The structural behaviour of single shear bolted connections, double shear bolted
connections and single shear screwed connections of thin sheet steels at elevated
temperatures has been investigated in this study. The current design rules on bolted
and screwed connections of thin sheet steels for cold-formed steel structures are
applicable for ambient temperature condition only. These design rules may not be
applicable for elevated temperature conditions. Therefore, design guidelines should
be prepared for bolted and screwed connections of cold-formed steel structures at
elevated temperatures.
A total of 30 tensile coupon tests were conducted to investigate the material
deterioration of the thin sheet steels at elevated temperatures, and also to determine
the critical temperatures for connection tests. A total of 510 tests on single shear
bolted connections, double shear bolted connections and single shear screwed
connections of thin sheet steels at elevated temperatures was performed in the
temperature ranged from 22 to 900?C using both steady state and transient state test
methods. The test results were compared with the predicted values calculated from
the North American, Australian/New Zealand and European specifications for coldformed
steel structures. In calculating the nominal strengths of the connections, the
reduced material properties of the thin sheet steels were used due to the deterioration
of material at elevated temperatures. It is shown that the design strengths predicted
by these specifications are generally conservative at elevated temperatures.
Finite element models for single shear bolted connections, double shear bolted
connections and single shear screwed connections were developed and verified
against the experimental results. Explicit dynamic analysis technique was used in the
numerical analyses. Extensive parametric studies that included 490 finite element
specimens were carried out using the verified finite element models to evaluate the
bearing strengths of bolted connections as well as the tilting and bearing strengths of
screwed connections of thin sheet steels at elevated temperatures.
Design equations for bearing strengths of bolted connections as well as design
equations for tilting and bearing strengths of screwed connections were proposed
based on both the experimental and the numerical results in the temperature ranged
from 22 to 900?C. The bearing strengths of bolted connections as well as the tilting
and bearing strengths of screwed connections obtained from the test specimens and
the finite element analyses were compared with the predicted strengths calculated
using the proposed design equations and also compared with the design strengths
calculated using the current North American, Australian/New Zealand and European
specifications with consideration of the reduced material properties at elevated
temperatures. It is shown that the proposed design equations are generally more
accurate and reliable in predicting the bearing strengths of bolted connections as well
as the tilting and bearing strengths of screwed connections of thin sheet steels at
elevated temperatures than the current design rules. The reliability of the current and
proposed design rules was evaluated using reliability analysis. The proposed design
equations are suitable for bolted and screwed connections assembled using thin sheet
steels of thickness ranged from 0.35 to 3.20mm. / published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy
| Identifer | oai:union.ndltd.org:HKU/oai:hub.hku.hk:10722/174462 |
| Date | January 2012 |
| Creators | Yan, Shu, 閆澍 |
| Contributors | Young, B |
| Publisher | The University of Hong Kong (Pokfulam, Hong Kong) |
| Source Sets | Hong Kong University Theses |
| Language | English |
| Detected Language | English |
| Type | PG_Thesis |
| Source | http://hub.hku.hk/bib/B47752828 |
| Rights | The author retains all proprietary rights, (such as patent rights) and the right to use in future works., Creative Commons: Attribution 3.0 Hong Kong License |
| Relation | HKU Theses Online (HKUTO) |
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