Steelcad Drafting model all of their structures in Tekla Structures – a 3D modelling software.
Layout points can be captured in the model and exported to a format read by most of the survey equipment being used on sites today. The format exported is in X-Y-Z coordinates.
Layout points can be used for site setout of:
- Grid setout
- Position and size footings for excavation
- Strip footing setout
- HD bolt positioning
- Masonry Anchor setout
- Precast Panel setout
- Steelwork Setout points
Conversely to the setout of a site; Information from site can be imported into the Steelcad model for verification purposes. The As Built Layout Points are reviewed against the model and decisions can be made on how to best work with what has been built on site.
In this case below, the red markers indicate the As Built positioning of a footing and HD bolt group. A revision to the length of the column and base plate to match the As built would be a solution to best rectify this situation:
Point Cloud Surveying
Point Cloud data can also be captured from site, referenced into the Steelcad model for site verification and the purpose of adding to As Built structures. In the image stream below, a shopping center entry has been captured and new steelwork is modelled to fit.
Interface Steelwork modelled over points:
New Steelwork Added in red:
More steelwork added in red:
New steelwork will be Detailed for fabrication and Erection drawings produced to locate new steelwork and details drawn for site rework.
3D Survey of As Built
The government building 1 William Street in Brisbane has a 90 meter spire at the top of the building. The spire is made from cylindrical and conical rolled steel plate and spliced @ 6 intervals along the shaft.
It is fixed to the building at two levels on the structure by bolting to HD bolt cages comprising of 32 M30 bolts.
The spire also has two steel box stubs, one bolting to the HD bolt cage and the other and intermediate piece between the primary stub and the spire its self.
Each connection to the structure and the splices all add possibility for constructibility error in erection of the steelwork.
The spire went together without incident because of the close working relationship we had with the builder, rigger and fabricator.
- Once the HD bolts were cast and the floor given time to settle, the HDs were surveyed in 3D and that information transferred into our model for verification. Any errors in HD bolt location were corrected in the primary stub.
- Once the primary stub @ the lower level was bolted on and torqued up, the end plate and holes for the secondary stub were surveyed and that information transferred into our model for verification. Any errors in the end plate position was made good by reworking the drawings for the secondary stub to match.
- The same process was also undertaken for the upper stubs and then a vertical check between stubs to check overall setout between these two critical points.
As the spire was being erected, a survey was taken of the mating faces to check the alignment of the as built, to determine how to approach the next lift.
Some images of our model and the survey overlays are below:
Every millimeter of error was carefully considered and discussed between the team to ensure the spire went together on site without a problem.