scholarly journals FRP-Confined Concrete Columns: A New Procedure for Evaluating the Performance of Square and Circular Sections

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Marinella Fossetti ◽  
Francesco Basone ◽  
Giuseppe D’Arenzo ◽  
Giuseppe Macaluso ◽  
Alfio Francesco Siciliano
Keyword(s):  
Concrete Columns ◽  
Confined Concrete ◽  
Analytical Models ◽  
Dissipated Energy ◽  
Element Analysis ◽  
The Many ◽  
Open Question ◽  
Semiempirical Models ◽  
Strength And Ductility

In the last few decades, the upgrading of existing reinforced concrete columns with the use of FRP jackets has met with increasing interest for its effectiveness and ease of application. The use of these kinds of jackets ensures an improvement of the affected column in terms of strength and ductility; however, the prediction of behavior of columns wrapped with FRP jackets is still an open question because of the many parameters that influence the effectiveness of the upgrading technique, and several semiempirical models are proposed. Because these models are often only applicable to specific cases, in this paper, a generalized criterion for the determination of the increase in strength, in ductility, and in dissipated energy for varying corner radius ratios of the cross section and fiber volumetric ratios is shown. Numerical results using a finite element analysis, calibrated on the basis of experimental data available in the literature, are carried out to calibrate the new analytical models. A comparison with some available models confirms the reliability of the proposed procedure.

Finite Element Analysis of Mechanical Property for Solid Multibarrel Tube-Confined Concrete Columns (CHS Inner and SHS Outer) under Monotonic Loading

2011 ◽  
Vol 94-96 ◽  
pp. 641-646
Author(s):  
Zhao Qiang Zhang ◽  
Yong Yao
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Failure Modes ◽  
Constitutive Models ◽  
Concrete Columns ◽  
Steel Tube ◽  
Monotonic Loading ◽  
Confined Concrete ◽  
Element Analysis ◽  
Load Displacement

Based on the constitutive models of steel and core concrete,the failure modes and the load-displacement curves of the solid multibarrel tube-confined concrete columns(CHS inner and SHS outer) under monotonic loading are calculated by using finite element analysis (FEA) method.The analytical results reveal the rules of stress distribution in steel and core concrete.The influences of axial compression ratio, yield strength of steel tube and concrete on the load-displacement curves are discussed.Through the results,it is deeply known the working mechanism of members(CHS inner and SHS outer) subjected to the static loads.

A practical method of design of concrete pedestals for columns for anchor rod tension breakout

2010 ◽  
Vol 37 (12) ◽  
pp. 1641-1645
Author(s):  
Konstantin Ashkinadze
Keyword(s):  
Tensile Force ◽  
Concrete Columns ◽  
Practical Method ◽  
Bearing Steel ◽  
Technical Note ◽  
Bending Moments ◽  
Reinforcing Bars ◽  
Failure Plane ◽  
Element Analysis

This technical note considers concrete pedestals bearing steel and concrete columns attached to the foundation with cast-in anchor rods. One mechanism of pedestal failure — the anchor rod breakout in tension — is considered. Uplift and shear forces and bending moments in the base cause tension in the anchor rods. Classical methods of statics and finite element analysis (FEA) are applicable to establish the anchor likely to fail first. For the design of the anchor rod embedment in the concrete, the new “cone balancing” method is proposed. It considers equilibrium of the pullout cone of concrete, ascertained by development of vertical reinforcing bars into the pullout cone and below the failure plane. The method allows determination of tensile force in each individual rebar and direct checking of its size and development length.

Finite Element Analysis of Axially Loaded Confined Concrete Columns

2010 ◽  
Vol 163-167 ◽  
pp. 1029-1032
Author(s):  
He Meng ◽  
Kun Yang ◽  
Qing Xuan Shi ◽  
Jin Jie Men
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Peak Load ◽  
High Strength ◽  
Concrete Columns ◽  
Confined Concrete ◽  
Stress Distributions ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Axially Loaded

The finite element analysis of high-strength concrete columns confined by high-strength spiral lateral ties under concentric compression is introduced in this paper. The variables of tie strength, tie spacing and tie configuration influencing the characteristics of confined concrete are discussed; and the stress distributions of lateral ties and concrete at cross-section are analyzed. Compared with the test results, this finite element analysis can predict well the behavior of axially loaded concrete confined by lateral ties. It’s indicated that after peak load, normal stirrups loss the effective constraint on concrete due to yielding early, while the high-strength stirrups can continue to provide larger constraint which can improve significantly the ductility of confined concrete.

