Order posts alphabetically using the posts_orderby hook

gistfile1.aw

<?php

add_filter('posts_orderby', 'blog_change_sort', 10, 2);

function blog_change_sort( $orderby, $query ) {

    // Only modify main query
    // On the tutorial category page
    if( $query->is_main_query() && is_category('tutorials') ) {
        return "post_title ASC";
    }

    return $orderby;
}

?>