The containment building (CB) is known as the third and last safety barrier to protect the environment from diffusion of radioactive products. In 2014, Électricité de France (EDF) launched the VERCORS project (J. Niepceron, 2021) to improve the knowledge of leak-tightness in the CB under air pressure loading and ageing effects. VERCORS consists in a 1/3 scaled containment mock-up representing a 1300 MWe CB of a typical French pressurized water reactor (PWR). The CB is well monitored by experimental approach, in parallel, international benchmarks have been proposed in order to compare different numerical simulations techniques. This paper presents the results of the simulation based on VERCORS mock-up, and the simulation includes early-age phase, prestress phase and pressurization phase. The finite element solver is performed by Castem (Castem, 2019). Concrete is modelled through 3D elements while rebar and tendons are modelled by 1D elements. The delayed strains including creep and shrinkage are calculated through the BPEL99 model (BPEL99, 1999). The effects of friction and relaxation on the prestress level are taken into account. Besides that, pressure load and ageing scenario are included. To describe cracks in concrete, an elastic damage model (Mazars, et al., 2015) is used for the concrete elements, and the post-processing of leak-tightness is based on the internal variable of the damage model and a hydraulic analysis. The mechanical results reveal different damage zones on the CB, which are distributed at gusset, hatch and dome. Under the constant relative pressure tests, the damage develops from the gusset to the wall, this is because of the increasing of prestress loss due to the delayed strains.