Steel Girder Research Articles

High-strength steel plate girders under patch loading: Numerical analysis and design recommendations

Systematic investigations on the patch loading resistance of plate girders with different Q460, Q550, Q690, and Q960 high-strength steels (HSSs) were numerically performed with the purpose of proposing a design method suitable for plate girders with different HSSs. A numerical modelling method was proposed to reveal the resistance performance of a steel plate girder under patch loading. 39 experimental results on HSS, stainless steel, mild steel, and aluminum plate girders were used to validate the accuracy of the proposed numerical modelling method. The different HSSs, web aspect ratios, relative load lengths, and web height-to-thickness ratios were included in the parametric study. Based on the results of 192 finite element models, the effects of the key parameters on the ultimate resistance, effective resistance, and effective resistance stiffness were revealed. Subsequently, the design methods in the Chinese standard (GB 50017-2017), European standard (EN 1993-1-5), and American standard (AISC 360-16) were validated. The results indicated that the design method in GB 50017-2017 overestimated the ultimate resistance of HSS plate girders under patch loading, whereas the design methods in EN 1993-1-5 and AISC 360-16 underestimated the ultimate resistance. Subsequently, the design equations in EN 1993-1-5 were modified to accurately predict the ultimate patch-loading resistance of plate girders with different HSSs.

Developing a benchmark study for bridge monitoring

AbstractStructural health monitoring is the process of implementing a continuous damage detection strategy to optimize the inspection and maintenance schedules of bridges, and extend their lifespans. One of the main challenges of automated damage detection is the lack of data on damaged states, which makes it difficult to validate new approaches in the research and development stage. To alleviate this problem, a monitoring campaign on a two‐span test bridge with defined defects is conducted and documented in this article. The bridge is a steel‐concrete composite structure with a length of 30 m, with two primary steel girders and a segmented concrete deck. The recorded data capture the long‐term ambient data from 18 test days and changing environmental conditions, as well as the short‐term ambient data and dynamic load tests from four damage scenarios with well‐defined damage extents. A mobile measurement system with numerous sensors is used for data acquisition. A shaker is placed on the bridge to excite white noise. The main goal of this article is to document the experimental procedure and perform preliminary plausibility checks on the measured data. First results demonstrate that system response data and environmental conditions are recorded reliably and that environmental effects significantly affect the long‐term measurements. Therefore, a suitable data set is provided as open‐source data for future studies on data normalization and automated damage detection.

A study on effective rehabilitation method of shear buckling strength by CFRP in steel girder

To increase the shear strength of steel girders, several conventional methods and materials exist, such as bolting or welding of steel plates to the girder end area. However, recently Carbon Fiber Reinforced Polymer (CFRP) has been widely studied and used as an effective material for increasing the shear strength of the web plate in steel girder ends. However, the conventional approach of covering the entire web area with CFRP can be costly and excessively conservative. To efficiently increase shear buckling strength, this research aimed to determine the suitable area for CFRP coverage on the web plate along with the impact of CFRP application direction and the effect of attaching CFRP only to the web center. Through adopting an experimental approach, the study tested eight specimens, and the CFRP was applied in two distinct patterns to tension and compression directions. Furthermore, as for the CFRP coverage area, initially, the whole web area was covered with CFRP, and subsequently, the CFRP coverage area was parametrically reduced. The findings indicate that covering around 40% of the web area by CFRP can produce similar results as CFRP covering the whole web area. Additionally, it was found that the web and CFRP act as a unified composite section until the initiation of shear buckling, making the direction of CFRP application insignificant.

