ثائر مطلب مزهر الموسوي

Abstract: Extensive research is going on now a days on the structural performance with steel fibers along silica fume as an extension of the recent advances in concrete technology. This research presents a study in this direction to investigate the shear behavior as well as determining the cracking and ultimate shear capacities of with steel fibers and silica fume beams. In the this study consist three simply supports beams and an additional with steel fibers along silica fume. Measurements were recorded for the cracking load, the ultimate shear load, midspan deflection, maximum crack width, concrete strains at important locations and pattern of failure. The variables considered in this experimental program was the steel fibers Volumetric ratio Vf. It was establish that the rise of steel fibers (Vf) from (1-2%) improved the diagonal cracking load (Pcr) from 22-63% and growing ultimate shear load (Pu) from 51.21-180.46% correspondingly as associated to nonfibrous beams.

Studies on the effect of using externally bonded fiber reinforced polymer (FRP) laminates and near surface mounted (NSM) FRP bars on the shear strengthening of reinforced concrete (RC) beams has been widely conducted by various researchers globally. However, an innovative technique using NSM CFRP as anchor bars on the shear strengthening of RC deep beams has never been conducted. Current experimental work on NSM anchor bars has shown good enhancement in the shear capacity for the RC deep beams. This paper presents results obtained from the analytical model of the RC deep beams shear strengthened by NSM CFRP Anchor bars. The study comprises of developing four analytical models using finite element method software ANSYS Version 14. Results of the analytical model and experimental findings were compared for validation. All deep beams were simply supported and subjected to four point bending test with shear span to depth ratio av/d of 0.864. CFRP NSM bars of 5 mm diameter with 450 mm length and spaced at 100 mm (for beams R1 and R2) and 150 mm (for beams R3 and R4) were anchors into their respective beams. Similar properties from the experimental work were adopted for the analytical model. Results from the analytical model such as crack pattern, failure mode and load displacement profile were observed to have good agreement with the experimental findings. Shear capacity shows proximity between the analytical model and experimental results observed at 15 % for beams R1 and R2, and 7 % for beams R3 and R4.

This paper presents the results of an experimental study for effective of high temperature and cooling by water with different temperature and different concrete mixture. The 36 concrete cubes with (100× 100 ×100) mm were cast at the same time to be ensure all cubes have same test condition. All concrete cubes were cured within 28 days. Twelve concrete cubes were used as a guide and another 24 cubes were subjected to fire with different temperature (400,600,900) C˚ and cooling before testing. Also finite element analysis by ANSYS V.14 was done to validate the results with experimental work. The compressive strength for cube that were tested under 400 C˚ was higher than another burned cubes. On the other hand, the cubes that burned till 900 C˚ showed a smallest compressive strength. The burn by fire decreased the compressive concrete strength 3-6 times when the temperature increased. Moreover, the results that recorded by Ansys model gave a good validation with experimental results.

The main objective of the work in this paper is to study Shear Strengthening of RC without stirrups Deep Beams with Near Surface Mounted CFRP Rods. The experimental work consists of fabrication and testing simply supported reinforced concrete deep beam with Near Surface Mounted CFRP Rods (NSM) beams , consists of five beams failed in shear and each beam had with dimensions (150 mm x400 mm x 1300 mm), with concrete compressive strength of about 30.54 MPa were casted and tested at 28 days. This research is devoted to investigate the behavior and load carrying capacity of reinforced concrete strengthened and repaired with carbon fiber reinforced polymer (CFRP) rods in shear. For NSM beams designed to fail in shear investigate how the orientation and spacing of CFRP rods affect the shear behavior and the load carrying capacity. The results, show that the beams strengthened externally by CFRP rods provided improvement in ultimate loads. The increase in ultimate loads reached (28.57 %) the behavior of strengthened and repaired NSM beams by CFRP rods increasing the ultimate strength and reducing the ultimate central deflection for increasing the load at the cracking stage and also the load capacity and reducing shear crack widths compared with the control beam.

The main objective of this paper to study the effective of using the Near Surface Mounted NSM CFRP technique as rehabilitation for shear in deep beam after 50-60% of ultimate load.

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