Nonlinear Thermo-Structural Analysis of Lightweight Concrete and Steel Decking Composite Slabs under Fire Conditions: Numerical and Experimental Comparison

Abstract

Composite slabs with steel decking profiles are widely used in building construction. However, the literature on the fire resistance of lightweight concrete (LWC) composite slabs with steel decking is limited. In this work, the thermo-structural performance of LWC composite slabs with trapezoidal steel decking was studied under fire conditions. A total of 12 experimental fire tests were carried out using specimens of 160 mm thickness, 1120 mm width and 2030 mm length, in which nine composite slabs were made of LWC and the remaining three slabs were made of normal concrete (NC) to serve as a benchmark for comparison. All the samples were tested in a furnace following EN 13381-5, applying the standardized time–temperature curve and constant load. During the experimental tests, phenomena such as the vaporization of the free water inside LWC, debonding between steel decking and concrete and changes in material properties affected the thermo-structural performance of composite slabs. The test results show that the load-bearing capacity of lighter slabs does not assure the minimum structural behavior of R30. However, the lighter the concrete is, the lower the thermal transmittance, improving the slabs’ thermal performance under fire conditions. Advanced nonlinear numerical models were developed to predict the thermal and structural performance of the studied LWC composite slabs in terms of temperature and time-displacement. The influences of key factors such as vaporization, thermal strains and debonding were included using material properties and a thermal contact conductance interlayer. Finally, the nonlinear models and the experimental results were compared. The difference between the experimental and numerical values was less than 15%, showing that the numerical results were in good agreement with the experimental results. The results of this study also compared the performance of LWC composite slabs with the NC composite slabs, giving rise to interesting conclusions from a practical point of view.

Natural Frequency of Lightweight Composite Slabs Based on Experimental Study and Numerical Modelling

“…In addition, the development of foamed concrete with high-strength characteristics as performed by Namsone et al [1], Khan et al [2], Wei et al [3] and Xian et al [4] indicate promising results. Previous investigations by Liu & Tian [5], Abbas et al [6] and Martinez-Martinez [7] pointed out that the performance of lightweight composite slabs is closely in line with and comparable to that of other types of floor systems.…”

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

“…In terms of bond strength, there is an insignificant difference between lightweight composite slabs and conventional composite slabs. A nonlinear thermos-structural analysis by Martinez-Martinez [4] showed that lightweight composite slabs do not meet the minimum bearing capacity of 30 minutes required by BS EN 1994-1-2 [29]. The lightweight concrete was produced from siliceous aggregates and expanded clay, and achieves a compressive strength of around 25 MPa to 30 MPa.…”

“…Since this experimental study focuses on the structural behaviour, the three-point bending test has proven to be appropriate. Previous researcher such as Martinez-Martinez [4], Holy et al [47] and Kita et al [48] also used the three-point bending test to measure the bending stresses and maximum deflection of slab specimens. The three-point bending test, as shown in Fig.…”

Study on the fire performance of novel G550 galvanized steel‐concrete composite slabs

“…When regarding to the fire performance, however, such slabs behave similarly to plain concrete slabs in fire condition [1] and fail to meet the fire resistance requirements specified in Eurocode 4 [2] without using any reinforcement or fire proof coatings. Furthermore, extensive research has been conducted to explore the incorporation of various materials into composite slabs, including lightweight concrete [3][4] and recycled concrete [5]. These studies have demonstrated that the shielding effect of the profiled steel sheeting significantly influences the fire resistance of composite slabs.…”