Fatigue properties of OSD in large cantilever cable-stayed bridge on highway-railway layer

To enhance the understanding of fatigue issues in orthotropic steel deck (OSD) bridges with cantilevered steel-box girders on highway–railway layers and ensure the fatigue life of similar bridges, this study focused on the OSD fatigue characteristics of the Jinhai Bridge, the world's widest dual-use–cable-stayed bridge for road and railway transport. The fatigue-stress distribution characteristics and variation rules were investigated using a full-scale fatigue test model. Four U-ribs were subjected to four million loading test cycles, and the OSD fatigue performance was evaluated using the nominal stress method. The results indicated that the stress-influence range of the crossbeam U-rib in a large cantilever steel box girder was approximately nine U-ribs wide and three crossbeams long, significantly exceeding that of a conventional closed-box steel girder. The stress difference in the crossbeam opening bottom-edge detail in the box girder with and without a cantilever was 85.4%. Along the transverse bridge, the most unfavorable stress amplitude difference among similar fatigue details in different regions reached 57%. After 4 million cycles, the crack length was 90 mm. The fatigue cracks had a minimal effect on the overall deformation performance of the model. Combining the traffic volume statistical data and damage accumulation, the estimated fatigue life of the crossbeam opening detail was 103.55 years. According to JTG-D64–2015, this satisfies the recommended fatigue design life requirement of 100 years for the crossbeam opening details of large cantilever steel box girders. However, the economic development trends and increasing traffic volumes necessitate further research.

Analytical study on flexural behavior of steel composite girder using truss element for shear connectors with different types and layouts

The key to improve the accuracy of behavior analysis of the steel composite girder lies in the reasonable modelling the intergration between the reinforced concrete slab and the steel girder. Based on design requirements and construction methods, the type and layout of the shear connectors between the concrete slab and the steel girder are different, significantly affecting the behavior of the composite girder. This study is conducted to (i) investigate the applicability of a truss element available in the popular simulation software Abaqus in modelling the shear connectors of composite girders, (ii) compare the flexural behavior of composite girders with different types and layouts of shear connectors. Two types of shear connectors considered in the study are headed studs and perfobond strips, and their layout corresponds to the construction methods using the cast-in-place and precast concrete slabs. The study results show that a truss element can be used to simulate the shear connector behavior through reasonable assignment of its shear force-slip relationship. With the design principle that the total shear capacity of the shear connector per unit length remains constant, the nonlinear behavior of the composite girder is significantly affected by the type and layout of the shear connectors.

Evaluation and retrofit of steel girder shiplap connections

Over time, owners may face challenges with management of bridges with outdated details. One such detail that is no longer used today is the steel girder shiplap connection. These were originally employed to simplify analysis of continuous girders while also moving joints away from the piers, improving longevity of bridge bearings and substructures. Unfortunately, fatigue issues have appeared in these connections resulting in cracking at critical load-carrying locations. In this project, analysis was performed to investigate connection fatigue and strength and retrofit design verification. Results utilizing non-linear analysis showed that while stresses from ultimate loading could adequately redistribute throughout the web, high stress concentrations were created, exacerbating fatigue. Stress calculations for shiplap web details are not well codified or easily assessed with simple hand calculations, so finite element analysis was utilized. Results showed web fatigue life had been exhausted with more cracking expected at other locations, convincing the owner retrofit was necessary even though the bridge was programmed for replacement.

Optimising the inherent fire capacity of structures

This paper introduces a structural design optimisation methodology aimed at minimising the consequences of a fire. The methodology considers the trade-off between implementing passive fire protection measures and enhancing a structure’s “inherent fire capacity”, defined as its ability to retain integrity/functionality without additional fire safety measures. The feasibility of the methodology is demonstrated through the fire safety design of a single-span, steel girder bridge. The optimisation process generates multiple Pareto-optimal solutions for minimising the maximum bridge deflection after a given fire exposure time. Passive protection ensures the bridge’s functionality when facing a heavy goods vehicle fire. In the case of exposure to a car fire, solutions requiring fire protection in specific limited girder regions are identified. The decision-making process is further supported by investigating the robustness of the solutions to uncertainties in material properties and the heat flux model.

