Stability of skewed I-shaped girder bridges using bent plate connections (original) (raw)

Stability of Curved Steel I-Girder Bridges during Construction

Transportation Research Record: Journal of the Transportation Research Board, 2012

Structural stability is one of the essential aspects of the construction of curved steel I-girder bridges. The AASHTO load and resistance factor design (LRFD) bridge design specifications require the consideration of stability-critical conditions during the construction of curved I-girder bridges through checking (a) nominal initial yielding due to combined major-axis bending and flange lateral bending, (b) strength under combined major-axis and flange lateral bending, and (c) web-bend buckling. These specifications limit the flange lateral bending stress to 0.6Fy. In some cases, these rules may not be sufficient unless global second-order amplification of the lateral-torsional response is considered. In particular, structures with narrow widths and long spans may be susceptible to large second-order amplification that could compromise the overall system constructability. This paper presents analytical studies of a slender curved and skewed I-girder bridge unit that exhibited diffic...

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

Engineering, Technology & Applied Science Research, 2021

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 l...

Field and Analytical Studies of the First Folded-Plate Girder Bridge

Journal of Bridge Engineering

An innovative Folded Plate Girder (FPG) system bridge was constructed in Uxbridge, Massachusetts. The University of Massachusetts at Amherst collaborated with the MassDOT Accelerated Bridge Construction Program to instrument the bridge with a total of 93 gages (strain gages, pressure cells, tiltmeters, displacement transducers, and convergence gages). Data was collected during construction, static live load testing, and long-term for twenty months. This paper presents data and comparisons to analysis (3-D bridge and girder modeling in SAP-2000 and ANSYS and 2-D hand calculations) to present an independent evaluation of the performance of this innovative bridge. Stresses in concrete and steel components are well below allowable design values through construction, long term data collection and truck load testing. Live-load test data indicate that the elastic neutral axis of the girders is higher than calculated, with measured strains being much lower than estimated from hand calculations and FE results. This was partially explained by non-linearity of strains in the bottom flanges of the FPG due to shear lag when truck axles were positioned near instrumented locations, as confirmed through analysis. However, higher superstructure stiffness than expected is likely a contributor as well. Through the first two years of service no signs of distress have been noted and readings are within the expected range of bridge behavior. Based on this study the FPG is an effective system for accelerated construction of short span bridges.

Challenges of Skew in Bridges with Steel Girders

Transportation Research Record: Journal of the Transportation Research Board, 2011

Steel girder bridges in particular can suffer the consequences of skew, and addressing the topic of how to mitigate the effects of skew in these structures is important. This paper addresses skew in several contexts, including how skew affects the behavior of steel girder bridges and their components as well as the impacts of skew on the detailing, fabrication, and erection of steel girder bridges. In addition to discussing the problems associated with skew, the paper offers ideas and techniques for minimizing or avoiding skew and for analyzing, understanding, and mitigating the effects of skew when it cannot be avoided.

Curved steel I-girder bridges: experimental and analytical studies

Engineering Structures, 2000

This paper describes the large-scale experimental and analytical program, initiated by the Federal Highway Administration (FHWA), aimed at developing new rational design guidelines for horizontally curved steel bridges. Analytical and experimental efforts dedicated to establish the size of the full-scale components that will be tested as part of an entire three-girder bridge system are also presented.

COMPARATIVE ANALYSIS OF HORIZONTALLY SKEWED COMPOSITE I-GIRDER BRIDGES

isara solutions, 2019

Analysis and design of modern intersections requires the utilization of slab bridges of different kinds of geometry with various boundary conditions. A number of methods for deck analysis are evolved in past 30 years. The Grillage Analogy method is the most widely used Computer-Aided method. It is not only reliable but accurate for different types of bridges. The gird is formed by constituting the designed arrangement of structural members connected together at discrete nodes. It also works absolutely fine when it comes to heavy skew, isolated supports and edge stiffening. The bending and torsional moments are related to the deformation of beam elements with two ends through their torsional and bending stiffness. The present study reports the major variations that arise in the distribution of Shear Force, Bending Moment and Torsion due to the change in skewness in Composite I-girder bridges. It also studies the torsional and Non-Torsional behavior of I-girders. The behavior of bridge decks are researched extensively under different loadings.

Analysis and Behaviour of Skewed Box Girder Bridge

2021

Box girder bridge is different from bridges which differ in reliability, economy and aesthetic appearance. Box Girder Bridge has excellent strength and torsional rigidity. Box girders are used for most long spans. This study shows the forces and moments of other results from 0 to 60-degree skew angles. The effect of the same span with a skew angle of 0 to 60 degrees is different. In this study the span is 31 m long and the effective span 30 m. A 2-cell box girder with a width of 9.5 m and a depth of 2.5 m. In this study, different IRC codes are used for the load. The STAAD PRO V8i software are used for the analysis of grillage models. Models are simply supported. Interestingly, the torsion was more exaggerated than the bending moment and deflection. The effects of reaction and torsion angle are mainly observed at obtuse corner rather than acute corner. The shear forces for the permanent load of each support are different and gradually increase and decrease from the LHS side to the R...

Effect of Web Inclination on Box Girder Bridges

Regular, 2020

Bridge is a key element in any transportation system which provides easy access over physical obstacles like road, valley, water bodies etc. without closing the way underneath. Among various types, use of box girder type bridges are gaining popularity in bridge engineering because of its better stability, serviceability, economy, aesthetics, structural efficiency and rigidity in torsion. In this study, a box girder is analyzed by changing its web inclination angle to the horizontal (90°, 83°, 76°, 69°, 62°) using finite element based software CSi Bridge. Finite element models are developed keeping material properties, span length, boundary conditions as constant parameters. All these models are analyzed for self-weight, including load of wearing coat and crash barrier, and live loads specified by Indian Road Congress (IRC) namely IRC Class 70R and IRC Class-A loading. Responses in terms of torsional moment, longitudinal moment, support reactions, displacement and stresses are determ...

Effect of Implementing Lean-on Bracing in Skewed Steel I-Girder Bridges

2016

Skew of the supports in steel I-girder bridges cause undesirable torsional effects, increase cross-frame forces, and generally increase the difficulty of designing and constructing a bridge. The girders experience differential deflections due to the skewed supports, and undesirable effects arise when the girders are linked transversely. Before the placement of the deck, the main method of linking the girders transversely is through the use of cross-frames. The cross-frames are designed to provide stability during construction and distribute transverse loads through the bridge girders; this is their primary role. Cross-frames also help control differential displacement during deck placement and distribute vertical loads in the bridge’s elastic and inelastic ranges. The cross-frames are not specifically designed for these tasks; these are the secondary roles of the cross-frames. Lean-On bracing has been proposed to reduce skew effects caused by traditional cross-frames. While having b...