چكيده
Abstractَ
Concrete and its application in civil engineering is the most common and interesting material in
the construction. Convectional concrete is brittle in nature and posses difficulties in executions.
Today the large and infra structures are constructed with high performance concrete. "High
Strength Self Compacting Fiber Reinforced Concrete" is categorized as this material. The goal
of this dissertation is to study about the rheolgy and the cyclic behavior of self compact
reinforced concrete in flexural elements. The scope of this research includes the technology and
structural engineering.
In order to perform this study, compressive strength of 60 Mpa is selected for self compact
concrete according to the current conditions of construction in country. First an applicable mix
proportioned is prepared according to existing method and recommendations. Then a
mathematical model is developed to estimate the coarse aggregate content in fiber reinforced
concrete by using the "covering mortar thickness" theory to keep proper workability. After that,
some mix proportioned of self compact fiber reinforced concrete with one type hooked-end steel
fiber and two type propylene fibers are produced. Toughness test are carried out in order to
choose the optimum mix for structural element testing. The result shows that the hooked-end
steel fiber increases the toughness and energy absorption in compare to propylene fibers. In order
to meet the self consolidation requirement, fiber content of 0.75% is selected for structural
specimen.
In continue fiber pullout test is conducted to interpret and evaluate the result of toughness test
which are presented the similar result in high and moderate strength specimens. New equipment
is designed and made to perform fiber pullout test. Fiber pullout test shows that the strength of
concrete doesn’t affect mainly the pullout response of hooked-end steel fiber behavior and the
hooks play considerable roles. Also the self compact concrete which utilize the viscosity modify
agenda (VMA) has lower level of fiber pullout response due more created pores in compare to
those utilize mineral additives.
In the next stage a complete analytical model is developed to predict the fiber pullout response.
This model is stress-controlled model. The concept of bond shear stress versus slip relation
between fiber and matrix has been used to develop fiber force and bond stress. In this model the
effect of curvatures on the forces and stresses distribution along the hook ended fiber length have
been analyzed at the. Then the theoretical relations for hook ended fiber have been developed
with using the force and stress distribution at the curvatures of anchorages. Finally the model has
been validated with the existing experimental report on the hook-end steel fiber. The result
shows that the model is capable to estimate the main pullout mechanism due to mechanical
anchorage of hooks.
Another simple analytical model is extended for predicting the pullout response of hooked-end
steel fiber. Two different assumptions are used in this model which is a new simple concept of