You address their concerns by addressing the (hopefully incorrect) root of their concerns.
People see a work history and they draw conclusions. A work history of mostly short gigs can present itself as if you're a job hopper. Employers looking for long term employees don't like that, since it makes them think they may lose you quickly. When in reality, there may be a good reason for your job hopping, and you may be at a turning point in your career where you're looking to stop doing short consulting gigs and settle down with a longer-term role.
So - you need to prepare for the inevitable interview questions by asking yourself: Why are you switching career styles? Why do you want to go from short term gigs to a long term role? If you're able to give an honest answer for that, you'll diffuse their concerns.
I can relate, as the first 10-15 years of my career were mostly short consulting gigs. I had reached a point then where I wanted to settle down. Short term engagements can be exciting - consultants are usually brought in because of change, or big projects, or other high-energy situations. However, you don't get to see the long-term rewards of strategy, when you're only ever engaged for a short, specific deliverable. That's why I wanted to switch - I wanted the opportunity to embed myself in a company's culture and strategy and help them in the long term.
When asked in interviews, I simply explained that. I've hired ex-consultants a few times since, and often received similar answers. Other times, people explained that the constant moving or traveling of consulting was wearing them out. Other people said they'd always been looking for long term employment, and were using consulting as a way to pay the bills while they took the opportunity to be choosy about the employer they ultimately settled with.
Regardless of the answer you give, it will be received based on it's honesty, and it's alignment with what the company is looking for. If they're looking for a long term employee, you need an answer that shows that you recognize that and you're both prepared and interested in doing that type of role with them.
You can take this a step further and show to your potential employer why consulting has put you in a good position to evaluate and select a long term employment role compared to other candidates. Consulting exposes you to a wide range of companies - and their policies, behaviors, standards, processes, industries, and cultures - in a short period of time. Consultants have to be good at learning and adapting quickly which are qualities any employer would like. Consultants have seen enough of the employment landscape that they're well suited for evaluating their fitness into a specific environment compared with someone who's worked at the same place, in the same style, for a long time. You don't want to ramble on, but it's good to have thoughts like this ready to go for when the conversation does come up.