WIM-Based Live-Load Model for Advanced Analysis of Simply Supported Short- and Medium-Span Highway Bridges

Abstract

4The accuracy of bridge system safety evaluations and reliability assessments obtained through refined structural 5 analysis procedures depends on the proper modeling of traffic load effects. While the live load models specified in the 6 AASHTO procedures were calibrated for use in combination with the approximate analysis methods and load distribution 7 factors commonly used in the U.S., these existing models may not produce accurate results when used in association with 8 advanced finite element analyses of bridge structures. 9This paper proposes a procedure for calibrating appropriate live load models that can be used for advanced analyses 10 of multi-girder bridges. The calibration procedure is demonstrated using actual truck data collected at a representative 11 set of weigh-in-motion (WIM) stations in New York State. Extreme value theory is used to project traffic load effects to 12 different service periods. The results are presented as live load models developed for a 5-year typical rating interval and 13 for a 75-year design life. The outcome of the calibration indicates that maximum traffic load effects can be calculated 14 using finite element models with the help of a single truck for short to medium one-lane multi-girder bridges and two 15 side-by-side truck configurations for multi-lane bridges. The proposed analysis trucks have the axle configurations of the 16 standard AASHTO 3-S2 and Type 3 Legal Rating trucks with appropriate factors to amplify their nominal weights. The 17 amplification factors reflect the presence of overweight trucks in the traffic stream and the probability of multiple-18 2 presence. The proposed live load models are readily implementable for deterministic refined analyses of highway bridges 19 and for evaluating the reliability of bridges at ultimate limit states considering the system's behavior. 20

[Retracted] Calibration of the Live Load Factor for Highway Bridges with Different Requirements of Loading

“…In Oregon, truck WIM data were also used to develop state-specific LRFR live load factors, and the factors were calibrated using the same statistical methods that were used in the original development of LRFR [6]. Recently, Eamon et al conducted a reliability-based calibration of live load factors for bridge design specific to the state of Michigan, and it was found that Michigan load effects were greater than those previously assumed, requiring higher load factors than those in current use [7]; Rasheed et al implemented a structural reliability analysis of superstructure of highway bridges on the China-Pakistan Economic Corridor [8]; Oudah et al calibrated live load factors for bridge systems conveying extremely heavy mining trucks [9]; Anitori et al proposed a WIM-based live load model for advanced analysis of simply supported shortand medium-span highway bridges [10], and Siavashi and Eamon developed traffic live load models for bridge superstructure rating [11]. Besides, some efforts have been made to enhance the accuracy of load effect projections to longer period of time needed for design and rating [12][13][14][15][16][17].…”

Methodology for development of live load models for refined analysis of short and medium-span highway bridges

“…The results presented in this paper are based on the traffic data from only one specific WIM station. The same methodology can be applied to a set of WIM stations in a specific region, state or country to develop specific amplification factors and live-load models, as presented in Anitori et al (2017). Furthermore, the calibration process provides information on site-to-site variability to calibrate different models for different traffic characteristics.…”

“…Thus, the proposed approach may in many cases lead to saving some bridges that may not traditionally rate well from immediate replacement or rehabilitation and may lead to a more efficient allocation of the limited resources currently available for managing our ageing bridge infrastructure. Additional work to extend the procedure proposed in this paper to cover different sets of WIM data and for the analysis of moment and shear effects on a wider range of bridge configurations is described by Anitori et al (2017).…”

“…When an advanced reliability analysis is to be performed, modeling the effects of heavy trucks on bridges must include additional statistical parameters to fully define the random nature of the applied live loads. The procedure developed in this paper will also provide statistical models to consider the uncertainties and variability in the proposed live load model (Anitori et al, 2017).…”

“…The method presented is general and can be applied to develop models applicable for any bridge design standard or code, such as the AASHTO specifications or the Eurocodes, as long as the WIM data used during the calibration are representative of the truck traffic at the bridge sites of concern. The generalization of the procedure described in this paper to cover different load effects and to consider truck traffic data with different characteristics is presented in the paper by Anitori, Casas and Ghosn (2017).…”