Allison, Robert William (1980) Cracking and tension field action in composite beams. PhD thesis, University of Warwick.

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Abstract

Two aspects of the behaviour of uncased composite 'T' beams of steel
and concrete are considered.
Flexural cracking in the reinforced concrete slab was studied by
subjecting seven 350-mm deep composite beams to hogging bending moment.
Measured strains were found to exceed those calculated from an elastic
analysis ignoring concrete in tension. Also, the first cracks to form in
the slab were much wider than expected. Both of these effects are shown
to be due to drying shrinkage in the slab of the composite beam. A
formula for calculating the mean surface strain in the slab, which allows
for both drying shrinkage and tension stiffening, is proposed.
Consideration of the parameters which affect cracking leads to a
formula for predicting crack widths in composite beams. Comparison with
experimental results shows that it is sufficiently accurate for design
purposes.
In a second series of tests, three 900-mm deep composite plate girders
with slender webs were subjected to combined shear and bending to study
their ultimate load behaviour. Failure was due to the formation of a
plastic collapse mechanism which closely resembles that observed in plain
steel girders under similar loading. The addition of a concrete slab
acting compositely with the girder increased the ultimate strength of the
beam, but variations in the size of the slab and the strength of the
shear connection had negligible effect on the beam's strength.
An idealised collapse model, based on the experimental observations,
is described and is used in the development of a method to calculate the
ultimate strength of composite plate girders. It is shown that a design
method for plain steel girders in the draft Part 3, BS5400 may, with
small modifications, be applied to composite plate girders.

Item Type:	Thesis (PhD)
Subjects:	T Technology > TA Engineering (General). Civil engineering (General)
Library of Congress Subject Headings (LCSH):	Composite construction, Concrete -- Cracking, Plate girders
Official Date:	February 1980
Dates:	Date Event February 1980 Submitted
Institution:	University of Warwick
Theses Department:	School of Engineering
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Johnson, R. P. (Roger Paul)
Sponsors:	Constructional Steel Research and Development Organisation
Extent:	xxxi, 275 p.
Language:	eng

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