Steel Deck Research Articles

Automated fatigue crack detection of orthotropic steel decks using an improved mask region-based convolutional neural network approach

Orthotropic steel decks (OSD) are widely used in the bridge industry, but they are susceptible to fatigue cracking due to various factors such as weld defects, overload traffic, and complicated welded joint configurations. Traditional crack detection methods rely mainly on visual inspection, which is time-consuming and prone to errors. Recently, many crack detection methods based on machine vision have been introduced. However, accurately and effectively detecting fatigue cracks of OSD remains challenging due to the indistinct nature of these cracks compared to the background and their susceptibility to various types of noise. To address these problems, this research proposes an improved Mask Region-based Convolutional Neural Network (Mask R-CNN). The proposed model enhances the feature extraction ability of the original Mask R-CNN by introducing a Convolutional Block Attention Module (CBAM) and Path Augmentation Feature Pyramid Network (PAFPN) into the backbone network. Additionally, a morphological closing operation is performed on the extracted fatigue cracks to address the problem of disjoint cracks. On the basis of crack mask closure, the pixel-wise quantization of cracks was achieved using relevant OpenCV functions. Evaluation on a crack dataset of OSD shows that the proposed model outperforms other methods with precision, recall, average precision (AP), and F1 score of 83.98%, 84.44%, 77.9%, and 84.21%, respectively. In conclusion, the experiment validates that the proposed model can effectively detect, segment, and quantify fatigue cracks of OSD.

Beamforming: a spatial de-noising approach for civil structural health monitoring

In the civil structural health monitoring fields, monitored data suffer from noise and sensor faults. In practice, redundant sensors are usually deployed to monitor structural condition to obtain more accurate and robust information. This paper proposes a beamforming-based spatial filtering method to improve the data quality by using the information redundancy within sensor networks. Data pre-processing is first implemented, including missing data imputation and thermal response separation. Subsequently, short-term Fourier transform is used to transform the measured time sequences into time–frequency domain to obtain more useful features. Finally, signals in the time and frequency domain are processed using the beamforming algorithm. In the beamformers, a linear filter is applied to suppress noise signals, which is formulated as a constrained optimization problem. Herein, interior point algorithm is used to optimize the allocation of the linear filter, wherein the objective function is to minimize the power of the noise component at the beamformer output. The effectiveness of the proposed method is verified by using signals from strain gauges installed on steel deck plates of the 3rd Nanjing Yangtze River Bridge. Results through the case study show that signals after spatial filtering have a satisfactory de-noising, which indicates the effectiveness of the proposed beamforming algorithm. We believe that the proposed beamforming algorithm has substantial potential applications, such as providing high quality data source for further investigations.

Research on Ultra-High Performance Concrete (UHPC) overlay composite steel deck to repair Thang Long bridge deck

Thang Long bridge, after many years of operation with increasing traffic volume, leads to the steel face plate of the bridge not ensuring the conditions of stiffness and deflection within the allowable limit. After scientific conferences and experimental studies, it was shown that the solution "using Ultra High Performance Concrete (UHPC) technology associated with orthogonal steel decks to form composite lightweight deck slabs" design selection to repair Thang Long bridge deck. In order to successfully apply UHPC coating in this project, it is necessary to determine the technological parameters such as: flow, setting time, rheology and shrinkage according to actual construction conditions at site ( temperature and humidity). In addition, other physical and mechanical properties of UHPC must be determined such as compressive strength, tensile strength, elastic modulus and dry shrinkage. This study has determined the technological parameters for the construction of UHPC coating during the period from August 25, 2020 to December 31, 2020 to meet the technical requirements of the Thang Long bridge deck repair project.

Fatigue resistance of rib-to-bimetallic steel deck welded joints in orthotropic steel bridge decks

The stainless-cladding techniques have been applied in the top plate of the orthotropic steel decks in the high-speed railway steel bridges to improve the corrosion and wear resistance. The rib-to-deck (RD) welded joint with the stainless-clad bimetallic steel deck plate becomes a new critical fatigue detail. This study firstly examines the fatigue performance of this full-scale new RD joint through six high-cycle constant-amplitude fatigue tests and two beach-mark tests under eccentric over-rib loading. The structural hot-spot stress at the weld toe on the deck plate is obtained by strain gauges and the linear extrapolation method for each RD specimen before the cyclic loading. Experimental results indicate that five RD specimens suffer from the toe-deck failure modes, while the rests encounter root-deck cracking. The fatigue strength of these new RD joints satisfies the FAT100 hot-spot stress S-N curve based on the IIW design recommendation. Numerical simulation is further conducted to investigate the effect of different cracking modes and welding technologies on the fatigue crack propagation behavior of this new RD joint. Root-deck cracking mode shows weakly higher fatigue resistance than the toe-deck failure case. Using the double-side welds between the U-rib and deck plate, and the thickened-edge U-rib technology can slightly enhance the fatigue life in terms of toe-deck cracking mode in contrast with the traditional single-side groove welds. Experimental and numerical validation quantify the excellent fatigue performance of this new RD joint in comparison with the other types of RD welded joints.