Refined analysis of steel girder bridges for computation of live load distribution factors considering effects of freight and emergency vehicles

Recent revisions to federal guidelines require state departments of transportation (DOTs) to rate bridges in their inventory with special hauling vehicles (SHVs) and emergency vehicles (EVs). In this research, refined analysis method was used to compute live load distribution factors of steel girder bridges considering the impacts of SHVs and EVs on the live load distribution behavior. To determine the live load distribution factors for interior and exterior girders under different lane loading conditions, finite element models of twenty-one steel girder bridges from the state of Virginia were developed and then analyzed. The effects of vehicle type and transverse position on the results of the refined analysis were evaluated. The results were comparatively evaluated with those obtained using AASHTO LRFD equations. The live load distribution factor of steel girder bridges with various geometrical parameters were predicted using a series of linear regression models that were built using the data from the numerical simulations. The developed models can be used to identify bridges whose rating factors will be improved through refined analysis when these bridges are susceptible to posting.

Behavior of Spliced Steel Girders under Static Loading

In this paper, the behavior of spliced steel girders under static loading is investigated. A group of seven steel I-girders were tested experimentally. Two concentrated loads were applied to each specimen at third points and the load was increased incrementally up to the yield of the specimen. Two types of splices were considered; the bearing type and the friction-grip type splices. For comparison, an analytical study was made for the tested girders in which the finite element analysis program (Abaqus) was used for analysis. It was found that the maximum test load for spliced girders with bearing type splices was in the range of (34%) to (67%) of the maximum test load for the reference girder. For girders spliced by using friction-grip type splices, the maximum test load was in the range of (90%) to (99%) of the maximum test load for the reference girder. The analytical results show a good agreement with the experimental results with a difference in maximum deflection at midspan was not more than (15%) at maximum load for all girders.

Seismic Study of Precast Steel-Reinforced Concrete Building using Shake Table Test

Precast Steel-Reinforced Concrete (PSRC) structural frame systems for moment-resisting, comprised of Prefabricated Steel (S) girders and Precast Reinforced Cement Concrete (RCC) columns. This structural system has the advantage of inherent stiffness and damping during a seismic event. PSRC’s moment-resisting frame system is also known for its construction efficiency, lightweight, and low cost. Earlier investigations have shown PSRC systems helpful in designing and constructing buildings while maintaining ample strength and high ductility during seismic incidents. Despite much previous research, the use of the PSRC structural system in India is still limited. Previous studies have accepted a vital need to test comprehensive structural systems, both experimentally and analytically - to validate the knowledge collected to date and act as evidence of concept for the PSRC moment-resisting frame system. This paper aims to facilitate more recognition and use of the PSRC structural system as a feasible choice for traditional RCC lateral resisting systems. A shake-table test was conducted to evaluate the PSRC building performance during maximum considered earthquake events. The comparative study of experimental and numerical results of the 1/4th scaled building is presented.

Finite Element Investigation of Angle Ring Confinement for Clustered Large-size Stud Shear Connector in Full-Depth Precast Concrete Bridge Deck Panel

Full-Depth Precast Concrete (FDPC) bridge deck panel system, consisting of concrete deck and steel girders, has been used widely for highway and bridge construction due to rapid construction and replacement as well as in terms of economics. This system could integrate with clusters of large size headed-stud shear connectors for more significant connection, although larger composite actions were experienced. Therefore, a new angle steel ring confinement was introduced and tested by push-off samples for the most effective shear transfer. The Finite Element Analysis (FEA) of the push-off model with an in-depth investigation of non-linear concrete properties, boundary parameters, and different geometries of angle ring confinement was developed in this study. The FE models were verified with the push-off test in terms of loads, displacements, and failure stages. Nonlinear concrete material models: Concrete Damage (CD) and Drucker Prager (DP) were identified the different abilities either for predicting initial cracks, or determining maximum resistance and critical failure, respectively. The thickness of the angle and the sizes of hook bars were investigated for the most effective aspects of the angle ring confinement. The results showed comparable stiffness and load resistance for various aspects. However, compatible geometries, either 5 mm thick angles with DB12 hook bars or 10 mm angles with DB25 hook bars, were suggested. The final non-linear FEA model was reliable for comparative studies to FDPC push-off with different confinement configurations.

