This information applies to the American Steel Industry
(Center of Standard Holea to Edge of Connected Part)
|At Rolled Edges of
Plates, Shapes or Bars
Gas Cut or Saw-cut Edges b
|7/8||1 1/2c||1 1/8|
|1||1 3/4c||1 1/4|
|1 1/8||2||1 1/2|
|1 1/4||2 1/4||1 5/8|
|Over 1 1/4||1 3/4 x Dia.||1 1/4 x Dia.||a For oversized or slotted holes, see the table below.
b All edge distances in this column may be reduced 1/8-in. when the hole is at a point where stress does not exceed 25% of the maximum design strength in the element.
c These may be 1 1/4 in. at the ends of beam connection angles.
Hole sizes for steel-to-steel structural connections are not the same as hole sizes for steel-to-concrete anchorage applications. In the case of steel-to-steel connections, the parts are made in a shop under good quality control, so standard holes (bolt diameter plus 1/16"), oversized holes (bolt diameter plus 3/16"), and short and long-slotted holes can be used quite successfully. However, the field placement of anchorage devices has long been subject to more permissive tolerances (and often, inaccuracies that exceed those tolerances anyway and may require consideration by the structural Engineer of Record).
AISC published Steel Design Guide Series 1, Column Base Plates back in the early 1990s. At that time, it was recognized that the quality of foundation work was getting worse and worse. To allow the erector (and designer) greater latitude when possible, the permissible hole sizes in base plates were increased. These same larger hole sizes were included in the 2nd ed. LRFD Manual. The values there are maximums, not a required size. Smaller holes can be used if desired. Plate washers are generally required with these holes because ASTM F436 washers can collapse into the larger-sized holes, even under erection loads.
The larger hole sizes are primarily intended for the majority of base plates that transfer only axial compression from the column into the foundation. The anchor rods don't usually do much after erection in that case.
To allow for misplaced bolts, holes in base plates are oversized. The AISC Manual of Steel Construction recommends the following oversized hole diameters for each bolt diameter:
|Bolt Diameter||Hole Size|
|1 1/4||2 1/16|
|1 1/2||2 5/16|
|1 3/4||2 3/4|
|2 1/2||3 3/4|
AISC, Steel Design Guide Series 1, Column Base
Plates, suggests that using oversize holes meeting
these criteria may still not accommodate field variations
in anchor bolt placement and suggests adding
1/4 in. to the hole diameter listed. The guide recommends
using a heavy plate washer over the holes.
The AISC Structural Steel Educational Council cites
the following example: "If bolts are misplaced up to
1/2 inch, the oversized base plate holes normally
allow the base plate and column to be placed near or
on the column line. If the bolts are misplaced by
more than 1/2 inch, then corrective work is
Based on AISC oversize holes, the AISC Structural Steel Educational Council recommendations, and concrete contractor anchor-bolt placement techniques, ASCC (American Society of Concrete Contractors) concrete contractors recommend the following tolerance for each bolt location:
Need drafting work?
We are having great success with Freelancer.com. With this website we can win all types of drafting work. People from all over the world are looking for freelancers skilled in AutoCAD, Revit, Civil 3D and Microstation, are you one of those people? If so you can live the freelancer lifestyle! and work from any location you want too. Freelancer.com, it works really well - we like it - and we believe you will too.
Looking for CAD drafters?
With modern construction, software and increased legal requirements, we often require specialized assistance with our projects. Putting skilled staff on full time is not always economically feasible for small businesses. Freelancer.com solves this problem. On this website you can engage skilled drafters. Either on fixed prices for specific tasks, or reasonably priced hourly rates for longer term contracts.
E-book: AutoCAD Block Best Practices
We draw repetitively when using AutoCAD. If we manage the drawing elements as reusable contents, it will increase our productivity significantly. Not only can we draw faster, we can add information to our blocks. Which allows us to generate useful reports. This is what Edwins e-book entitled AutoCAD Block Best Practices is all about. Yes, increase your productivity with the block!
|Turning arrows.zip||Span direction.zip||North point.zip||North point1.zip|