Trapezoidal Deck Research Articles

Structural robustness evaluation of steel frame buildings with different composite slabs using reduced-order modeling strategies

This study presented reduced-order modeling methods for evaluating the structural robustness of steel frame buildings with different composite floor slabs under ground floor column loss scenarios. The adequacy of the reduced-order modeling technique was justified by relatively high-fidelity models, which were verified by a full-scale composite floor test and detailed material coupon tests. This reduced-order modeling method was applied to the progressive collapse simulation of a five-story prototype building. The effect of floor slabs, slab rebars, and steel decks' longitudinal continuity on its progressive collapse resistance was examined. Composite slabs with four different profiled steel decks were considered in this study, which are trapezoidal deck, dovetail deck, reentrant deck, and rebar-truss deck; in addition, reinforced concrete (RC) slab was also considered for comparative purposes. To account for the possible sudden column failure scenario in practice, an energy-based approach was used to convert the quasi-static response curves to dynamic response curves. The structural robustness was evaluated by comparing each column failure case's dynamic ultimate capacities with corresponding design requirements. The structural robustness of prototype buildings under progressive collapse scenarios was summarized and discussed. The analysis results showed that the structural robustness of the prototype building with rebar-truss composite slab was higher than that with RC slab or other composite slabs. The prototype building with floor slabs using HRB400 rebars had higher structural robustness than that using CRB550 rebars.

Performance of semi lightweight concrete composite deck slabs under falling mass

In the present scenario probability of unexpected and accidental loading is high for the infrastructures. There is an urgent need to analyse these structures to check their viability against impact load. Composite structures are currently used to utilize the benefits of different materials. Past research works focused on the response of composite slabs under static load. Studies related to the impact response of composite slabs are limited, and the behaviour of less dense slabs is still to be explored. There is a demand to focus on the reaction of semi-lightweight aggregate concrete for composite grooved trapezoidal decking slabs subjected to drop mass impact. The study focused on the cushioning effect of six composite slab specimens (1000 mm × 930 mm × 80 mm) along with welded wire mesh and steel fibers as secondary reinforcements. Two were cast using control concrete (NC), and four were cast using lightweight concrete (LC). The collision was achieved by dropping a 55 kg steel cylinder to hit the center of the slab from a height of 1 m. Numerical modeling and analysis of similar slabs under impact load were carried out in ANSYS. The parameters concentrated are impacted force–time history, acceleration, crack pattern, bond-slip behaviour, and stress contours. The results show that lightweight concrete with welded wire mesh as secondary reinforcement could be effectively utilised as a cushioning layer for the composite deck system under falling mass scenarios.

Bond between very-high and ultra-high performance fibre reinforced concrete and profiled deck sheeting

The behaviour of steel concrete composite slabs at all load levels is controlled by the shear transfer between the profiled steel deck and concrete slab. To apply new concrete technologies, such as high-strength and fibre-reinforced concretes, to steel concrete composite slabs, it is therefore essential to quantify the interfacial bond-slip properties. In this paper, a testing approach based on single-lap shear tests, commonly applied to quantify interfacial shear properties for external reinforcement, is applied to measure the bond between profiled sheets and concrete. The testing regime consists of 6 trial tests used as the basis for developing the test methodology and 48 tests to quantify the impact of concrete strength (very-high and ultra-high-strength), high volumes of steel micro fibres, and coarse aggregate, on the bond between concrete and dovetailed and trapezoidal profile decks. The results show that the concrete strength and the presence of coarse aggregate have limited impact on the bond properties, however the presence of fibres significantly improves bond strength and toughness for dovetailed profiled decks but has limited influence on trapezoidal decks.

Experimental Studies on the Behaviour of Headed Shear Studs for Composite Beams in Fire

Steel and concrete composite structures are commonly applied in multi-story buildings as they maximise the material strength through composite action. Despite the popularity of employing a trapezoidal deck slab, limited experimental data are available under elevated temperatures. The behaviour of the headed shear stud embedded in a transverse trapezoidal deck and solid slab was investigated at both ambient and fire conditions. Twelve push-out tests were conducted according to the ISO 834 standard fire utilising a customised electric furnace. A stud shearing failure was observed in the solid slab specimen, whereas the failure mode was changed from a concrete-dominated failure to the stud shearing in the transverse deck specimen with an increase in temperature. Comparisons between the experimental observations and design requirements are presented. The Eurocode design guidance on the transverse deck slab gives a highly conservative estimate for shear resistance. A new design formula was proposed to determine the capacity of the shear connection regardless of the slab type when the stud shearing occurs at high temperatures.

