The Effect of Intermediate Stiffeners on Steel Reinforced Concrete Beams Behaviors

Eight steel reinforced concrete beams (SRC), were fabricated and tested under earthquake type cyclic loading. The effectiveness of intermediate stiffeners, such as mid-span stiffener and plastic hinge zone stiffeners, in enhancing composite action and ductility of SRC beams was investigated. The effectiveness of strengthened beam-to-column (SBC) and weakened beam-to-column (WBC) connections in enhancing beam ductility was also studied. It was found that: (1) All the specimens possessed fairly high flexural ductility and were found adequate for structures in high seismic zones. (2) WBC connections induced stress concentration which caused extra damage to concrete near the flange tapering zone. This extra damage inhibited the flexural strength development and the ductility of the specimens with WBC connections to some extent. (3) Specimens with SBC connections demonstrated higher flexural strength and ductility compared to specimens with WBC connections. (4) The intermediate stiffeners, especially combination of plastic hinge zone stiffener and mid span stiffeners, have an obvious effect in enhancing the ductility of the beams with SBC connection.

Authors:

• Teguh Sudibyo
• Cheng-Cheng Chen

Keywords:

• Composite beam
• concrete encased steel beam
• steel reinforced concrete
• stiffeners.

References:

[1] Chen C.C. and Chen C.C., "Flexural behavior of steel encased composite
beams," Journal of the Chinese Institute of Civil and Hydraulic
Engineering, vol. 13, pp. 263-75, Feb. 2001.
[2] Plumier A., "Behavior of connections," Journal of Constructional. Steel
Research, vol. 29, pp. 95-119, 1994
[3] Chen, S.J., Yeh, C.H. and Chu, J.M., "Ductile steel beam-to-column
connection for seismic resistance," Journal of Structural
Engineering.-ASCE, vol. 122, pp. 1292-9, Nov. 1996.
[4] Chen, S.J., Chu, J.M. and Chou, Z.L., ÔÇÿDynamic behavior of steel frames
with beam flanges shaved around connection," Journal of Constructional
Steel Research, vol. 42, pp. 49-70, Jan. 1997.
[5] Kim, T., Whittaker, A.S., Gilani, A.S.J., Bertero, V.V. and Takhirov,
S.M., "Cover-plate and flange-plate steel moment-resisting connections,"
Journal of Structural Engineering.-ASCE, vol. 128, pp. 474-482, April
2002.
[6] Sumner, E.A. and Murray, T.M., "Behavior of extended end-plate
moment connections subject to cyclic loading," Journal of structural
engineering,-ASCE, vol. 128, pp. 501-8, April 2002.
[7] AISC., Specification for structural steel buildings. American Institute of
Steel Construction, 2005, Chicago. IL.
[8] Chen C.C. and Cheng C.L., "Flexural analysis and design methods for
SRC beam sections with complete composite action. Journal of the
Chinese Institute of Civil and Hydraulic Engineering, vol. 31, pp.
215-229, Feb. 2008.