Open Page in New tab of Same browser with update panel C#.NET

Try this on Any event such as button click,dropdown_SelectedIndexChanged.......etc i am sure it is work for you...........

ScriptManager.RegisterStartupScript(Page, typeof(System.Web.UI.Page),
                     "click", @"<script>window.open('StudentProfile.aspx','_newtab');</script>", false);