Steel Deck Research Articles

Experimental investigations on the load‐bearing behavior of shear studs in trapezoidal sheet in fire

AbstractComposite slabs, consisting of a steel section, profiled sheet and concrete, have been used successfully in composite construction for many years. In order to increase the maximum span widths, trapezoidal sheets with deeper ribs are increasingly being used. The use of modern deep steel decking changes the load‐bearing behaviour of the shear studs towards greater flexibility and ductility, but also towards a lower load‐bearing capacity. In recent years, a significant amount of research has been carried out into the load bearing behaviour of shear studs in profiled sheets, resulting in the development of a new design approach in the draft prEN 1994‐1‐1. Compared to the Ultimate Limite State (ULS), scarce research has been conducted for elevated temperature. It is therefore difficult to evaluate the compatibility of the new design approach from the draft with the existing regulations from EN 1994‐1‐2. In order to fill this gap in knowledge, push‐out tests have been carried out on trapezoidal sheets under elevated temperature. The focus of this paper is to describe the experimental approach and the first results.

Fatigue performance evaluation of stiffener‐to‐deck plate weld in orthotropic steel decks based on generative adversarial network

AbstractThe stiffener‐to‐deck plate welds are one of the weak areas of orthotropic steel decks (OSDs). Accurate evaluation of fatigue performance of stiffener‐to‐deck plate welds is important for the design and service of OSDs. Traditional fatigue performance evaluation method of stiffener‐to‐deck plate welds based on S‐N curves requires a large amount of experimental data as support. However, fatigue tests are time‐consuming and costly‐approach. In this paper, generative adversarial network (GAN) was used to augment hot spot stress range data and fatigue life of rib‐to‐deck welded joints based on a small amount of test data. Then, the least‐squares regression was used to fit S‐N curves base on original data and generated data. The fitted S‐N curves were compared with experimental curve. Compared with the S‐N curve fitted by a small amount of original data, the S‐N curve fitted by generated data is closer to the experimental result, which indicates that the fatigue data generated by GAN has the potential to be an effective tool in the fatigue performance evaluation of fatigue critical details.

Three-dimensional finite element modeling for bending and pull-out tests of composite slabs

This article introduces a novel modeling and simulation methodology that advances the understanding of steel deck and concrete slab micromechanics for bending and pull-out composite slab tests. Three-dimensional composite models detailed the embossment depth, slope, steel thickness, and tilting angle to overcome previous model simplification assumptions. Newton-Raphson was the simulation method that enabled the consideration of material non-linearities. The validity of each model was contrasted against the results from actual laboratory tests. The model incorporating the non-linearity of materials and a crack inducer was very consistent with the tests. The other two models, which did not account for non-linear behaviors, were partially consistent with test results at complementary bending stages and thus could be combined to reproduce the tests. The robustness of the simulation approach was leveraged to analyze the influence of parametric and boundary conditions in pull-out simulations. Also, micromechanics phenomena that cannot be observed during laboratory tests were investigated. The proposed computing method offers the opportunity to model, predict, and hence optimize the composite slab and steel deck profile design without the need to perform expensive and time-consuming tests on actual specimens.

Experimental study and numerical modelling of a novel two-way steel-concrete composite slab

This study proposes a new innovative two-way steel-concrete composite slab system. The experimental work investigates the structural capacity, shear behaviour and two-way load distribution of the proposed composite slabs consisting of a new profiled steel deck and concrete. The innovative deck is developed by providing 90° bends in corrugated steel sheets to form hat sections, which then are placed on a corrugated base sheet in the perpendicular direction. Five composite slabs were tested under uniform loading, in which three slabs contained shear studs, and the remaining two were tested without shear studs. The slabs failed by flexural failure and shear bond failure, and the composite slabs with and without studs showed comparable load-carrying capacity and two-way action. The unique geometry of the deck profile provides good longitudinal shear capacity in the main direction. The slip is absent in the main longitudinal direction of the slab due to the corrugated top-hats. The provided shear studs further complement the role of the top-hats by resisting interface shear failure in the perpendicular direction. Therefore, the new deck type can be used effectively in two-way composite slabs for shear and load capacity by reducing the quantity of additional shear connectors, which is a significant advantage of the proposed deck compared to conventional deck types. A finite element (FE) model of the composite slabs with and without shear connectors is developed and validated against the experimental results and then used to investigate the slab's performance in two-way load distribution.

