Effect of the Truss System to the Flexural Behavior of the External Reinforced Concrete Beams

The aesthetic qualities and the versatility of reinforced
concrete have made it a popular choice for many architects and
structural engineers. Therefore, the exploration of natural materials
such as gravels and sands as well as lime-stone for cement production
is increasing to produce a concrete material. The exploration must
affect to the environment. Therefore, the using of the concrete
materials should be as efficient as possible. According to its natural
behavior of the concrete material, it is strong in compression and weak
in tension. Therefore the contribution of the tensile stresses of the
concrete to the flexural capacity of the beams is neglected. However,
removing of concrete on tension zone affects to the decreasing of
flexural capacity. Introduce the strut action of truss structures may an
alternative to solve the decreasing of flexural capacity. A series of
specimens were prepared to clarify the effect of the truss structures in
the concrete beams without concrete on the tension zone. Results
indicated that the truss system is necessary for the external reinforced
concrete beams. The truss system of concrete beam without concrete
on tension zone (BR) could develop almost same capacity to the
normal beam (BN). It can be observed also that specimens BR has
lower number of cracks than specimen BN. This may be caused by the
fact that there was no bonding effect on the tensile reinforcement on
specimen BR to distribute the cracks.

• Rudy Djamaluddin
• Yasser Bachtiar
• Rita Irmawati
• Abd. Madjid Akkas
• Rusdi Usman Latief

• External Reinforcement
• Truss
• Concrete Beams.

[1] James K.Wight and James G MacGregor (2005). "Reinforced concrete
mechanics and design.”. Sixth Edition, Pearson
[2] Mindess, S., Young, J. F. and Darwin D. 2003, Concrete in Special
Applications. Chapter 20. Second Edition, Pearson Education Inc. USA
[3] Rudy Djamaluddin, 2013, "Flexural Behavior of External Reinforced
Concrete Beams”, Procedia Engineering 54, Elsevier, pp.252-260,
[4] Despandhe, V. S. and Fleck, N. A. 2001. Collapse of Truss Core
Sandwich Beams in 3-Point Bending. International of Solid and
Structures, Pergamon, 38, 6275-6305.
[5] Jae-ll Sim and Keun-Hyeok Yang. (2009). "Flexural behavior of
reinforced concrete columns strengthened with wire rope and T-Plate
units.” ACI Structural Journal. V.106. No.5. pp.697-705.
[6] Li, B. and Tran, C. T. N. 2012, Determination of Inclination of Strut and
Shear Strength Using Variable Angle Truss Model for Shear-Critical.
Journal Engineering and Mechanics, Vol. 41, No.4, 459-477.
[7] Li, B. and Tran, C. T. N. 2008. Reinforced Concrete Beam Analysis
Supplementing Concrete Contribution in Truss Models, Journal
Engineering Structures, 30 (11), Elsevier, 13 June 2008, 3258-3294
[8] Nes, L.G., Overli, J.A. 2011. Composite and Hybrids Investigation of
Material Parameters and Structural Performance of a Concrete
Sandwich Slab Element. fib Symposium PRAQUE 2011, Session 5-6
[9] Stevees, C. A., Fleck, N. A. 2004. Collapse Mechanism of Sandwich Beams with Composite Faces and A Foam Core. International Journal of
Mechanical Science, Elvesier 46, 30 April 2004, 561-583.