I-girder Bridges Research Articles

Development of Improved Frequency Expressions for Composite Horizontally Curved Bridges with High-Performance Steel Girders

Composite curved I-girder bridges are often used in modern highway systems, but the open sections of I-girders mean that these structures suffer from low torsional resistance. The curvature also results in quite complex behaviors due to the coupled bending and torsional responses of curved I-girder bridges. High-performance steel, which adds strength, enhances durability and improves weldability, addresses both the economic and structural problems associated with curved bridges. However, as yet, there are no simplified design methods in the form of practical equations with which to optimize the design parameters of curved bridges and their dynamic behavior remains controversial. This study evaluated the effects of various design parameters on the free vibration responses of curved HPS I-girder bridges. A sensitivity analysis of 278 prototype simple-span and continuous bridges was conducted using CSIbridge software to create a set of simple, practical expressions for the fundamental frequencies of these structures.

Cost Estimation Model for I-Girder Bridge Superstructure Using Multiple Linear Regression and Artificial Neural Network

One of the owner’s common problem before executing construction projects is the complexity in estimating the project cost in an early stage. Inaccurate cost estimation will force the owner to make further arrangement to the project budget. This study aims to develop an initial cost estimation model for superstructures of Precast I-girder Bridge. Cost estimation model was developed based on thirteen data of detail engineering design of I-girder bridge in Daerah Istimewa Yogyakarta (DIY). Factors influencing the cost of the superstructures of the I-girder bridge were identified. Bridge span and width, the size of the sidewalk, and railing’s type are considered as variables affecting the cost of superstructures. These variables are then arranged into two different analysis Multiple Linear Regression (MLR) analysis and Artificial Neural Network (ANN), in order to obtain the best estimation model. The results of the analysis showed that bridge span and width were the significant factors influencing cost. The correlation value of bridge span is 89.0%, bridge width is 74.2%, the size of the sidewalk is 66.1%, and railing’s type is 46.1% as identified factors that affect the cost of the superstructure. A comparative model of two approaches shows that the ANN has better accuracy than that of MLR, although the difference was not significant.

Determination of load distribution factors of steel–concrete composite box and I-girder bridges using 3D finite element analysis

This paper has utilised a comprehensive numerical investigation to assess the load distribution factors of steel–concrete composite box and I-girder bridges when subjected to different international bridge design loading configurations such as Australian Bridge Design Code and American Association of State Highway and Transportation Officials (AASHTO). In this study, the effect of different parameters such as span length, number of loading lanes and number of cells/girders are investigated. Different types of elements such as solid element, shell element and beam element are examined to find a suitable finite element model to accurately simulate the components of these bridge structures. The accuracy of the finite element models is confirmed with available experimental results. A large number of results are produced by varying the values of the different parameters which are used to determine the load distribution factors for bending moment and shear force of box and I-girder bridges. Design guidelines in the form of empirical expressions for the load distribution factors are also derived from this big database.

Structural Response of Plan-Curved Steel I-Girder Bridges from an Equivalent Straight Bridge Analysis

Structural Response of Plan-Curved Steel I-Girder Bridges from an Equivalent Straight Bridge Analysis

The effect of load position to the accuracy of deflection measured with LVDT sensor in I-girder bridge

Serviceability of a bridge will decrease based on the function of time. Most likely due to the cyclic load from the traffic. The indicators which can be measured to determine the serviceability is the deflection of the girder. In this research, the PCI-Girder and vehicle load are analyzed by using the finite element method (Midas/Civil) Program. For comparison, the running vehicle test to the bridge has been conducted where the bridge deflections are measured using LVDT sensors on PCI-Girder Bridge. To find the effect of vehicle distance to the LVDV position, the running vehicle goes through on several lanes. The finite element program (Midas/Civil) gives relatively similar result to the measured deflection using LVDT sensors. However, when the vehicle load is situated far from the sensor, the result from both analysis showed significant differences.

Assessment of Replacement Bridge using Proof Load Test

This work begins with an overview of the condition assessment of old bridge and explained reasons for demolishing of the bridge. Briefly presented flexural analysis of two stage post-tensioned prestressed concrete girder, which will be replace the old (new bridge). Construction of I-girder and composite girder at first stage and second stage prestressing respectively is explained with figures. Assessment of the load-caring capacity of the one span of the replacement bridge with simple supports using proof load test is presented which is mandatory according to Indian standards. Weighted sand bags were used to load the bridge up to a predetermined service load with impact factor. Deflections of the I-girders of the bridge were measured at selected locations along and across the bridge span and compared with computed values. Linear response was observed during loading and unloading. Considering the load test results, theoretical estimation and criteria as stipulated in codes of practice, it can be inferred that prestressed concrete I-girder bridge span has adequate capacity to carry the loads and hence, deemed to have passed the test.

