Behavior of Normal and High Strength Confined Concrete Under Compression Load
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Date
2016-03
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Addis Ababa University
Abstract
In this study high strength concrete with a specific compressive control cube strength at 28days
of age fcu=50MPa, and normal-strength concrete with a specific compressive control cube
strength at 28 days of age fcu=41MPa are considered to study the confined property of highstrength
and normal-strength concrete under axial compression load. Material used for highstrength
concrete are; OPC Derba cement, basaltic coarse aggregate, crushed sand, water, and
conplast SP430 chemical admixture. And material used for normal-strength concrete are; OPC
Derba cement, crushed sand, river sand, basaltic coarse aggregate and water. The mix design for
high-strength concrete was designed to obtain fcu=60Mpa, but from the test result it is obtained
fcu=50MPa, and this compressive strength of concrete is considered to study the behavior of
high-strength concrete in this research. Deformed reinforcing bar diameter 8mm with yield
strength about 503MPa and 580Mpa were used to confine the specimen. The reinforced
specimens contained rectilinear lateral steel ties, and four diameter 10mm longitudinal
reinforcement with yield strength about 628MPa was used in the tested specimens.
Test can be performed on 18 prismatic high-strength concrete specimens and 18 prismatic
normal-strength concrete specimens having a size of (150mm150mm300mm) with three steel
tie spacing (s=54mm,68mm,90mm). The test specimen include 6 plain unreinforced prismatic
specimens; 3 for high strength and 3 for normal strength concrete. Specimens were tested by
compression testing machine having a capacity of 3000KN subjected to generalized compression
load with rate of loading 0.28MPa/s.
The test parameters considered in this study are; concrete compressive strength, volumetric ratio
and spacing of transverse reinforcement and yield strength of transverse reinforcement. The
models proposed by previous researchers were used in addition to the test result to study the
effect of test parameters. Finally the influence of confinement and concrete compressive
strength on the behavior of high-strength and normal-strength concrete specimens confined by
rectilinear steel tie bars were examined. From the result obtained in the study the effect of
volumetric ratio and spacing of transverse reinforcement has more pronounced effect on the
behavior of normal and high-strength column specimens as compared to the other test
parameters, which is agreed with the result of previous researchers.
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Structures