Title:
Effect of Staggering Distances on Splice Strength of New- Generation Glass Fiber-Reinforced Polymer Reinforcing Bars
Author(s):
Seyed Arman Hosseini, Ahmed Sabry Farghaly, Abolfazl Eslami, and Brahim Benmokrane
Publication:
Structural Journal
Volume:
122
Issue:
3
Appears on pages(s):
71-87
Keywords:
bond strength; concrete structures; design codes; development length; glass fiber-reinforced polymer (GFRP) reinforcing bars; lap splicing; splice length; splice strength; staggering effect
DOI:
10.14359/51745640
Date:
5/1/2025
Abstract:
This study addressed a critical knowledge gap by examining
the influence of staggering on the bond strength of lapped glass
fiber-reinforced polymer (GFRP) bars in concrete members. It
involved a comprehensive investigation of new-generation GFRP
bars with varying staggering configurations in nine large-scale
GFRP-reinforced concrete (RC) beams with a rectangular cross
section of 300 x 450 mm (11.8 x 17.7 in.) and a length of 5200 mm
(204.7 in.). The tests investigated splice strength with three staggering
distances: 0, 1.0, and 1.3 times the splice length (ls) from
center-to-center of two adjacent splices, and three splice lengths
of 28, 38, and 45 times the bar diameter (db). Results revealed
a slight improvement in ultimate load-carrying capacity (less
than 10%) for partially and fully staggered splices compared to
non-staggered ones, with the latter exhibiting a more ductile failure
mode. The effect of staggering was consistent across different
splice lengths, demonstrating that splice length was not a factor.
Although staggering reduced flexural crack width, it increased
the total number of cracks due to expanded splice regions. Bond
strength improved with staggering, with gains of 4.0% and 8.0%
for partially and fully staggered splices, respectively. ACI CODE-
440.11-22 provides more accurate predictions of the bond strength
of lap-spliced GFRP bars than the other design codes, showing an
average test-to-prediction ratio of 1.03 for non-staggered splices.
Nevertheless, it requires some reconsiderations when it comes to
staggered splices. To address this, a proposed modification factor
was introduced to account for staggering conditions when calculating
bond strength and splice length in ACI CODE-440.11-22.