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

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.

Free Vibration Analysis of Horizontally Curved Composite Concrete-Steel I-Girder Bridges

The presence of a crack in civil structures has a significant effect on their vibrational characteristics. The objective of the current research is to investigate the effect of crack on vibrational characteristics of bridges using FE simulation. The CAD modeling and modal analysis are conducted using ANSYS software. The natural frequencies are computed and mode shape is generated for each frequency. Then I shaped a girder with the crack that has lower natural frequencies as compared to bridge design without crack. The deformation obtained for bridge deck with cracked I-shaped girder beam is higher than bridge deck design without cracks.

Review on Analysis of Free Vibrational Horizontally Curved Bridges

Curved I-girder concrete bridges give an outstanding answer to urban congestion, traffic, and pollution concerns, but the combined flexibility and torque responses of the bridges make their behavior exceedingly complex. That is why structural design parameters for simplified design procedures are in high demand, as measured by empirical equations. To analyze the effect on the free vibrational reaction of curve composite steel-concreteI-girder bridge with varying vibration parameters, this research employs a sensitivity analysis. To learn the fundamental frequency and the geometric configuration of the model forms, a parametric investigation is performed. Finite element Modelling of composite steel/concrete frameworks, deformable shear model, fine element formula, finite element mounting, finite element calibration, and finite element modeling, etc. Modeling finite element. Sensitivity research to draw the fundamental frequencies for the evaluated bridges. The parametric research outcomes. The results. Curved I-girder bridges of composite steel with single span or multi-span lengths are presented.

Experimental and Analytical Study of Horizontally Curved I-Girders Subjected to Equal End Moments

If bending and torsional moments are applied to an I-shaped beam member, the coupling of those two forces could reduce the bending moment capacity of that member. Therefore, the interaction between bending and torsional moments is an important issue for horizontally curved members that are always simultaneously subjected to bending and torsion. In this study, the behavior of the horizontally curved steel I-beam was investigated through numerical analysis. The ultimate state of sharply curved members that showed large displacement was defined in accordance with the stiffness reduction ratio to consist of strength curves. Based on the analysis results, interaction curves were established, and a strength equation was derived. The uniform torsional moment capacity, curvature, and slenderness parameters were considered in the equation, which were the main factors that affected the ultimate strength of curved members. The curvature effect was considered individually, so that the strength of the straight or curved girder could be estimated with a unified equation. To verify the accuracy of the suggested equation, experimental studies were also conducted. Consequently, the suggested equation shows very good agreement with the test results, and is expected to provide useful information for the design of curved members.

Study of Horizontally Curved Slab-on-Steel I-Girder Bridges with Integral Abutments Under Thermal Loading

Integral abutment bridges have started to become part of the construction industry worldwide. However, they present challenges arising from the monolithic connection between bridge deck and the abutment. Thermal loading induced by daily cycles superimposed on seasonal cycles result in complex soil-structure interaction. Due to uncertainties in integral abutment bridge performance, there is no consensus among different codes on the bridge maximum length limit. A parametric study was carried out, using SAP2000 software, to examine the behavior of horizontal curved concrete slap-on-steel Igirders, under the effect of thermal loading conditions (±65°c). The self-weight of the bridge was considered. Spatial variables, including abutment height, radius of curvature, bridge span length, stiffness of backfill and types of foundation soil, were considered. The numerical analysis results were used to drive equation relating abutment height and bridge span with the maximum bridge length limit, which produces 40 mm horizontal displacement on pile head.

Shear Distribution in Curved Composite Multiple Box Girder Bridges

Horizontally curved composite box girder bridges are used in interchanges of modern highway systems. This type of structure has created design problems in estimating its live load. North Americans Codes of Practice recommends some analytical methods for design of such curved bridges. However, practical requirements arising during the design process necessitate a simple design method. On the basis of the literature review, such load distribution factors due to CHBDC truck loading are as yet unavailable. An extensive parametric study, using the finite-element modelling, was conducted, in which 225 prototype bridges were analysed to evaluate their shear distribution factors when subjected to CHBDC truck loading conditions. The parameters considered were number of steel boxes, number of lanes, span length, and span-to-radius curvature ratio. Based on the data generated, empirical expressions for shear distribution factors were deduced. An alternative to the developed expressions were introduced using the Artificial Neural Network (ANN) application.

Load Distribution Factors for Curved Concrete Slab-on-Steel I-Girder Bridges

The use of complex interchanges in modern highway urban systems have increased recently in addition to the desire to conform to existing terrain; both have led to increase the demand for horizontally curved bridges. One type of curved bridges consists of composite concrete deck over steel I-girders which has been the preferred choice due to its simplicity in fabrication, transportation and erection. Although horizontally curved steel bridges constitute roughly one-third of all steel bridges being erected today, their structural behavior still not well understood. Due to its geometry, simple presence of curvature in curved bridges produces non uniform torsion and consequently, lateral bending moment (warping or bi-moment) in the girder flanges. The presence of the lateral bending moments would significantly complicate the analysis and the design of the structure. Hence, a parametric study is required to scrutinize a simplified method in designing horizontally curved steel I-girder bridges. A parametric study is conducted, using the finite-element analysis software "SAP2000", to examine the key parameters that may influence the load distribution on the curved composite steel girders. Based on the data generated from the parametric study, sets of empirical equations are developed for the moment and shear distribution factors for straight and curved steel I-girder bridges when subjected to the Canadian Highway Bridge Design Code (HCHBDC) truck loading.