Effective Notch-Stress-Based Stress Concentration Factors of the Rib-Deck Weld in Orthotropic Steel Decks Considering the Effect of Asphalt Surfacing.

Effective notch stress (ENS) approaches have many application prospects in fatigue damage assessments; however, an ENS can only be obtained by conducting complex and time-consuming numerical analyses, deterring many engineers from applying such an approach. In terms of the rib-deck weld in orthotropic steel decks (OSDs), predictive formulae for determining the ENS concentration factors (ENS-based SCFs) have been proposed; however, the effect of asphalt surfacing is not involved, which limits their applications in practical engineering. In the present study, refined finite element (FE) models, including asphalt surfacing, were developed to obtain the ENS-based SCFs which could be applied to practical engineering. Parametric analyses were conducted to investigate the effect of the transverse loading position, the combined effect of the transverse loading position and asphalt surfacing, and the effect of the temperature of the asphalt surfacing. The amplification coefficients (kSCF, kSCF1, and kSCF2) were introduced to determine the ENS-based SCFs on the basis of the predictive formulae without considering the effect of asphalt surfacing. Results show that the ENS-based SCFs of the rib-deck weld is considerably affected by the transverse position of wheel loading and the asphalt surfacing. The cubic polynomial function could be employed to fit the numerical results of the ENS-based SCFs and amplification coefficients (kSCF, kSCF1, and kSCF2) with high fitting precision. Predictive formulae for determining the ENS-based SCFs corresponding to arbitrary transverse loading position and temperature of asphalt surfacing are proposed. The validation investigation turns out that the relative error of the proposed formulae is within 10%, indicating the feasibility of using this approach for engineering applications.

Rewelding Residual Stress of Fatigue Crack at U-Rib-to-Deck of an Orthotropic Steel Deck

The orthotropic steel deck is a prevalent stiffening girder structure utilized in long-span cable-stayed bridges and suspension bridges. Nonetheless, the issue of fatigue cracking has persisted in in-service orthotropic steel decks, significantly impacting the longevity of bridges. This study examines the analysis of the distribution of residual stress during the rewelding process of a fatigue crack at the U-rib-to-deck-plate joint of an orthotropic steel bridge deck. Additionally, the impact of the initial welding and the stiffness of the boundary constraint on the residual stress field during rewelding is discussed. The findings indicate that the removal of the fatigue crack prior to rewelding alleviates the transverse residual stress caused by the initial welding. After undergoing the rewelding procedure, both the transverse residual stress and the longitudinal residual stress exhibited a significant stress peak. More precisely, the transverse tensile stress underwent a rise from 21 MPa to 385 MPa, while the longitudinal tensile stress experienced an increase from 345 MPa to 525 MPa. Furthermore, the range of tensile stress within the longitudinal residual distribution expanded by 88%. Moreover, the stress redistribution during the rewelding of the local fatigue crack varied depending on the constraints imposed on the steel bridge deck. Notably, the transverse residual stress increases by 40.6% when compared to the absence of constraints. The findings of this research offer valuable insights for the implementation of rewelding repair techniques on steel bridge decks, emphasizing the significance of considering the effects of residual stresses induced during the rewelding process.

Fatigue analysis of orthotropic steel-ultra-high-performance fiber-reinforced concrete (UHPFRC) composite deck considering accelerated deterioration and self-healing of fractured ultra-high-performance fiber-reinforced concrete in surface water condition

In this study, an orthotropic steel bridge deck overlaid with ultra-high-performance fiber-reinforced concrete (UHPFRC) is investigated using the finite element analysis. The composite bridge deck which is undergone moving-wheel load is examined under environmental surface water conditions. Two phases, i.e., Phases 1 and 2, are considered for the material model of the UHPFRC with stagnant water. In Phase 1, mechanical recoveries of the tensile strength and reloading stiffness are considered for the cracked UHPFRC caused by the autogenous self-healing behavior. In Phase 2, under the moving-wheel load, the crack bridging stress degradation in reinforced overlayer accelerates due to the closing–opening actions of surface cracks in water. In both phases, the deformation behaviors of the steel deck plate and UHPFRC overlayer are numerically examined. The results of the current numerical model agree with the experimental data in terms of the strain tendency, wherein the strain range of the steel deck plate and UHPFRC overlayer decreases in Phase 1 and progressively increases in Phase 2. Therefore, it can be asserted that, under the surface water condition, scenarios considering two phases of the material model of cracked UHPFRC, have governed the strain behaviors of the tested composite bridge deck.

