Field Evaluation of Cross-Frame and Girder Live-Load Response in Skewed Steel I-Girder Bridges

McConnell, Jennifer; Radović, Matija; Ambrose, Kelly

doi:10.1061/(asce)be.1943-5592.0000846

Cited by 9 publications

(5 citation statements)

References 12 publications

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“…This position was intended to maximize the stress and induce differential deflection in Girder #4. Pass #2 was designed to produce a high level of stress in both Girder #3 and Girder #4, while Pass #3 had the truck travel with the left side wheels aligned with the centerline of the two lanes, intending to maximize differential deflections between the instrumented girder and the adjacent one [14]. Three additional passes are implemented using FEA and are labeled as Passes #4-#6 which mimic Passes #1-#3 respectively, but with different travel speed of 104km/hr (65mph).…”

Section: B Instrumentation Layout and Loading Patternmentioning

confidence: 99%

Evaluation of the Variation in Dynamic Load Factor Throughout a Highly Skewed Steel I-Girder Bridge

Almoosi

McConnell

Oukaili

2021

Eng. Technol. Appl. Sci. Res.

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The Dynamic Load Factor (DLF) is defined as the ratio between the maximum dynamic and static responses in terms of stress, strain, deflection, reaction, etc. DLF adopted by different design codes is based on parameters such as bridge span length, traffic load models, and bridge natural frequency. During the last decades, a lot of researches have been made to study the DLF of simply supported bridges due to vehicle loading. On the other hand, fewer works have been reported on continuous bridges especially with skew supports. This paper focuses on the investigation of the DLF for a highly skewed steel I-girder bridge, namely the US13 Bridge in Delaware State, USA. Field testing under various load passes of a weighed load vehicle was used to validate full-scale three-dimensional finite element models and to evaluate the dynamic response of the bridge more thoroughly. The results are presented as a function of the static and dynamic tensile and compressive stresses and are compared to DLF code provisions. The result shows that most codes of practice are conservative in the regions of the girder that would govern the flexural design. However, the DLF sometimes exceeds the code-recommended values in the vicinity of skewed supports. The discrepancy of the DLF determined based on the stress analysis of the present study, exceeds by 13% and 16% the values determined according to AASHTO (2002) for tension and compression stresses respectively, while, in comparison to BS5400, the differences reach 6% and 8% respectively.

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Section: B Instrumentation Layout and Loading Patternmentioning

confidence: 99%

Evaluation of the Variation in Dynamic Load Factor Throughout a Highly Skewed Steel I-Girder Bridge

Almoosi

McConnell

Oukaili

2021

Eng. Technol. Appl. Sci. Res.

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“…These cross-section positions are labeled as BF-1 and BF-2. The other pair was placed on opposite sides of the web at approximately mid-height of the web and its members were labeled as W-1 and W-2 [15] (Figure 3). Four different truck passes, with 24km/hr (15mph) speed, were conducted for the load test (Figure 5).…”

Section: B Instrumentation Layout and Loading Patternmentioning

confidence: 99%

“…This position was intended to maximize the stress and induce differential deflection in Girder #4. Pass#2 was designed to produce a high level of stress in both Girder #3 and Girder #4, while Pass#3 had the truck travel with the left side wheels aligned with the centerline of the two lanes, intending to maximize differential deflections between the instrumented girder and the adjacent one [15]. Pass#4 is a new one implemented using FEA and had the loaded truck travel in the center of the left shoulder with 24km/hr.…”

Section: B Instrumentation Layout and Loading Patternmentioning

confidence: 99%

The Response of a Highly Skewed Steel I-Girder Bridge with Different Cross-Frame Connections

Almoosi

Oukaili

2021

Eng. Technol. Appl. Sci. Res.

