Concrete Composite Slab Research Articles

Flexural Behaviour of Concrete Composite Slabs with Different Configurations of Truss Type Shear Connectors

Flexural Behaviour of Concrete Composite Slabs with Different Configurations of Truss Type Shear Connectors

Study on the Preparation and Performance of a Prefabricated Pervious-Cement-Based Concrete Pavement Slab

Based on the design of a prefabricated pervious composite cement concrete pavement slab, the interface properties and bending deformation properties of basalt pervious concrete (BPC) and PVA fiber base impervious concrete (PFBIC) composite specimens were studied. The effects of the different interfacial agents on the interfacial bonding performance were compared using a splitting tensile strength test and interfacial shear test. The deformation capacity of the composite specimens under bending load was tested using a three-point bending test, with the symmetry of the model considered and compared with the deformation capacity of the BPC specimen and PFBIC specimen. The results showed that the compressive strength of the BPC prepared using an orthogonal test reached 40.30 MPa, while the permeability coefficient was 2.41 mm/s. Different interface treatment processes determine the interface bonding properties. The best interface treatment method can induce the interface bonding strength to be higher than the strength of the BPC matrix itself, while the interface transition zone matrix will be denser without obvious microscopic defects. Under the bending tensile load, the ultimate bending stress reached 6.58 MPa and the maximum deflection in the midspan was 0.81 mm. As a protective layer, the PFBIC can alleviate the disadvantage of the insufficient strength of the BPC and can improve the bending ultimate bearing capacity of the BPC-PFBIC through its own stiffness.

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.

Compounding effect between influences of fine and coarse recycled aggregates on non-uniform shrinkage behavior of steel-concrete composite slab section

The steel-recycled aggregate concrete (RAC) composite slab is a practical structural member for applying RAC with the fine recycled aggregate (FRA). Despite its advantages, the non-uniform shrinkage (NUS) of composite slabs makes its long-term behaviour the critical factor controlling its design. The use of recycled aggregates would further enlarge the influence of the NUS, while no study has focused on the influence of FRA. Therefore, this paper aims to investigate the influence of FRA on the RAC NUS with different coarse recycled aggregate (CRA) contents. Fifteen RAC slab specimens were fabricated to monitor the shrinkage strain development, considering the replacement ratios of CRA and FRA (rCRA and rFRA), slab thickness, and moisture-transferring boundary conditions. Experimental results showed that 1) the FRA significantly increased both the shrinkage strain value and its gradient through slab thickness, 2) the FRA and CRA had a significant compounding effect (i.e. the influence of FRA varied with rCRA) on the NUS of RAC, and the compounding effect varied with slab thickness. The test results were used to develop a model for the NUS of RAC made with both FRA and CRA. The predicted results well matched the test data from the literature and this study. Finally, a parametric analysis was conducted based on the proposed model.

Experimental study on demountable steel ultra-high performance concrete composite slabs under hogging moment

Experimental study on demountable steel ultra-high performance concrete composite slabs under hogging moment

Experimental study and prediction model for bond behaviour of steel-recycled aggregate concrete composite slabs

Using recycled aggregate concrete in a composite slab among the most promising solutions to effectively increase the utilisation of construction and demolition waste concrete. Longitudinal shear failure is a critical failure mode of composite slabs directly determined by the interfacial bond behaviour between concrete and profiled steel decks. However, the influence of recycled concrete aggregate (RCA) on interfacial bond behaviour remains unclear. Thus, this study conducted a pull-out test on the interfacial bond behaviour of composite slabs on 15 groups of specimens considering variables of replacement ratios of RCA (0, 50, and 100%), water-to-cement ratios (0.31, 0.45, and 0.60), steel deck thicknesses (0.8, 1.0, and 1.2 mm), and steel deck rib heights (48 and 65 mm). The bond-slip curves for all slabs were obtained, based on which the failure mechanism and influence of RCA under different parameters were discussed. Finally, an empirical prediction model for the bond-slip curve was established on the basis of the test data. The results showed that (1) the failure mode of composite slabs was independent of RCA, while the decrease in the steel deck rib heights induced more cracks in the failed slabs; (2) incorporating RCA decreased the ultimate bond stress by 4%–20% and the stiffness by 8%–14%; (3) the influence of RCA was coupled with other parameters; and (4) the proposed model exhibited a good prediction capability for the bond-slip behaviour of steel-RAC composite slabs.

