RELIABILITY-BASED RATING OF THE BS 8110 DESIGN CRITERIA FOR REINFORCED CONCRETE COLUMNS
RELIABILITY-BASED RATING OF THE BS 8110 DESIGN CRITERIA FOR REINFORCED CONCRETE COLUMNS
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Date
1997-01
Authors
ABONGWA, ABONGWA
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Abstract
A reliability-based rating of the BS8110 (1985) design
criteria for reinforced concrete columns is attempted in this
thesis. The rating is based on the First-Order Second Moment
Integration Technique. Limit state equations for axially loaded
short columns, short columns with bending, slender columns and
short columns subjected to biaxial bending are derived and
their implied reliability levels evaluated.
All the basic design variables involving cross-sectional
resistance and loading are treated as random variables with
their statistical characters adopted from literature. The
results show that the BS8110 (1985) design requirements are
highly inconsistent and very conservative having a range of
reliability index, 0, from 1.04 to 8.03. Considering varying
practical values of the decision variables, the code provides
an average 0-value of 4.35 (i.e. pf = 6.79 x 10-6) for the
different columns studied. It is also found that the criterion
for the design of short columns in biaxial bending is the most
inconsistent and conservative while short columns with bending
have the least indicating a better capacity prediction.
Sensitivity analyses show that the 0-values for axially loaded
short columns are influenced most by cross-sectional dimensions
and load while for short columns with bending and slender
columns the effective depth is the most influential. The 0-
values for short columns in biaxial bending is influenced
substantially by all design variables except concrete strength
and concrete cover. The work concludes by providing some
sample charts suitable for designing to specific reliability
levels.
Description
A thesis submitted to the Postgraduate School Ahmadu Bello
University, Zaria in partial fulfillment of the requirements
for the degree of Master of Science (M.Sc) in Structural
Engineering,
JANUARY, 1997
Keywords
RELIABILITY-BASED,, RATING,, DESIGN CRITERIA,, REINFORCED,, CONCRETE COLUMNS