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Braces in straight bridge systems improve the lateral-torsional buckling resistance of the girders by reducing the unbraced length, while in horizontally curved and skew bridges, the braces are primary structural elements for controlling deformations by engaging adjacent girders to act as a system to resist the potentially large forces and torques caused by the curved or skewed geometry of the bridge. The cross-frames are usually designed as torsional braces, which increase the overall strength and stiffness of the individual girders by creating a girder system that translates and rotates as a unit along the bracing lines. However, when they transmit the truck’s live load forces, they can produce fatigue cracks at their connections to the girders. This paper investigates the effect of using different details of cross-frames to girder connections and their impacts on girder stresses and twists. Field testing data of skewed steel girders bridge under various load passes of a weighed load vehicle incorporated with a validated 3D full-scale finite element model are presented in this study. Two types of connections are investigated, bent plate and pipe stiffener. The two connection responses are then compared to determine their impact on controlling the twist of girder cross-sections adjacent to cross-frames and also to mitigate the stresses induced due to live loads. The results show that the use of a pipe stiffener can reduce the twist of the girder’s cross-section adjacent to the cross-frames up to 22% in some locations. In terms of stress ranges, the pipe stiffener tends to reduce the stress range by 6% and 4% for the cross-frames located in the abutment and pier skew support regions respectively.

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“…Bridge superstructure behavior is complicated by skew effects caused by additional load paths introduced via the skewed supports and through load transfer at cross-frames. In prior research, skewed steel I-girder bridge live load response was sometimes not well predicted by current analysis procedures and design requirements, including unexpectedly large stress variations in the bottom flanges of I-girders during long-term field data collection ( 3 ), as well as steel I-girder web out-of-plane response (also referred to as web warping) and biaxial bending of cross-frames during live load testing ( 4 ). Large torsional rotations and locked-in web plate initial imperfections that are not considered in design have been reported at bridge exterior girders during deck placement ( 5 ), and such rotations were found to increase with greater bridge skew ( 6 ).…”

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confidence: 99%

“…Although 3-D finite element analysis (FEA) is now a more common and efficient tool for predicting and understanding the behavior of large and complicated bridge structures, the accuracy of numerical simulations largely depends on refined modeling of bridge component and connection details, sufficient representation of boundary conditions at supports, and correctly capturing site conditions unique to specific projects. Incorporating modeling techniques and experience from previous research ( 7 , 8 ), this study has implemented a robust numerical simulation framework through refinements in: 3-D modeling of cross-frame elements; connection of superstructure components; representation of girder-deck composite behavior and the girder-formwork connection; and boundary conditions. The current research investigates a newly-constructed bridge, so field inspections were arranged to thoroughly understand actual bridge conditions.…”

mentioning

confidence: 99%

Construction and Live Load Behavior of a Skewed Steel I-Girder Bridge

Zhou

Fahnestock

LaFave

et al. 2022

Transportation Research Record: Journal of the Transportation R

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As part of a long-term monitoring project, a two-span continuous steel I-girder bridge (skewed 41° with seat-type abutments) was instrumented and evaluated in the field during construction and after the bridge was in service. This paper discusses data from when the first stage (of a three-stage sequence) was constructed and initially opened to traffic. Girders and cross-frames were instrumented with strain gauges using a data acquisition system with a high sampling frequency (up to 20 Hz). Data collection began just before deck placement, and a series of live load tests was then conducted on the completed Stage I (half of the bridge) using a loaded truck. Three-dimensional finite element analyses were carried out to provide enhanced understanding of bridge behavior. Good agreement was observed between the numerical simulation results and the field monitoring data for both deck placement and live load testing. A slight inconsistency between numerical simulation and field measurement data at one girder section and an adjacent cross-frame indicated an unexpected local site condition, which was confirmed through a targeted field inspection. Live load distribution factors used during design conservatively overestimate bridge girder strong-axis bending response under live load (by around 50%). Maximum flange lateral bending stresses of 6.3 MPa (0.9 kips per square inch [ksi]) and 2.5 MPa (0.4 ksi) were observed during deck placement and truck tests, respectively. In addition, out-of-plane response of 10.6 MPa (1.5 ksi) was observed at girder web plates under concrete dead load.

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Field Evaluation of Cross-Frame and Girder Live-Load Response in Skewed Steel I-Girder Bridges

Cited by 9 publications

References 12 publications

Evaluation of the Variation in Dynamic Load Factor Throughout a Highly Skewed Steel I-Girder Bridge

Evaluation of the Variation in Dynamic Load Factor Throughout a Highly Skewed Steel I-Girder Bridge

The Response of a Highly Skewed Steel I-Girder Bridge with Different Cross-Frame Connections

Construction and Live Load Behavior of a Skewed Steel I-Girder Bridge

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