Effect of ultrasonic impact treatment on welding residual stress and fatigue resistance of doubly-welded rib-to-deck joints in OSD

Innovative doubly-welded rib-to-deck joints (DRJ) have been developed to enhance the fatigue life of orthotropic steel decks (OSD) used in steel bridges. However, the welding process and welding residual stress (WRS) distribution of DRJ are more complicated than those of conventional single-side welded rib-to-deck joints. To release WRS and improve the fatigue resistance of DRJ, ultrasonic impact treatment (UIT) and fatigue tests were performed in this study. The effect of the UIT process on the WRS distribution and fatigue resistance of the DRJ was investigated. Furthermore, the welding processes of the DRJ and UIT were simulated using the finite element method and validated against the relevant measurements. Subsequently, they were used to investigate the effect of the UIT process on the WRS distribution and represent the mechanism of fatigue failure of the DRJ. Compared with the as-welded specimens without UIT, the fatigue strength of the DRJ increased by more than 60%, and the UIT process altered the dominant fatigue failure mode of the DRJ. The fatigue crack, caused by a UIT-induced fold defect, tends to initiate at the bottom of the impact pit. Owing to the UIT process, the adverse tensile WRS in the weld toe is eliminated, and beneficial compressive residual stress is introduced, leading to an improvement in the fatigue strength of the DRJ.

Fatigue Performance of Rib-to-Deck Double-Sided Weld Joint of Orthotropic Steel Deck on Plate Girder Railway Bridges

This research work presents the stress behavior of rib-deck weld joints in Orthotropic Steel Deck (OSD) railway bridges. It is essential to determine the most vulnerable load mode of the wheels for fatigue failure of OSD bridges and to improve the fatigue resistance of the welded rib-deck connection. Fatigue performance largely depends on the weld stress. Double-sided welds for rib-deck welds improve fatigue performance. The fatigue behavior of the rib-deck double-sided weld joint has been compared with the single-sided one. This study used Abaqus software to create the global shell model and the solid submodel of the OSD. The results of the structural stress-based finite element analysis indicated that when the center line of the front axle pair of a locomotive coincides with the center line of the midspan of the bridge, the most severe loading condition occurs. The rib near the main girder experiences the maximum structural stress in the weld toe of the rib-deck joint. Moreover, the rib-deck double-sided weld joints have 43.7% less structural stress compared to single-sided weld joints at the root of the weld, and this improves the performance during fatigue of OSDs.

Numerical Simulation on Crack–Inclusion Interaction for Rib-to-Deck Welded Joints in Orthotropic Steel Deck

Weld defects such as porosity, inclusion, burn-through, and lack of penetration are difficult to detect and control effectively in an orthotropic steel deck (OSD), which will be a fatigue crack initiation site and lead to several fatigue cracking. The crack growth behavior in defective welded joints is different from that of defect-free joints. This study investigates crack–inclusion interaction for rib-to-deck welded joints in OSDs based on numerical simulation and linear elastic fracture mechanics (LEFM). A refined finite element model of a half U-rib with cracks and inclusions was established by using the FRANC3D-ABAQUS interactive technology. The full processes of the crack–inclusion interaction from approaching and penetrating were accurately simulated. Critical parameters, including the stress intensity factor (SIF), the shape factor, the growth rate, and the growth direction were analyzed. The stiff and soft inclusions amplify and shield the SIF of cracks when the crack grows to the local area of inclusions. During the entire process of crack growth, the soft and stiff inclusion accelerate and inhibit the crack growth, respectively. The stiff inclusion will lead to asymmetric growth of the crack shape, where the portion of the crack away from the inclusions has a higher growth rate. The soft and stiff inclusions will attract and repel the direction of crack growth at the proximal point, respectively.

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.

