ANALYSIS AND DESIGN OF ANCHOR BOLT WITH CONSIDERATION OF FRACTURE MECHANICS KYUICHI MARUYAMA AND KEIJI SHIMIZU Department of Civil Engineering Nagaoka University of Technology 1603-1 Nagaoka, Niigata 940-21, JAPAN ABSTRACT It was discussed in this paper how the anchor bolt system carried the load, and what was the proper design formula with wide applicability. The authors conducted the pull-out test of anchor bolts which were mounted singly in concrete with embedment length of 4 through 24 cm. With careful observation of the behavior of specimen during test and with measurement of the ruptured cone shape, the stress transfer mechanism was examined. The fracture mechanics was, then, introduced to analyze the micro behavior in the cracked region. Comparing the analytical results with the test results, the authors proposed a design formula for the maximum capacity. INTRODUCTION Post-installed anchor bolts have been widely used for fastening acces sories to concrete structures, and for strengthening the existing structures against earthquakes. A lot of effort has been done to evaluate the pull-out capacity of anchor bolts. The results, however, were limited to short anchor bolts having the embedment length of 10 cm or less. Since the anchorage has become an important problem in reinforced concrete columns or in steel towers, the above study should be extended to large size of anchor bolts. In order to develop a rational model for design purposes, it is necessary to examine the stress transfer mechanism of the anchor bolt system in detail. First, the static pull-out test was conducted on the anchor bolts with the embedment length of 4 through 24 cm. The analysis on the stress transfer mechanism was, then, done with help of the elastic finite element method. In particular, the fracture mechanics was introduced to express the stress condition of concrete near the tip of a crack. Comparing the analytical results with the experimental ones, the stress transfer model was proposed and the discussion was extended to the load-bearing mechanism of anchor bolt. Based on the findings, a rational equation was proposed for estimating the ultimate capacity of anchor bolts.