Deck Plate Research Articles

Multi‐Response Optimization of an Orthotropic Steel Deck Section with Thermo‐mechanical Tensioning

In this investigation, Taguchi's grey relational analysis (GRA) is utilized to optimize parameters in an orthotropic steel deck section subjected to thermo‐mechanical tensioning. In this study, it is aimed to determine optimal values for deck thickness, welding sequence, and welding speed, which are evaluated through finite‐element analysis based on outputs such as longitudinal stress, transverse stress, and deflection. In this study, a previously validated numerical simulation model is extended by conducting a parametric analysis to investigate the influence of varying parameters on the model's behavior. An analysis of variance is conducted to identify the most significant variable affecting the input parameters. Additionally, a confirmatory test is also performed to validate the characteristics of the Grey Relational Grade. In the results, it is indicated that faster welding speeds result in increased deflection of the deck plate. Furthermore, the transition from compressive to tensile longitudinal stress is more abrupt in thinner decks (9–10 mm) compared to thicker decks (11–12 mm). This redistribution of residual stresses is attributed to the increasing thickness of the deck plate. Optimal input levels (A2–B1–C1: 10 mm deck thickness, welding sequence case 1, and 0.005 m s−1 welding speed) are determined using GRA. Welding speed contributes the maximum to the optimization results among the evaluated variables.

Comparative analysis of the heavy-weight floor impact noises using different types of EVA resilient materials

The present study aims to improve the floor impact noises using various shapes of EVA resilient materials in composite floor structures. In order to this, three different types of EVA resilient materials were used including flat plate, deck plate type and cavity type of EVA boards. All the composite structure consisted of PP panel, PET and EVA resilient materials with a total depth from 30mm to 40mm. Total of 9 specimens were made for floor impact sound measurements. All the floor impact sound measurements were done at the recognized testing authority using bang machine. The values of L'I,Fmax,AW were deduced from every measurements. As a result, among the various types EVA resilient materials, most high performances were drawn when cavity type of EVA resilient material was used. It was shown that the average L'I,Fmax,AW value of cavity type was 46dB while 47dB for deck plate type, 48dB for flat plate were measured in average. It can be recognized that the good performance of cavity type EVA materials is caused by the both air layer gap beneath EVA board and air cavity inside the EVA board as well as the low dynamic elastic modulus of EVA.

Investigations On the Effective Width of Wide Flange Steel Girders

AbstractEffective width, as presented in Eurocode 3 is analysed. Efforts have been made to distinguish between the behaviour of the various structural parts acting as wide flanges. Different mechanical models are adopted: for the bridge deck plate between girders, for the cantilever deck part, and for the bottom plate of box girders with the presumption to reflect more adequately their actual participation in the complex girder work at bending. Also, the interaction between girders in a superstructure at loading is simulated as far as possible in order to replace to some extent a sophisticated spatial analysis. The Eurocode 3 way of presenting the matter is preserved. The results obtained are compared with the corresponding Eurocode parts and an assessment on the reported differences is given. The goal is to supply the designers with extended understanding the effects arising from the shear lag phenomenon.

Fatigue performance of innovative open-rib orthotropic steel deck for super-long suspension bridge

This paper presents experimental and numerical studies on the fatigue performance of an innovative orthotropic steel deck (OSD) with open-ribs, apple-shaped cut-outs, and additional transverse ribs, which is employed by the Zhangjinggao Yangtze River Bridge. This bridge is set to become the world's longest suspension bridge upon completion. A full-scale section of the OSD was fabricated and subjected to fatigue loading with a total cycle of 12.3 million times. The interested cracking-prone fatigue details include rib-to-deck and rib-to-crossbeam welded joints, along with the apple-shaped cut-outs of the crossbeam. Experimental results indicated that fatigue cracks initiated separately beneath the deck plate, on the flange of the rib, and at the rib-to-crossbeam welded joint, with equivalent stress amplitudes of 159 MPa, 148 MPa, and 99 MPa at 2 million cycles, respectively. In addition, detailed finite element model of the OSD was developed using ABAQUS and validated against the experimental results. The effects of the geometry dimensions and structural details of the bridge deck, longitudinal ribs, crossbeams and transverse ribs that influence the fatigue performance of this OSD were analyzed and discussed. Parametric analyses revealed that increasing the thickness of the deck plate, the thickness or the height of the longitudinal rib, and the number of transverse ribs can effectively reduce the stress amplitudes at corresponding fatigue details, which therefore improves their fatigue performance. This study provides useful references for the fatigue evaluation and design of OSDs with open-ribs and apple-shaped cut-outs.

