Non-linear finite-element (FE) method is today commonly used to simulate the behavior of rein forced concrete structures. The study presented in this paper comprises non-linear FE analyses of the behavior of two-way RC slabs and a comparison with experimental results. In the analyses, the con crete in compression was described by an isotropic damage constitutive law. In tension, a total strain model with rotating crack was adopted. The reinforcement was described by a Von Mises plasticity model, including hardening. The load-displacement relationship, and crack pattern of the two-way slabs under a concentrated load were compared to experimental results. The influence of some model ling choices, such as element type, mesh density, and reinforcement-concrete interaction were inves tigated. Analyses with varying mesh size resulted in very small difference in the results. The analysis including bond-slip gave lower stiffness at the cracking stage, and displayed more localized cracks compared to the analysis with full interaction, while both had the same ultimate load capacity.

2014): Two-way slabs: Experimental investigation of load redistributions in steel fibre reinforced concrete, Engineering Structures 80 (2014) pp. 61-74, http://dx. AbstractIn the design of two-way reinforced concrete slabs, e.g. using the strip or yield line design method, the possibility of redistributing the load between different loading directions is used. The main aim of the present study was to investigate how fibres affect the structural behaviour such as the possibility for redistribution, crack patterns and load-carrying capacity. The investigation was conducted by means of experiments on two-way octagonal slabs, simply supported on four edges, centrically loaded with a point load. The slabs spanned 2.2 m in both directions and the reinforcement amount was twice as large in one direction as in the other, in order to provoke uneven load distribution. Three slabs of each reinforcement configuration were produced and tested: conventionally reinforced slabs, steel fibre reinforced slabs and a combination of both reinforcement types. The reaction force on each supported edge was measured on five rollers per edge. A moderate fibre content (35 kg/m 3 ) of double hook-end steel fibres was used. The steel fibres affected the structural behaviour significantly by providing post-cracking ductility and by increasing the ultimate load-carrying capacity by approximately 20%. Most significant, the steel fibres influenced the load redistribution in such a way that more load could be transferred to supports in the weaker direction after cracking. Further, more evenly distributed support reactions were obtained in the slabs containing both reinforcement types compared to the case when only conventional reinforcement was used. The slabs reinforced by steel fibres alone did not experience any bending hardening; however, a considerable post-cracking ductility was observed. Furthermore, the work presented in this paper will provide results suitable for use in benchmarking numerical and analytical modelling methods for steel fibre reinforced concrete, as the experimental programme also included extensive testing of material properties.

This paper proposes a multi-level assessment strategy for reinforced concrete bridge deck slabs. The strategy is based on the principle of successively improved evaluation in structural assessment. It provides a structured approach to the use of simplified as well as advanced non-linear analysis methods. Such advanced methods have proven to possess great possibilities of achieving better understanding of the structural response and of revealing higher load-carrying capacity of existing structures. The proposed methods were used for the analysis of previously tested two-way slabs subjected to bending failure and a cantilever slab subjected to a shear type of failure, in both cases loaded with concentrated loads. As expected, the results show that more advanced methods yield an improved understanding of the structural response and are capable of demonstrating higher, yet conservative, predictions of the load-carrying capacity. Nevertheless, the proposed strategy clearly provides the engineering community a framework for using successively improved structural analysis methods for enhanced assessment in a straight forward manner.

Type of publication:Peer reviewed journal article a b s t r a c tReinforced concrete (RC) two-way slabs without shear reinforcement are commonly used in many structural systems. This paper investigated the structural behaviour of RC slabs subjected to concentrated loads leading to punching shear failure using shell and continuum nonlinear finite element analysis (NLFEA). Shear force distributions are studied for four types of slabs with different geometry of support, geometry of slab and layout of reinforcement. All factors investigated have been proven to influence the shear force distributions along the control perimeter around the support. Significant shear force redistributions due to cracking and reinforcement yielding have been observed using NLFEA. Reduced control perimeters to be used for simplified approaches accounting for calculated shear force distributions are calculated using both NLFE approaches.

a b s t r a c tAnalyses of tested two-way reinforced concrete (RC) slabs were carried out with varying modelling choices to develop better modelling strategies. The aim was to study how accurately the response of a slab subjected to bending could be predicted with nonlinear finite element (FE) analysis using three-dimensional (3D) continuum elements, and how the modelling choices might influence the analysis results. The load-carrying capacity, load-deflection response, crack pattern and reaction-force distribution of the two-way slab studied were compared to experimental data available. The influence of several modelling parameters was investigated, including geometric nonlinearity, element properties, concrete model, reinforcement model and boundary condition. The results show the possibility of accurately reflecting the experimental results concerning load-carrying capacity, load-deflection response and crack pattern giving proper modelling choices. Moreover, the reaction force distribution was found to be highly influenced by the stiffness of the supports.