Experimental data on the shear resistance of headed studs welded within the ribs of profiled steel decking transverse to the supporting beams.

This article describes a dataset with 464 push test results for studs welded within the ribs of profiled steel decking transverse to the supporting beams. The experimental data were collected from 30 publications dated from 1980 to 2017. The dataset presents the measured shear resistance per stud, with over 20 nominal or measured parameters, including: the properties of studs, deck, and concrete; the number of studs within a concrete rib; and the dimensions determining stud position within the concrete rib. This article presents and discusses the statistical parameters of the dataset variables, their distributions, and correlations. The dataset supports the identification of the key design variables that affect the stud shear resistance. It also provides information for evaluating the accuracy and reliability of existing design models, and may be used to form the basis for developing new predictive models.

Effects of Shear Studs and Openings in The Mechanical Performance of Composite Floor Deck using Finite Element Analysis

The composite floor deck system is the most popular floor system used in the construction industry, especially in industrial structures. A composite floor deck is a floor system that consists of a steel deck bonded with concrete. The shear bond between the steel deck and concrete slab normally controls the shear capacity of a composite floor deck system. In the current construction industry, shear studs are normally used to improve the shear performance of the structure. However, the literature review shows that there were very limited studies on identifying the efficiency of these shear studs and their effects on the composite floors' mechanical performance. In addition, there were always openings for M&E equipment in the floor deck system, which needs further analysis to determine their effects on themechanical performance of the composite floor deck system. Thus, the main objective of this study was to identify the effects of shear studs and openings on the mechanical performance of composite floor decks. The method adopted in this study was the Finite Element Analysis (FEA) using ANSYS software. The outcome of the result has shown that the presence of shear studs improves the mechanical performance of a composite floor deck while the presence of openings reduces the mechanical performance of a composite floor deck system.Keywords: composite floor deck, opening, shear studs, mechanical performance

Optimization of crack healing in steel bridge deck asphalt pavement based on the microwave heating technology

Microwave technology can heal cracks in asphalt pavements by heating the pavement. When it is used to repair cracks in steel deck asphalt pavement (SBDAP), the temperature of the SBDAP is greatly increased because the steel deck reflects the microwaves, allowing the microwaves to reheat the SBDAP. This study established a numerical model for microwave-heated SBDAP, and analyzed the effects of the waveguide height above the pavement surface, the thickness of the SBDAP, microwave power and heating time on the average of the temperature gradient (Tavg) and the standard deviation of the temperature gradient (Tstd) of the SBDAP. The feasibility of the numerical model was validated through the laboratory microwave heating tests. The prediction models of Tstd and Tavg under the effect of four influencing factors were developed by response surface methodology, and the validity of the prediction models was verified based on the analysis of R2 values and analysis of variance. With the prediction models of Tavg and Tstd as optimization functions, the optimal combination of the aforementioned influencing factors was determined using the genetic algorithm. In summary, the results of this study can effectively guide the field construction of microwave heating technology to repair SBDAP cracks.

Experimental, numerical and analytical investigation of bending performance of bolted demountable composite beams with profiled steel decking

This paper presents the results of a detailed experimental, numerical and analytical study to investigate the flexural bending performance of prefabricated demountable composite beams (PDCBs) with bolted shear connectors. Four full–scale tests were carried out for two profiled steel decking configurations (parallel and perpendicular to the steel section) with two different degrees of shear connection. The experimental results were used to validate a numerical simulation model established by the ABAQUS platform. A detailed parametric study was then performed using the validated numerical model to evaluate the effects of using different numbers of bolted shear connectors. The experimental results show that the final failure modes of the demountable composite beams are the same as conventional composite beams using welded shear studs, and the demountable composite beams behavior is ductile. The results of a comparison of load carrying capacity and elastic stiffness of the demountable beams calculated using the analytical equations for conventional composite beams against the experimental and numerical simulation results for the demountable composite beams confirm that the conventional composite beam theory can be used for the demountable composite beams. However, the experimental results indicate that longitudinal cracking in the grout between concrete slabs along the steel beam can happen, due to unsymmetrical location of the shear studs. Anti-cracking mesh would be necessary in practical applications for crack control.

