The Effect of Confinement Shapes on Over-Reinforced HSC Beams
High strength concrete (HSC) provides high strength
but lower ductility than normal strength concrete. This low ductility
limits the benefit of using HSC in building safe structures. On the
other hand, when designing reinforced concrete beams, designers
have to limit the amount of tensile reinforcement to prevent the
brittle failure of concrete. Therefore the full potential of the use of
steel reinforcement can not be achieved. This paper presents the idea
of confining concrete in the compression zone so that the HSC will
be in a state of triaxial compression, which leads to improvements in
strength and ductility. Five beams made of HSC were cast and tested.
The cross section of the beams was 200×300 mm, with a length of 4
m and a clear span of 3.6 m subjected to four-point loading, with
emphasis placed on the midspan deflection. The first beam served as
a reference beam. The remaining beams had different tensile
reinforcement and the confinement shapes were changed to gauge
their effectiveness in improving the strength and ductility of the
beams. The compressive strength of the concrete was 85 MPa and the
tensile strength of the steel was 500 MPa and for the stirrups and
helixes was 250 MPa. Results of testing the five beams proved that
placing helixes with different diameters as a variable parameter in the
compression zone of reinforced concrete beams improve their
strength and ductility.
[1] Nawy, E. (2001). Fundamentals of High-Performance Concrete. Canada:
John Wiley & Sons.
[2] Sargin.M (1971). Stress-strain relationships for concrete, and the
analysis of structural concrete sections, Waterloo, Solid Mechanics Div.,
Univ. of Water loo.
[3] Richart, F., Brandtzaeg, A., and Brown, R. (1929). the Failure of Plain
and Spirally Reinforced Concrete in Compression. Illinois University,
Engineering Exp-erimental Stat ion, Bulletin, No. 190, Vol.26, No.31,
pp 1- 74.
[4] Martinez, S., Nilson, A.H., and Slate, F.O. (1984) Spirally Reinforced
High Strength Concrete Columns, Journal of the American Concrete
Institute, No. 81, Vol. 5, pp 431-442.
[5] Kwan, A. (2004). Effects of Confinement on Flexural Strength and
Ductility Design of HS Concrete Beams. Structural Engineer, 38-44.
[6] Hadi, M.N.S. and Schmidt, L.C. (2002). Use of Helixes in Reinforced
Concrete Beams, ACI Structural Journal, Vol. 99, No2, pp 191-198.
[7] Whitehead. P. A. and Ibell T. J. (2004). Deformability and Ductility in
Over- reinforced Concrete Structures. Magazine of Concrete research,
Vol. 56, No. 3, pp 167-177.
[8] Hadi, M.N.S. and Elbasha, N. (2005). Effect of Tensile Reinforcement
Ratio and Compressive Strengths on the Behaviour of Over-Reinforced
Helically Confined HSC Beams, Construction and Building Materials,
Vol. 21, pp 269-276.
[9] Australian Standard for Concrete Structures. (2001). AS3600 .North
Sydney, Australia: Standard Association of Australia.
[10] Warner, R., Rangan, B., Hall, A., and Faulkes, K. (1998). Concrete
Structures, Longman.
[11] Warner, R., Rangan, B., Hall, A., and Faulkes, K (1998). Concrete
Structures, Longman.
[12] Onesteel Reinforcing Design Guide (2004) 500+ Rebar, Onesteel
Australia.
[13] Onesteel Reinforcing Product Catalogue (2004) 500+ Rebar, Onesteel
Australia.
[1] Nawy, E. (2001). Fundamentals of High-Performance Concrete. Canada:
John Wiley & Sons.
[2] Sargin.M (1971). Stress-strain relationships for concrete, and the
analysis of structural concrete sections, Waterloo, Solid Mechanics Div.,
Univ. of Water loo.
[3] Richart, F., Brandtzaeg, A., and Brown, R. (1929). the Failure of Plain
and Spirally Reinforced Concrete in Compression. Illinois University,
Engineering Exp-erimental Stat ion, Bulletin, No. 190, Vol.26, No.31,
pp 1- 74.
[4] Martinez, S., Nilson, A.H., and Slate, F.O. (1984) Spirally Reinforced
High Strength Concrete Columns, Journal of the American Concrete
Institute, No. 81, Vol. 5, pp 431-442.
[5] Kwan, A. (2004). Effects of Confinement on Flexural Strength and
Ductility Design of HS Concrete Beams. Structural Engineer, 38-44.
[6] Hadi, M.N.S. and Schmidt, L.C. (2002). Use of Helixes in Reinforced
Concrete Beams, ACI Structural Journal, Vol. 99, No2, pp 191-198.
[7] Whitehead. P. A. and Ibell T. J. (2004). Deformability and Ductility in
Over- reinforced Concrete Structures. Magazine of Concrete research,
Vol. 56, No. 3, pp 167-177.
[8] Hadi, M.N.S. and Elbasha, N. (2005). Effect of Tensile Reinforcement
Ratio and Compressive Strengths on the Behaviour of Over-Reinforced
Helically Confined HSC Beams, Construction and Building Materials,
Vol. 21, pp 269-276.
[9] Australian Standard for Concrete Structures. (2001). AS3600 .North
Sydney, Australia: Standard Association of Australia.
[10] Warner, R., Rangan, B., Hall, A., and Faulkes, K. (1998). Concrete
Structures, Longman.
[11] Warner, R., Rangan, B., Hall, A., and Faulkes, K (1998). Concrete
Structures, Longman.
[12] Onesteel Reinforcing Design Guide (2004) 500+ Rebar, Onesteel
Australia.
[13] Onesteel Reinforcing Product Catalogue (2004) 500+ Rebar, Onesteel
Australia.
@article{"International Journal of Architectural, Civil and Construction Sciences:50977", author = "Ross Jeffry and Muhammad N. S. Hadi", title = "The Effect of Confinement Shapes on Over-Reinforced HSC Beams", abstract = "High strength concrete (HSC) provides high strength
but lower ductility than normal strength concrete. This low ductility
limits the benefit of using HSC in building safe structures. On the
other hand, when designing reinforced concrete beams, designers
have to limit the amount of tensile reinforcement to prevent the
brittle failure of concrete. Therefore the full potential of the use of
steel reinforcement can not be achieved. This paper presents the idea
of confining concrete in the compression zone so that the HSC will
be in a state of triaxial compression, which leads to improvements in
strength and ductility. Five beams made of HSC were cast and tested.
The cross section of the beams was 200×300 mm, with a length of 4
m and a clear span of 3.6 m subjected to four-point loading, with
emphasis placed on the midspan deflection. The first beam served as
a reference beam. The remaining beams had different tensile
reinforcement and the confinement shapes were changed to gauge
their effectiveness in improving the strength and ductility of the
beams. The compressive strength of the concrete was 85 MPa and the
tensile strength of the steel was 500 MPa and for the stirrups and
helixes was 250 MPa. Results of testing the five beams proved that
placing helixes with different diameters as a variable parameter in the
compression zone of reinforced concrete beams improve their
strength and ductility.", keywords = "Confinement, ductility, high strength concrete,reinforced concrete beam.", volume = "2", number = "4", pages = "71-8", }