NEW YORK CITY—Gaining RXR Realty as a joint venture partner, developer Youngwoo & Associates—the company that won the right to redevelop Pier 57 into a  retail and events hub along 12th avenue—has reached a deal to build more of the complex as office space, according to Crain’s New York Business. RXR plans to convert 200,000 to 300,000 square feet of the pier space to office use, allowing it to jump on the increased interest in the area on the part of tenants.