The PBSJ Corp., a Tampa-based architecture, engineering and construction firm, is conducting an internal investigation into whether its subsidiary, PBS&J International Inc., broke the law in pursuing projects overseas. The $618-million, employee-owned company disclosed the investigation in a Dec. 30 filing to the federal Securities and Exchange Commission. In the filing, it told the SEC that it could not file its required year-end annual report for 2009 on time because the audit committee of its board of directors was seeking “to determine whether any laws have been violated, including the Foreign Corrupt Practices Act, in connection with certain projects undertaken