Experimental study on flexural and interfacial shear properties of the steel-UHPC glued composite deck

This paper proposes a Steel-UHPC Glued Composite Deck (SUGCD) to mitigate the fatigue cracking of orthotropic steel deck and improve the destructible paving layer of bridge, respectively. A series of flexural tests are conducted on 20 SUGCDs and shear tests are performed on 20 push-out specimens, respectively. The objective is to examine the effects of various interface treatment methods, reinforcement ratios, and types of epoxy adhesive on the flexural and shear properties of the composite decks. Additionally, the characteristic strength of the UHPC layer is calculated by the section conversion method. The results demonstrate that the elastic phase of SUGCD under hogging moment depends on the material properties of UHPC and the interface properties of the composite deck, respectively. The maximum difference of the cracking load of UHPC layer is 150.2% for various interface treatment methods. The composite deck has a higher elastic limit and cracking load under sagging moment than the hogging moment. The interface remains intact when the composite deck reaches its yielding strength, indicating that the interface has sufficient bonding strength. Finally, the cast-in-situ push-out specimens exhibit the optimal interfacial performance with ZR14 epoxy adhesive and 3–5 mm bauxites, and the prefabricated push-out specimens with ZR14 epoxy adhesive demonstrate the best interfacial performance, respectively. Therefore, the proposed steel-UHPC glued composite decks may meet the requirement in practical engineering.

Fatigue performance of cracked diaphragm cutouts in steel bridge reinforced employing CFRP/SMA

Under long-term service conditions, fatigue cracking occurs at the diaphragm arc-shape cutouts in the orthotropic steel deck (OSD) bridges subjected to vehicle-induced vibration and cyclical wheel load. To repair cracks of the diaphragm cutouts, this study proposes two repair methods of the carbon fiber reinforced polymer (CFRP) sheets and shape memory alloys (SMA)/CFRP composite patches on the basis of crack-stop holes. The crack-stop hole eliminates the obvious source of fatigue propagation at the crack tip, but it weakens the section and harms the entirety of the diaphragm. The edge of the crack-stop hole in the cracked section becomes a new stress concentration site and the potential crack initiation point. The CFRP sheets can effectively improve the stiffness and reduce the stress amplitude of the cracked part. Moreover, the SMA/CFRP composite patches can further introduce precompression by activating SMA to reduce the stress level. Relative to the reinforcement by the crack-stop hole only, the fatigue notch factor is reduced by 12.28% and 30.76% after bonding CFRP sheets and SMA/CFRP composite patches, respectively. The fatigue tests show that the bonding of CFRP sheets and SMA/CFRP composite patches can effectively postpone the initiation of fatigue cracks and inhibit crack propagation, so they are ideal repair methods for strengthening fatigue cracks of the diaphragm cutouts in the OSD bridges.

Experimental studies of the reusable steel deck forms for concrete slabs

Recently, many flyover steel bridges have been built due to high demand of transportation development mega cities in Vietnam, especially in Ho Chi Minh City and Ha Noi City. The steel bridges are selected as effective solutions in urban area because of their advantages such as rapid construction, aesthetic design, high performance. For the construction method of concrete deck slab, wood panels, plastic panels, and precast concrete panels are often used to reduce construction costs. From actual construction projects, these form solutions may not be suitable for large span over 2.0 meters and take more time to install and to dismantle. This study aims to develop an improved solution with reusable steel deck forms for bridge slabs which has been used as permanent deck forms in buildings. Experimental studies are conducted to investigate the frequency of reusability and to verify the bending capacity of the steel deck after many times of reuse. The experiments are separated into two phases including concrete casting stage and strength tests in laboratory. Bending strengths of reused forms are compared with that of new one. Results shows that steel deck forms are still in good condition and provide sufficient bending capacity after 10 times of concrete casting comparing. Therefore, reusable steel deck forms can be effectively applied in the construction of bridge slabs to optimize the construction time and cost.

DETERMINATION OF THE RIB-TO-CROSSBEAM STRESSES IN ORTHOTROPIC STEEL DECKS

For long span bridges, the orthotropic steel deck (OSD) is the most popular option for the bridge deck. Normal OSDs consist out of the steel bridge deck, the longitudinal stiffeners (ribs), and the transversal beams. All of the elements are welded together. The welds create geometrical discontinuities that will result in concentrations, which lead to fatigue damage under repetitive loading. In this research, a simplified calculation method for determining the dimensions of OSDs is developed. This method shares the same notion as the Pelikan-Esslinger method, which is using an idealized orthotropic plate. Solving the idealized orthotropic plate, the internal forces of the actual OSD may be acquired. To calculate the distortional stresses, the shear deformation is treated as an independent variable and added to the simplified calculation method. The system of partial differential equations is derived through the equilibrium relationships of the substituting plate. Three rigidity coefficients are required in this method, namely the flexural rigidity coefficient, the torsional rigidity coefficient, and the shear rigidity coefficient. The former two are the same as in the Pelikan-Esslinger method. By performing a frame analysis, the formulas of the shear rigidity coefficient are achieved. Then, a simple local model is proposed for calculating the nominal distortional stress under the weld of the wall of the rib. To summarize, this research shows the possibility of optimizing the prevailing design the rib-to-crossbeam connection. The proposed fatigue life assessment method and simplified calculation method could be adopted in the future.

