The American Arbitration Assn. has opened an office in Irvine to capitalize on what it sees as a growing trend to resolve business disputes out of court. Orange County has a heavy concentration of business litigation, and companies are turning more to arbitration organizations to avoid the long delays in the public court system, said Lori S. Markowicz, director of the Irvine office. Newport Beach lawyer Peter D. Collisson chairs the association’s 17-member Orange County advisory committee. The Irvine office is its fourth in California and 34th nationwide. Through attorneys, business executives, university professors and retired judges, the 63-year-old nonprofit organization offers alternatives to court trials, including arbitration, mediation and mini-trials.