The Kennedy Center is expanding an initiative to provide management help to more than two dozen struggling small and mid-size orchestras. “Sustaining the American Orchestra,” the new initiative, is an effort to design strategies that will change the way many orchestras do business. Initially the center will work with 23 orchestras, ranging from the Indianapolis Symphony, which has a $23 million budget, and the St. Louis Symphony, a $21 million budget, to the Reno Philharmonic and Berkeley Symphony Orchestra, both with $1 million budgets. The Kennedy Center is using a model it developed three years ago to help minority-run dance, theater and music companies.