Application of Foamed Concrete and Cold-Formed Steel Decking as Lightweight Composite Slabs: Experimental Study On Structural Behaviour

This paper presents an investigation of ultimate load, maximum deflection and failure mode of foamed concrete composite slabs (FCCS). Of interest are the effects of dry density and slab thickness. Unlike conventional composite slabs, FCCS has the advantage of eliminating the selfweight penalty and thus reducing the underlying structural members.With the advanced research in concrete technology, foamed concrete with sufficient strength propertiesto meet the requirements of standard code of practise has been successfully introduced. Foamed concrete isknown for its lightweight and versatility.In the experimental study, the slab specimens with a span of 1800 mm, a width of 840 mm and different slab thicknessesof100 mm to 150 mm were prepared for the three-point bending test. The dry density of foamed concrete is 1400 kg/m3, 1600 kg/m3, and 1800 kg/m3, which has a compressive strength of about 20 MPa to 40 MPa. Dry density and slab thickness have been observed to have significant effects on ultimate load and maximum deflection. Higher dry density of foamed concrete provides better slip resistance and thus reduces shear bond failure. On the other hand, slab specimens with a higher slab thickness tend to have better bearing capacity due to greater bending stiffness. The main failure mode is dominated by localised bending on the profiled steel deck, slip-displacement and fracture ofthe foamed concrete.

Performance of Rib-to-deck weld joint of an orthotropic steel deck through structural stress method

Performance of Rib-to-deck weld joint of an orthotropic steel deck through structural stress method

Experimental and numerical study on welding temperature field by double-sided submerged arc welding for orthotropic steel deck

Orthotropic steel deck (OSD) is susceptible to fatigue damage when subjected to repeated traffic loads, and the welding residual stress (WRS) is an important factor contributing to fatigue damage in OSD. WRS is formed by the shrinkage of the welds due to the inhomogeneous temperature field during the welds fabrication process, and thus the study of the welding temperature field is of significance for accurately predicting the WRS. As an emerging welding technology, the double-sided submerged arc welding (DSSAW) technology can generate higher welding temperature and consequently higher welding penetration rate on U rib and deck for welding thicker base metal. However, the DSSAW technology generates more complex welding temperature field compared to the traditional arc welding technology, which has not been evaluated so far. In this study, the finite element model (FEM) of OSD with U rib-to-deck (RTD) welded joints is established to simulate the welding temperature field generated by DSSAW. Moreover, the temperature field in OSD by DSSAW is measured by using the infrared thermal imager (ITI) and the industrial temperature measurement gun (TMG) to verify the FEM simulated temperature results. It is found that large surface temperature gradient and large temperature gradient along the thickness direction would be formed at the weld toe of U rib and deck, which is generally the location where the maximum WRS is distributed and where the fatigue cracks are susceptible in OSD. Compared to the inside welding, the outside welding may generate higher welding temperature, higher temperature gradient, and larger molten pool area, resulting in larger WRS in the OSD. The findings in this study can help to an in-depth understanding of the welding temperature field caused by the new DSSAW technology and support further studies on WRS.

Research on Reasonable Construction Plan for Cast-in-Place UHPC Bridge Deck Plate of Cable-Stayed Bridge

This article takes a single-tower cable-stayed bridge with a steel-UHPC composite deck steel box girder as the research object and develops different casting plans for the UHPC layer on the bridge deck. It analyzes the influence of factors such as the block casting sequence of the UHPC layer on the bridge deck, whether or not to set up a post-casting section, whether or not to set up bridge deck counterweights and the range of it on the additional deformation and stress of the formed UHPC bridge deck during the construction stage, exploring the impact of various factors on the structural target bridge’s completion status (cable force, bridge completion linearity, bridge deck and steel box girder stress) under different pouring schemes. Research has shown that under the constant initial tension of stay cables, adjusting the pouring sequence of UHPC bridge decks and setting post-pouring sections is not significant in reducing the tensile stress of UHPC bridge decks. The more effective technical measure is to use bridge deck counterweight pouring during construction; the closer the counterweight is to the later stage constant load loading value, the more significant the decrease in UHPC tensile stress is. When factors such as on-site construction conditions, construction period, and labor costs are limited, local weight balancing on the bridge deck can be used.

