Presuming concrete frame, as soon as the formwork deck is stabilized, you are up there with a harness and retractable at the edge getting line from control on the ground. Then you tape control, snap lines on the deck for trades. Ideally agreed upon offsets because the trades get measurements from their office to simplify and reduce errors, but often the progress of the carpenters nullifies this pipe dream. You are about to get buried by rodbusters.
As soon as you can walk on the freshly poured slab, throw control up there again and drag a tape for vertical because here they come. Sometimes that is 4 AM.
Meanwhile, post-tensioning is about to proceed, which wracks the slab. Columns never perfectly stack.
Eventually tower cranes get tied off to the structure, amplifying sway. Split the difference and work off hours.
Throw control up from the ground and keep it as simple as possible. Back in the day we did that with a theodolite and offsets, the guy up top with a piece of painted, marked up emt conduit. Doubling is fun with a 90 degree eyepiece.
Eventually, you have to give way to block-outs, but that is only feasible incrementally, say in five story bursts, as trades progress and the need to return to ground control.
Shaft construction is ideal for deck blockouts, aircraft cable and a concrete test cylinder cast with an eyebolt suspended in a bucket of water. As so is high-rise core/elevator shaft construction but incrementally.
On low to mid-rise, I know guys who use blockouts and a plumb laser (almost said PLS) to transfer control from the ground, rotating it for a mean and casting it to a taped down piece of plexiglass.
For a real PLS, anything beyond control and monitoring, don??t touch it. These guys don??t care. That missed blockout someone mentioned? Pft! They ain??t waiting for you to re-establish control.
As for elevations, we brought them up floor to floor but tied it to the ground every few floors. Marking elevations on a tower crane is handy. The design is from the ground floor which includes precast or other pre-constructed skins. Compression of concrete is significant above twenty stories as I have only seen it considered on a 45 story for which a PLS was hired to monitor, but then, that is a design concern for the engineer, not a floor to floor dimension concern for line and grade.
As I have only five useful years left in me, I hope never to do elevated work again.
I was a fresh out of school engineer. The layout surveyor was an uneducated acholic. I helped him layout the piers for a rotating kiln with a 100 foot steel tape and a Hilger Watts 20 second theodolite. Neither the chain or the theodolite had ever been calibrated. We pulled the chain by feel. When the kiln was set on the towers after they were built, the rings on the kiln missed matching the rollers by about 6 inches. The Superintendent made a big deal out of that. About two months later when they lit the fire in the kiln it expanded and the rings were exactly centered on the rollers. To this day I don't know how he did it. No computers, not even a calculator.
?ÿ
I went on to be a road building engineer. Our motto was survey it to a hundredth, design it to a tenth, and build it with a D9 Cat.
@dmyhill?ÿ
Here's some information on the Empire State Building that I learned earlier today, by coincidence.
https://en.wikipedia.org/wiki/1945_Empire_State_Building_B-25_crash
@holy-cow my Dad was a retired Naval Aviator.
Besides Cal drinking songs another favorite was a spoof on the USAF song: Off we fly into the Empire State Building CRASH!
I've done several 4 story buildings and one of 14 stories. In every case I used control on the ground and resected the instrument positions as required on the deck. Usually the control was across the street but in the case of the 14 story job it was a block away.?ÿ Frequently you can find a corner shear wall that you can get the 3 legs of the tripod footed on. If not it still works out alright. As Tim V. said the necessary precision is not extraordinary.?ÿ ?ÿ?ÿ
@jonathan50 what you say is true, Engineers don't want to hear it and will be the first to point a finger when things go south.?ÿ Contractors will also immediately deflect blame when they build things wrong.
As Surveyors, we should always make sure that we document everything we do so that when something gets built wrong, we can instantly pull up out data and prove that things were not built as they were laid out.?ÿ When my points layout points are within tolerance of where they should be, I'll look them straight in the eye and tell them that their sloppy measurement are not my problem.