The Maintenance Effect of Diaphragm-to-Rib Fatigue Cracks in Orthotropic Steel Deck via Steel Plate Reinforcement

To investigate the maintenance effect of diaphragm-to-rib fatigue cracks via steel plate reinforcement, finite element models of different-shaped steel plates were established. Stress intensity factors at the crack tip before and after reinforcement were obtained, and the variations in stresses were studied. Polygonal steel plate reinforcements were then carried out on a real bridge based on the finite element calculation results. The changes in stress amplitudes and fatigue damage degrees at the crack tip were analyzed via the rain-flow counting method and Miner’s linear damage accumulating theory. The results show that both the polygonal steel plate and the rectangular steel plate could effectively eliminate the stress concentration and restrain the propagation of cracks. The stresses in other parts of the arc notch increased after reinforcement and polygonal steel plates had less influence. After the reinforcement in a real bridge, the cycle number of high stress amplitudes at the crack tip decreased significantly. The fatigue damage degree of the repaired part reduced by 70.1%, which verified the maintenance effect via polygonal steel plate reinforcement on diaphragm-to-rib fatigue cracks.

Measurement of the Performances of Various Asphalt Mixtures on Suspended Steel Deck Bridge Pavements

Measurement of the Performances of Various Asphalt Mixtures on Suspended Steel Deck Bridge Pavements

Thermostatic shrinkage effect monitoring and analysis of novel Post-Combination Steel-UHPC composite decks

Combining Ultra-High-Performance Concrete(UHPC) layers to orthotropic steel decks through connectors has been increasingly applied to improve the latter’s fatigue resistance. However, a low water-binder ratio resulting in rapid and large UHPC shrinkage becomes a challenge since the constraint of connectors may cause shrinkage-induced stress and even cracks. To this end, a novel post-combination steel-UHPC composite deck was proposed to induce a low shrinkage constraint effect. It mainly refers to a relatively free shrinkage process due to absence of interlayer connectors in the early construction period. Particularly, 3 full-scale segmental steel-UHPC composite decks were prepared for 120 days shrinkage effect monitoring in a constant 18.5℃ space. Meanwhile, simulation and parametric analysis with shrinkage and damage plasticity constitutions were also conducted. The monitoring results showed that the shrinkage-induced UHPC strain in a post-combination specimen was 43% larger than a normal specimen, while the strain on a steel deck and rib became 60% and 79% lower. It tells an obvious lower-shrinkage constraint feature. Moreover, the lower shrinkage constraint of post-combination also resulted in a nearly 15% larger reinforcement compressive strain. Furthermore, the parametric analysis showed a detailed relationship between the low shrinkage constraint extent and the shrinkage-induced effect. Finally, a simplified theoretical shrinkage effect evaluation method was proposed. The research results provide fundamental knowledge for the shrinkage mechanism understanding of such a novel post-combination operation.

Innovative orthotropic deck strengthening design for the Suurhoff lifting bridge

AbstractFrom 2018, a significant amount of deck plate cracks have been discovered on the movable part of the Suurhoff bridge. These cracks reduce the strength of the bridge and might lead to unplanned hindrance and costly repairs. Renovation of the ortho‐tropic steel deck was chosen instead of frequent inspections and repairs or replacing the structure from a risk and cost perspective.The innovative strengthening scheme consists of the addition of a steel plate which is connected to the top of the existing deck plate by a combination of preloaded‐injection bolts and epoxy. The strengthening steel plate reduces the stress in the existing deck plate thereby improving the fatigue performance. The new and old steel work compositely due to the combined effect of bolts and epoxy resulting in a relatively light‐weight strengthening scheme. The design followed a risk‐based approach in which Arup closely collaborated with Rijkswaterstaat, contractors and research institutions to finish the full design and implementation in less than a year. The design objective is to provide at least 15 years additional fatigue life for the existing deck.The design was developed with the help of a combined numerical and experimental campaign. The novelty of the strengthening scheme and the use of different materials required experimental validation on small and large scale. The extensive validation resulted in sufficient confidence for the Rijkswaterstaat to implement this innovative scheme on an important bridge in The Netherlands. This scheme is especially beneficial from a weight and construction time perspective and therefore suitable for further implementation on other bridges.

