Abstract:

Objective: The bearing properties and failure modes of single bolted steel-bamboo scrimber (BS)-steel connections were studied, to provide some references for the design and application of bolted connection for bamboo structure. Method: Influence factors such as bolt diameter, main member thickness and end distance were designed by orthogonal scheme, to systematically analyze the influence laws of the initial stiffness (K₁), post-yield stiffness (K₂), yield load (F_y), ultimate load (F_u) and ductility rate of the connections which were tested under the uniaxial compression, by means of variance analysis and multiple comparisons, in order to reveal the bearing properties and failure modes of the single-bolted connections of steel-BS-steel. Result: The bolt diameter had significant effects on initial stiffness (K₁), post-yield stiffness (K₂), yield load (F_y), ultimate load (F_u) and ductility rate, of which the former four parameters were all increased with bolt diameter, while the latter ductility rate was decreased. Except for the yield load (F_y), the effects of the main member thickness on the initial stiffness (K₁), post-yield stiffness (K₂), ultimate load (F_u) and ductility rate were all prominent. Besides, the post-yield stiffness (K₂), ultimate load (F_u) and ductility rate were remarkably affected by the end distance, while its effects on the initial stiffness (K₁) and yield load (F_y) were reversely. Moreover, the effective failure modes of the single-bolted steel-BS-steel connections were presented as type-Ⅱ or type-Ⅲ. The yield mode of bolt was presented as "single-hinge" failure when the L/D value was from 3.75 to 6.00, while it was presented as "double-hinge" failure mode when the L/D values was from 6.00 to 13.50. Conclusion: The bearing capacity and failure mode of the single-bolted steel-BS-steel connection were affected by the bolt diameter, end distance and main member thickness simultaneously. It was suggested that the minimum dimensional requirement of the main member thickness and end distance could be set as 90 mm and 4d, respectively, for the bearing capacity tended to be stable and the ductility rate reached to the best state. Furthermore, the yield mode of bolt was gradually changed from "single-hinge" to "double-hinge" with the increase of L/D value, when the specimen satisfied to the minimum dimensional requirements of the end distance and main member thickness. Certainly, the failure mode of the connections that the dowel-bearing failure and bolt bending failure turned out simultaneously were relatively reasonable, which could give full play to the mechanical properties of all the members.

Key words: steel-bamboo scrimber(BS)-steel, bolted connection, bearing properties, influence factors, failure mode