Structural Performance of Modular Sandwich Composite Floor Slabs Containing Basalt FRP-Reinforced Self-Compacting Geopolymer Concrete

A newly developed innovative steel–geopolymer concrete composite floor slab for use in modular construction is investigated in this study. We present experimental results on the flexural behaviour of eight modular sandwich composite floor slabs with different configurations containing self-compacting geopolymer concrete (SCGC) as infill and Basalt FRP (BFRP) bars as reinforcement. The use of sustainable infill material such as SCGC and non-corrosive BFRP in the proposed composite floor slabs is beneficial from the perspective of environmental sustainability. This study also compares the performance of these composite floor slabs against their hollow counterparts. The overlap between the cells in multi-cell panels acts as additional partitioning walls. The infill material offers the sandwich composite floor slabs significant advantages by improving their load-carrying capacity. A critical analysis of the composite floor slabs for load displacement, failure modes, and strain behaviour is also conducted. The study concludes that the sandwich panels with multiple smaller cells and infill materials exhibit a sound structural performance, reporting a 6–8 times higher load-carrying capacity than their hollow counterparts. A comparison of hollow and infilled panels shows that the infill sandwich panels are suitable as structural slabs. At the same time, the former is more suitable for temporary formworks, shelter, and pedestrian platform applications.

Analysis and design of long-term responses of simply-supported steel–concrete composite slabs

Steel–concrete composite slabs have several advantages such as fast construction and a high degree of industrialization. Due to the sealing effect of profiled steel sheets (leading to the non-uniform shrinkage through the thickness of concrete), the composite slabs exhibit an additional deflection. At present, most design formulas for calculating the long-term deflection of composite slabs have ignored the effect of non-uniform shrinkage, while some other methods usually have complex procedures when considering the effect of non-uniform shrinkage. Furthermore, the influence of non-uniform shrinkage on the stress on the profiled steel sheet of composite slabs has not been studied to date. In this manner, this paper establishes a finite element model (FEM) of simply-supported composite slabs while considering the impacts of the non-uniform shrinkage, cracking in the concrete, and the creep of the concrete; then, the reliability of the FEM is verified against the experimental data in the literature. Next, a systematic parameter analysis is conducted to study the influence of the non-uniform shrinkage on the deflection of the composite slabs and on the stress on the profiled steel sheet; the key influencing factors are also determined. We then propose a new simple formula for calculating the deflection of the composite slabs by considering the effect of the non-uniform shrinkage; another equation is also developed for determining the stress on the profiled steel sheet. The results show that the non-uniform shrinkage has a significant impact on the long-term performance of the composite slabs. In particular, the non-uniform shrinkage increases the long-term deflection of the composite slabs by 37–285% and enlarges the stress on the profiled steel sheets by 65–98%. The proposed calculation formula is in good agreement with the FEM. The average ratio of the results predicted by the calculation formula to those computed by the FEM is in the range of 1.004–1.044, and the coefficient of determination (R2) ranges from 0.811 to 0.828.

Load Transfer Efficiency Analysis and Void Evaluation of Composite Pavement Cement Concrete Slab

The void at the bottom of a cement concrete slab is a common problem of composite pavements. It is of great significance to evaluate the spring stiffness, void size, and soil base elastic modulus at the bottom of cement concrete slab timely and accurately for the maintenance and guarantee of the pavement performance. In this paper, the composite pavement at a joint is modeled and the load transfer mechanism is realized by using spring groups for simulating the dowels that connect the two slabs of the joint. A database is established based on a large number of simulation results of joint load transfer efficiency and voids and the changing law of load transfer efficiency of cement concrete slab reveals their relationship. Taking into consideration the spring stiffness, void size, and soil base elastic modulus, the void evalua\tion method of composite pavement cement concrete slab is established by using back propagation neural network algorithm. The results show that the void evaluation method can provide the void determination map with two parameters. The values of the two parameters can be determined by the deflection basin. After querying the Atlas, the void determination can be more accurate. The research results provide scientific guidance for the void identification of the composite pavement and can effectively extend the service life of the pavement.

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.

