With the concrete poured a little above grade and the post clip added to the bottom of the posts, you have a good set up for long lasting posts. The biggest thing will be is, you will need to provide bracing so the pergola does not rack.
The concrete footings were built up to create a nice square, raised post bases. This keeps them out of any possible standing water. The pergola pictured is an attached design so there are just two posts secured into the ground.
Previously, you would dig a hole for each post and pour a concrete footing at the bottom of each hole for each post to set in. Once the concrete had set, you would build the pergola on the posts.
So, based on my experience, I never let a post touch soil or concrete unless I absolutely need to. E.g., with fence posts, you don't have an option. For a pergola, I would keep the posts above ground and use any of various common techniques to resist lateral loads you mentioned one .
what's the material for your posts? secondly, if using stirrups onto concrete pads, is this a free standing pergola? whats to stop lateral movement of posts-on-stirrups? thirdly, 10.5m / 5.3m is quite a large structure. whats your soil/subsoil like in pakenham, do you have soil test details to tell you how far your footings have to go down?
Smarter post footings for your landscaping projects. The GroundPlug Easy Mounting System TM is suitable as pergola footings, trellis anchoring and arbor footings. The GroundPlug Twister TM footings are easy to use, fast installable and more durable than concrete footings.
So Im considering a floating deck. I think this could work, but Im wondering about footings for the pergola posts. Should the pergola posts be anchored to the ground with concrete piers, while the deck floats around it? I can position the pergola so that its clear of the septic line. Or should be posts and the deck be allowed to move