[PDF] Effect Of Transverse Reinforcement On Bond Strength Of Reinfocement In Silica Fume Concrete eBook

Author : Mahmoud Farouk Machaka
Publisher :
Page : 282 pages
File Size : 39,36 MB
Release : 1997
Category :
ISBN :

GET BOOK

The use of silica fume has been steadily increasing all over the world as designers utilize the resulting high performance concrete (HPC) to increase the concrete compressive strength and to reduce or eliminate durability problems such as sulfate attack and corrosion. Very few researchers investigated the effect of silica fume on bond-slip characteristics of deformed bars in high performance concrete. Researchers who worked on this topic like Itani and Azizinamini, concluded that the presence of silica fume reduced the bond strength and induced a brittle mode of failure. They suggested the use of transverse reinforcement over the splice region in order to increase the bond strength and provide a ductile mode of failure. The objectives of the proposed research program were to investigate the effect of transverse reinforcement on the bond-slip characteristics of tension lap splices in high performance silica fume concrete, to study the validity of the upper limit of 70 MPa (10,000 psi) imposed by the ACI Building Code 318-95 on the concrete compressive strength for determination of development length, and to evaluate the reliability of the empirical equation of Orangun, Jirsa, and Breen in estimating the bond strength of deformed bars embedded in high strength concrete. Twelve beam specimens were tested. Each beam specimen included two bars in tension, spliced at the center of the span. The beams were designed in way that bars would fail in bond, splitting the concrete cover in the splice region, before reaching the yield point. The beams were loaded in positive bending with the splice in a constant moment region. The variables used were the percentage replacement by weight of cement by silica fume and the amount of confinement over the splice region. Test results indicated that silica fume decreased the bond strength and that specimens containing silica fume but without any transverse reinforcement in the splice region had a brittle, sudden and noisy mode of failure. The use of transverse reinforcement in the splice region increased the bond strength and the ductility of the mode of failure of the beam specimens. Minimum amounts of transverse reinforcement were recommended.

Author : Maher Samir Itani
Publisher :
Page : 278 pages
File Size : 25,78 MB
Release : 1996
Category :
ISBN :

GET BOOK

In the last 15 years, high performance concrete with compressive strength exceeding 70 MPa (10,000 psi) and ranging up to 120 MPa (17.0(H) psi) has been achieved consistently and utilized in bridges and high rise building construction. Production of this concrete depends on the use of very low water-to-cementitious material ratio with the aid of high-range water-reducers or superplasticizers. and on a careful selection and dosage of a mineral pozzolanic admixture such as silica fume. Little research is reported in the literature on the effect of pozzolans such as silica fume on structural behavior of reinforced concrete, namely on bond and anchorage characteristics of reinforcing bars in concrete. The objectives of the study were to investigate the effect of silica fume on bond and anchorage characteristics of reinforcing bars in high performance concrete, to study the validity of the upper limit of 70 MPa (10.000 psi) imposed by the AC! Building Code 318-95 on the concrete compressive strength for determination of development length, and to evaluate the reliability of the empirical equation of Orangun, Jirsa, and Breen in estimating the bond strength of deformed bars embedded in high strength concrete. Sixteen beam specimens were tested. Each beam was designed to include two bars in tension, spliced at the center of the span. The splice length was selected so that bars would fail in bond, splitting the concrete cover in the splice region, before reaching the yield point. The beams were loaded in positive bending with the splice in a constant moment region. The variables used were the percentage replacement by weight of cement by silica fume, casting position, and the superplasticizer dosage. Test results indicated that replacement of 5 to 20 percent of the cement by an equal weight of silica fume resulted in an average 10 percent reduction in bond strength regardless of casting position or the superplasticizer dosage used.

