Behavior of reactive powder concrete beams in bending

Dissertant

Hinnawi, Samir Philip Yaqub

Thesis advisor

al-Husni, Hisham Muhammad
al-Shaarbaf, Ihsan Ali Saib

University

University of Technology

Faculty

-

Department

Department of Building and Construction Engineering

University Country

Iraq

Degree

Ph.D.

Degree Date

2010

English Abstract

Reactive powder concrete (RPC) is one the latest result of development process in concrete technology.

It is also known as an ultra high performance concrete which is characterized by dense mix, high cement content, very high mechanical strength, high durability and contains in most cases steel fibers to decrease its brittleness.

The present research is devoted to study the mechanical properties of RPC as a material as well as studying the flexural behavior of RPC beams.

The experimental program includes investigating the effect of steel fiber volumetric ratio (Vf) and silica fume content (Sf) on some important mechanical properties of RPC such as compressive strength, uniaxial stress-strain relationship in compression, splitting tensile strength and modulus of rupture.

Additional experimental tests are also conducted to study the effect of Vf , Sf The flexural behavior of RPC beams is also theoretically predicted in this research throughout special computer programs by following two analytical methods, a simple analytical method which considers horizontal equilibrium of forces on the beam section as well as compatibility of axial strains.

The second analytical method is the finite element method in which a three-dimensional non-linear finite element model is adopted by using 20-node quadratic brick elements to model the beam.

According to these two analytical methods, the effects of the three mentioned important parameters (i.e.

Vf, Sf It is found from the experimental tests that increasing V flexural behavior of RPC beams are theoretically obtained and compared with the corresponding experimental results.

f by 2% and Sf from 5% to 15% increases each of compressive strength by 38% and 16% respectively, splitting tensile strength by 162% and 14% respectively and modulus of rupture by 280% and 8% respectively.

New relations are suggested to estimate each of splitting strength and modulus of rupture.

A third order polynomial is found suitable to represent the ascending part of stress-strain relation while the descending branch is represented by a straight line following Hognestad.

The cracking pattern in a RPC beam has been found to be largely affected by the Vf, as Vf The results of analysis using the two analytical methods showed good agreement with the experimental results.

Experimental and analytical results showed that failure load increases as each of V increases the cracks increase in amount and decrease in width.

f, Sf and increases.

For most tested beams, the experimental failure load was higher than analytical ones, except for beams having <0.0819.

All results showed that within the range of materials used Vf and Sf have negligible effect on mode of failure while still Depending on a new rectangular stress block in compression and tension zones, new expressions are derived for the nominal moment capacity Mn and balanced steel ratio b Parametric study using the finite element analysis showed that an increase in steel bar ratio up to 0.0324 leads to an increase in the failure load and consequently increase in maximum deflection and maximum curvature for all ratios of Vf, while higher values of higher failure load and lower values of both maximum deflection and curvature.

Also the study showed that the increase in Vf.

Main Subjects

Civil Engineering

Topics

• Reinforced concrete

• APA
• MLA
• AMA

Language

English

Data Type

Arab Theses

Record ID

BIM-305172