Plate Girders Research Articles

Experimental Testing of Shear Web Panels of Steel Plate Girders Strengthened by Fiber-Reinforced Polymer Composites

Experimental Testing of Shear Web Panels of Steel Plate Girders Strengthened by Fiber-Reinforced Polymer Composites

An analytical method to determine the ultimate shear strength of continuous steel plate girders

An analytical method to determine the ultimate shear strength of continuous steel plate girders

Design and Analysis of Curved Steel Bridges Using 3D Shell Modelling

AbstractSteel bridge designers and erectors primarily rely on approximate methods, such as 1D line girder analyses and 2D grid analyses. For curved or skewed bridges, this can give erroneous indications of the structure's true behaviour. Refined methods of analysis, such as 3D shell modelling, aim to bring a significant change in the practice of bridge engineering. By moving the industry away from simplistic design assumptions, refined analysis methods lead to more accurate, less conservative results, which in turn brings true benefits such as improved structural safety and increased economy. In this paper, several case studies on curved plate girder and tub girder bridges are presented, which cover the full bridge life cycle, from erection of the steel structure and placement of the concrete deck, down to live load analyses using influence surfaces and load rating. The case studies will be modelled with mBrace3D, a dedicated FEA software for curved steel bridges.

Comprehensive exploration of technological tensioning effects in welded thin plate girders: an in-depth investigation

Comprehensive exploration of technological tensioning effects in welded thin plate girders: an in-depth investigation

Stress characteristics and cracking mechanism of web-to-stiffener weld in steel plate girder bridges under bending-shear action

The web-to-stiffener weld was subjected to bending-shear action, which was always neglected in previous research and affected the accuracy of fatigue evaluation. In this study, multi-scale FEMs (finite element models) of steel plate girder bridges were established to investigate the deformation characteristics, thus revealing the generating mechanism of bending-shear action. The fatigue comparison tests under bending-shear load and bending load were conducted to identify the cracking mechanism and its impact. The stress characteristics at the weld end were further explored through the structural mechanical model and verified by FEMs. The results show that the bending-shear action was caused by the inward and downward pulling by the stiffener on the web, and would lead to a premature transition from fatigue cracking to brittle fracture. The ratio of shear stress to normal stress was independent of load, inversely proportional to gap height, and positively related to web thickness, which could provide support for the accurate fatigue evaluation of web-to-stiffener weld.

Experimental and theoretical investigation on flexural behavior of concrete-filled tubular flange girders

Concrete-filled tubular flange (CFTF) girders offer superior torsional stiffness compared to traditional I-shaped plate girders, providing enhanced flexural performance. To accurately assess the flexural capacity of CFTF girders, both flexural tests and theoretical analyses were conducted on specimens with and without concrete decks. The experimental data were meticulously analyzed to understand the flexural mechanism, yielding sequence, interface slip, strain distribution, and confinement effect of CFTF girders. Subsequently, finite element models were then utilized to analyze the influence of cross-section dimensions and material optimization on the flexural behavior of CFTF girders. Comparative analyses with I-shaped girders were also performed to highlight the structural advantages of CFTF girders. The proposed flexural calculation formulas were validated against both experimental and analytical results, demonstrating a fitting accuracy between 95 % and 98 % for the yield moment and between 96 % and 98 % for the ultimate moment. The method proposed in this paper provides a reliable and accurate approach for evaluating the flexural capacity of CFTF girders, significantly contributing to the advancement of design and analysis practices in structural engineering.