Free vibration analysis of horizontally curved composite concrete-steel I-girder bridges

Curved composite concrete-steel I-girder bridges provide an exceptional solution to the problems of urban congestion, traffic, and pollution, but their behavior is quite complex due to the coupled bending and torsion response of the bridges. Moreover, dynamic behavior of curved bridges further complicates the problem. The majority of curved bridges today are designed using complex analytical methods; therefore, a strong need exists for simplified design methods in the form of empirical equations for the structural design parameters. In this paper, a sensitivity study is conducted to examine the effect of various design parameters on the free-vibration response of curved composite concrete-steel I-girder bridges. In order to determine their fundamental frequency and corresponding mode shapes, an extensive parametric study is conducted on 336 straight and curved bridges. ABAQUS software package was employed to carry out the numerical simulation for the considered bridges in order to obtain the fundamental frequencies. From the results of the parametric study, simple-to-use equations are developed to predict the fundamental frequency of curved composite concrete-steel I-girder bridges. It is shown that the developed equations are equally applicable to curved composite steel I-girder bridges of simple span or multi-spans with equal span lengths.

Comparison of curved prestressed concrete bridge population response between area and spine modeling approaches toward efficient seismic vulnerability analysis

This paper presents two finite element modeling approaches for seismic evaluation of curved precast-prestressed concrete (PSC) I-girder bridges and compares the results in a statistical and graphical manner. These approaches, including area and spine models, were applied to a simply-supported, curved PSC I-girder bridge under an ensemble of 3D synthetic ground motions. Along with performing non-linear time history (NLTH) analyses of the bridge to capture its separate seismic response, the efficiency of each approach was evaluated with respect to execution time and each was compared. This comparison reveals that the seismic responses that were computed at low computational cost from the spine approach are reasonably analogous to those from the area model. Seismic fragility curves of a portfolio of curved PSC bridges using the spine approach are also created to assess their vulnerability and then compared to those gained from past studies. This comparison shows a reasonable agreement for the PSC portfolio.

Performance of Composite Twin I-Girder Bridges with Fatigue-Induced Cracks

Performance of Composite Twin I-Girder Bridges with Fatigue-Induced Cracks

TSUNAMI INDUCED FORCES IN BRIDGES: LARGE-SCALE EXPERIMENTS AND THE ROLE OF AIR-ENTRAPMENT

In this study large scale hydraulic experiments of tsunami waves impacting a straight composite I-girder bridge were conducted in the LWF at Oregon State University. Both solitary waves and turbulent bores were tested and the experimental results revealed the existence of 4 different phases in the vertical force histories, among which is (i) a phase with a large applied moment and bridge rotation at the time of the first impact of the tsunami bore on the bridge, and (ii) a phase with a governing uplift mode of the bridge during the passage of the wave through the bridge. The first phase introduced the largest tensile forces in the offshore bearings and must be considered in order to prevent the progressive damage of bearings. In addition, the air-entrapment occurring in bridges with diaphragms was seen to (a) alter significantly the pattern of the applied pressures on the girders and below the deck in the internal chambers, (b) consistently increase the total uplift forces for all examined wave heights, and (3) cause a complex nonlinear wave-air interaction phenomenon with significant 3D effects.

An efficient approach for the optimization of simply supported steel-concrete composite I-girder bridges

This paper presents an efficient two-stage optimization approach to the design of steel-concrete composite I-girder bridges. In the first step, a simplified structural model, usually adopted by bridge designers, is employed aiming to locate the global optimum region and provide a starting point to the local search. Then, a finite element model (FEM) is used to refine and improve the optimization. Through this procedure, it is possible to combine the low computational cost required on the first stage with the accuracy provided on the second one. For illustration purposes, a numerical example of a composite bridge designed by Pinho and Bellei (2007) and studied by Leitao et al. (2011) is assessed. The objective function is based on the material cost of the structure. Due to the non-convex nature of the problem and to the presence of discrete variables, the first stage optimization is conducted through five well-known meta-heuristic algorithms: Backtracking Search Algorithm (BSA), Firefly Algorithm (FA), Genetic Algorithm (GA), Imperialist Competitive Algorithm (ICA) and Search Group Algorithm (SGA). The SGA is chosen to pursue the second stage because a statistical analysis has shown that it achieved the best performance. It is shown that the proposed scheme is able to reduce the structural cost in up to 7.43% already in the first stage and can reach up to 9.17% of saving costs in the end of the optimization procedure.

