Layout work is increasingly being performed by using total stations. They're fast and very accurate, and robotic total stations make it a one-person job.
Layout piece of work is increasingly existence performed by using total stations. They're fast and very authentic, and robotic full stations brand information technology a one-person task.

Setting ballast bolts may sound like a simple chore in preparing a slab or foundation for placement. Just for industrial/commercial physical contractors it can get a very complicated and of import particular. Some contractors are selected specifically because they can accurately and efficiently set ballast bolts for heavy machinery and steel columns. Locating and installing anchor bolts can have a tremendous touch on the rest of the project. Here are some of the steps that professionals take.

Layout

Two silos holding fly ash will be anchored to this mat slab. The circular templates will hold the anchor bolts for securing the tanks.
2 silos property fly ash will exist anchored to this mat slab. The circular templates will concord the ballast bolts for securing the tanks.

When Lavy Concrete Construction, Piqua, Ohio, decided to purchase a robotic total station (a surveying instrument that combines the features of a digital theodolite and electronic distance measuring (EDM) engineering science) for its commercial/residential physical foundation business, it also began working for other construction companies to lay out anchor bolts for machine pads and steel columns. Ben Lavy, the company's layout specialist, says they showtime past drawing out the locations with calculator assisted design (CAD) software, correcting whatsoever errors on plans, and making the inevitable changes that occur in most projects. Dimensions are included for all anchor bolt locations, which CAD automatically converts to x-y coordinates. The coordinates are loaded into the data collector of the robotic full station. Then the layout person does the layout work lonely on the jobsite.

Traditionally ballast bolts are located past string line and tape measures, simply Lavy says accuracy, efficiency, and consistency are greatly improved with total station technology. Human error and cumulative errors are greatly reduced compared with record measured layouts. Lavy's goal is accurateness inside 1/viii inch of the true point on most projects, but he tin can get closer tolerances.

Positioning and securing

Anchor-bolt assemblies are securely positioned with welded template supports. The bottom rebar is set before the anchor bolts are positioned, then the anchor bolts, and finally the top rebar.
Ballast-bolt assemblies are securely positioned with welded template supports. The bottom rebar is prepare before the anchor bolts are positioned, then the anchor bolts, and finally the summit rebar.

Setting anchor bolts can exist as like shooting fish in a barrel as cutting out a plywood jig to hold the bolts and positioning the assembly simply above a slab during physical placement. More precision requires much more than elaborate methods. Brian Long, a superintendent for Lindblad Structure, Joliet, Ill., specializes in highly accurate anchor bolt placements. His company'southward goal is to practice the job right then that remedial action isn't needed after concrete is placed.

Long says that the length of an ballast commodities is of import, besides. Shorter bolts are much easier to secure than longer ones. In either case, before piece of work starts in the field, Lindblad constructs CAD shop drawings for each of the templates needed for a projection. Its steel fabricator uses the CAD files to guide the machines in the product of extremely accurate templates from ¼-inch-thick steel plate. The templates hold the ballast bolts, and usually two or three template plates agree each anchor assembly in position.

For this assembly, universal strut was used to position the anchor bolts, and there were no steel templates.
For this assembly, universal strut was used to position the ballast bolts, and in that location were no steel templates.

On the jobsite, concrete "mud mats" are kickoff cast under the slab. Layout on the mud mats locates the position for the templates. Long says his company hires surveyors who use theodolites to locate the centerlines in both directions for the templates. With the centerlines marked on the mud mats, workers tin can employ tape measures to mark out the template locations.

After locations are marked, rigid steel frames are erected and bolted into the mud mats to concord the templates at the proper position and elevation. Depending on the size and complication of a template, either bending-iron or universal strut is used to build the frame. The final step is checking. Past setting lines at the top of a slab on the template middle marks, workers can easily check to see that the positioning is right.

Even though anchor bolts are very secure when physical is being placed, Long says the placing crew is told: "Don't touch the anchor bolts." There is constant monitoring during placement. Long adds that it'south helpful to have the same concrete crew for each placement.

The process starts with the installation of mud mats. Layout is done, and framework for the anchor bolts is bolted into the mud mats so that there is no movement during concrete placement.
The process starts with the installation of mud mats. Layout is washed, and framework for the anchor bolts is bolted into the mud mats so that there is no movement during physical placement.