Bond strength of tension lap splice specimens in UHPFRC: Fid-Bau Portal

Bond strength of tension lap splice specimens in UHPFRC

Lagier, F. / Massicotte, B. / Charron, J.-P.

Highlights • Study of bond splitting strength of splice joint with UHPFRC under direct tension. • Effect of fibre contents in UHPFRC, splice length, bar diameter were investigated. • With UHPFRC, splice length can be reduced by almost 3 times the design code required. • Significant increase in bond strength was noted by increasing the fibre content. • No significant effect of bar diameter between 25mm and 35mm on bond strength was noted.

Abstract Outstanding tensile properties of ultra-high performance fibre reinforced concrete (UHPFRC) initiate innovative applications that take advantage of the bond improvement with reinforcement (precast element connections, seismic strengthening of deficient lap splices, etc.). Tests on lap splice specimens under direct tension were performed to investigate the influence of UHPFRC fibre content on bond strength. Three fibre contents (Vf) were examined with large reinforcing bar diameter (db) and multiple splice lengths. According to strain hardening response of UHPFRC under direct tension, results show a considerable improvement of bond performance and splitting crack control. For UHPFRC mix with Vf =4% per volume, a splice length of 12 db was found sufficient to achieve yielding of 400MPa reinforcement; with 10 db length a bond stress around 10MPa is reached. The contribution of the fibres was clearly highlighted through this experimental study, a strong relationship between the bond performance and both the maximum tensile strength and strain ductility of UHPFRC was noted.