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RISS 인기검색어
- 검색키워드
- 저자 : Muhammad N.S. Hadi (검색결과 5 건)
- 무료
- 기관 내 무료
- 유료
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Flexural behavior of beams reinforced with either steel bars, molded or pultruded GFRP grating
Muhammad N.S. Hadi,Mohammed H.A. Almalome,Tao Yu,William A. Rickards 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.34 No.1
This paper investigates the flexural behavior of concrete beams reinforced longitudinally with either steel bars, molded glass-fiber reinforced polymer (GFRP) grating mesh or pultruded glass-fiber reinforced polymer (GFRP) grating mesh, under four-point bending. The variables included in this study were the type of concrete (normal weight concrete, perlite concrete and vermiculite concrete), type of the longitudinal reinforcement (steel bars, molded and pultruded GFRP grating mesh) and the longitudinal reinforcement ratio (between 0.007 and 0.035). The influences of these variables on the load-midspan deflection curves, bending stiffness, energy absorption and failure modes were investigated. A total of fifteen beams with a cross-sectional dimension of 160 mm × 210 mm and an overall length of 2400 mm were cast and divided into three groups. The first group was constructed with normal weight concrete and served as a reference concrete. The second and third groups were constructed with perlite concrete and vermiculite concrete, respectively. An innovative type of stirrup was used as shear reinforcement for all beams. The results showed that the ultimate load of the beams reinforced with pultruded GFRP grating mesh ranged between 19% and 38% higher than the ultimate load of the beams reinforced with steel bars. The bending stiffness of all beams was influenced by the longitudinal reinforcement ratio rather than the type of concrete. Failure occurred within the pure bending region which means that the innovative stirrups showed a significant resistance to shear failure. Good agreement between the experimental and the analytical ultimate load was obtained.
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Qasim S. Khan,M. Neaz Sheikh,Muhammad N.S. Hadi 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.30 No.6
This research study investigates experimentally and analytically the axial compressive behaviour of Concrete Filled Fiber Reinforced Polymer Tube (CFFT) columns with and without Fiber Reinforced Polymer (FRP) bars. The experimental program comprises five circular columns of 204-206 mm outer diameter and 800-812 mm height. All columns were tested under concentric axial compressive loads. It was found that CFFT columns with and without FRP bars achieved higher peak axial compressive loads and corresponding axial deformations than conventional steel reinforced concrete (RC) column. The contribution of FRP bars was about 12.1% of the axial compressive loads carried by CFFT columns reinforced with FRP bars. Axial load-axial deformation (P ‒ δ) curves of CFFT columns were analytically constructed, which mapped well with the experimental P ‒ δ curves. Also, an equation was proposed to predict the axial compressive load capacity of CFFT columns with and without FRP bars, which adequately considers the contributions of the circumferential confinement provided by FRP tubes and lower ultimate strength of FRP bars in compression than in tension.
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Axial compressive behaviour of circular CFFT: Experimental database and design-oriented model
Qasim S. Khan,M. Neaz Sheikh,Muhammad N.S. Hadi 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.21 No.4
Concrete Filled Fibre Reinforced Polymer Tube (CFFT) for new columns construction has attracted significant research attention in recent years. The CFFT acts as a formwork for new columns and a barrier to corrosion accelerating agents. It significantly increases both the strength capacity (Strength enhancement ratio) and the ductility (Strain enhancement ratio) of reinforced concrete columns. In this study, based on predefined selection criteria, experimental investigation results of 134 circular CFFT columns under axial compression have been compiled and analysed from 599 CFFT specimens available in the literature. It has been observed that actual confinement ratio (expressed as a function of material properties of fibres, diameter of CFFT and compressive strength of concrete) has significant influence on the strength and ductility of circular CFFT columns. Design oriented models have been proposed to compute the strength and strain enhancement ratios of circular CFFT columns. The proposed strength and strain enhancement ratio models have significantly reduced Average Absolute Error (AAE), Mean Square Error (MSE), Relative Standard Error of Estimate (RSEE) and Standard Deviation (SD) as compared to other available strength and strain enhancement ratios of circular CFFT column models. The predictions of the proposed strength and strain enhancement ratio models match well with the experimental strength and strain enhancement ratios investigation results in the compiled database.
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Patel, Vipulkumar Ishavarbhai,Liang, Qing Quan,Hadi, Muhammad N.S. Techno-Press 2012 Interaction and multiscale mechanics Vol.5 No.2
There is relatively little numerical study on the behavior of eccentrically loaded high strength rectangular concrete-filled steel tubular (CFST) slender beam-columns with large depth-to-thickness ratios, which may undergo local and global buckling. This paper presents a multiscale numerical model for simulating the interaction local and global buckling behavior of high strength thin-walled rectangular CFST slender beam-columns under eccentric loading. The effects of progressive local buckling are taken into account in the mesoscale model based on fiber element formulations. Computational algorithms based on the M$\ddot{u}$ller's method are developed to obtain complete load-deflection responses of CFST slender beam-columns at the macroscale level. Performance indices are proposed to quantify the performance of CFST slender beam-columns. The accuracy of the multiscale numerical model is examined by comparisons of computer solutions with existing experimental results. The numerical model is utilized to investigate the effects of concrete compressive strength, depth-to-thickness ratio, loading eccentricity ratio and column slenderness ratio on the performance indices. The multiscale numerical model is shown to be accurate and efficient for predicting the interaction buckling behavior of high strength thin-walled CFST slender beam-columns.
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Hu Feng,M. Neaz Sheikh,Muhammad N. S. Hadi,Lu Feng,Danying Gao,Jun Zhao 한국콘크리트학회 2019 International Journal of Concrete Structures and M Vol.13 No.4
A series of pullout tests were conducted to investigate the interface bond properties of seven types of steel fibres embedded in the magnesium phosphate cementitious matrix. The micromorphology of the interface transition zone between MPC and different types of fibres was examined by scanning electron microscope. Test results showed that smaller diameter steel fibres with brass coating surface achieved higher average bond strength, higher pullout energy per unit volume and a higher ratio of material use. The end hook deformation provided the mechanical bond locally whereas the deformation along the length of fibre provided the mechanical bond distributed along the fibre. The failure mode and group effect of steel fibres were also investigated and reported.
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