Laboratorial study of anchorage performance in different rib spacings of bolt

To determine the relationship between rib spacing and anchorage performance of right-screwing rebar bolt, the pull-out test was conducted with the rib spacing of 12 mm,24 mm,36 mm,48 mm and wall thickness of 5. 5 mm and 7 mm. Four parameters including pulling force,shear expansion displacement,energy dissipation,and circumferen- tial strain were monitored and calculated. The test results show that the pulling force,dilatancy displacement,and ener- gy dissipation increased with the increase of rib spacing;in the pull-out test with sleeve wall thicknesses of 5． 5 mm and 7 mm,the rib spacing of 48 mm specimens compared with the 12 rib spacing of MM specimen the pulling force were increased by 27． 4% and 50． 43% ,the shear displacement amounts were increased by 379． 18% and 813． 55% , the energy dissipations were increased by 52. 06% and 124． 32% . The circumferential strain increases first at the rib spacing of 24 mm and 36 mm and then decreases at the rib spacing of 48 mm,and the maximum value is 36 mm,which is increased by a factor of 95． 14% and,112． 84% respectively,compared with the rib spacing of 12 mm. The increase of the rib spacing can improve the anchorage performance,and the best rib spacing is 48 mm.