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Home > Publications > International Concrete Abstracts Portal
Showing 1-5 of 11 Abstracts search results
Document:
16-236
Date:
November 1, 2017
Author(s):
R. Nilforoush, M. Nilsson, L. Elfgren, J. Ožbolt, J. Hofmann, and R. Eligehausen
Publication:
Structural Journal
Volume:
114
Issue:
6
Abstract:
An extensive numerical study was carried out to evaluate the influence of concrete member thickness and orthogonal surface reinforcement on the tensile capacity and performance of anchor bolts in uncracked concrete members. Anchor bolts at various embedment depths (hef = 50 to 300 mm [1.97 to 11.81 in.]) in unreinforced and reinforced concrete members of various thicknesses (H = 1.5 to 5.0hef) were simulated. The reinforced concrete slabs were considered to be lightly reinforced and over-reinforced to also evaluate the influence of amount of reinforcement. Furthermore, the behavior of anchor bolts at various embedment depths in precracked reinforced concrete members was numerically investigated. The numerical results were compared with predictions from current design models, including the Concrete Capacity (CC) Method. The numerical results show that in uncracked concrete, the tensile capacity of anchor bolts increases up to 20% and the anchorage behavior becomes more ductile with increasing member thickness or by having surface reinforcement. The numerical results also show that the CC Method underestimates the tensile capacity of deep anchors (hef ≥ 200 mm [7.87 in.]), while it slightly overestimates the capacity of short anchors (hef ≤ 100 mm [3.94 in.]) in thin unreinforced members. It was also found that the over-reinforced concrete does not improve the anchorage capacity and performance any further than the lightly reinforced concrete. Based on the numerical results, several recommendations are proposed to account for the influence of member thickness, surface reinforcement, and cracked concrete. Further experimental studies are ongoing to verify and generalize the recommendations of this study.
DOI:
10.14359/51689505
110-S06
January 1, 2013
Derek Petersen and Jian Zhao
110
1
Existing design codes recommend hairpins and surface reinforcement consisting of hooked bars encasing an edge reinforcement to improve the behavior of anchor connections in shear. Concrete breakout is assumed to occur before anchor reinforcement takes effect in the current design methods. This paper presents an alternative design method for anchor shear reinforcement. The proposed anchor shear reinforcement consists of a group of closed stirrups proportioned to resist the code-specified anchor steel capacity in shear and placed within a distance from the anchor bolt equal to the front-edge distance. Steel fracture was achieved in the tests of twenty 25 mm (1 in.) reinforced anchors with a front-edge distance of 152 mm (6 in.). Meanwhile, the observed anchor capacities were smaller than the code-specified anchor steel capacity in shear because concrete cover spalling caused combined bending and shear action in the anchor bolts. Reinforcing bars are needed along all concrete surfaces to minimize concrete damage in front of reinforced anchors for consistent seismic behavior in shear.
10.14359/51684329
107-S14
March 1, 2010
Nam Ho Lee, Kwang Ryeon Park, and Yong Pyo Suh
107
2
This paper presents shear test results for large cast-in-place anchor bolts in concrete. The tests were performed to evaluate the shear performance of large anchors, that is, anchors with a diameter greater than 2 in. (50.8 mm) or an embedment depth greater than 25 in. (635.0 mm), which are not addressed by ACI 318-08, Appendix D and ACI 349-06, Appendix D. The tests were also intended to investigate the safety of such anchors for use in nuclear power plants, and the effects of regular (conventional) and special reinforcement on the shear strength of such anchors. The test results are used to assess the applicability of existing design formulas valid for smaller anchors to large anchors. Suggestions are made for incorporating the effects of deep embedment or large diameter in existing design provisions for cast-in-place anchor bolts under shear load.
10.14359/51663530
106-S79
November 1, 2009
Sungjin Bae, Oguzhan Bayrak, James O. Jirsa, and Richard E. Klingner
106
In Texas, many drilled-shaft concrete foundations of high-mast illumination poles (HMIPs) constructed in the late 1980s were found to have premature concrete deterioration due to alkali-silica reaction (ASR) and delayed ettringite formation (DEF). To investigate the effect of ASR/DEF damage on the structural performance of deeply embedded bolts anchoring the pole to the HMIP foundation, six full-scale field tests were conducted in Houston, TX. In this study, two types of drilled-shaft foundations were examined: drilled shafts with 16 anchor bolts supporting 150 ft (46 m) poles, and shafts with 20 anchor bolts supporting 175 ft (53 m) poles. One of the tested drilled shafts with 20 anchor bolts was repaired by wrapping it with carbon fiber-reinforced polymer (CFRP) sheets. Failure modes and related load-transfer mechanisms were investigated and design refinements were developed to current ACI requirements for these deep anchor bolts.
10.14359/51663186
105-S56
September 1, 2008
Matthew S. Hoehler and Rolf Eligehausen
105
5
Experimental tests with post-installed anchors in cracked concrete were performed to investigate anchor failure mechanisms associated with tension cycling at near-ultimate load levels. The test results challenge existing assumptions about the behavior of anchor bolts used to connect structural and nonstructural elements in the event of an earthquake. Specifically, they demonstrate that the current definition of ductility in anchor design guidelines must be improved. The influence of the tension load cycling frequency and cycling pattern on anchor behavior are also discussed.
10.14359/19943
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