Shear Capacity of Channel Shear Connectors Applied in Composite Slabs with Profiled Steel Decking

AbstractThis paper assesses the shear capacity and the structural behaviour of channel connectors in composite slabs. Push‐out specimens were analyzed numerically by using the finite element program ABAQUS. For the studied solution, regular openings at the lower flange in the profiled decking are considered to allow the welded channel connector to pass through. The numerical model was calibrated against experimental outputs on push‐out tests found in the literature. Then, the influence of steel decking thickness on load capacity, stiffness and ductility of channel connectors in composite slabs was also assessed. In addition, it was concluded that safe predictions of load capacity could be obtained by including reduction factors in the Canadian design approach.

Orthotropic composite slabs for road bridges

AbstractLarge increases in traffic loads led to extensive fatigue damages to existing orthotropic steel deck slabs of road bridges. Reinforced concrete bridges and conventional composite bridges are less susceptible to fatigue but considerably heavier. The ortho‐composite slab is a lightweight and robust alternative construction method, which retains the advantages of the previously mentioned construction methods, but eliminates their disadvantages. Within the framework of the AiF‐FOSTA research project P1265 [1], the construction of the bridge deck was developed using dowel strips as composite elements with high load‐bearing capacity and fatigue resistance. The principle of area composite with loading of the dowel strips in longitudinal and transverse direction was used. Extensive experimental and structural mechanics studies were conducted, particularly investigating the load‐bearing capacity and fatigue strength of the ortho‐composite slab under local load application. The following article describes the load‐bearing structure of the ortho‐composite slab and the motivation for the research project P1265. It gives an overview of the experimental investigations carried out. Finally, the article presents pilot projects that were carried out to apply the construction method. In further articles on Eurosteel, the experimental investigations and structural‐mechanical calculations are described in more detail (see [2] and [3]).

Experimental determination of the fatigue behavior of dowel strips in ortho‐composite slabs for road bridges

AbstractIn contrast to reinforced concrete and conventional composite bridges, the orthotropic steel deck slab offers a high load‐bearing capacity combined with a low dead weight. It is therefore ideally suited for slender and long‐span structures. However, the notch sharpness in the details and drastically increased traffic loads led to extensive fatigue damage and, as a consequence, often to premature repair or replacement work. With the ortho‐composite slab a lightweight and robust construction is currently being developed as an alternative. It combines the significant advantages of a low dead weight, long service life and economical production. The construction consists of a modified orthotropic stiffened steel plate and a thin, single‐layer reinforced in‐situ concrete. Composite dowel strips (CDS) with a clothoid shape are provided as shear connectors. In this paper, the experimental test program will be introduced. It comprises static push‐out tests on CDS in longitudinal and transverse directions as well as static and cyclic beam and segment tests. The focus lies on the test set‐ups, sample preparations, measurement concepts and the results of the so‐called beam tests. The investigations presented here were carried out as part of the AiF‐FOSTA research project P1265 [1].

Bulb versus Trough

AbstractWith the increasing traffic intensity and traffic loads, it can be questioned whether the application of orthotropic steel decks with troughs as longitudinal stiffeners is still the best solution. Possibly, the use of bulb profiles as longitudinal stiffeners could offer a better solution. Bulb profiles were commonly used till the late sixties but are no longer applied due to high manufacturing costs. However, new welding techniques have become available nowadays, which could possibly eliminate this disadvantage. In this study, a comparison is made between an orthotropic deck with troughs and with bulb profiles. For both deck types, an optimized design is made with respect to fatigue, after which both designs are compared with respect to weight, costs, production, maintenance, and inspection. Surprising outcome is that the bulb deck can be more favorable on certain aspects compared to the more recent trough deck.

Fatigue improvement of rib‐to‐deck welded joints using adhesively bonded steel patches ‐ LEFM‐based parametric study

AbstractRib‐to‐deck welded joints in orthotropic steel decks of bridges are prone to develop fatigue cracks. Repairing such cracks allows for prolonging the life of the infrastructure, provided that structural safety is guaranteed. Among others, the repair technique of adhesively bonded steel patches is relatively simple and inexpensive. Moreover, it has the advantage that the original structure is not altered, e.g. as in the case of crack stop holes. This technique has been used in other details like the diaphragm of steel bridges. However, limited information is available when applied to rib‐to‐deck joints, which are the most common joint type in orthotropic steel decks. This study proposes two repair schemes using adhesively bonded steel patches for the rib‐to‐deck joints. A 3‐D finite element model which takes account of the crack size is established. Based on linear elastic fracture mechanics (LEFM), a parametric study is performed to investigate the effect of patch geometry and adhesive thickness on the performance of repair schemes.