Greetings,
A friend of mine called this morning and asked if I had seen one of the building construction shows which depicted a new multi story high rise under construction where the project surveyor was able to maintain control of the different floors by having a tube inserted into the floors and a beam or total station shot was shot thru the tube upwards to the next floor to a reflective target which was positioned over the red dot.
This procedure was done in a couple places on each floor from ground level to the top floor.
In this case, the total station was setup over one of the tube/target points and then a shot was taken on a second tube/target point to reference or orintate the instrument and some secondary shots were taken on other tube/target points as a check.
He is working on a 30 story tower building and as you may know, seeing your ground control as you get higher up can be a problem especially on fog or rain/snow days.
Has anyone seen the program and what was the name of the system being implimented.
Thanks
Bob
Laser plummet?? or you could use an optical plummet
Scott Zelenak posted extensively on this subject on RPLS.
I think they use a specialized tool for this.
>I think they use a specialized tool for this.
Wild or Leica ZNL. It is like a super-duper precision optical plummet, maybe 1:20,000 or better.
They aren't cheap, as shown by this discussion.
An old discussion of this topic.
There are numerous things you have to be concerned about.
Is there a superelevation plan?
What is the predicted compression?
Is there floor camber?
Will the floor finish be raised or slab?
Will there be shim plates in the field splices?
What are the tolerance for the floor stops?
What are the tolerances for the facade clips?
What are the tolerances for elevator rails?
Are there high speed elevators?
If you don't know enough to ask question like that and more, you don't know enough to take the job.
High rise construction is a case where, what you don't know, can really bite you where you'd rather not be bitten.
Actually, the latest technique discussed here involved using RTK in the elevator...
_
LOL !!!!
radu
The only "high rise" construction show I ever saw was LA Hard Hats.
The surveyors were highlighted breifly and from what I remember they were projecting control from adjacent rooftops. It seems that the horizontal specs for placement of utilities and such in the building were of primary concern, at least in the episode I saw.
Hope this helps.
Hi guys,
I guess I ahould have been a little clearer. The show apparently was of a building in Sweden and they were projecting the horizontal control points vertically thru the flow and not the vertical control.
I did a Google search and nothing has popped up yet.
I'll let you know if I find something. My friend was looking at another option other than the external control points located off site. This is in downtown Milwaukee and long backsights are eliminated as you go up in floors.
He did a 40 story building a few years ago and fog and mist along the lake caused alot of delays in the layout because they couldn't see the BS targets 3 blocks away.
There seemed to be a little bit of semantics problem in this thread from the top.
Vertical control: means to me "elevation" and 'differences in elevation'.
Horizontal control would be xy position.
So if one is trying to push a correct xy position up vertically, that is NOT what most people would consider 'vertical control'. However facing the problem one can imagine how someone could call it that, i.e. 'controlling how vertical these various elements are.'
Nevertheless when you say vertical control I would immediately assume you want to carry elevation up the structure. Not horizontal or plumb.
just a thought after the fact. Controlling a vertical alignment is not vertical control in the normal lexicon of survey lingo.
In fact what you seem to be describing is actually "Extending horizontal control thru (sic) floors"
- jlw
I traversed once in dense fog and used a high beam light behind the backsite and foresite and had great angular closure results.
I can agree with Scott about the variables that come with high rise elevations.
The main steel falls in place and much of the rest is an as you go procedure. You measure what item you have and determine how it fits into your building.
Give me tall trees any day over a high rise.
The wild / Leica ZNL was the way to go, but have long been discontinued.
Sokkia has a speciality laser LV1, 5" plum and 10" up to 100' for around 3,700.00
or you can take a Total Station with a stovepipe eyepiece, point the telescope to zenith, level up using the compensator to 1"-3" and have the guy on the next floor above mark the spot on a clear plastic target. You could then reset up over the target and go vertically from floor to floor. the higher you go the more the compensator will tilt and change, so you need to take that into consideration as well.
PSS man
Vertical to me is elevation, so I guess shooting vertical with a total station could be used, I wonder if there would be problems shooting through a series of holes affecting accuracy. The only tall tower I worked on, 240 feet cement plant building, we just hung a steel tape and used a level to take off the readings, mm accuracy between floors not really critical.
One interesting horizontal control of a vertical structure was slip forming some large silos. On the base floor they set some cans to hold a vertical laser around the inside of the wall. They set some targets on the slip form work. As the silo went up, a long continuous concrete pour (days), ever so often they would move the laser around the base cans and note where the beam hit the targets. The guys going the job knew what to do to correct and keep the silo going up vertical and also control the tendency of the forms from twisting. Kind of fun to watch other than the long hours.