Shear behavior of stainless steel girders with corrugated webs

In this paper, the shear strength of corrugated web girders made of EN 1.4162/LDX 2101 stainless steel is investigated. Four full-scale trapezoidal corrugated web girders were tested under shear. Before conducting the tests, DIC was used to measure the real geometric imperfections in the web panels. Complementary finite element analysis studies were conducted to assess the sensitivity of the shear strength to initial imperfections. The experimental results indicated that all the tested girders with a local slenderness ratio of λ = 0.7 attained the shear yield strength, which was then followed by strain hardening in the material at a level that was 8–18% higher than the yield strength. This implies that the Eurocode's limit of λ = 0.25 to attain the plastic shear strength in corrugated webs can be quite conservative for stainless steel. According to the findings of the imperfection sensitivity studies, an initial geometric imperfection based on the first eigen buckling mode and with a maximum amplitude of amax/200, where amax is the maximum corrugation fold length, yielded ultimate strength within 3% of the test results. When the amplitude was increased to hw/200, where hw is the web height, the ultimate strength was estimated to be 25% lower on average than in the experiments. In three of the studied girders, initial imperfections with other forms than the first buckling mode were found to be more critical. Further, it was found that regardless of mode number, mode shapes that are more extended over the web panel result in a higher degradation of the ultimate shear strength.

Ultimate behaviour of hybrid stainless steel cross-sections

Hybrid steel plate girders are used worldwide as primary structural members in steel and composite bridges, when there is a need for deeper sections with greater stiffness and bending resistance than rolled sections to carry heavy loads. With the increasing importance of sustainability and lifecycle (cost) analysis, design for maintenance has become an important consideration for infrastructure projects like bridges which have a design working life exceeding 100 years over which they need to be regularly inspected and maintained. Stainless steels are known for their excellent corrosion resistance and low maintenance costs and thus the application of hybrid plate girders in bridge designs could be explored. This paper reports a numerical study on stainless steel hybrid plate girders subjected to compression and to bending and assesses relevant recommendations for their design. Previously developed FE models validated against stub column and four-point bending tests are employed and a parametric study is conducted on hybrid I-sections over a wide range of cross-section slenderness and aspect ratios. Based on the obtained results, the EN 1993-1-4 design predictions for stainless steel cross-sections in compression and in bending are assessed and the accuracy of the codified slenderness limits for both homogeneous and hybrid stainless steel girders is discussed. Furthermore, the numerically obtained deformation capacity at ultimate load is plotted against the CSM base curve originally derived for homogeneous sections and the accuracy of the CSM predictions of the cross-section resistance is also assessed, demonstrating that the CSM can be employed to predict the cross-section resistance of hybrid girders.

Probability Assessment of the Seismic Risk of Highway Bridges with Various Structural Systems (Case Study: Tehran City)

Considering the development of urban transportation systems and the importance of highway bridges in a city’s resilience against earthquakes, it is critical to pay special attention to the seismic risk evaluation of highway bridges. The most significant issue to consider is the assessment of possible direct and indirect damages imposed on bridges before an earthquake. After this, the best practices for bridge rehabilitation can be adopted to minimize the induced damage. In this paper, we assessed the seismic risks associated with all 713 highway bridges in Tehran province (the capital of Iran). These bridges were initially divided into six categories according to their structural system and construction year and were also classified by whether or not seismic design was included. Among the 84,000 earthquakes recommended by the researchers’ ten-thousand-year catalog, a set of 50 ground motion records was selected in the course of a probabilistic approach via the Optimization-based Probabilistic Scenarios (OPS) algorithm in an attempt to obtain the least amount of error compared to the original catalog in the final hazard curve in different regions of Tehran province. Afterward, the seismic fragility curves were plotted in four damage states of slight, moderate, extensive, and complete for the six bridge structural systems of simple, steel, concrete slab box, concrete slab–steel box, concrete slab, and steel girder–concrete slab. The results of the fragility curves extracted from the decision tree analysis were validated with those developed from incremental dynamic analysis (IDA) for a bridge case study modeled in the OpenSEES software V2.5.0. Later, using logical relationships, seismic risk curves were drawn for each structural system. The results show that, in general, the average seismic damage of bridges over ten years old is 0.88 times the average damage of bridges less than ten years old. The highest level of vulnerability is associated with the simple bridge system with a median vulnerability of 0.44. Moreover, the lowest level of vulnerability is related to the steel girder–concrete slab bridge system with a median vulnerability of 0.98, showing an increase of approximately 2.2 times in the median vulnerability. In addition, based on the sensitivity analysis results, the indirect and total risk levels increase almost exponentially with increasing the reconstruction index.

