try this JQUERY
first give the id  to your ul
<ul class="nav nav-tabs" id="nav_tabs">
then use jquery
$(document).ready(function(){
    $('ul#nav_tabs li a').each(function(index, element) {
        var li = $(element).attr('href');
        $(element).parent().removeClass("active");   
       var filename = window.location.href.substr(window.location.href.lastIndexOf("https://stackoverflow.com/")+1);
        if(filename==li)
        {
                $(element).parent().addClass("active"); 
        }
    });
});
also you can use PHP as
<?php
$my_url = $_SERVER['REQUEST_URI'];
$page = substr($my_url, strrpos($my_url, "https://stackoverflow.com/") + 1)
?>
<ul class="nav nav-tabs" id="nav_tabs">
    <li <?php if($page=="https://stackoverflow.com/questions/21477563/admin.php") echo 'class="active"'; ?>><a href="https://stackoverflow.com/questions/21477563/admin.php">{"_MENUINFO"|lang}</a></li>
    <li <?php if($page=="admin.php?site=ban_add") echo 'class="active"'; ?>><a href="admin.php?site=ban_add">{"_ADDBAN"|lang}</a></li>
    <li <?php if($page=="admin.php?site=ban_add_online") echo 'class="active"'; ?>><a href="admin.php?site=ban_add_online">{"_ADDBANONLINE"|lang}</a></li>
</ul>
1
solved Jquery add li class active