Hi guys
Later this week I have to survey 20 vertical steel columns in a building. The builder is extending the building upwards and needs to know the exact location of the columns so the new floor steel can be designed and fabricated.
Below is a plan view of them. What is the best method to use? I've shot steels using reflectorless in the past and had mixed results. I recently bought some Reflexite tape and was thinking of using it for this project. I work on my own with a robotic total station so shooting horizontal angle offsets for corners would be very time consuming.
Should I get reliable results if I stick targets on the steels? How far off 90 degree can you shoot the targets? Two sides of the steel are difficult to shoot as there is only 3/8" to aim at - what do I do there?
The building is about 30m x 30m or 90 foot x 90 foot.
Any advice warmly received.
Cheers, Andrew
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We used a nodal prism with a 1" S7 for similar work. Any more you have a variety of skill levels on the steel. Find out what they can work with and develop a plan together. Guide them away from stupidity and overkill...
We used a nodal prism with a 1" S7 for similar work.
I don't have access to the tops of the steel columns as there is a roof above them. I'll be surveying from below the tops of the steels - I don't think a nodal prism would work for that? You'd have to do horizontal angle offsets
You are plumbing the steel column. You use the vertical crosshair in a total station for left and right tilt. Then use your reflectorless shots reduced to horizontal distance to verify towards and from direction.
You are plumbing the steel column. You use the vertical crosshair in a total station for left and right tilt. Then use your reflectorless shots reduced to horizontal distance to verify towards and from direction.
I am not plumbing the steel columns. All I need to do is give x, y, and z for the tops of the columns.
I would make a jig that slipped on the column, and 2 points to shoot, say a couple of tenths off of the face, and inline with the flange using my mini-prism.?ÿ You can then easily place a block in cad on those 2 points that would create the center of the column.?ÿ The bonus of that is you are getting a better read on the column rotation then on anything you could shoot on the steel itself.?ÿ Granted everything is up and built already so I doubt rotation is a real issue, but it is nice to check.?ÿ 2 quick shots and you are done.?ÿ If you wanted to get fancy you could place a mark on your jig, mark the column and measure the top offset from your mark - BUT, since you only have 20 to do, personally I would level bottom of the columns, and measure up instead.
does your TS have a retroreflector only mode? If so I would cut the reflexite to fit over a magnet and make a vertically oriented line on the reflexite. Measure the the center of the 206mm face and align the magnet with the reflexite to that line at the point the column hits the ceiling and shoot that point with the TS. If you did that on both 206mm faces you could draw a line and the midpoint of the line would be the center of the column. I buy reflexite in 30yard rolls or 8?x8? sheets and cut it to the size I need.
Dont know if this will work, but I will usually get geometric dimension of each column, then with a reflectorless gun, turn an agle to the left side of the object, then to the right side, average the angle, turn to angle and shoot reflectorless, adding the geometric dimension later...i will even occupy somewhere else if possible and do the same thing to check against it. This is of course easier with a circular column. You can also create baselines to some type of North assumption, and measure due cardinal directions each way from square columns by measuring the geometric shape and marking a center point on each side of the column, then turning down your due cardinal directions and reading a ruler or tape over to the line drawn on the column. This of course can take two or three people.?ÿ
Scan?
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don't have a scanner
Rent/lease one...
I have a few rules for clients that want me to locate existing steel.
1 remove whatever is covering the steel
2 decide what part of the steel to be located, center of column, center of side, what corner
3 remove whatever is covering the steel
4 can not locate what can not see
Shoot every coloumn of steel from every setup/control point and set xtra control outside of construction zone?ÿ
Leave any stickon targets in place forever
