You can use ReadyAPI to run several load scenarios at the same time and create complex scenarios that simulate several load patterns at the same time. You can simulate different behavior patterns of your users during the test. For example, some users log in, add some items to the cart and log out, while others use your API to query about price changes. You can simulate both scenarios at the same time. To do that, you create two SoapUI tests that simulate these user actions, and then create a load test with two or more simulated scenarios.
By default, load scenarios in ReadyAPI run in parallel. To run serial test runs, add multiple targets to a single scenario. Also, you can schedule a scenario run to create a complex simulation pattern.