Civil Engineering Reference
In-Depth Information
Chapter 3
Simply-supported composite
slabs and beams
3.1
Introduction
The subjects of this and subsequent chapters are treated in the sequence in
which they developed. Relevant structural behaviour is discovered by
experience or research, and is then represented by mathematical models.
These make use of standardised properties of materials, such as the yield
strength of steel, and enable the behaviour of a member under load to be
predicted. The models are developed into design rules, as found in codes
of practice, by simplifying them wherever possible, defining their scope
and introducing partial factors.
Research workers often propose alternative models, and language barriers
are such that the model preferred in one country may be little known
elsewhere. The writers of codes try to select the most rational and widely-
applicable of the available models, but must also consider existing design
practices and the need for simplicity. The design rules used in this topic
are taken from the Eurocodes, which differ slightly from the correspond-
ing British codes; but the underlying models are usually the same, and
significant differences will be explained.
The methods to be described are illustrated by the design calculations
for part of a framed structure for a building. To avoid repetition, the
results obtained at each stage are used in subsequent work.
The notation used is that explained and listed in the section 'Symbols,
terminology and units'.
3.2
Example: layout, materials and loadings
In a framed structure for a wing of a building, the columns are arranged at
4 m centres in two rows 9 m apart. A design is required for a typical floor,
which consists of a composite floor slab supported by, and composite
with, steel beams that span between the columns as shown in Fig. 3.1.
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