English Abstract
Abstract:
Ultra-High Strength Concrete (UHSC) reinforced with High Strength Steel (HSS) bars is a
composite material utilized as a structural member that reduces cross-sectional dimensions
causing the reduction of the structure's self-weight and cost. To avoid the shear failure of
reinforced concrete beams, it is important to investigate the shear behavior of a structural
member. Shear failure is considered a major structural problem because it usually occurs without
warning. Hence, the aim of this thesis is to study the shear behavior of (UHSC) reinforced with
(HSS) bars without web reinforcement.
In this study the shear behavior of UHSC reinforced with HSS is investigated experimentally
and numerically. Three groups of beams were examined, three for each group with nine beams,
combined with three cubes as a control specimen for each beam. The beams have been
experimentally tested, numerically compared using the analysis tool ANSYS, and theoretically
compared to international codes ACI 318, BS 8110, and Eurocode 2.
The span-to-depth ratio (a/d), flexural reinforcement ratio (p), and compressive strength of
concrete (fcu) are the main variables investigated in this study. The values for the first variable (a/d)
in Gl taken as 2.62, 3.16 and 4.21 with p equal to 0.041 (= 1.088 pb) and fcu Grade C110. On the
other hand, the values for the second variable (p) in G2 taken as 0.019, 0.031, and p = 0.041 (=
0.521 pb. 0.838 pb, and 1.088 pb respectively) with a/d = 4.21 and fca Grade C110. While the values
for the third variable (feu) in G3 are 76.8 MPa, 102.2 MPa and 112.8 MPa with a/d = 2.63, and p =
0.041 (= 1.088 pb). All the beams were casted without stirrups to investigate (a/d), (p), and (feu)
respectively. The bchavior of the tested beams was studied in terms of crack pattern, failure
mechanisms, load deflection relationships, and shear strength of beams.
The experiment results indicate that at the same load level, as (a/d) ratio increases, deflection
increase and shear strength decreases. Further, as p or fou increases, deflection decrease and shear
strength increases. The experimental study on shear strengths of ultra-high strength concrete
reinforced with high strength steel bars without web reinforcement was compared with ACI 318,
BS 8110, and Eurocode 2 equations, The results show that the measured shear strength was larger
than those predicted by code equations by varying the amount depending on (a/d), (p) and (fcu);
hence, these codes were underestimated in this investigation and instead increase for the identified
type of concrete.
The Finite Element Analysis (FEA) results show a linear relationship for the beams with
higher steel ratio (p / pb > 1) and lower (a/d <4.21), where the relationship shows linear up to 60
to 80% then non-linear for lower steel ratio (p / pb < 1) and higher (a/d ≥ 4.21). The FEA results
also indicatethat for the same load level, increasing the (a/d) ratio increases the deflection and
decreases the shear strength. Furthermore, increasing (p) or (feu) decreases the deflection and
increases the shear strength. This is consistent with experiment results. The shear strength of FEA
is about 6% higher than the experiment results.