Assessment of Innovative Repair Methods for Corroded Steel Girder Bridges Using the House of Quality Matrix

Across the U.S.A., steel girder bridges experience significant deterioration caused by corrosion, and the current repair methods for corroded steel girders require considerable time and cost. Corrosion is typically found at end-span locations above girder supports at abutments and piers caused by deicers and water leaking from the deck joints. Therefore, there is a need for effective, rapid, and robust repair strategies that can be implemented by bridge maintenance personnel. This paper presents five innovative repair methods for rehabilitating corroded steel girder bridges. The five innovative repair methods were evaluated to select two repair procedures that can be implemented by the local Department of Transportation (DOT) in Indiana. During the evaluation process, typical and critical requirements associated with repair methods for corrosion-damaged steel girders were considered, including robustness, reduction of implementation cost, and time. Furthermore, feedback from the local DOT in Indiana was collected to identify any additional requirements. The evaluation was completed by choosing two innovative repair methods through a selection process called the house of quality matrix, which is a commonly used tool in the consumer product industry. After completing the evaluation, two repair methods, “sandwich panel” and “web strengthening with diagonally oriented angles,” were selected.

Numeric simulation of corroded steel bridge girder end region repairs

An extensive finite element (FE) modeling campaign focusing on different means of repairing corrosion-damage steel girder ends is presented. Significantly corroded end regions were repaired using three approaches: conventional bolted steel repair, encasement in ultra-high performance concrete (UHPC), and encasement in conventional reinforced concrete (RC). ABAQUS-based models were developed and validated based on a previously-reported experimental program (Mash et al. 2023). The modeling of the test specimens proved to be robust and captured observed behavior well. Once the test specimen modeling was “benchmarked” against the observed behavior, the models were expanded to archetypal plate girders to verify the validity of the repair methods. The models confirmed the validity of adopting AASHTO-prescribed equations for estimating residual capacity of damaged girder ends. The numerical analyses presented were able to capture tension field behavior and, therefore, illustrate the potential degree of conservativeness – under ultimate loading conditions – in actual repair designs in which relative stiff bearing stiffeners are used. Similarly, by encasing the web, the shear panel length is reduced and capacity may be increased. Based on the robustness of the models, the analyses presented in this work may be adopted as a benchmark for future studies.

Light-weight design of an overhead crane’s girder with a non-symmetric box cross-section

The proper choice of material and geometric properties of the girder of the bridge crane can significantly reduce its weight and production cost. This research presents the weight optimization of the main girder with a non-symmetric box-like cross-section. The strength analysis in characteristic points of the critical cross-section and the local stability of plates were conducted using Eurocodes. This study aimed to prove that a proper choice of geometry for the cross-section plates and their additional design elements can have a meaningful impact on the weight. The optimization procedure was done using Water Evaporation Optimization (WEO) algorithm, with the implementation of all necessary criteria and conditions which must be fulfilled. This study revealed that the application of the light-weight design philosophy to the structure of the main girder could significantly reduce its weight, which is verified in the existing examples of double-beam bridge cranes. Achieved savings in girder weight are between 24.43% and 34.73%, dependingly on the considered example. Also, the study showed the influence of the chosen material on the steel girder’s optimum weight and geometric parameters. Depending on the studied example of the bridge crane and selected material, the WEO algorithm gave the same solution through simulations. The value of the optimum weight had a slight deviation at the second decimal place, which is neglectable. The algorithm successfully avoided the trap of getting into the local minimum during the search. In the end, it can be stated that the application of the WEO algorithm was successful in the considered engineering problem since it was the optimization of a complex steel structure with 11 variables and more than 20 constraint functions.

