Performance of mechanical steel bar splices using grouted couplers under uniaxial tension

In this study, grouted couplers were used to connect steel bars as an alternative approach to the conventional steel bar lapping method. The aim is to avoid bar congestion problems and to reduce the required quantity of steel bars in order to achieve the development length in practice. Two categories of couplers, i.e., short-threaded grout coupler and long grout coupler, in nine groups as well as one group of deformed bars, were tested under uniaxial tension. In total, 30 samples (including three repeated samples in each group) were tested. The examined parameters were types of couplers, embedded bar length, and bar eccentricity. For the short-threaded grout couplers, the embedded bar length, which is equivalent to 8 times bar diameter with bar eccentricity equal to zero, exhibited the best performance in terms of strength, ductility, energy absorption, and failure mode, which is suitable to be used in the high seismic zone. Additionally, the short-threaded grout couplers with the embedded bar length equal to 7 times bar diameter and the long grout couplers that required embedded bar length that is equal to 8 times bar diameter, are suitable to be used in the low-to-medium seismic zone. Besides, the embedded bar length that is smaller than or equal to the 6 times bar diameter was not sufficient to be utilised in the short-threaded grout couplers and long grout couplers to resist the seismic load due to inadequate bar embedded length. Also, the predicted model is sufficient to estimate the ultimate tensile strength of the grouted couplers.

Automated summary

Grouted couplers were used as an alternative to traditional steel bar lapping method to avoid bar congestion issues and reduce the required quantity of steel bars. Short-threaded grout couplers performed best in high seismic zones, while short-threaded grout couplers and long grout couplers were suitable for low-to-medium seismic zones.