Behavior of fiber reinforced high performance concrete columns

مقدم أطروحة جامعية

Mahdi, Zaynab Rad

مشرف أطروحة جامعية

al-Nawfali, Iqbal Naim Kurkis Numan
Khalil, Wasan Ismail

الجامعة

الجامعة التكنولوجية

الكلية

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القسم الأكاديمي

قسم هندسة البناء و الإنشاءات

دولة الجامعة

العراق

الدرجة العلمية

ماجستير

تاريخ الدرجة العلمية

2012

الملخص الإنجليزي

High performance concrete (HPC) is mainly used in high-rise buildings where it can significantly decrease the dimensions of columns, which makes it a more cost-effective choice for building than normal strength concrete.

In seismic area, high performance concrete posses more problems, since it has less ductility in comparison with ordinary concrete.

The aim of this investigation is to examine the combined confinement effect of fibers and transverse steel reinforcement (ties) on the behavior of reinforced HPC columns and to improve their ductility.

This study presents an experimental and analytical evaluation of strength and ductility of normal and high performance concrete short columns confined by tie reinforcement with and without steel fibers and polypropylene fibers.

Sixteen square concrete columns (100×100×1000) mm were tested.

The variables studied were, concrete strength type (normal and high performance concrete), volumetric ratio of longitudinal reinforcement (2.01%, 3.14% and 4.52%), volumetric ratio of lateral reinforcement (spacing between ties) (2.79%, 3.72% and 5.58%), volume fraction of fibers (0.5% and 0.75%), type of fibers (hooked steel fiber and polypropylene) and aspect ratio of steel fibers(100 (length 50mm and diameter 0.5mm) and 60 (length 30mm and diameter 0.5mm)).

The column specimens were tested under concentric axial compression load.

The load axial strain relationship, ultimate strength and concrete axial strain were investigated.

The mechanical properties of the concrete used in manufacturing columns were also investigated, which include, compressive strength, splitting tensile strength, flexural strength, and static modulus of elasticity, toughness and resilience.

The results showed that the addition of steel fibers (volume friction 0.75% and aspect ratio 100) for HPC improves the compressive strength, splitting tensile strength, flexural strength, and static modulus of elasticity by about 9%, 75%, 64%, 3%, respectively.

The toughness and resilience significantly improved for HPC with steel fibers relative to non fibrous concrete.

Generally, the results also showed that the addition of fibers to normal and high performance concrete columns increases the maximum strength and improves their behavior.

It was also found that the percentage increase in peak strength of columns at constant steel fiber volume fraction is slightly decreased with the increase in fiber aspect ratio.

The percentage increase for HPC columns containing 0.75% steel fibers is about 42% and 21% for specimens with short and long fibers, respectively.

Also, the results exhibited that the addition of 0.5% steel fibers with aspect ratio of 100 to NSC columns causes an increase in column peak strength of about 54% relative to non fibrous NSC columns, while the percentage increase for HPC columns containing the same steel fiber volume fraction and aspect ratio is about 23% in comparison with non fibrous HPC columns.

This suggests that HPC requires more fibers to acquire the same percentage increase in strength and ductility as that provided by normal strength fibrous concrete.

Thus, the same percentage of fibers had different effects on the behavior of two concrete mixes with different concrete strengths.

The volumetric ratios of longitudinal and transverse reinforcement slightly affect the peak strength of column specimens.

Finally the results show that the stress – strain relationship extend beyond the peak load for HPC columns containing long fibers (aspect ratio 100) with volume fraction 0.75% and reinforced with longitudinal bars with diameter 10mm and 12mm, which means that the ductility of these columns significantly improved.

التخصصات الرئيسية

العلوم الهندسية والتكنولوجية (متداخلة التخصصات)

الموضوعات

• الخواص الميكانيكية
• الأعمدة الخرسانية

• APA
• MLA
• AMA

لغة النص

الإنجليزية

نوع البيانات

رسائل جامعية

رقم السجل

BIM-419075