Alternative Support Systems for Cantilever - National Transportation ...
Alternative Support Systems for Cantilever - National Transportation ...
Alternative Support Systems for Cantilever - National Transportation ...
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in<strong>for</strong>mation obtained in the late 1960s and late 1970s (4). The updated anchor bolt in<strong>for</strong>mation<br />
contained in Report 411 included an Appendix C which addressed minimum embedment length<br />
of headed cast-in-place anchor bolts, effect of edge distance, and the effect of spacing between<br />
anchor bolts (4). However, Appendix C of NCHRP Report 411 was not included in the 2001<br />
<strong>Support</strong>s Specifications (2).<br />
A second phase of Project 17-10 was initiated and published as NCHRP Report 494 in<br />
2003. NCHRP Report 494 addressed additional updates to the <strong>Support</strong>s Specifications. In<br />
NCHRP Report 494, further in<strong>for</strong>mation is provided regarding anchorage to concrete. In addition<br />
to restating the in<strong>for</strong>mation in Appendix C of NCHRP Report 411, NCHRP Report 494 provided<br />
a simplified design method <strong>for</strong> design of anchorage to concrete based on the then recently added<br />
Appendix D to American Concrete Institute (ACI) 318-02 (2). The simplified design method <strong>for</strong><br />
anchorage required the following conditions be met (2):<br />
• Anchor bolts be hooked or headed<br />
• Foundations have vertical rein<strong>for</strong>cing steel and vertical confinement, with anchor bolts<br />
placed inside of the rein<strong>for</strong>cement<br />
• Foundation rein<strong>for</strong>cing steel is uncoated<br />
• If hooked anchor bolts are used, the length of the hook is at least 4.5 times the anchor bolt<br />
diameter<br />
The simplified design method would design the diameter and bearing area of a headed<br />
anchor or the required anchor bolt diameter of a hooked anchor as well as the bolt length so that<br />
the failure plane would intersect the foundation’s rein<strong>for</strong>cing steel below the point at which the<br />
rein<strong>for</strong>cing steel is fully developed (2). The transfer of flexural moment is thoroughly addressed<br />
in the simplified design method through its treatment of tension. While the simplified method<br />
does well to address anchor bearing on concrete, it makes the assumption that if confining<br />
rein<strong>for</strong>cement is provided, failure by concrete breakout and concrete side-face blowout can be<br />
5