Improved 2D-Grid Construction Analysis of Curved and Skewed Steel I-Girder Bridges

AbstractStructural analysis methods for steel I-girder bridges can be grouped in three categories: 1D line-girder, 2D-grid, and 3D finite-element analysis. This paper discusses the qualities and li...

Comparison of detailing methods for straight skewed steel I-girder bridges

The effects of support in steel bridges can present significant challenges during construction. The tendency of the girder to twist or layover during the placement of the deck can present a particularly challenging problem regarding detailing the cross-frames that provide bracing to the steel girders. There are generally three alternatives regarding the detailing for the cross-frames to achieve an approximate plumb condition of the webs: 1) detailing for no load fit, 2) detailing for steel dead load fit, or 3) detailing for total dead load fit. In the past, different detailing methods have been investigated to identify and compare structural responses affected by the detailing methods. However, the use of wrong camber diagrams in these studies lead to erroneous calculations of structural responses for total dead load fit.The objectives of this paper are: 1) to identify structural responses that are affected by different detailing methods, and 2) to compare different detailing methods for straight skewed I-girder bridges using correct cambers.Different structural responses affected by detailing methods, henceforth called lack-of-fit effects, are discussed for each method. It has been shown that line girder analysis cambers should be used instead of 2D grid analysis cambers to simulate lack-of-fit for the final fit detailing method. It has been found that lack-of-fit effects for the final fit detailing method at steel dead load stage are equal and opposite to the lack-of-fit effects for the erected fit detailing method at total dead load stage.

Analysis of load test on composite I-girder bridge

This paper showcases the importance of field testing in efforts to deal with the deteriorating infrastructure. It shows that when tested, bridges do not necessarily behave as expected under load, particularly with respect to boundary conditions. This is demonstrated via a load test performed on a healthy but ageing composite reinforced concrete bridge in Exeter, UK. The bridge girders were instrumented with strain transducers and static strains were recorded while a four-axle, 32 tonne lorry remained stationary in a single lane. Subsequently, a 3-D finite element model of the bridge was developed and calibrated based on the field test data. The bridge deck was originally designed as simply supported, however, it is shown (from the field test and calibrated model) that the support conditions were no longer behaving as pin-roller which affects the load distribution characteristics of the superstructure. Transverse load distribution factors (DFs) of the bridge deck structure were studied for different boundary conditions. The DFs obtained from analysis were compared with DFs provided in Design Manual for Roads and Bridges (DMRB) Standard Specification. Having observed in the load test that the ends of the deck appeared to be experiencing some rotational restraint, a parametric study was carried out to calculate mid-span bending moment (under DMRB assessment loading) for varying levels of restraint at the end of the deck.

Reliable Fit-Up of Steel I-Girder Bridges

This paper summarizes recently completed research supporting the development of improved design, detailing, and erection guidelines to ensure reliable fit-up of skewed or curved (or both) steel I-girder bridges. Twenty-one bridges, including several with multiple framing arrangements, were analyzed to provide quantitative support for, and refinements to, guidelines produced by an affiliated National Steel Bridge Alliance Steel Bridge Collaboration Task Group. The quantitative data of this research support recommended fit conditions (i.e., cross-frame detailing methods) as a function of the bridge geometry. Forces required to assemble the steel during erection were evaluated, and difficult cases were highlighted. Suggested erection considerations to facilitate fit-up were provided. In addition, the research investigated and specified beneficial staggered cross-frame arrangements for straight skewed bridges, as well as framing arrangements around bearing lines at interior piers in continuous-span bridges. The research emphasized identification of the impacts of the chosen fit conditions on girder elevations, girder layovers, cross-frame forces, girder stresses, and vertical reactions in completed bridge systems. This paper provides simplified methods of accounting for steel dead-load fit and total dead-load fit detailing effects. Procedures are provided for direct calculation of the locked-in forces due to steel dead-load fit and total dead-load fit detailing in cases in which a more precise calculation of these effects may be beneficial. Construction inspection best practices are recommended to ensure that the erected geometry sufficiently meets the specified fit conditions, and design specification provisions that synthesize the key guidelines are recommended.

