Nonlinear finite element analysis of u-shaped RC core walls: insights from a blind prediction contest

A recent blind prediction competition involving large-scale U-shaped reinforced concrete core walls under cyclic loading conditions was held to assess the adequacies of existing reinforced concrete modelling procedures and analysis tools for estimating core wall structural response. This paper presents the modelling approaches employed and results obtained by two of the competition participants. One of the entrants used a reinforced concrete-dedicated solid finite element modelling approach, while the other employed a layered thick-shell finite element modelling approach. In both cases, cracked concrete material modelling was done according to the formulations of the Disturbed Stress Field Model and blind core wall response predictions were generated without model calibration exercises. Post-competition analyses were performed to assess model sensitivities and to gain insights into the responses of the core walls comprising the competition. Despite the different finite element schemes employed, it was found that both approaches could be used to provide meaningful estimates of core wall response, provided that adequately fine finite element meshing was used and that simulated cyclic loading protocols closely-matched the experiments. The results obtained showed that out-of-plane (i.e., through-wall-thickness) shear deformations contributed little to the computed responses of the non-planar walls, thus suggesting that alternative thin-shell and other more cost-effective analysis procedures may also serve as viable options in the analysis of U-shaped core walls.