Strength Optimisation and Static Performance Analysis of Arch Ribs of Steel-tube Concrete Arch Bridge

By means of finite element simulation, the axial compressive stiffness of different steel-tube concrete short columns was imported into the finite element model, and the effects of adopting new steel-tube concrete arch ribs on the mechanical properties of the key components of steel-tube concrete arch bridges, such as internal forces and displacements, were analyzed. The results show that: with the increase of the axial compressive stiffness of the arch rib chord, under different load combinations, the vertical displacement of the arch rib chord will increase, and the structure will be lifted up, with a maximum of 31.85%; the vertical displacement of the deck slab will also increase, with a maximum increase of 6.8%, which is smaller than the vertical displacement of the arch rib chord; the absolute value of the downward and transverse displacements of the arch rib chord will be reduced, with a maximum reduction of 7.1% respectively. The absolute values of the transverse and crossover displacements of the arch rib chord tube will be reduced, with the maximum reduction of 7.1% and 6.8%, respectively. In the project of arch bridge, the deflection and deformation of the arch rib, deck plate and other components of the more stringent restrictions, especially the vertical displacement, it is recommended to use the higher axial compressive stiffness of the steel pipe concrete arch rib.

Mechanical analysis and interior stiffeners arrangement discussion of a specific ship side collision situation

Collision between ships of different sizes may result in a situation where a vessel with a higher deck height impacts another vessel with a lower deck height. In such case, the absence of bearing structure above the lower-draft struck ship's deck means that the bow of the high-draft striking ship transfers pressure to both the deck and side plates of the struck ship during collision. According to this situation, the numerical simulation of small scale compartment impacted by a higher-draft ship bow was carried out. Based on the analysis of the numerical results, the main impact area of the small scale compartment was simplified into a typical L-shaped plate-frame structure to facilitate the experiment. A small scale quasi-static experiment was implemented and the force-displacement curve and energy absorption data of the L-shaped structure penetrated by a rigid approximate bow indenter were obtained. Moreover, material tensile tests provided parameters for numerical simulation and the deformation process of the structure was analyzed. Based on that, several L-shaped structure cases with different stiffeners of height and position were calculated in LS-DYNA. Failure process, structural energy absorption and efficiency were summarized and the excellent structural characteristics for this ship side collision situation were obtained.

Fatigue crack detection in orthotropic steel deck bridges applied by FMC/TFM using reflected waves of multiple paths (1)

We introduce the latest developed FMC/TFM (Full Matrix Capture and Total Focusing Method) and its application for fatigue crack detection in orthotropic steel deck bridge. This developed inspection system consists of the advanced high-speed ultrasonic inspection equipment and the remotely operated four-wheel scanner with a 32- channel ultrasonic array probe for angle beam inspection. We developed MP-FMC/TFM (Multiple Paths Phased- array FMC/TFM) in this project. MP-FMC/TFM enables to visualize outline image of cracks clearly by image synthesis based on the propagation route information of direct path and the other paths reflected on the bottom of an inspection object against clacks. This developed inspection system enables to generate clear B-scope images of deck plate crack and bead (in deck-to-rib weld) crack with high-resolution. Furthermore, it enables to synthesizes 3D images of crack propagation with high-resolution along the weld line in real time by integrating the B-scope images every time the scanner moves 2mm. As a result of verification test of fatigue crack propagation test specimens, it was confirmed that this inspection system enables to visualize crack shape clearly and to achieves measurement accuracy of ±0.8mm for depth of deck plate crack, and ±1.0mm for depth of bead crack. Currently, verification tests are being conducted on an actual bridge, and practical application is planned in near future.

