Hi,
looks like chemical or resin anchors then! They are great when used properly.
Mark the bolt positions very accurately and predrill. Use an airline to blow the dust out, or a small tube duct taped onto the end of the wife's vacuum cleaner to suck it out before any resin anchor bolts are used. Ideally the top of the concrete base would be set lower than the theoretical level. On most general steel structures we allow 25mm grout thickness and 100mm bolt projection to provide a generous tolerance as most ground workers mess up the levels. Anything is better than nothing though. Normally mild steel shims of about 100mm x 50mm are placed at the centre of the base and accurately levelled, then finally the column goes on top and gets bolted down. It depends on the circumstances whether you drill and fix the bolts before or after erecting the steel. I recently built a steel framed workshop at home where I drilled and fixed after erection as there was nothing that needed the bolts to provide stability during erection, everything was tied together by other members or temporary bracings.
It is a potentially dangerous time once the column is bolted to the base if it starts getting blown over or gets hit by anything as there are the tremendous forces trying to pull the bolts out of the ground. Stay clear of unsupported columns! Think of the mechanical leverage a long column has over your little bolt group at the bottom. So, get the column tops tied to something very quickly and be very careful until they are. I have seen columns pull out holding-down bolts and it isn't pretty. Structural engineers don't always consider these temporary issues when designing the hd bolt groups, they are usually more inclined to consider the working loads. In some circumstances expanding bolts give you that instant fix that chemical anchors don't.
Once everything is aligned, plumb and level, make some simple timber frames around the base plates and pour in a runny sand/cement grout so that it fills the voids. It's purpose is to spread the load from the flat column baseplate onto what is a very uneven surface of concrete. That is why a void under the column is highly preferable to a close fit.
As an aside, talking about resin anchors reminds me of an incident I remember from many years ago. I was working on a job where we had a steel erector who got upset at a former employer who owed him money. He allegedly 'borrowed' a load of tubes of the two-part chemical resin we were using to fix stainless steel bolts into tunnel liners and paid the guy a nocturnal visit where he apparently injected it around his car doors. Not really sure how that saga ended but I'll bet if he really did it, they would have had to grind the doors off.
regards
