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Computers and Concrete
  Volume 5, Number 2, April 2008 , pages 117-134

Deep-beams with indirect supports: numerical modelling and experimental assessment
Mario Pimentel, Paulo Cachim and Joaquim Figueiras

    An experimental and numerical research was conducted to gain a deeper insight on the structural behaviour of deep-beams with indirect supports and to assess the size effects in the ultimate state behaviour. The experimental campaign focused on the influence of the reinforcement tie distribution height on the compression check of the support region and on the benefits of using unbonded prestressing steel. Three reduced scale specimens were tested and used to validate the results obtained with a nonlinear finite element model. As a good agreement could be found between the numerical and the experimental results, the numerical model was then further used to perform simulations in large scale deep-beams, with dimensions similar to the ones to be adopted in a practical case. Two sources of size effects were identified from the simulation results. Both sources are related to the concrete quasi-brittle behaviour and are responsible for increasing failure brittleness with increasing structural size. While in the laboratory models failure occurred both in the experimental tests as well as in the numerical simulations after reinforcement yielding, the numerically analysed large scale models exhibited shear failures with reinforcement still operating in the elastic range.
Key Words
    non-linear analysis; non-linear fracture mechanics; deep-beams; shear; strut-and-tie models; size effects; unbonded post-tensioning.
Mario Pimentel; LABEST, University of Porto, Faculty of Engineering, Rua Dr. Roberto Frias s/n 4200-465 Porto, Portugal
Paulo Cachim; University of Aveiro, 3810-193 Aveiro, Portugal
Joaquim Figueiras; LABEST, University of Porto, Faculty of Engineering, Rua Dr. Roberto Frias s/n 4200-465 Porto, Portugal

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