Assessment of cyclic degradation effects in composite steel-concrete members

This paper investigates the inelastic behaviour of composite steel concrete beams, with particular emphasis on cyclic deterioration effects. A detailed continuum model is firstly developed to represent the hysteretic response of composite steel beam and concrete slab assemblages, validated against available experimental cyclic results on both steel and composite members. The proposed model is then adopted to perform detailed parametric assessments which are used to gain insights into the key response characteristics related to the inelastic cyclic performance of composite steel/concrete members, including their stiffness, capacity, and ductility. A synthetically generated numerical database is subsequently used to develop relationships governing the plastic rotation and cyclic degradation of dissipative composite beams as a function of the main geometric and material properties, with focus on members designed to European codified procedures. The deterioration effects are shown to be dependent on a number of key factors including, most significantly, the composite beam depth and the steel cross-section slenderness. In addition to the asymmetry in behaviour under sagging and hogging moments, it is shown that composite members typically exhibit 20% more degradation under cyclic loading compared to their bare steel counterparts. Importantly, the proposed cyclic degradation expressions for composite beams also enable the calibration of widely used uniaxial deterioration models which are suitable for implementation in computationally efficient nonlinear inelastic frame analysis for structural systems. These expressions also provide fundamental information required for idealised pushover representations for practical seismic assessment and design purposes.

Analysis of Mechanical Properties of Long-span Reinforced Concrete Composite Slabs under Different Splicing Methods

Based on the long-span slab in an assembled building project, ABAQUS is used to simulate the mechanical properties and failure modes of the slab under the condition of the whole span cast-in-place slab and the two-way rebar truss composite slab (hereinafter referred to as composite slab) with different splicing methods, in which the slabs adopt fixed support and the slab loads are uniformly distributed load. The finite element simulation results show that the integrity and mechanical properties of the whole span cast-in-place slab are not different from those of the parallel splicing two-way composite slab, but they are obviously better than the parallel cross splicing two-way composite slab; In the same slab span, the cast-in-place seam of the composite slab in the middle cracks first due to stress concentration, and with the increase of the uniformly distributed load of the slab, the crack will pass through the cast-in-place seam and develop to the composite slab on both sides, and finally all the concrete at the bottom of the slab will crack and fail. According to the simulation results, the following suggestions are given: if the truss rebar composite slab is adopted for the long-span slab, the two-way composite slab should be adopted, and the cast-in-place seam should be arranged in the direction of less stress, and the seam should not be arranged in both directions.

Multilayer bamboo composite hollow-core: Lab-scale and non-destructive testing of full-scale concrete bridges considering transverse bamboo pole as shear reinforcement

Due to bamboo's superior mechanical qualities, it has been often used in rural construction, however research on bamboo poles as structural reinforcement has been fairly limited. The purpose of this paper is to introduce a novel composite system made of several layers of bamboo hollow-core, named Mulbamcomphol concrete system for simplicity. On that premise, this paper analyzes the implementation of a composite slab system on a short span bridge consisting of concrete and multilayer bamboo arranged in a cross-section, without any utilization of steel reinforcement. Mulbamcomphol is so termed because to the presence of entire bamboo in this composite system (multilayer cross-ply bamboo composite hollow-core). Non-destructive testing will be utilized to analyze the flexural behavior of a full-scale vehicle under an actual service load. Due to the difficulties of obtaining exact results and the potential for bias, the study is conducted using a FEM-based model (thick shell and solid element). Bamboo slabs with a weak axis can sustain less stress than regular slabs, but they deflect by 81% less when subjected to the same 21 kN force. Simultaneously, when tested on a rigid axis, multilayer bamboo pole slabs can withstand a force 52 % more than conventional slabs at the same concrete volume, resulting in a 73 % reduction in deflection. Bridges constructed using Mulbamcomphol cross-ply bamboo composite concrete slab systems, on the other hand, demonstrate higher resistance to flexural loads in terms of ductility and maximum load that can be carried in both analysis and experimental testing.

Experimental and numerical study of the ductility of open-rib and reentrant composite slabs

The most restrictive failure mode of steel–concrete composite slabs is longitudinal shear. The partial connection method (PCM) is a design method for longitudinal shear capacity limited to slabs showing ductile failure and assumes the complete yielding of the slab cross-section. Ductility is defined in Eurocode-4 in terms of additional strength after the first slip occurs, regardless of the total slip magnitude. This article shows that the slip behavior is significantly different depending on the shape of the sheeting profile. The slip magnitude in reentrant slabs can be large enough to drive the steel sheeting and the concrete to their yielding stresses since the two materials remain vertically clamped always. Conversely, in open-rib profiles, the slip mechanics cannot drive the materials to the yielding stresses since the vertical release of the two materials occurs earlier, when the slip exceeds specific values related to the embossments’ geometry, after which the vertical clamping is no longer possible. The results show that the vertical release between the concrete and the profiled steel sheeting is reached after the slip values about 2–5 mm in open rib profiles, whereas they remain permanently clamped in reentrant profiles. This paper demonstrates that the maximum load in open-rib slabs is related to the vertical release before the materials reach their yielding stresses. These findings are consistent with both the FEM and experimental tests presented and suggest the need to review the ductility definition in standards or the applicability of the PCM in open-rib slabs. The experimental campaign includes tests conducted at the Laboratory of Elasticity and Strength of Materials, LERMA, Universitat Politècnica de Catalunya, and external resources.