Corrosion models for steel plates in ship structure based on statistical data

To have a proper maintenance policy for ships and offshore structures, it is necessary to predict corrosion wastage accurately. It is the main aim of the present work to propose corrosion models for plates in ship structures. In total 66,480 data were collected from thickness measurements carried out by different classification societies. The data were sorted out based on the position of the plate, the age of the ship, the country where the ship was built, and the type of ship. Using regression analysis, some models were proposed as a function of the ship’s age and position of plate. Based on this study, the proposed models are checked against existing corrosion models in the literature and it is found that other corrosion models underestimate the corrosion rate in the inner bottom plates, and deck plates. However, they overestimate the amount of corrosion in the side plates of ships. The existing corrosion models are justified for the prediction of corrosion wastage in hatch-coaming plates. For corrosion of outer bottom plates, the existing corrosion models are applicable for ships under 20 years old. They overestimate corrosion wastage for ships older than 20 years. Also, existing corrosion models overestimate corrosion wastage of plates at the side structure of ships above the water line at the early age of ships and underestimate in older ships.

Fatigue behaviour of root crack in stiffener-to-deck plate weld at crossbeam of orthotropic bridge decks

Steel Orthotropic Bridge Decks (OBDs) are widely used in long-span and movable bridges. Fatigue resistance analysis plays an important role in the design or assessment of OBDs. One possible fatigue failure is the crack initiating from the weld root of stiffener-to-deck plate connections at crossbeams. A full-scale experimental investigation in this study using a 20 mm thick deck plate with a dimension of 9.4 m × 5.1 m, including three crossbeams, represents the modern designed OBDs. The experiments show an arrest of crack propagation with a final crack depth of approximately 75% of the deck plate thickness. On the contrary, through thickness cracks develop in deck plates of 10 or 12 mm. Hot spot stress based fatigue detail categories (DC) using various failure criteria derived from the tests. Analysis with the effective notch stress shows that the DC has low sensitivity to the amount of weld penetration. The results of analyses with the eXtended Finite Element Method (XFEM), employed to analyse the fatigue crack propagation path and crack arrest, are in line with the experimental study.

A Two-Stage Optimisation of Ship Hull Structure Combining Fractional Factorial Design Technique and NSGA-II Algorithm

The intricate nature of ships and floating structures presents a significant challenge for ship designers when determining suitable structural dimensions for maritime applications. This study addresses a critical research gap by focusing on a three-cargo hold model for a multipurpose cargo ship. The complex composition of these structures, including stiffening plates, deck plates, bottom plates, frames, and bulkheads, necessitates thorough structural analysis to facilitate effective and cost-efficient design evaluation. To address this challenge, the research utilises FEMAP-integrated NX NASTRAN software (2021.2) to assess hull girder stress. Furthermore, a novel approach is introduced, integrating the Design of Experiments (DOE) principles within Minitab 21.4.1 software to identify critical parameters affecting hull girder stress and production costs. This method determined the top five key parameters influencing hull girder stress: Hatch coaming plate, Hatch coaming top plate, Main deck plate, Shear strake plate, and Bottom plate, while also highlighting key parameters that impact production costs: the inner bottom plate, Inner side shell plate, Bottom plate, Web frame spacing, and Side shell plate. Ship design optimisation is then carried out by incorporating regression equations from Minitab software into the Non-dominated Sorting Genetic Algorithm II (NSGA-II), which is managed using Python software (PyCharm Community Editon 2020.3.1). This optimisation process yields a significant 10% reduction in both ship weight and production costs compared to the previous design, achieved through prudent adjustments in plate thickness, web frame positioning, and stiffener arrangement. The optimally designed midship section undergoes rigorous validation to ensure conformity with industry standards and classification society regulations. Necessary adjustments to inner bottom plates and double bottom side girders are made to meet these stringent requirements. This research offers a comprehensive framework for the structural optimisation of ship hulls, potentially enhancing safety, sustainability, and competitiveness within the maritime engineering industry.