Steel I-girder geometries for enhanced stability in shear loading

This paper challenges the design provisions that rely on the traditional assumptions of simply supported web boundary conditions for shear. While some literature discuss the flange stiffening effect on the web, the detrimental impact of flexible flanges on the shear strength has not been addressed before. Through a detailed analysis of excessive deformations at the web-flange junctions, this study shows that the assumption of simply supported web boundary conditions may be unsafe, contradicting expectations of conservative design in some girders that comply with current design specifications. Accordingly, minimum flange dimensions are proposed to ensure adequate support at the web edges. In addition to categorizing cross-sections that do not achieve simply supported boundary conditions, the paper proposes a modified elastic shear buckling coefficient, which can enhance the estimate of elastic shear buckling stresses of I-girders by up to 60% compared to simply supported web plates. The improved elastic buckling stress is also shown to improve the overall shear strength predictions of I-girders by means of geometric and material nonlinear analyses. This revised coefficient considers the intricate interplay between the flanges, transverse stiffeners, and the web, which shall enable a more mechanistic and consistent interpretation of the ultimate shear capacities in future studies. The findings presented in this paper have implications for cross-sectional proportioning and shear design of plate girders, given that the ultimate design shear capacities of I-girders are typically estimated by summing the web elastic shear buckling stresses with their post-buckling strengths.

Experiment and Analysis of a Hybrid Composite Post-tension Plate Girder

Steel plate girders have been employed as structural bridge parts since the 19th century. They are typically made up of built-up sections in the shape of I-beams. Web and flange plates withstand shear force and bending moment, respectively. However, plate girders are vulnerable to shear buckling. Shear buckling resistance is increased by adding reinforced vertical stiffeners and, in some cases, longitudinal stiffeners. Nevertheless, these stiffeners are sometimes not enough to prevent extreme shear buckling and only delay the shear buckling of slender web panels. This study investigated a hybrid composite post-tension (HCPt) plate girder by experiment and finite element (FE) analysis. The structural performance of the HCPt plate girder was tested using three specimens: a double-web plate girder, an in-fill concrete double-web plate girder and an in-fill concrete double-web plate girder with prestress. Results showed that the steel web filled with concrete presented preferable strength and behaviour to the hollow steel web because of the concrete in-fill. It had high load capacity, strength and ductility. The concrete in-fill prevented the steel web plate from buckling, and beams generally failed in a ductile manner. Applying prestressing techniques reduced deflection under external loads, increased the load-carrying capacity and enhanced its flexural behaviour by 126% compared to the double web plate girder. The failure mode was changed from web shear buckling in a double web girder to bending in a hybrid composite plate girder, with an improvement of web shear buckling by 88%. The FE analysis result showed excellent consistency with the experimental result.

Fire resistance and stability of non-uniformly heated steel plate girders with slender section

The results of experimental tests and computer simulations pertaining to the bearing capacity of unevenly heated girders made of slender thin walled class 4 sections are presented in this paper. It has been shown, that for the analyzed group of elements the value of lateral-torsional buckling coefficient depends on the initial load level applied to the considered element and the cross section bearing capacity reduction level under fire conditions. It has been determined as well that the influence of steel grade used on the value of buckling coefficient is negligible. Based on the research conducted, a new proposal for calculation of the lateral-torsional buckling coefficient for considered group of elements has been prepared. A simplified method to determine the bearing capacity of non-uniformly heated class 4 sections is proposed in this paper as well. It has been shown that both proposed methods exhibit sufficient convergence of results with the results of computer simulations, and satisfy appropriate acceptance criteria as well.

Comparison of analytical models for shear strength estimation of steel plate girders

Web shear buckling of steel plate girders limits their load-carrying capacity in bending. Several analytical models have been suggested in the literature to estimate the shear capacity of plate girders. This paper presents a critical evaluation of several of these analytical models using the data of experimentally tested plate girders available in the literature. It was found that these analytical models make a conservative estimation of critical buckling strength for plate girders with larger slenderness and/or aspect ratios. Although the predicted ultimate shear strength varied across the different analytical models, no particular trend was identified to show that the aspect and/or slenderness ratios influenced the shear strength. A parametrically conducted analysis indicated that the threshold slenderness ratio (to cause buckling in the web panel) decreases with increasing yield strength and aspect ratio. The paper proposes simplified guidelines for the preliminary sizing of steel plate girders by avoiding shear buckling. It has been shown that the sizes of plate girders determined using the proposed guidelines satisfy design requirements for both flexure and shear.