Development of Creep Deformations during Service Life: A Comparison of CLT and TCC Floor Constructions

Cross-laminated timber (CLT) slabs in residential buildings need additional weight, e.g., in the form of screeds or gravel layers, to fulfill the criterion for the highest impact-sound class. The additional mass is, however, not exploited for the load bearing behavior, but adds additional weight and leads to an increased height of the floor construction. In this study, such a CLT floor construction with a construction height of 380 mm is compared with a composite slab consisting of a CLT plate with a concrete layer on top with a floor construction height of 330 mm. The timber concrete composite (TCC) slab has a different creep behavior than the CLT slab. Thus, the development of the time-dependent deflections over the service life are of interest. A straightforward hybrid approach is developed, which exploits advanced multiscale-based material models for the individual composite layers and a standardized structural analysis method for the structural slab to model its linear creep behavior. The introduced approach allows to investigate load redistribution between the layers of the composite structure and the evolution of the deflection of the slab during the service life. The investigated slab types show a similar deflection after 50 years, while the development of the deflections over time are different. The CLT slab has a smaller overall stiffness at the beginning but a smaller decrease in stiffness over time than the investigated TCC slab.

Flexural performance and design method of the prefabricated RAC composite slab

Prefabricated buildings recently became more prominent, providing significant benefits. Thus the development of prefabricated buildings is a long-term industrial policy in China. In the prefabricated frame structure, the slab is a critical component. In order to provide more and better floor options, the paper proposed a kind of prefabricated concrete composite slab, which adopts the profiled steel sheeting as the prefabricated formwork and the shear connector connected with the surface concrete. Combined with the test results, based on the analysis of load–deflection curves, the finite element software ABAQUS was used for the numerical parametric study of the prefabricated RAC composite slabs. The steel deck thickness, concrete strength, the yield strength of the reinforcements, the tensile reinforcement ratio, the wave height of profiled steel sheeting, and the RCA percentage have carried on the finite element analysis. The results show that the steel deck thickness, the strength of concrete, and the RCA percentage slightly influence the flexural performance of prefabricated RAC composite slabs, the reinforcement yield strength and the wave height of profiled steel sheeting have a certain influence on the flexural performance of prefabricated RAC composite slabs, and the reinforcement ratio of tensile steel bars significantly impacts the flexural performance of the prefabricated RAC composite slabs. In addition, the peak load of specimens increases with the increase of the reinforcement ratio of tensile steel bars. A comparative analysis was carried out between the theoretical calculation results and the experimental or finite element simulation results. And the bending design method of the new prefabricated composite slab was proposed based on the analysis result, including the calculation formula of flexural bearing capacity, short-term stiffness, and the maximum crack width. This study will provide a theoretical basis for designing and engineering the new prefabricated RAC composite slab.

Flexural fatigue mechanism of steel-SFRC composite deck slabs subjected to hogging moments

This paper aims to investigate the flexural fatigue mechanism of the steel-steel fiber reinforced concrete (SFRC) composite deck slab under hogging moments. Firstly, fatigue tests were implemented on two full-size slab specimens reinforced by different steel fibers, i.e. mill-cut steel fibers (MF) and corrugated steel fibers (CF). The failure mode, steel-concrete composite action, and crack behavior were measured and discussed. It finds that the fatigue failure of the composite slab under hogging moments was governed by the fracture of rebar in tension. Under service loads, the use of MF achieves lower stress amplitude of rebar in tension (Δσs) by 6–9% and higher slab stiffness by 2–7%, compared with CF. Subsequently, both finite element and theoretical analysis are employed, through which the influence mechanisms of SFRC’s strength parameters (fL, fR1, fR3) and slab’s structural parameters on Δσs are clarified, and the calculation method of Δσs is developed. Results showed that Δσs can be reduced by up to 7% with a 1.19 MPa increase in fL and by 12% as fR1/fL is raised by 0.4, whereas the effects of the fR3 are minimal where a reduction of lower than 1% is obtained as fR3/fR1 goes up by 0.4. The advantage of MF can be attributed to its better improvement on fL and fR1 than CF. It also reveals that steel members with greater bending stiffness can attract higher moments, which decreases the moment sustained by the SFRC layer and thus reduces Δσs. The proposed calculation method yields satisfactory prediction accuracy and is capable of capturing the effects of strength and structural parameters.

