Title:
Prepublished: Effect of Staggering Distances on the Splice Strength of New-Generation GFRP Reinforcing Bars
Author(s):
Seyed Arman Hosseini, Ahmed Sabry Farghaly, Abolfazl Eslami, and Brahim Benmokrane
Publication:
Structural Journal
Volume:
Issue:
Appears on pages(s):
Keywords:
concrete structures; bond strength; design codes; development length; GFRP reinforcing bars; lap splicing; splice length; splice strength; staggering effect
DOI:
10.14359/51745640
Date:
2/11/2025
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-RC beams with a rectangular cross-section of 300 mm × 450 mm and a length of 5,200 mm. The tests investigated splice strength with three staggering distances: 0, 1.0, and 1.3 times the splice length (ls) from the 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 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 reconsideration 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 440.11-22.