Author : Saad Mohannad Sabbah
Publisher :
Page : 324 pages
File Size : 43,49 MB
Release : 1997
Category :
ISBN :

GET BOOK

The work reported in this thesis is the third phase of a multiphase research program conducted at the American University of Beirut to investigate and assess the effect of silica fume on the bond and anchorage characteristics of reinforcing steel bars in high performance concrete (HPC). The objective of the research work was to investigate the effect of specimen type and specimen size on the role of silica fume in the bond strength of the reinforcing bars, and to evaluate the effect of bar size and concrete confinement on the anchorage characteristics of the reinforcing bars in silica fume concrete. The specimen consisted of a deformed bar embedded 25 mm (10 in.) in a 305 mm x 305 mm x 254 mm (12 x 12 x 10 in.) concrete block. The short embedment length was chosen to avoid yielding of the bar before bond splitting failure takes place. The small size of the specimen allowed testing a large number of specimens to cover different variables. The main variables were the percentage replacement by weight of cement by silica fume (0, 4, 8, 12, 16, or 20 percent), the concrete cover over the reinforcing steel bar (25 mm or 50 mm), and the bar size (25 mm or 32 mm). The test results showed that as silica fume content increass, there is a reduction in load-slip stiffness of the specimens regardless of the bar size or concrete cover used. The test results also showed that the bar size does not affect the anchorage characteristics of the reinforcing bars in silica fume concrete. Finally, the results also indicate that the concrete confinement slightly improves the bond resistance in concrete containing more than 10 percent silica fume.

Author : fib Fédération internationale du béton
Publisher : fib Fédération internationale du béton
Page : 448 pages
File Size : 12,69 MB
Release : 2000-01-01
Category : Technology & Engineering
ISBN : 9782883940505

GET BOOK

"In 1993, the CEB Commission 2 Material and Behavior Modelling established the Task Group 2.5 Bond Models. It's terms of reference were ... to write a state-of-art report concerning bond of reinforcement in concrete and later recommend how the knowledge could be applied in practice (Model Code like text proposal)... {This work} covers the first part ... the state-of-art report."--Pref.

Author : Rami Alexandre Akik
Publisher :
Page : 364 pages
File Size : 38,41 MB
Release : 2001
Category :
ISBN :

GET BOOK

This thesis reports on a study designed to investigate the effect of silica fume, bar size, and concrete confinement on the bond-slip characteristics of bottom cast reinforcing bars anchored in eccentric pullout silica fume specimens. The main objective was to assess the effect of casting position by comparing the test results with those of top cast specimens tested earlier and identical except for the casting position.--Forty-eight eccentric pullout specimens were tested. The variables were the percentage replacement by mass of cement by silica, the concrete cover over the reinforcing bar, and the bar size. Failure of the specimens were governed by the splitting of the concrete cover over the anchored bar.--The test results indicated that as the percentages silica fume increased, the maximum load capacity and the stiffness of the load-slip curve of the bottom cast bar decreased regardless of the bar size or the concrete cover used. The reduction in the ultimate load due to presence of silica fume was independent of casting position. Companion bottom and top cast anchored bars developed similar ultimate load capacity regardless of the percentage replacement silica fume.

Author : Julio A. Ramirez
Publisher : Transportation Research Board
Page : 131 pages
File Size : 27,84 MB
Release : 2008
Category : Concrete
ISBN : 030911747X

GET BOOK

"This report documents research performed to develop recommended revisions to the AASHTO LRFD Bridge Design Specifications to extend the applicability of the transfer, development, and splice length provisions for prestressed and non-prestressed concrete members to concrete strengths greater than 10 ksi. The report details the research performed and includes recommended revisions to the AASHTO LRFD Bridge Design Specifications. The material in this report will be of immediate interest to bridge designers."--Foreword.

Author : Shadi Sam Najjar
Publisher :
Page : 372 pages
File Size : 10,11 MB
Release : 2001
Category :
ISBN :

GET BOOK

Several studies are reported in the literature on the effect of transverse reinforcement on bond and anchorage characteristics of reinforcing bars in normal and high strength concrete specimens. Transverse reinforcement provides concrete with confinement and increases its tensile resistance against splitting. When used to confine splices, transverse reinforcement leads to an increase in the bond capacity and to a more ductile and gradual mode of failure.--In 2000, a research program was carried out by Joumaa to study the effect of fiber reinforcement on bond strength and mode of failure of tension lap splices in high strength concrete. In this research, the effect of transverse reinforcement on bond strength and mode of failure of tension lap splices in beam specimens similar to those tested by Joumaa, will be investigated.