The design of column base anchorages for shear and tension

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Virginia Tech

A unified and consistent design procedure is proposed for column base anchorages loaded in shear and tension. A literature review of previous work was done to identify discrepancies. A design procedure for anchorages loaded in shear, tension and combined shear and tension was developed which attempted to coordinate c;lnd resolve the discrepancies in previous work. A design methodology utilizing shear lugs was developed. The overall design procedure is for column bases loaded in shear and tension and uses two design methods:

Method 1: Headed anchor bolts are used to resist both shear and tension Loads. Method 2: A shear lug welded to the bottom of the base plate resists shear loads and the headed anchor bolts resist only tension loads.

The proposed design method differs form the design method used by Shipp and Haninger (Reference 23) as follows:

  1. The proposed procedure incorporates both shear and tension design stress based on the ultimate strength of the anchor bolts times a reduction factor.
  2. Separate capacity reduction factors are introduced for shear and tension.
  3. The use of shear lugs is incorporated in the proposed design.
  4. The incorrect use of the "shear-friction" concept is noted and not used in the design.
  5. The safety factor for the required embedment depth is applied to the projected area of the failure cone not the embedment depth of the bolt.

Several design examples are presented using the two methods. A computer program (using Microsoft QuickBasic 4.0) has also been developed using the proposed design procedure.