The behaviour of long tension reinforcement laps
File(s)
Accepted version
Author(s)
Micallef, M
Vollum, RL
Type
Journal Article
Abstract
Over time, the length of reinforcement laps required by design standards has increased significantly. By way of illustration, fib Model Code 2010 can require over twice the lap length required by the superseded UK code BS8110:1997. The need for this increase is debatable since, outside the laboratory, there is no evidence that laps designed to BS8110 are unsafe. The paper describes an experimental programme which was undertaken to compare failure modes of beams with laps of varying length loaded in four point bending. Tested laps are classified as “short”, “long” and “very long” with “long” laps just sufficient to develop reinforcement yield. The “very long” laps were between 1.5 and 2.0 times the length of the “long” laps. Tested laps were between bars of equal as well as mixed diameter with diameters ranging between 16 mm and 25 mm. Instrumentation included strain gauges and digital image correlation which was used to record crack development. Bond failure was very sudden and brittle in “short” laps. The failure modes of both “long” and “very long” laps were ductile due to flexural reinforcement yield. However, bond failure occurred subsequent to yield in “long” laps including at least one 25 mm diameter bar.
Date Issued
2018-06-07
Date Acceptance
2017-11-16
Citation
Magazine of Concrete Research, 2018, 70 (14), pp.739-755
ISSN
0024-9831
Publisher
Thomas Telford
Start Page
739
End Page
755
Journal / Book Title
Magazine of Concrete Research
Volume
70
Issue
14
Copyright Statement
© 2017 Thomas Telford Ltd. Original article available at http://www.icevirtuallibrary.com/doi/10.1680/jmacr.17.00285. Permission is granted by ICE Publishing to print one copy for personal use. Any other use of these PDF files is subject to reprint fees.
Subjects
0905 Civil Engineering
Building & Construction
Publication Status
Published
Date Publish Online
2017-11-27