i did something like this with glass block infill. i put a block-width rabbet along the outside edge of the timbers and set the bricks into that. this gave a clean wood to glass fit. a strip of expansion foam is the insulation inside the rabbet. used galvanized strapping anchored to the post and set in the mortar every 3rd course, much as Ken said. i'd do this again- one change i'd make though would be to align the braces against the inside of the timber and inside of the blocks- infilling against the 45 was picky (my wife made some fused glass 'shelves').