In order to iterate the tabs, menuItem, etc. you could not use repeate components neither <ui:repeat> nor <a4j:repeat> because they work during page render time and do not create components in JSF tree. You should use <c:forEach> tag instead which works at view build phase and causes actual tabs components to be added to JSF tree. For more details refer to c:forEach vs ui:repeat in Facelets article.
"Using dynamically created RichFaces TabPanel for search results" article describes how <c:forEach> is successfuly used to create tabs dynamically.