Fatigue durability of proposed vertical stiffener to deck connection details in orthotropic steel decks

Many fatigue cracks were reported at welded joints between vertical stiffeners and deck plates in orthotropic steel decks (OSDs) in Japan. These fatigue cracks were caused by restraining deck’s deflection by stiffeners. To prevent such cracks, reducing stiffness of stiffener top can be a solution. For newly fabricated OSDs, the Japan Road Association recommends cutting off the top of vertical stiffeners on cross beams. However, stiffeners with the gap have very little vertical load carrying capacity and it could not be applied to main girders. Half-circle notch method is retrofitting method for existing structures. For new OSD structures, it can be installed. Whereas a fillet detail is currently used for the beam-to-column connections of steel bridge frame piers to reduce stress concentration at right-angle corners of flanges. The fillet detail, which has not been considered for stiffeners, may be effective for new OSDs. In this study, fatigue durability of the half-circle notch detail and the fillet detail for new OSDs are evaluated through finite element analyses and fatigue tests using a full-scale specimen. As a result, the fillet detail showed superior fatigue durability without no fatigue cracks, while some fatigue cracks were developed in the half-circle notch detail.

Experimental study of friction performance degradation in sliding layer of CRTS II slab track considering dust incursion

The track-bridge interaction force in the China Railway Track System II slab track can be significantly reduced due to the effect of the sliding layer, thus its friction performance is crucial for the operational safety of the track. However, because of the micro delamination between the base plate and bridge deck under certain conditions, the dust inevitably infiltrates the sliding layer. This study performed abrasion experiments to investigate the influence of dust incursion on the friction performance of the sliding layer. The experimental apparatus was designed to simulate repeated sliding and normal pressure between the base plate and the bridge under actual working conditions. Different sizes of dust particles were employed, and the friction performance, characterized by the friction coefficient and surface topography of the geomembrane, was obtained and analyzed. The experimental results show that the growth rate of the friction coefficient was 1.46–2.88 times greater than that without dust incursion. The results of this study can serve as a reference for the actual friction performance degradation of the sliding layer and shed light on maintenance decision-making.

A Strain Fitting Strategy to Eliminate the Impact of Measuring Points Failure in Longitudinal Bending Moment Identification

The identification of longitudinal bending moments is a critical component in the health monitoring of ship structures. This study examines the effect of the failure of measurement points on the accuracy of bending moment identification and presents a solution using an XGboost fitting method. The impact of failure point position and quantity on strain fitting accuracy and bending moment identification was investigated by performing a four-point bending experiment in typical failure scenarios. Further numerical analysis was conducted to identify potential sources of errors in the measurement process. Additionally, several XGBoost-based fitting schemes were tested under practical conditions to provide reliable fitting suggestions. The results indicated that the XGboost strain fitting method outperforms conventional methods for removing failed measurement points, resulting in improved accuracy of identification. When the most critical failure condition occurs (i.e., the deck plate measurement points and deck stiffener measurement points fail), the XGboost method can still estimate the strain at the failure points with acceptable accuracy. These results also hold in complex load scenarios. Moreover, in the practical measurement conditions, the arrangement of measuring points includes two sections that are sufficient to support the fitting of failed measurement points by using the XGboost method. The XGboost strain fitting method exhibits promising potential in strain fitting applications.

Development of residual stress model of orthotropic steel decks using measurements

Orthotropic steel decks are widely used in the bridge engineering practice due to light weight, high performance and high ultimate strength-to-weight ratio. Purpose of the current paper is developing the first residual stress model for orthotropic steel decks (OSDs) with U-shaped stiffeners based on residual stress measurement results. The proposed simplified residual stress model is valid for OSDs with single-bevel butt welds, manufactured from steel grade up to S355. Distribution and magnitude of manufacturing-induced residual stresses due to hot rolling, thermal cutting, cold-forming, welding, etc. are determined using contour method with thin-plate smoothing spline. It makes it possible to interpret two-dimensional full-map residual stresses, instead of conventional pointwise residual stress measurement techniques, resulting in higher spatial resolution. Longitudinal residual stress patterns are evaluated in representative cross-sections clearly indicating high stress peaks near the welds, even exceeding yield strength of the base material, while the influence of thermal cutting and cold-forming can be addressed as well. Statistical evaluation of measurement results is carried out, which resulted in mean standard deviation of 22 MPa and 34 MPa in the stiffener and deck plate, respectively, which is comparable with the accuracy of other measurement techniques, e.g., X-ray diffraction method or hole-drilling technique.

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.

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.

