Modelling of a PsD hybrid test on a RC column/beam junction combining a multifibre beam model and a POD-ROM approach

In this paper, a pseudo dynamic (PsD) hybrid experimental setup allows for assessing the nonlinear behaviour of a reinforced concrete (RC) column/beam junction under earthquake is proposed. The specimen is linked to a numerical substructure made of multifibre beam elements modelling the other parts of the building. To reduce the CPU time related to the numerical substructure, a proper orthogonal decomposition (POD) projection modal basis is computed from an offline implicit finite element analysis and used to reduce the size of the matrix system. A bilinear elastic-plastic law is used for steel rebars, and a unilateral damage law is used for concrete. Step-by-step calculations are performed using a non-iterative, unconditionally stable and explicit α-OS splitting scheme during the hybrid test (i.e. the online phase). A substructuring method is applied to the column-beam junction located at the first-floor level. The reliability of the modelling assumptions as well as the use of POD-modes in the case of quasi-brittle materials are discussed. The analyses are performed by using MATLAB © software. In a first attempt, the column-beam junction response is computed using a 2D nonlinear numerical model defined in Cast3M © software. Results show that using a POD projection modal basis does not significantly reduce the computational cost when the α-OS method is used but improves the response of both numerical and tested substructures thanks to the nonlinearities taken into account into the POD-modes.