With the increasing use of dynamic page generation, asynchronous page loading (AJAX) and rich user interaction in the Web, it is possible to capture more information for web usage analysis. While these advances seem a great opportunity to collect more information about web user, the complexity of the usage data also increases. As a result, traditional page-view based web usage mining methods have become insufficient to fully understand web usage behavior. In order to solve the problems with current approaches our framework incorporates semantic knowledge in the usage mining process and produces semantic event patterns from web usage logs. In order to model web usage behavior at a more abstract level, we define the concept of semantic events, event based sessions and frequent event patterns.