Experimental study on ferritic stainless steel trapezoidal decks for composite slabs in construction stage

The use of composite floor slabs is well established and provides an opportunity to promote the use of visually exposed composite slabs. Stainless steels, with the combination of good mechanical properties and excellent corrosion resistance, are key to this strategy, specially ferritic stainless steels, whose price is lower and more stable than that corresponding to the more widely used austenitic grades, due to their low nickel content whilst still maintaining good mechanical properties and aesthetic appeal. In addition, the emissivity of these grades contributes to lowering the heating and cooling requirements of buildings, reducing the costs associated to maintenance. Generally used as cold-formed members with high resistance-to-weight ratios, stainless steel decks are slender and highly sensitive to buckling phenomena and so the study of the structural performance of composite slabs using ferritic stainless steel decking is required due to the complex nonlinear behaviour of stainless steels, which is very different from that exhibited by carbon steel. Thus, this paper presents a comprehensive experimental programme on ferritic stainless steel trapezoidal decks for composite slabs under several structural configurations occurring during construction stage: simply supported decks under positive and negative bending moment, continuous decks and internal and end support tests. All the experimental results have been compared with the predicted ultimate loads in EN 1993-1-4, which remits to EN 1993-1-3 for carbon steel, and also with some previous tests on galvanized carbon steel decks. The paper concludes that EN 1993-1-3 provisions are applicable to ferritic stainless steels.

Minimum weight design of composite floors under human induced vibrations

The paper is concerned with a minimum weight design of composite floors subjected to dynamic loading, deriving from the rhythmic activity of a group of people. The floor structure consists of concrete slab cast, on thick trapezoidal deck, which is supported by a grid of steel beams. The structure is vibration-prone and exhibits a number of natural frequencies, which are within a range of loading function. Mini-mum weight design consists in assigning, from catalogues of prefabricated plates and beams appropriate elements assuring fulfillment of imposed constraints on dis-placements and accelerations. Applied, practical discrete optimization method is based on graph theory and finite element analysis. Efficiency of the proposed de-sign is demonstrated in an example of real-world engineering structure.

Strength and serviceability of continuous composite slabs with deep trapezoidal steel decking and steel fibre reinforced concrete

An experimental study is described of the behaviour of short-term static load tests on two-span composite slabs fabricated with deep trapezoidal decks and steel fibre reinforced concrete. The aim was to study the effects of varying the steel fibre dosage on the cracking behaviour at the negative moment region, on the redistribution of moments, on the end slip between the decking and the concrete, and on the load carrying capacity of the slabs. In total, 8 two-span composite slab specimens were cast and moist cured for a period of 14days and then loaded monotonically to failure at an age of at least 28days. In addition to the steel decking, one of the specimens contained no reinforcing steel and no steel fibres, four of the specimens were reinforced only with steel fibres in the concrete (with nominal fibre contents of either 20, 30 and 40kg/m3). In the other three specimens, welded wire-mesh was included over the interior support, one with plain concrete and two with steel fibres in the concrete. The concrete properties, including compressive strength, tensile strength, modulus of elasticity and fracture energy, were measured on companion specimens for every test slab. Compared to the plain concrete composite slab and the slab containing SL62 welded wire mesh in the negative moment region over the interior support, the slabs containing steel fibres in excess of 20kg/m3 provided significant improvements in the slip load and the peak load. In addition, at service load levels the fibres provided crack control that was of similar effectiveness to that provided by the SL62 mesh.

Probabilistic three-dimensional finite element study on composite beams with steel trapezoidal decking

This paper presents a probabilistic study based on Monte Carlo simulation (MCS) to evaluate the influence of material uncertainties on the numerically simulated structural response of composite steel–concrete floors consisting of concrete slabs cast on steel profiled sheeting and connected to steel beams by means of shear connectors. The numerical analyses are performed using a three-dimensional finite element model developed using the commercial software Abaqus, implemented using an explicit formulation. The constitutive behaviour of all materials is nonlinear. Contact regions between the concrete and steel elements are simulated using surface-to-surface and embedment techniques. Analyses are carried out for three case studies including simply-supported and continuous beams for which experimental results are available in the literature. Different realization sizes are considered for the MCS in order to evaluate their influence on the statistical characterization of the structural response. Based on the obtained results, it is observed that the adopted realization sizes provide similar statistical representation of the structural behaviour, which highlights how even a reduced number of nonlinear analyses can lead to satisfactory approximations of the statistical description of the response uncertainties in composite steel–concrete floors.

