During propped construction the steel-concrete composite action resists dead as well as
imposed loads. Conversely, the steel section alone resists the floor self-weight in unpropped
beams. The major difference between propped and unpropped composite beams lies in the
ductility requirements rather than in the strength requirements. Relatively few studies have
been carried out to assess the rotation requirements for unpropped semi-continuous
composite beams. The outstanding critical factor in the case of unpropped construction is the
dead load stress that must be carried by the steel beam alone prior to hardening of the
concrete.
This research overcomes the difficulties involved in modelling the composite and noncomposite
stages by using a numerical integration technique developed from the basic
principles of structural mechanics. The method incorporates the fully non-linear material
properties and requires very little assumption. The technique was initially validated using the
experimental results from plain steel beam bending tests. The subsequent comparison
between the model predictions and the results from the large-scale frame test carried out for
this research purpose, showed that the method is capable of predicting non-elastic load vs.
end rotation behaviour within a high degree of accuracy. Thus the model can be used with
confidence in order to predict the connection rotation requirements for a wider range of
loading configurations than is practically possible from experimental testing alone.
A parametric study is carried out using the numerical integration technique developed for the
semi-continuous composite beam on a total of 2160 different beam configurations, utilising
different steel grades and loading conditions. In this study the influence of dead load stress on
the connection rotation requirement has been thoroughly evaluated along with several other
factors including span to depth ratio, location within the building frame, ratio between the support (connection) moment capacity and span (beam) moment capacity, loading type, steel
grade and percentage of the beam strength utilised during design. The connection rotation
capacity requirements resulting from this study are assessed to establish the scope for
extending the use of composite connections to unpropped beams.
The large-scale experiment that has been carried out provided an opportunity to investigate
the behaviour of a modified form of composite connection detail for use at perimeter
columns (single-sided composite connections) with improved rebar anchorage.
Additionally, another extensive parametric study is carried out using the numerical
integration technique developed for the steel beam to establish the influence of strainhardening
on elastic-plastic frame instability design.
| Identifer | oai:union.ndltd.org:CRANFIELD1/oai:dspace.lib.cranfield.ac.uk:1826/3974 |
| Date | 17 November 2009 |
| Creators | Muniasamy, D |
| Contributors | Byfield, M P |
| Publisher | Engineering systems department |
| Source Sets | CRANFIELD1 |
| Language | English |
| Detected Language | English |
| Type | Thesis or dissertation, Doctoral, PhD |
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