influence lines, which is based on the responses of crossing vehicles, a method that deals with measurement errors caused by cracks in concrete, and a procedure that takes into account the impact of temperature on the behaviour of bridges. Also shown is the procedure to determine the dynamic loads that the commercial vehicles induce, and their impact on the measurement results. The following chapter elaborates quality control of bridge WIM data. The proposed procedures check and correct typical errors that occur during the measurements, assess quality and reliability of data and significantly shorten the time needed for its verification. Simulation procedures, which are predominantly used for calculating the traffic load effects on bridges, are complex and time intensive. The convolution method, a less demanding procedure appropriate for short to medium-span bridges, was thoroughly investigated. The results were compared with the ones obtained by comprehensive simulations. Convolution method has facilitated the detailed analysis of the impact of quantity and quality of WIM data on calculated moments and shear forces, for simply supported bridges with spans between 5 and 45 meters, which represent the vast majority of all bridges. The size of data samples was varied to investigate its influence on the load effects. Then, various data sources, with respect to quality of data (measured, electronically corrected, visually verified), were examined. The results give clear indications about the required number and quality of WIM data for effective modelling of traffic loads on bridges.
Author: Arturo Gonzalez
Publisher: LAP Lambert Academic Publishing
ISBN: 9783838304168
Category :
Languages : en
Pages : 456
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Book Description
Weigh-in-Motion (WIM) data can be used to predict future traffic volumes and weights for the planning of new infrastructure, the management of maintenance activities, the identification/reduction of overloading problems and the evaluation of the performance of pavements and bridges. Most WIM systems are based on sensors placed in or on the pavement that measure the wheel force applied over them during a very short time. The value of this force varies as a result of road roughness and vehicle dynamics leading to limited accuracy for estimating static weights. Additionally, these systems experience durability problems due to traffic and environmental conditions. An alternative approach to WIM that addresses these limitations is the use of an instrumented bridge to weigh vehicles (B-WIM). This approach is the subject of research in this book. Inaccuracies derived from discrepancies between theoretical B-WIM algorithms and bridge measurements are investigated both theoretically and experimentally. The text also describes the development of a B-WIM system in Ireland, including all aspects of installation, calibration, data collection and its processing into useful traffic information.
Author: Keith M. Chase
Publisher: Transportation Research Board
ISBN: 0309129427
Category : Transportation
Languages : en
Pages : 90
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Book Description
" TRB's second Strategic Highway Research Program (SHRP 2) Report S2-C20-RR-1: Freight Demand Modeling and Data Improvement documents the state of the practice for freight demand modeling. The report also explores the fundamental changes in freight modeling, and data and data collection that could help public and private sector decision-makers make better and more informed decisions. SHRP 2 Capacity Project C20, which produced Report S2-C20-RR-1, also produced the following items: A Freight Demand Modeling and Data Improvement Strategic Plan, which outlines seven strategic objectives that are designed to serve as the basis for future innovation in freight travel demand forecasting and data, and to guide both near- and long-term implementation: A speaker's kit, which is intended to be a "starter" set of materials for use in presenting the freight modeling and data improvement strategic plan to a group of interested professionals; and; A 2010 Innovations in Freight Demand Modeling and Data Symposium " -- publisher's description
Author: Zhisong Zhao
Publisher:
ISBN:
Category : Bridges
Languages : en
Pages : 198
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Book Description
Bridge weigh-in-motion system (B-WIM) testing is a popular technology in bridge applications. The B-WIM system can track extensive information about loading conditions to which bridges are subjected, and engineers can evaluate the responses of bridges and assess their performance relative to the safety index and serviceability. FAD (Free-of-Axle-Detector) or NOR (Nothing-On-Road) B-WIM system works well, but only if the system detects axle locations. In the USA, there are challenges for some beam-and-slab bridges. In the first manuscript, we describe a study with alternative strategies for sensor types and sensor installation locations for beam-and-slab bridges. The sensor layouts are identified and two new sensors are investigated. Most of the commercially available B-WIM systems are based on an algorithm developed by Moses (1979). The performance of this method is acceptable for estimating gross vehicle weight (GVW), but it can be unsatisfactory for estimating single axle loads. In order to improve the accuracy to an acceptable level, two algorithms are proposed. The second and third manuscripts present the measurement of axle weights and GVWs of moving heavy vehicles based on these algorithms. As determined in a case study of a bridge on US-78, both algorithms significantly improved the accuracy of measurements of axle weights in comparison with the commercial B-WIM system. Existing bridges may be functionally obsolete or have deficient structures based on older design codes or features. These bridges are not unsafe for normal vehicle traffic, but they can be vulnerable to specific traffic conditions. We propose, in manuscript 4, use of a simulation model based on B-WIM experimental data derived during extreme events. The results provide an improved understanding of the possible deficiencies of this bridge, and an appropriate retrofit is suggested. Finally, the dynamic amplification factor (DAF) is a significant parameter for design new of bridges and for evaluation of existing bridges. AASHTO guidelines provided very conservative values. So, improved methods for determination of DAF values need to be developed to evaluate the safety of existing bridges. This manuscript presents a simulation method to evaluate the DAF of existing bridges by use of the B-WIM data. The accurate results are obtained based on site-specific data.
Author: National Cooperative Highway Research Program
Publisher: Transportation Research Board
ISBN:
Category : Roads
Languages : en
Pages : 29
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Book Description
Author:
Publisher:
ISBN:
Category : Bridges
Languages : en
Pages :
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Author:
Publisher:
ISBN:
Category : Bridges
Languages : en
Pages : 178
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Book Description
This report presents the results of a 30 month investigation at Lehigh University during which an FHWA WIM system was redesigned and used to acquire and process simultaneous truck weight plus bridge response data from 19,402 trucks crossing 4 inservice bridges in Pennsylvania. The new system is designated the WIM+RESPONSE system in the report. The WIM+RESPONSE system is capable of acquiring and processing data to provide information on simultaneous bridge loading and response including GVW distributions for the four inservice bridges plus stress range distributions, strain rates, and maximum stresses at 16 locations on each of the 4 bridges. Girder stresses are compared with AASHTO design stresses and with stresses from a detailed finite element analysis of the superstructure.
Author: Sasan Siavashi
Publisher:
ISBN:
Category : Civil engineering
Languages : en
Pages : 129
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Book Description
The first objectives of this research are to propose a simplified procedure to reduce the vehicle dataset need to be considered for load rating of bridge superstructures. The second objective is to explore the effectiveness of Reliability Based Design Optimization (RBDO) to develop a State-specific rating load model for a set of bridge superstructures. Finally, an alternative novel approach to develop rating models as effective as an ideal RBDO solution is proposed. The proposed solutions can substantially reduce the computational effort while not compromising the level of accuracy.