Stiffened Plate Analysis by Considering the Effect of Uniaxial Load on FPSO Vessels

Abstract: Plates are a very important part of shipbuilding and offshore structures. The reinforced plate is used to withstand loads acting in the axial and bending directions. The structure of the deck or bottom plate exhibits buckling or yielding behavior. Thus, it is very important to analyze the ultimate bearing capacity of a plate structure subjected to compressive loads for safe ship structure design. The material configuration used is the most important aspect in the FPSO structure design criteria. Plates and stiffened plates experience local buckling due to the external load when the hull girder collapsed. The objective of the present study is to analyze the effect of flange and web thickness to the ultimate strength on the FPSO in terms of plate deformation located of the bottom and deck area under compression stages. In this study, the attached plate thickness is varied according to FPSO data and BKI Rule. The stiffened plates element located at the bottom and deck area are modelled by Tee-Bar and Angle-Bar element. The simply supported condition is applied to the model and the anon-liniear Finite Element Method is used for the analysis. The result obtained by NLFEM shows that under tension and compression, the stiffened plate of Tee-Bar model, the deformations are 1,75 mm and 1,8 mm respectively. While for Angle-Bar model the deformation are 12,4 mm and 13 mm under compressing respectively.
 

The Structural Design and Optimization of Top-Stiffened Double-Layer Steel Truss Bridges Based on the Response Surface Method and Particle Swarm Optimization

A lightweight design optimization algorithm is proposed to optimize the design parameters of stiffened double-layer steel girder bridges, the aim of which is to improve structural safety and reduce superstructure works. Taking a top-stiffened double-layer steel truss bridge as the reference project, a multiscale mixed-element model of the initial design parameters is established, and its computational accuracy is verified. Considering the structural configuration and loading characteristics of the bridge, the elastic modulus of steel, the deck plate thickness, the stiffening vertical bar height, and the relative distance between the double-layer main girders are selected as the design parameters for optimization. The mid-span vertical deflection, the axial forces in the stiffeners, the bottom plate of the deck, the compressed web tube at the pier top, and the quantity of superstructure works are chosen as the objective functions to be minimized. A lightweight calculation equation reflecting the relationship between the optimization parameters and the objective functions is established using the response surface method (RSM). Subsequently, an improved weighted particle swarm optimization (WPSO) model is employed to perform the multi-objective optimization of the design parameters for the bridge, and the results are compared with those obtained from the multi-objective genetic algorithm NSGA-II. The results show that the RSM accurately fits the numerical relationship between the optimization parameters and the objective response functions. When minimizing the quantity of superstructure works as the primary control objective and minimizing the mid-span vertical deflection and the axial forces in the compressed web tube at the pier top as secondary control objectives, the optimization results achieved by WPSO outperform those obtained by NSGA-II. The optimized results lead to reductions of 11.09%, 3.92%, 7.56%, 4.45%, and 8.38% in the respective objective function values of the structure. This method has important theoretical significance for the optimization of structural design parameters.

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.

Comparative analysis of the heavy-weight floor impact noises using various shapes of EVA resilient materials

Social issues concerning the floor impact noises are increasing as apartments are being increased in Korea. The present study aims to improve the floor impact noises using various shapes of EVA resilient materials in composite floor structures. In order to this, three different shapes of EVA resilient materials were used including flat plate type, deck plate type, and cavity type of EVA. boards. All the composite structure consisted of PP panel, PET sound absorption materials and EVA resilient materials with a total depth of 40mm. Also, each shape of EVA has two different types according to the use of foothold of EVA materials. For the mount type of structure, the used numbers of EVA foothold was 25, 56, and 41 per 1 m2 of area. All the floor impact noise measurements were done at the recognized testing authority using impact ball as the standard heavy-weight floor impact sound source. The values of L’i, Fmax, and AW were deduced from every measurements. As a result, regardless of the EVA shapes, better performances were drawn when EVA footholds were used, i. e., mount type. It was shown that the average L’i, Fmax, and AW value of mount types was 41–42dB while average value of 47–48 dB for deck plate type. 50–55 dB for flat plate and cavity type were measured. It can be recognized that the good performance of mount type EVA materials is caused by the air layer gap around the EVA footholds as well as the low dynamic elastic modulus of EVA.