I stake building envelopes, not actual building corners.?ÿ It's the contractor's responsibility to pull whatever measurements they need to to dig the hole and construct footings, including setting their rebar in the footings prior to the pour.?ÿ Some of the holes are 15' or deeper depending on the building.?ÿ Without fail, they will call us back to pin the footing and 50% of the time, my footing pins don't match what they poured.?ÿ The first reaction is that it is my fault.?ÿ When that happens, I will bring the Engineer, Contractor and Site Manager into my office, reprocess my raw field collected data for both the layout and my pin locations, then, show the X, Y, and Z deltas showing how much the footing was off.?ÿ After that it turns into money that I would rather not make because I have to work with the Project Engineer to figure out how to make what was built work.?ÿ Lot's of time and aggrevation involved in that process while new jobs are stacking up.?ÿ?ÿ
That's why the contractor I work for hired people like me to take care of the layout every step of the way, from excavation , footing and rebar layout, to form setting for walls, openings and anchor bolts. They?ÿ never had to re-do, or fix anything so long as I had the correct information at the time the work was performed. We usually get a few offsets for the building in the beginning and a benchmark, after that it is our job to build things the right size and in the right place. After a few days on the job I develop a mental picture with the shape and size of all items including rebar type and anchor bolts. The hardest thing is,?ÿ when starting a new job, you have to forget everything about the previous one.?ÿ
@jonathan50 what you say is true, Engineers don't want to hear it and will be the first to point a finger when things go south.?ÿ Contractors will also immediately deflect blame when they build things wrong.
As Surveyors, we should always make sure that we document everything we do so that when something gets built wrong, we can instantly pull up out data and prove that things were not built as they were laid out.?ÿ When my points layout points are within tolerance of where they should be, I'll look them straight in the eye and tell them that their sloppy measurement are not my problem.
I stake building envelopes, not actual building corners.?ÿ It's the contractor's responsibility to pull whatever measurements they need to to dig the hole and construct footings, including setting their rebar in the footings prior to the pour.?ÿ Some of the holes are 15' or deeper depending on the building.?ÿ Without fail, they will call us back to pin the footing and 50% of the time, my footing pins don't match what they poured.?ÿ The first reaction is that it is my fault.?ÿ When that happens, I will bring the Engineer, Contractor and Site Manager into my office, reprocess my raw field collected data for both the layout and my pin locations, then, show the X, Y, and Z deltas showing how much the footing was off.?ÿ After that it turns into money that I would rather not make because I have to work with the Project Engineer to figure out how to make what was built work.?ÿ Lot's of time and aggrevation involved in that process while new jobs are stacking up.?ÿ?ÿ
That's why the contractor I work for hired people like me to take care of the layout every step of the way, from excavation , footing and rebar layout, to form setting for walls, openings and anchor bolts. They?ÿ never had to re-do, or fix anything so long as I had the correct information at the time the work was performed. We usually get a few offsets for the building in the beginning and a benchmark, after that it is our job to build things the right size and in the right place. After a few days on the job I develop a mental picture with the shape and size of all items including rebar type and anchor bolts. The hardest thing is,?ÿ when starting a new job, you have to forget everything about the previous one.?ÿ
That's a critical item that seems so simple but slips by a lot of surveyors and their clients.
We get lots of construction work where they want us to be on-call and immediately available, but only for a limited number of layout items, and they don't want us to work a minute more than necessary. As a result we will often have several of these projects going on at once to keep crews busy, and sometimes go weeks or even months between site visits, and sometimes it's a different crew due to scheduling issues. Plans change, stuff gets field-fitted or field-engineered, control gets wiped out, and we have very little connection to the day-to-day operations. So we have to re-orient to the site each time. Being out of the loop means there's a much higher chance of something going sideways, which leads to slowdowns, reworks, backcharges and animosity.
I try to avoid that type of situation, but construction work is still pretty lucrative for my employer so we just have to deal with it.
@larry-best yes, I was going to say the same about Leica
One of the reasons why I hate and don't do construction work is the difficulty in dealing with engineers and foremen.
And Architects!
I work on major civil jobs but I have never done a high-rise before, just a few multistories which were nicely enough apart to observe across from one another without any harsh angles. ?ÿ
But this is a good presentation for high-rise survey problems, solutions, methods etc: