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This research studies the structural behaviour of bridge deck slabs under static patch loads in steel–concrete composite bridges and investigates compressive membrane action (CMA) in concrete bridge decks slabs, which governs the structural behaviour. A non-linear 3D finite element analysis models was developed using ABAQUS 6.5 software packages. Experimental data from one-span composite bridge structures are used to validate and calibrate the proposed FEM models. A series of parametric studies is conducted. The analysis results are discussed and conclusions on the behaviour of the bridge decks are presented.

In the past 40 years, it has become increasingly evident that durability of the concrete bridge deck slabs was directly related to the corrosion of reinforcement. De-icing salt has been one of the major factors in the deterioration of reinforced concrete bridge decks [2]. However, bridge deck slabs in the typical beam-and-slab type bridge have inherent strength due to in-plane forces set-up as a result of the restraint provided by the slab panel boundary conditions. This is known as compressive membrane action (CMA) or arching action [3] and [4]. Although the effect of compressive membrane action in concrete bridge deck slabs has been recognised for some time, it is only recently that there has been acceptance of a rational treatment of compressive membrane action in concrete slabs. Some design and assessment codes now acknowledge the benefits of CMA. These include the Department of Regional Development (NI), Design Specification for Bridge Decks [5]; The Canadian Highway Bridge Design Code [6] and the UK Highways Agency Standard BD81/02 [7]; the latter came about as a direct result of research at Queen’s University Belfast [8], [9], [10] and [11]. In the past, most of research works on the structural behaviour of deck slabs under compressive membrane action has focused on experimental studies [8], [9], [10], [11] and [12]. However, due to the high cost and significant time requirement in conducting full-scale physical testing, it is difficult to develop comprehensive parametric studies for this structural type. Furthermore, some structural values were difficult to measure by experimental tests, such as the stress–strain relationship through the depth of decks. Therefore, refined and completed studies are needed to investigate the structural behaviour of slabs on composite steel–concrete bridges, which are one of the most common types of bridge form. The availability of high-speed computers and commercial finite element packages facilitate the development of these tools through 3D FEA [13]. The objective of this paper is to study how the deck slabs work in composite bridges under the static patch loads and the remaining structural components of bridges influence the response of concrete deck slabs. To this end, a commercial software named ABAQUS [14], which accommodates non-linear 3D FEM models, can be employed. The proposed numerical model showed good convergence ability and an excellent agreement of structural behaviour with the validations of experimental tests by authors [12] and [15]. Subsequently, the observed structural behaviour of bridge deck slabs were presented. Finally, a series of parametric studies is conducted: (a) steel supporting beams; (b) presence and position of steel reinforcement; (c) presence of diaphragm; (d) connection between concrete slabs and steel beams.

This paper presents a study of NLFEA for the structural behaviour of concrete bridge deck slabs under static patch loads in composite bridges. NLFEA results indicate that compressive membrane action developed in concrete bridge deck slabs. The suggested numerical analysis has been shown to accurately capture the ultimate loading capacities of authors’ experimental model. However, current design standards were highly conservative in predicting the strength of bridge deck slabs. Based on accurate validation of proposed numerical procedure with experimental results, NLFEA provided the capability of investigating some structural parameters, such as stress and strain distribution through the thickness of deck slabs, which are not easily obtained through other methods of analysis. In the investigation of failure mechanisms of the authors’ test models, it was found that flexural punching failure was the common failure mode and the punching effects became stronger with increasing compressive membrane effects. Furthermore, the proposed numerical model is effectively used to conduct a series of parametric studies with respect to steel beam sizes, presence and position of reinforcement, existence of diaphragm and composite action. In the study of effects of steel supporting beam sizes, it was found that the strength of deck slabs enhanced significantly with an increase of the stiffness in minor axis bending (IyyIyy value) of steel supporting beams, equivalent to an increase in the external restraint stiffness. Based on the cheap cost and lower time requirement compared with the experimental tests, the proposed NLFEA models can be used by engineers and researchers for the structural analysis, assessment of the loading capacity and parametric studies of composite steel–concrete bridge decks.