Wow, you have 5 million elements LOL! I won't be surprised at all that it takes a long time to run. Your concrete element mesh looks quite coarse, so I guess the mesh around the rebars is really small. Did you use solid elements or beam elements for the rebar? If using beam elements the contact between the rebar and concrete is a bit tricky (Please refer to this post: https://forum.ansys.com/forums/topic/error-contact/), but it can probably make your element number drop down significantly.