Behaviour of Headed Shear Stud in Composite Beams with Profiled Metal Decking

This paper presents a numerical investigation into the behaviour of headed shear stud in composite beams with profiled metal decking. A three-dimensional finite element model was developed using general purpose finite element program ABAQUS to study the behaviour of through-deck welded shear stud in the composite slabs with trapezoidal deck ribs oriented perpendicular to the beam. Both static and dynamic procedures were investigated using Drucker Prager model and Concrete Damaged Plasticity model respectively. In the dynamic procedure using ABAQUS/Explicit, the push test specimens were loaded slowly to eliminate significant inertia effects to obtain a static solution. The capacity of shear connector, load-slip behaviour and failure modes were predicted and validated against experimental results. The delamination of the profiled decking from concrete slab was captured in the numerical analysis which was observed in the experiments. ABAQUS/Explicit was found to be particularly suitable for modelling post-failure behaviour and the contact interaction between profiled decking and concrete slabs. It is concluded that this model represents the true behaviour of the headed shear stud in composite beams with profiled decking in terms of the shear connection capacity, load-slip behaviour and failure modes.

Full-scale tests on composite steel–concrete beams with steel trapezoidal decking

This paper describes the detailed testing of two full-scale steel–concrete composite beams comprised of composite slabs with deep trapezoidal decking connected to universal beams by welded stud shear connectors. The ribs of the decking were orthogonal to the longitudinal axes of the steel beams. This situation exists in secondary beams in flooring systems of steel framed buildings, and beams with deep trapezoidal slabs of this type are economic since they are able to span large distances, with or without propping. Despite the popularity of these decks and many useful research contributions over several decades, there are some concerns related to the strength and ductility of the shear connection because of the large voids in the slab and the need to place the studs off-centre to circumvent welding them through the longitudinal stiffener in the rib. There is also significant disquiet as to the applicability of push test results on much smaller specimens to the design of full-scale beams. The experimental work in this paper therefore intends to provide benchmark data for the calibration of theoretical models and of design recommendations. The beams were 8 m long with low degrees of shear connection. The tests showed that both beams behaved in a very ductile fashion with the ultimate moment capacities being above those predicted from the Eurocode 4 guidelines.

Development and Application of Innovative Composite Beam Shear Connection Enhancements for Australian Construction

After over a decade of research, new generic forms of ladder and waveform reinforcement have been developed, including a shear stud performance-enhancing device, to provide strong, ductile and reliable shear connection of composite beams incorporating profiled steel sheeting. They prevent undesirable local failure modes, and improve on-site construction practices and quality. The situations when they are required are explained. Their use is particularly important in beams incorporating trapezoidal decks now produced in Australia, but these decks are not addressed in Australian Standard AS 2327.1 for composite beams, so important recommendations in this regard are made to Australian engineers.

Numerical predictions on the dynamic response of a suspension bridge with a trapezoidal cross‐section

A numerical method is developed to predict the dynamic behavior of a suspension bridge under wind action in a two dimensional sense. In particular, the behavior of a vibrating deck with a trapezoidal cross‐section is examined. The simulations contain two parts of computations, which are performed alternatively during the calculation process. The solutions of the instantaneous flow field and the deck motions are considered the basis to analyze the problem of deck instability. Wind tunnel measurements are conducted in parallel to measure the response of a sectional bridge model. The vertical and torsional deflections of the model are measured under various wind speeds with several selected attack angles. The results are used to confirm the accuracy of the numerical predictions. Results show that the numerical predictions of the structural response agree well with those from the experiments, indicating that the proposed method is capable of predicting the deck motion with good accuracy. Based on the time‐series numerical results, finally, the interactive behavior of the vibrating trapezoidal deck is examined extensively.

Influence of Bend Radii on Local Buckling in Cold Formed Shapes

The stress that causes local buckling is related to the width/thickness ratio of the element in compression. In current codes for the strength design of shapes cold formed from sheet metal, the presence of corner bend radii is treated by considering only the “flat width” portion of the element. This can lead to serious errors in the predicted buckling stress. An analysis of the influence of the corner radii is given together with the justification that the full distance between the intersections of the median lines of the elements be used for the design of typical cold formed shapes. In the case of simple formed angle shapes, a radiused bend at the heel actually reduces the critical stress. For trapezoidal deck sections and box shapes the critical stress calculated using the distance between the intersections of the median lines is not significantly influenced by the presence of corner radii <1/20 of the plate width. The theoretical critical stress is compared with that obtained using the “flat width,” which is shown to be unconservative.