Flexural behavior of high strength self compacting concrete beams reinforced with FRP bars

مقدم أطروحة جامعية

Sabir, Muhammad Ali Ihsan

مشرف أطروحة جامعية

al-Saraf, Subayh
Jasim, May

الجامعة

الجامعة التكنولوجية

الكلية

-

القسم الأكاديمي

قسم هندسة البناء و الإنشاءات

دولة الجامعة

العراق

الدرجة العلمية

دكتوراه

تاريخ الدرجة العلمية

2013

الملخص الإنجليزي

Deterioration of reinforced concrete structures has become a serious problem in the last decades.

This situation is mainly due to corrosion of the embedded steel reinforcing bars in concrete.

That has led to the development of new reinforcing materials.

With their high strength and corrosion resistance, low weight, nonconductive for electric and magnetic field , fiber reinforced polymer (FRP) bars represent an alternative to steel reinforcement .Self-co mpacting concrete is the most revolutionary development in concrete construction for several years with their many advantages , such as faster construction, reduced noise levels due to absence of vibration, safe working environment, improved durability etc .

This research is an experimental and theoretical study on the flexural behavior of high strength self-compacting concrete (HSSCC) beams reinforced with different types of FRP bars .

Experimentally, twenty seven HSSCC beams reinforced with different FRP bars types were tested under two -points loading system .

The main variables considered are the concrete compressive strength (60, 7 0 and 90 MPa), FRP bar type s (Carbon-CFRP ,Aramid-AFRP and Glass-GFRP) and reinforcement ratio (as a ratio of balanced reinforcement ratio ρfb .)In addition to measuring the ultimate load capacity, deflections and curvature, strain gage s were used to obtain the main bar strains at midspan, near the support s and at shear stirrups.

Concrete strains were also measured using strain gages at several locations.

An appropriate common link for the data is the applied load.

Therefore, the experimental load -deflection, load-FRP bars strain s , load -concrete strains , load -concrete strain distribution over depth, load -num ber of cracks number, load -cracks s pacing, load-cracking pattern, load -crack width and ductility index relationships are prepared for all tested beam specimen.

The beams reinforced with carbon fiber reinforced polymer (CFRP) bars showed better flexural behavior than those reinforced with aramid fiber reinforced polymer ( AFRP )and glass fiber reinforced polymer ( GFRP) bars .

The reinforcement ratio (ρf )which is related to the type of failure of concrete beams reinforced with FRP bars, pres ented by ACI 440.1R -06 is (1.4 ρfb .)According to the experimental test results, it is found that (1.75 ρfb )is a more accurate reinforcement ratio which can be used to determine the type of concrete compression failure of such beams.

For over-reinforced concrete sections, the experimental ultimate load for the concrete beams reinforced with AFRP and CFRP bars are 31% and 27% higher than those expected according to ACI 440.1R -06 ( 14 ) respectively , while it is 4% lower for the beams reinforced with GFRP bars .Although ACI 440.1R-06 prefers compression failure mode (concrete crushing) for beam members reinforced with FRP bars, it is still very conservative in d esign of the ultimate load.

Depending on the results, d uctility index based on deformability approach 72 ) gives a better indication than the d uctility index based on an energy approach ( 71 ) for HSSCC beams reinforced with FRP bars.

The ductility index for all under-reinforced HSSCC beams reinforced with FRP bars, are found to be very low and lead to a sudden brittle failure, therefore tension failure is not recommended .Theoretically , finite element analysis was carried out , using a ready program package (ANSYS 14).

The discrete modeling techniques were used for modeling the r einforcement in the HSSCC beams .

The FE model was used to determine the ultimate load capacity, load -deflection curve, FRP bar strains , concrete strains and failure mode for all tested beams .

Furthermore , the FE model was used to t est t he perfo r mance o f similar beams wit h new variables not included i n t he experimental program, such as beam section depth ,type of end supports, adding extra steel bars and very high FRP reinforcement ratio.

The analytical results show good agreement with experimental work results.

Adding steel bars with main FRP bars enhanced the behavior of the beams under loading, in term s of increasing the ultimate load, decreasing the final deflection and chang ing the load-deflection curve of the concrete beam from the linear to nonlinear relationship .

التخصصات الرئيسية

العلوم الهندسية والتكنولوجية (متداخلة التخصصات)

الموضوعات

• الخرسانة المسلحة

• APA
• MLA
• AMA

لغة النص

الإنجليزية

نوع البيانات

رسائل جامعية

رقم السجل

BIM-418127