1. What is the purpose of the simulation? What is the output you want? The answers to these questions determine the answer to this question.
  2. Please read the Ansys Help on a Joint Type Bushing for answers to your questions.
  3. You can ignore this warning if you are satisfied with the time it took to solve, or you can’t afford to upgrade your computer hardware. If you can afford to upgrade your computer hardware you can install more RAM up to the maximum supported by that computer and/or you can install an SSD if you currently have a HDD because the access time on an SSD is much lower than a HDD.
  4. There is a lot less computation when you make solid bodies rigid instead of flexible. Since the elastomer is orders of magnitude less stiff than concrete or steel, you could make a first model where they are both rigid. The warning in question 3 might go away. After you get some results, you can change the steel to flexible and get some new results. Then you can change the concrete to flexible and get some final results.