Experimental study on the buckling behavior of double steel plate concrete composite slabs with stiffening ribs and tie plates

Double steel plate concrete (DSC) composite slabs consist of two outside steel plates and a concrete core that are connected by welded studs or cross tie bars. If weak restraints are designed for the interface between the steel plates and concrete core, the surface steel plate of the DSC slabs may suffer local buckling when subjected to a compressive load. In this paper, a new type of DSC slab with stiffening ribs and tie plates (SDSC slab) is proposed to improve the stability of surface steel plates. Two groups of bending tests are carried out to investigate the buckling behavior of both SDSC slabs and ordinary DSC slabs (ODSC slabs). Furthermore, the influence of the B/t ratio, that is, the ratio between the stud spacing and the steel plate thickness, is intensively analyzed. The experimental results reveal that compared with that of the ODSC slabs, the buckling behavior of steel plates in the SDSC slabs is delayed or even prevented owing to the additional stiffening ribs and tie plates. Thus, the bending capacity and ductility of SDSC slabs are both enhanced. According to the test results, calculation formulas are derived to predict the bending capacity of the ODSC slabs and SDSC slabs, respectively. In addition, design models for buckling analysis are proposed to determine the buckling stress and critical B/t ratio for different types of DSC slabs. The accuracy of the theoretical methods is validated against the test data, and two examples are provided in detail to illustrate the design process of the steel plate in SDSC slabs.

LCA & LCC analysis of hybrid glued laminated Timber–Concrete composite floor slab system

The increasing request for energy-saving and saving materials and growing concern related to the impacts of materials used on environmental and economical has driven the construction industry toward redesigning critical structural systems and elements. This research proposes solutions for mitigating ecological effects and sustainable built environments. For example, the floor slab is considered the top environmental impact emission after walls compared to other non-load-bearing elements among different building components. Therefore, this research expands the new slab comprising Glued laminated timber (GLT) with concrete as a novel lightweight flooring system. The related methodology includes life cycle assessment (LCA) and life cycle cost (LCC) analysis. Thus, the environmental and economic impacts of three common slab systems were compared to the proposed slab. The evaluation results revealed that GLT-concrete has lower emissions in all environmental categories, namely: Global warming potential (GWP), Eutrophication Potential (EP), human toxicity potential (HTP), fossil depletion potential (FDP), terrestrial Ecotoxicity (TE), and Acidification Potential (AP). Likewise, Embodied energy value showed that GLT-concrete has a lower value by 26%, 9%, and 24% than Lightweight steel slab, Precast reinforced slab, and Cofradal slab. Finally, the result of LCC shows a new GLT-concrete slab despite having a higher construction cost, but by considering the end of life scenario as reuse, it will have a lower total cost. Thus, current research can expand the assessment of environmentally friendly floor structures and step toward sustainable construction.

Prediction of bending performance for a separable CLT-concrete composite slab connected by notch connectors

In this study, the bending performance of a separable cross-laminated timber (CLT)–concrete composite slab for reducing environmental impact was investigated. The slab has consisted of CLT and eco–concrete, and round-notch shape shear connectors resist the shear force between the CLT and eco-concrete. The eco–concrete was composed of a high-sulfated calcium silicate (HSCS) cement, which ensures low energy consumption in the production process. The bending stiffness and load-carrying capacities of the slab were theoretically predicted based on the shear properties of the notch connectors and validated with an experimental test. The shear properties of two types of notch shear connectors (Ø100 mm and Ø200 mm) were measured by planar shear tests. As a result, the stochastically predicted bending stiffness of the slab (with Ø100 mm shear connector) was 0.364 × 1012 N mm2, which was almost similar to test data. The load-carrying capacities of the slab were governed by the shear failure of the notch connectors, and the lower fifth percentile point estimate (5% PE) was 21.9 kN, which was 7.9% higher than the prediction (20.2 kN). In a parameter study, the effect of notch diameter for the CLT-concrete slab span was analyzed depending on the applied loads, and the maximum spans of the slab with Ø100 mm notch or Ø200 mm notch were not significantly different.