Load Rating Based Maintenance Approach for Corrosive Twin I-Girder Railway Bridges in India

In Indian Railways, about 75% of the bridges are exceeding 60 years’ life period and 80% of steel bridges population adopt simply supported twin I-girder structure. Corrosion has become one of the biggest challenge for maintenance of these old steel bridges. Currently the index called Condition Rating Number (CRN), utilized to assess the structural conditions and determine the maintenance strategy. CRN is a qualitative approach with individual bias in decision, therefore it is difficult to identify the prioritization of corrosion damages in same CRN category. In this study, a new approach based on load rating factor (LRF) for corrosion maintenance on typical twin I-girder bridges is proposed. Firstly, by considering frequently occurring corrosive location and the absolute maximum load effect, three categories of critical corrosive location and pattern are summarized. Secondly, LRF based on physical inspection is calculated using simplified theoretical approach and FEM approach. Various degree of corrosion is utilized to investigate the influence on the load capacity by incorporating the nonlinear phenomena such as buckling. It is found that the simplified approach is conservative enough to evaluate the structure practically within safety side. Finally, the practical decision flow regarding to the maintenance action is proposed, summarizing the relationship between the corrosion and the remaining load capacity by means of LRF. This approach is expected to provide not only an objective evaluation to load capacity of corrosive railway bridges, but also instructive information for the retrofit of structures with limited fund availability.

A Study on countermeasures against fatigue damage of bearings in steel I-girder bridges

A Study on countermeasures against fatigue damage of bearings in steel I-girder bridges

Effect of pavement maintenance cycle on the fatigue reliability of simply-supported steel I-girder bridges under dynamic vehicle loading

In this study, the effect of the pavement maintenance cycle on the fatigue reliability of simply-supported steel I-girder bridges under dynamic vehicle loading is studied. The bridge model and the fatigue load model are both adopted from the Load and Resistance Factor Design (LRFD) Bridge Design Specifications of the American Association of State Highways and Transportation Officials (AASHTO). A three-dimensional vehicle-bridge coupled model is developed to simulate the vehicle-bridge interaction and used to obtain the stress ranges of the steel bridge girders under the dynamic vehicle loading. Numerical simulations are carried out to study the influence of three important parameters, including the road surface condition, bridge span length and vehicle speed, on the fatigue damage induced by the fatigue truck. The results from this study show that the bridge fatigue reliability decreases dramatically under repeated dynamic vehicle loads when the road surface condition is very poor and that the pavement maintenance cycle has a significant influence on the bridge fatigue reliability. A procedure for determining the desired pavement maintenance cycle to achieve the target fatigue reliability of steel bridge girders is developed. An example is also provided for demonstrating the proposed procedure.

Probabilistic seismic restoration cost estimation for transportation infrastructure portfolios with an emphasis on curved steel I-girder bridges

This paper develops a rapid probabilistic seismic restoration cost estimate framework for transportation infrastructures (i.e., bridge portfolios) by integrating Response Surface Metamodels (RSMs) coupled with Monte Carlo Simulation (MCS) into seismic restoration cost curve generation. A portfolio of curved steel I-girder bridges located in the Eastern United States is used for this study. As part of the restoration curve generation, joint RSM-MCS models are created and utilized to assess seismic vulnerabilities of the target bridge portfolio and estimate their damage ratios. Probabilistic damage factor models in conjunction with MCS to treat uncertainties in damage ratios, curved bridge characteristics, and volatile construction conditions are simulated with the joint RSM-MCS-based vulnerability functions. Relevant restoration cost curves are then generated based upon average construction cost data of the United States. Findings reveal that characteristics for the restoration curves vary relying on variability in damage ratios and vulnerabilities, emphasizing that an increase in the difference between lower and upper cost bounds occurs as the seismic intensity increases. This evidence highlights the significance of considering variability in both damage ratios and vulnerabilities for more reliable decision-making for seismic restoration on such bridge portfolios.

Vulnerability Sensitivity of Curved Precast-Concrete I-Girder Bridges with Various Configurations Subjected to Multiple Ground Motions

Abstract Curved bridges provide a vital benefit to the nation’s infrastructure system by allowing for accessibility and ease of transition in irregular highway layouts. Curved bridges using straight prestressed concrete I-girders with curved decking can fulfill this need. A number of such bridges have been constructed both in seismically and nonseismically active zones. This paper determines the seismic vulnerability sensitivity of the bridges with vastly different configurations via use of conventional fragility-assessment techniques. Experimental design established a statistical setting using core variables to produce a wide variety of hypothetical bridges to represent both as-built and proposed bridge configurations. Each bridge was designed following the strength and serviceability limit states stipulated by current bridge design specifications. As part of the sensitivity analysis, nonlinear time history analyses (NLTHAs) using numerous synthetic ground motions were performed to establish seismic dema...