Experimental Investigation on Fatigue Improvement of Orthotropic Steel Bridge Deck Using Steel Fiber Reinforced Concrete

AbstractThe high-performance topping concrete overlay would significantly reduce the fatigue stresses at susceptible details of orthotropic steel deck (OSD) and effectively improve the fatigue performance. Full-scale fatigue tests and numerical simulations were carried out to quantify the effects of steel fiber reinforced concrete (SFRC) topping pavement in reducing the OSD fatigue stresses based on a practical bridge design. Fatigue stress of the OSD critical details was measured from tests and cracking was observed in the SFRC overlay. Both an innovative pre-pump-pulse Brillouin optical time domain analysis (PPP-BOTDA) distributed optical fiber sensor and strain gauges were also used to measure the stress at OSD fatigue-prone details, including the crossbeam cut-out, rib-to-deck weld, rib-to-crossbeam weld and splice of U-rib. The corresponding three-dimensional (3-D) finite element model was then established and verified by the test results, and used to conduct a parametric study to obtain a quantitative expression of fatigue stress reduction factor, in terms of relative elastic modulus and thickness of overlay and steel deck plate. The proposed quantitative model of the fatigue stress reduction effect can guide the cost-effective design of composite bridge deck.

Study on Fatigue Cracking of Diaphragm's Arc Opening of OSD in Steel Bridges by Using Biaxial Stress Method.

Changes in loading position have a significant impact on the stress field of each vulnerable area of an orthotropic steel deck (OSD). The arc opening area of the diaphragm and the connecting area between the U-rib and the diaphragm under the moving load are prone to fatigue cracking. By comparing the stress responses under different methods, the hot spot stress (HSS) method is used as the main stress extraction method in fatigue performance evaluation. The control stress of fatigue cracking was analyzed by comparing the direction of the principal stress field with the crack direction in this experiment. According to the stress amplitude deviation under the biaxial stress state, a set of methods for evaluating the effects of in-plane biaxial fatigue was developed. An improved luffing fatigue assessment S-N curve was applied to analyze the fatigue life of the diaphragm's arc opening area. The results show that when the moving load is exactly above the connection of the deck and the web of the U-rib on one side, it is in the most unfavorable position in the transverse direction, and the diaphragm is mainly under the in-plane stress state. The longitudinal range of the stress influence line of the arc opening is approximately twice the diaphragm spacing. Two to three stress cycles are caused by one fatigue load. Fatigue crack control stress is the principal stress tangential to the arc opening's edge in this area. The normal direction of the principal stress in the model test is roughly consistent with the crack initiation direction. The variation in the stress amplitude deviation in this area is caused by changes in the action position of the moving load. When the moving load is at a certain distance from the involved diaphragm, it is reduced to zero, implying that the in-plane fatigue effect is the greatest in this area.

Fatigue strength evaluation by measurable stresses for root cracks in U-rib to deck welded joints of orthotropic steel decks

Fatigue strength evaluation by measurable stresses for root cracks in U-rib to deck welded joints of orthotropic steel decks

Experimental study on fatigue behavior of cracked steel plates repaired with adhesively bonded steel patches

Fatigue cracking is prone to occur in orthotropic steel decks (OSDs) due to its complex geometry. To guarantee structural safety and extend the fatigue life of OSDs in steel bridges, the repair technique of adhesively bonded steel patches, which has the advantage of lower cost, easy operation, and not damaging the original structure, is experimentally studied using simplified cracked steel plate specimens. Four repair schemes were considered including bare plate, single-sided patched, double-sided patched, and stop-hole repaired. The failure mode, fatigue crack propagation, and adhesive damage were studied to evaluate the effects of steel patch repair. The morphological analysis was performed to investigate the fatigue fracture characteristics and metal interface performance. The outcomes showed that adhesively bonded steel patches could significantly improve the fatigue life of cracked steel plates and the strengthening was more effective for double-sided patched specimens than single-sided patched specimens. In comparison, the repair effect of the stop-hole method is limited for cracked specimens.