Some non-frame options that come to mind ...
You could use AJAX to load content into a container. I can't imagine this would be good for SEO. I think you'd be making accessibility an uphill battle as well. It should be easy to maintain content.
Depending on how much content you have you could have each 'page' in a div and then toggle between them as users navigate the site. After a while you will find your page difficult to maintain unless you're using includes of some sort but you'll also likely find your single page bloated and taking a long time to download.
I don't think either of these options would allow your users to easily bookmark locations on your site. You'd need to add that functionality in.
Any particular reason your menu needs to be loaded only once? You may find it easier to refactor your menu as opposed to accommodating its requirements with the rest of the site.
hth