Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : strength concrete

Shear Capacity of High-Strength Fiber Reinforced Concrete Beam-Column Joints

Kaiss Sarsam; Zaid Muhammad Kani Al-Azzawi

Engineering and Technology Journal, 2010, Volume 28, Issue 6, Pages 1253-1266

This work examines the work of 13 high-strength concrete (HSC) beamcolumn
joints (BCJ)-with and without steel fibers. Several shear design methods
(with modification for fiber content, where applicable) were found to be
conservative within a range of the following variables: 1) concrete compressive
strength, 2) type and volume fraction of steel fibers, 3) content of hoops in the
joint, and 4) column axial load. The coefficient of variation (COV) of the ratio
of test strength to design strength (VTEST / VrDES) was found to be appreciably low
for two of the five existing safe design methods. A conservative design method,
which lowers the COV even further to a value of 7.8 percent, is proposed for HSC
joints, with and without steel fiber reinforcement

Bond Strength-Splice Length in Concrete Beams Confined by Transverse Reinforcement

Sameh Badry Tobeia Shuker

Engineering and Technology Journal, 2010, Volume 28, Issue 2, Pages 322-339

This work aim to study the effect of transverse reinforcement , area of splice
bar, concrete cover thickness , rib area and the increasing in concrete strength (highstrength
concrete) on bond strength between concrete and reinforcing spliced bars .
Therefore, a new simple equation is derived for beams with spliced bars and
confined by transverse reinforcement to calculate bond strength and reflects the
effects of these factors .Where many of existing codes and provisions used to
calculate the spliced strength do not include or reflect the influencing of these factors
in bond strength estimation . Based on experimental results from previous works ,
(116) confined beams with spliced bars are investigated in this study , where
concrete compressive strength ( c f ¢
) ranging from 25 MPa to 113.793 MPa ,amount
of transverse reinforcement vary in a wide range and , conventional and high
relative rib area of deformed bars are present in these beams . The proposed method
exceed the limitation of ( f MPa c ¢ £ 69 ) that given by ACI code .Where the
proposed method is examined and applicable for concrete compressive strength up
to 113 MPa . Also, in this work the second root of c f ¢
is examined , as concrete
strength increased with high-strength concrete , to reach a suitable value for both
normal and high- strength concrete and to be more appropriate with the heavy
present of transverse reinforcement . Power of (0.35) is adopted and used in this
work instead of the second root of c f ¢