Destructive Testing of the Pinkabach Railway Bridge – Large scale Testing of Sensor Systems for Fatigue Crack Monitoring and System Identification

The work presents experiments carried out on an out-of-service steel railway bridge, the so called Pinkabach bridge. The objective was to test advanced and novel sensor systems, i.e. Distributed Fiber Optic Sensing (DFOS) and Acoustic Emission (AE), for the monitoring of fatigue cracks, both for crack initiation and subsequent crack growth, in steel railway bridges. Also, sensor systems for overall system identification, i.e. Tiny Motion (TM), Distributed Acoustic Sensing (DAS) and dynamic response analysis, have been tested. The Pinkabach bridge was a single span plate girder railway bridge with a span width of 21,5m that was taken out of service and transported to a secure environment that allowed for destructive testing with permanent access to the structure itself under controlled conditions. By harmonic excitation of the structure at its first resonance frequency, cyclic stress levels comparable to the stress levels during train passage were generated and it was possible to emulate the fatigue load from decades of train traffic within the limited period of the experiments. Crack initiation and growth happened at two locations of the flanges and crack growth was monitored till the crack length was half of the flange width of the main girder. To end the experiments a static load test showed the remaining capacity of the damaged structure. A conventional sensor system was used for validation and comparison with calculated predictions based on linear fracture mechanics, used for the design of the experiments. An overview over the whole set of experiments as well as (intermediate) results and findings on the applicability of the novel sensor systems are presented in this paper. The experiments are a collaborative work of multiple scientific and industrial partners and have been carried out as part of Area 3.1 of the COMET Project Rail4Future, funded by the Austrian Research Promotion Agency FFG.

Serviceability limit state of incrementally launched steel bridge I-girders

Bridge girders are subjected to repeated patch loading during incremental launching (i.e. travelling over supports). Plastic deformations are likely to occur in the girder already at the first patch loading. They influence the girder’s structural response and bring about a decrease in the ultimate resistance at subsequent patch loadings. This problem is analysed in the present paper through the serviceability limit state (SLS) of incrementally launched bridge I-girders (ILBGs). The SLS of ILBGs is a current problem since only a few studies, with contrasting conclusions and certain limitations, have been recognised in the literature. Research is limited on plate girders without longitudinal stiffeners made of structural steel. Flat slide-type launching shoes are considered in this paper.The serviceability requirement (repeatable behaviour of ILBGs) and criterion (that effective membrane strains should remain in the elastic range) are adopted from the literature. So, the serviceability resistance is adopted as a load at the start of the effective membrane plastic strains in the girder. In order to propose a practical and simple SLS design procedure, the serviceability resistance is normalised against the ultimate resistance, so a serviceability correction factor (ksls) is defined. The paper presents a parametric numerical analysis of the factor (ksls). A finite element model previously developed and validated by the author is employed to simulate a nonlinear response of patch-loaded girders. The parametric study includes 599 girders. ksls is inversely proportional to the web thickness and directly proportional to the flange thickness and the yield strength of the steel material. The load length, web depth and flange width do not influence ksls. The influence of the spacing between transverse stiffeners on ksls is negligible. Finally, by regression analysis of the results of parametric study, an original and reliable serviceability correction factor is proposed as the main objective of the research. The range when the SLS of ILBGs should be checked is also defined.

A simplified method for estimating bridge frequency effects considering train mass

