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    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
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      <title>RES2020-14: Design Considerations and Limitations of Rock Dowels/Anchors 
Loaded in Shear</title>
      <link>https://rip.trb.org/View/1851967</link>
      <description><![CDATA[In Tennessee, cut rock slopes with exposed discontinuities are often reinforced with grouted steel anchors
installed across the discontinuity to stabilize the system by immobilizing the rock material above the sliding
surface. These elements resist shear loading rather than function in tension. Yet, the steel bar may bend in cases
where the discontinuity is sufficiently large. The purpose of this study was to investigate the performance of
simulated un-tensioned dowel-jointed rock block systems subjected to shear loading and evaluate whether bending
likely occurred as well as its contribution to the reduction in dowel capacity. Variables studied were aperture size
(joint spacing), dowel diameter, and dowel angle of inclination with respect to the joint normal. Physical
experiments were conducted using large concrete blocks to simulate the jointed rock material, steel rebars to
simulate the dowels, and tested in a large-scale direct shear apparatus. A numerical model was developed to extend
the dowel size and joint thickness. A dowel shear capacity design chart was also developed. The chart identifies
the threshold between the pure shear capacity and the reduced capacity due to bending effects as a function of joint
thickness and bar size. Conclusions from this study include (1) rebar double bending phenomenon was inferred
from strain gage data in the case of a large aperture size, (2) bending starts at an aperture size relative to bar
diameter and strength, and reduces the dowel shear capacity by a quantity related to bar size and aperture size, (3)
all results from physical and numerical analyses show sufficient agreement with the governing equations for
theoretical dowel shear and bending conditions to warrant the conservative use of the developed design chart (4)
dowel inclination angle had little influence on ultimate shear resistance, and (5) free and fixed dowel placement
show no significant difference in resistance.]]></description>
      <pubDate>Tue, 11 May 2021 18:22:21 GMT</pubDate>
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