Following recent events such as the World Trade Center building collapse and the Cardington large scale structural fire research program, the fire behavior of connections has now become an important research subject. This thesis presents the results of experimental, numerical and theoretical studies into the behavior of simple welded fin-plate to concretefilled tubular (CFT) columns loaded by tensile or shear force. Such connections represent a simple single-sided joint solution to steel CFTs which are considered an attractive and robust structural element. Experiments have been performed at both ambient and elevated temperatures against the results of which numerical finite element models have been validated. The ranges of parameters encompassed by the tests include column cross-section shape; column and finplate thickness; concrete in-fill; elevated temperatures and connection lever arm. The observed failure modes include fracture of the fin-plate and tearing out of the tube around the welds. By considering the results of previously published research, the current design method for similar connections under purely tensile load, in CIDECT Guide 9, based on a deformation limit of 3% of the tube width is shown to be inadequate when evaluating the ultimate strength of such connections. By comparing the results from the current test program which failed in the fin-plate with Eurocode guidance for failure of a fin-plate alone under shear and bending load it is shown that the column face influences the overall connection strength regardless of failure mode. Concrete in-fill is observed to significantly increase the strength of connections over empty specimens, and circular column specimens were observed to exhibit greater strength than similarly proportioned square columns. When validating the numerical model against elevated temperature tests it was found that the strength reduction factors suggested by Eurocode for steel at elevated temperature are appropriate. The numerical models developed have been used to perform extensive parametric studies from which simple hand calculation methods have been developed for evaluating the strength of the column component of square CFTs under either tensile or shear load imparted through a fin-plate connection. The simple hand calculation procedures are based upon defining a rigid plate deformation pattern for the connection and then applying the internal work principle. For connections under shear load a method is presented for combining the column failure load with the fin-plate failure derived from existing Eurocode guidance. Both simple hand calculation methods are compared favorably with available test results. A limited number of tests and numerical validation have also been performed for reverse channel to CFT connections loaded in shear at both ambient and elevated temperatures.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:504745 |
| Date | January 2008 |
| Creators | Jones, Mark Hadyn |
| Publisher | University of Manchester |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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