The dynamic response of a railway bridge depends on several parameters; the primary parameter is the fundamental natural frequency of vibration of the bridge itself. It is considered a critical parameter of the bridge as the driving or the forcing frequencies arising from moving trains may coincide with the fundamental frequency of the bridge and initiate a resonant response amplifying the bridge load effects. This condition may adversely affect the stresses experienced on bridge members and, consequently, the remaining fatigue life of the structure. Because the train adds additional time-varying mass to the bridge, this introduces a time-varying change in the bridge’s fundamental natural frequency of vibration. As a result, train critical speeds will have a certain range depending on the train configuration. This article presents a simplified method using a power-law relationship to predict the frequency characteristics of a bridge as a function of the train-to-bridge mass ratio. The method is presented in a generalized form, which enables the frequency characteristics to be determined for any given combination of trains and simply supported bridges of short to medium span typically found on the UK rail network. The method is then demonstrated in a case study of a single-span, simply supported plate girder bridge. By considering the BS-5400 train traffic types, the proposed method is used to calculate bridge frequency effects, dynamic amplification, and train critical speed bandwidth for each train type. The simplicity of the proposed method, as it does not require any complex computational modeling, makes it an ideal and effective tool for the practicing engineer to carry out a quick and economical assessment of a bridge for any given train configuration.

Shear buckling resistance and intermediate transverse stiffeners internal forces of full-scale steel plate girders – Experimental tests and numerical investigation

This paper presents the results from two full-scale transversally stiffened plate girder’s load tests in shear and bending. The plate girder’s internal stiffener forces and shear buckling resistance are estimated using the web and stiffener measured strains. These results show that the reported axial compression and bending moment of the intermediate transverse stiffeners for the tested plate girder are 70% of the FprEN 1993–1-5: 2022 [1] design force. The two full-scale plate girders fail due to buckling shear. Nonlinear FEM analyses based on the test girder geometry, measured initial geometric imperfections, and the material properties from the tensile tests, show excellent agreement with the test results, with less than 5% on the maximum applied forces and related displacements. The principal membrane stresses path that triggers the failure of the web plate are investigated based on numerical results and compared with the test measurements. Contrary to the assumption of a rotated stress field model, the principal compression stress obtained in the experimental test was higher than shear buckling stress in the vicinity of the intermediate transverse stiffener.

Estimation of the Minimum Lateral Resistance of Continuous Welded Rail Tracks Installed on Ballastless Railway Plate Girder Bridges

Estimation of the Minimum Lateral Resistance of Continuous Welded Rail Tracks Installed on Ballastless Railway Plate Girder Bridges

Optimal Reinforcement Model based on the Shape and Installation Position of the Lower Horizontal Bracing of a Ballastless Railway Plate Girder Bridge

Optimal Reinforcement Model based on the Shape and Installation Position of the Lower Horizontal Bracing of a Ballastless Railway Plate Girder Bridge

Optimized Transverse–Longitudinal Hybrid Construction for Sustainable Design of Welded Steel Plate Girders

I-section girders with different types of steel in the flanges and web (fyf > fyw, respectively) are known as transverse hybrid girders. These have proven to be more economical than their homogeneous counterparts. However, the use of hybrid configurations in the longitudinal direction of the element has yet to be studied. This paper uses optimization techniques to explore the possibility of constructing transverse and longitudinally hybrid (TLH) steel girders. The optimization objective is to minimize the manufacturing cost, including seven activities besides the material cost. The geometrically double symmetric I-girder design subjected to a uniform transverse load is performed using Eurocode 3 specifications. Nine case studies are implemented, varying the element span (L) and the applied load. The results show that establishing various configurations along the length of the element is beneficial. The optimum number of transition points is six, meaning the girder will have four configurations, i.e., one central and three others symmetrically distributed toward each half of the element. The optimum position for the first transition would be at 0.24∗(L/2), the second at 0.40∗(L/2), and the third at 0.60∗(L/2). The optimum extreme configuration is usually homogeneous (fyf = fyw = 235 MPa). The others increase the steel quality in the plates, maintaining hybrid arrangements to reach the central one that usually remains with S700 steel for the flanges and S355 for the web. The study shows that TLH configurations are more effective for elements with larger spans. By applying the formulated design recommendations in a different case study, the manufacturing cost dropped by over 50% compared to the traditionally designed element and by more than 10% relative to the optimized element with a homogeneous configuration. The study’s limitations and encouraging results suggest future lines of research in this area.

