Description:
This one-day seminar was presented by Dr. S. K. Ghosh of S. K. Ghosh Associates Inc. and John Silva, S.E. of Hilti North America in Southern California in August 2008. This seminar provides an overview of the anchor design provisions in Appendix D of ACI 318-05, presents design examples, and points out some of the difficulties facing designers, particularly when it comes to seismic design of anchors.
Cast-in-place anchors into concrete that are subject to seismic design forces could, before the adoption of the IBC, be designed by the allowable stress design method or the strength design method of the UBC and the other two legacy codes. They must now be designed in accordance with the strength design method in Appendix D of ACI 318-05.
The seminar illustrates the four different failure modes for a group of anchors subject to tension and three different failure modes for a group of anchors subject to shear, and the calculation of the corresponding anchor strengths through a design example. The related detailed provisions of Appendix D are introduced and discussed in the course of presenting the example. The strength of an anchor or a group of anchors subject simultaneously to tension and shear is also discussed, as well as the prevention of splitting failure. Post-installed anchors used to be outside the scope of anchor design provisions in legacy model codes.
Post-installed mechanical anchors are included in the scope of ACI 318 Appendix D, and post-installed adhesive anchors are addressed in ICC-ES acceptance criteria that reference ACI 355.2. The seminar addresses the types of post-installed anchors addressed by the code and by the relevant ICC-ES acceptance criteria, as well as conditions not explicitly addressed by the code. The qualification of proprietary anchor types under ACI 355.2 is reviewed, and the use of data provided in ICC-ES Evaluation Service Reports in conjunction with the provisions of Appendix D is addressed. Design situations addressed include single anchors, anchor groups, anchors near edges, and special cases (sill plates).
