Due to their aesthetic appeal, high stiffness and hence buckling resistance about both axes, tubular members are ideal as compression members. Furthermore, the possibility to further increase their strength, stiffness and ductility via filling them with concrete, tubular columns are an effective design solution for high rise buildings where very high compressive forces are applied to lower story columns. Key to the successful application of empty or concrete filled HSS tubular members in construction is the existence of reliable and efficient design guidance, underpinned by relevant research. Insufficient access due to the closed form of the hollow sections necessitates the use of blind bolts, many types of which are commercially available.
This project aims at quantifying the strength, stiffness and rotation capacity of beam-to-tubular column connections under cyclic loading and devising relevant design guidance. Extending an earlier experimental and numerical research on the behaviour of the tension zone of blind bolted beam-to-tubular column joints under static loads, cyclic loads will be considered. Both empty and concrete filled tubular columns and several bolting arrangements and infill strengths will be considered. Initially, the effectiveness of symmetric and asymmetric cyclic loading protocols to accurately simulate the near collapse strength and ductility demands on blind-bolted joints will be assessed experimentally. Thereafter, numerical models will be validated against the test results and parametric studies will be conducted to allow a comprehensive investigation of the effects of key design parameters on the joint response to be obtained. Based on the obtained results, design equations and recommendations will be developed. Both the experimental and the numerical research will be underpinned by material characterisation studies to enable constitutive material models accounting for the progressive strength and stiffness degradation of steel under cyclic loading to be formulated. Finally, full-scale joint tests will be carried out and the effectiveness of the developed design procedures for the isolated joint component will be assessed.
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