Theoretical evaluation of tapered composite plate girders subjected to shear loads

The behavior of prismatic composite steel plate girders subjected to shear loads was thoroughly investigated, and different theories were evaluated. However, the behavior of tapered composite plate girders with and without openings has not yet been investigated. Therefore, this paper presents a new method for predicting the ultimate capacity of tapered composite plate girders subjected to shear loads. The shear capacities of tapered composite plate girders with and without web openings were developed based on the classical theory of tension-field action for prismatic composite plate girders. It is assumed that the shear capacity of such girders can be predicted from the steel plate girder and reinforced concrete slab anchored using shear studs. The effect of the composite action on the top flange owing to the shear studs was considered in the derivation of the equations to calculate the shear capacity of the steel plate girders. In addition, the shape and size of the opening were also considered. The proposed method was verified by comparing the results of the shear capacity with experimental results from previous studies. It can be concluded that the proposed method can predict the shear capacities of tapered composite plate girders with solid and open webs with acceptable accuracy.

Static Bending Mechanical Properties of Prestressed Concrete Composite Slab with Removable Rectangular Steel-Tube Lattice Girders

In recent years, with the development of building technology, the Chinese construction industry has begun to gradually promote the prefabricated buildings to save on construction costs. Among them, composite slabs, as essential components of prefabricated buildings, have been widely used by designers mainly in favor of their low cost. However, is it possible to further reduce the cost without affecting the quality? Researchers think so if the operation cycle of support from the bottom of composite slabs can accelerate and the mechanical properties of their bottom plate can be optimized. To prove this hypothesis, researchers proposed a new type of prestressed concrete composite slab with removable rectangular steel-tube lattice girders (referred to as CDB composite slabs), whose bottom plate consists of a temporary structure composed of a prestressed concrete prefabricated plate and removable rectangular steel-tube lattice girders. Through static bending performance tests on three prefabricated bottom plates and one composite slab, researchers measured corresponding load-displacement curves, load-strain curves, crack development, and distribution, etc. The test results show that the top chord rectangular steel tubes connected to the bottom plate concrete through web reinforcement bars significantly improve the rigidity, crack resistance, and load-bearing capacity of the bottom plate and possess better ductility and out-of-plane stability. The number of supports at the bottom of the bottom plate is effectively reduced, with the maximum unsupported span reaching 4.8 m. Beyond 4.8 m, only one additional support is needed, and the maximum support span can be up to 9.0 m, which provides space for cost reduction. The cooperative load-bearing performance of the prefabricated bottom plate and the post-cast composite layer concrete is good. The top chord rectangular steel tubes are easy to dismantle and can be reused, which reduces the steel consumption by about 24% compared to that used for the same size of ordinary steel-tube lattice-girder concrete composite slabs. It can greatly decrease the cost. In conclusion, the results have shown that the new method researchers proposed here is practically applicable and also provides great space to save on financial costs.

Evaluation on structural performance of hybrid composite post-tension plate girder through finite element analysis

ABSTRACT Plate girders are typically formed by the built-up of I-shaped plates. It is vulnerable and weak in resisting buckling. In this study, FE analysis models were developed to evaluate the flexural performance of a hybrid composite post-tension (HCPt) plate girder. The HCPt plate girder is made of double-web and in-fill concrete with pre-stressed tendon to prevent shear web buckling and improve flexural resistance. The sensitivity of design parameters to the performance of the girder was also investigated through a parametric study using four different configurations. The selected parameters are span length, steel grade, concrete grade, and level of pre-stressed force. The statistical analysis was performed using linear multiple regression model to predict the girder’s flexural load and displacement. The results showed that web shear buckling was eliminated for models with in-fill concrete and pre-stressed tendon and failed by bending. Failure of the girder with double web was demonstrated by the combination of bending and web shear buckling. The concrete in-fill prevents the web plate from buckling and the beams generally fail in bending with high ductility. The load capacity of the hybrid composite plate girders with pre-stressing improved by 76% and 44% compared to conventional single-web plate girders and double-web plate girders, respectively.