Flexural strength of steel girders with perforated web and tubular compression flange

Lateral torsional buckling reduces the moment capacity of steel I-girders. To redress this weakening, one approach is to replace the conventional plate flange with a rectangular tube, which has higher lateral stiffness and is thus helpful to resist lateral buckling. At the same time, web openings are introduced to enable services to pass through, but this causes a reduction in strength. Girders with tubular flange plus web openings have not yet been discussed in the literature. In this paper, finite-element method modelling is used to fill this gap, studying different slenderness classifications, as well as parameters such as size of web openings, spacing and location. The results for a solid web are found to be more comparable to the Eurocodes for steel structures than the American Institute of Steel Construction codes, enabling good prediction of the flexural capacity. By introducing web openings, the flexural capacity is reduced by 10–20%, closer to the higher side for openings with large diameters located near the compression flange. Openings with an oval shape have less reduction in strength, whereas the square is unfavourable. Tubular flange girders, even if perforated, provide flexural strength enhancement and a considerable reduction in material compared with plate flange girders. This section also behaves better in relation to carbon dioxide emissions.

The Multi-Scale Model Method for U-Ribs Temperature-Induced Stress Analysis in Long-Span Cable-Stayed Bridges through Monitoring Data

Temperature is one of the important factors that affect the fatigue failure of the welds in orthotropic steel desks (OSD) between U-ribs and bridge decks. In this study, a new analysis method for temperature-induced stress in U-ribs is proposed based on multi-scale finite element (FE) models and monitoring data First, the long-term temperature data of a long-span cable-stayed bridge is processed. This research reveals that a vertical temperature gradient is observed rather than a transverse temperature gradient on the long-span steel box girder bridge with tuyere components. There is a linear relationship between temperature and temperature-induced displacement, taking into account the time delay effect (approximately one hour). Then, a multi-scale FE model is established using the substructure method to condense each segment of the steel girder into a super-element, and the overall bridge temperature-induced displacement and temperature-induced stress of the local U-rib on the OSD are analyzed. The agreement between the calculated temperature-induced stresses and measured values demonstrates the effectiveness of the multi-scale modeling strategy. This approach provides a valuable reference for the evaluation and management of bridge safety. Finally, based on the multi-scale FE model, the temperature-induced strain distribution of components on the OSD is studied. This research reveals that the deflection of the girder continually changes with the temperature variation, and the temperature-induced strain of the girder exhibits a variation range of approximately 100 με.

Structure-borne noise of steel and concrete box girders in an urban metro system: A hybrid evaluation and parametric study

Metro systems provide an efficient, convenient, and expeditious way to travel around crowded routes. Because these systems are established in cities, residential buildings close to metro viaducts are significantly affected by structure-borne noise (SBN). Although most previous studies developed SBN prediction with a focus on the accuracy and computational efficiency of a specific bridge type, only limited studies on parameters for the SBN on bridges were carried out. Thus, eliminating SBN is still a challenging task for both the design and operation phases of bridge design. Therefore, this study integrates simplified experiments with numerical analyses to evaluate the influential parameters on the structure-borne noise level (SBNL) for two types of bridge girders, that is, the double-box pre-stressed concrete girder and the double-box steel girder. The present study also proposes an optimization method for reducing the SBNL in the bridge design and operation phases and identifies the sources of SBN for these two types of bridges. In this paper, the solutions to mitigating SBN are first reviewed and briefly introduced. Theories associated with SBN are then derived and experimentally verified using a concrete or steel plate with a unit area. A hybrid evaluation method is developed to integrate transient finite-element simulation with experimental results, and the main sources (e.g., plate thickness, train speed, fastener stiffness, and track irregularity) that induce SBN are examined by this hybrid method. Consequently, the approach to resolving the SBN problem can be optimally determined. As demonstrated in the results from the hybrid evaluation method, the track condition dominates the SBNL for both types of bridges, and the relationship between train speed and plate eigenfrequency should be carefully investigated to avoid the effect of plate resonance. The pre-stressed concrete box girder is the recommended bridge type for use in urban areas from the viewpoint of minimizing the SBNL.