Stirrup effects on compressive strength and ductility of confined concrete columns

2013 ◽  
Vol 10 (6) ◽  
pp. 497-506 ◽  
Author(s):  
Jure Radnic ◽  
Radoslav Markic ◽  
Alen Harapin ◽  
Domagoj Matesan ◽  
Goran Baloevic
Keyword(s):  
Compressive Strength ◽  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Cross Section ◽  
Experimental Testing ◽  
Rectangular Cross Section ◽  
Concrete Columns ◽  
Confined Concrete ◽  
Reinforced Concrete Columns ◽  
Strength And Ductility

The results of experimental testing of stirrup effects on compressive strength and ductility of axially loaded confined reinforced concrete columns of rectangular cross-section are presented. Effects of different concrete strengths, different stirrup bar diameters and different stirrup spacing on column's bearing capacity and ductility have been researched.

Experimental Study on Concrete Columns with Various Sizes Confined by BFRP and Hybrid FRP under Axial Compression

2013 ◽  
Vol 838-841 ◽  
pp. 407-411 ◽  
Author(s):  
Yue Ling Long ◽  
Jiang Zhu
Keyword(s):  
Experimental Study ◽  
Size Effects ◽  
Peak Stress ◽  
Plain Concrete ◽  
Concrete Columns ◽  
Confined Concrete ◽  
Confining Effect ◽  
Strain Model ◽  
Strength And Ductility ◽  
Better Than

Fourteen concrete columns with various sizes confined by BFRP and hybrid FRP and six plain concrete columns as the control specimens were axially loaded to failure in order to investigate both confining effects and size effects in concrete columns confined by BFRP and hybrid FRP. Experimental results show that BFRP and hybrid FRP can increase considerably both the capacity and ductility of the concrete specimens. Furthermore, the peak stress of the unconfined concrete decreases with the size of the specimens increasing. Similarly, the peak stress of BFRP confined concrete decreases with the size of the specimens increasing when the lateral confining stresses are the same. Hence, both confining effect and size effects should be considered carefully in the stress-strain model of concrete confined by BFRP. In addition, both strength and ductility of concrete confined by hybrid FRP in case of CFRP as inner layers and BFRP as outward layers are better than those in case of BFRP as inner layers and CFRP as outward layers.

scholarly journals Determination of Detachment Frequencies of Ripe Coffee Fruits (Coffea Arabica Var. Colombia) by Means of a Numerical and Experimental Approach

2019 ◽  
Author(s):  
Hector Andres Tinoco
Keyword(s):  
Coffea Arabica ◽  
Experimental Approach ◽  
Geometric Model ◽  
Numerical Approach ◽  
Analytical Models ◽  
Element Analysis ◽  
Ripening Stages ◽  
Dynamic Excitations ◽  
Coffea Arabica L

In this study, it is proposed an experimental and numerical approach to identify a bandwidth of harmonic frequencies where ripe fruits of Coffea arabica L. var. Colombia can be selectively stimulated. For this purpose, a geometric model was designed computationally to represent the topology of the coffee fruit-peduncle system in all ripening stages. Using analytical models and pseudo-experimental data, the mechanical properties were estimated to carry out a finite element analysis of the system. It was verified with a detachment model that fruits can be detached when a specific harmonic force (mechanical vibrations) is applied on the fruits in determined frequencies which correspond to the second vibration mode of the fruits. Results indicate that dynamic excitations between 130 to 150 Hz could detach only ripe fruits since fruits that were in other ripening stages were not stimulated until detachment in that bandwidth.

The many faces of STEM in materials science

1991 ◽  
Vol 49 ◽  
pp. 440-441
Author(s):  
John Silcox
Keyword(s):  
Materials Science ◽  
Auger Spectroscopy ◽  
Dark Field ◽  
High Tc Superconductors ◽  
High Tc ◽  
Acoustic Environment ◽  
Electromagnetic Vibration ◽  
The Many ◽  
Serial Mode

Determination of the microstructure and microchemistry of small features often provides the insight needed for the understanding of processes in real materials. In many cases, it is not adequate to use microscopy alone. Microdiffraction and microspectroscopic information such as EELS, X-ray microprobe analysis and Auger spectroscopy can all contribute vital parts of the picture. For a number of reasons, dedicated STEM offers considerable promise as a quantitative instrument. In this paper, we review progress towards effective quantitative use of STEM with illustrations drawn from studies of high Tc superconductors, compound semiconductors and metallization of H-terminated silicon.Intrinsically, STEM is a quantitative instrument. Images are acquired directly by detectors in serial mode which is particularly convenient for digital image acquisition, control and display. The VG HB501A at Cornell has been installed in a particularly stable electromagnetic, vibration and acoustic environment. Care has been paid to achieving UHV conditions (i.e., 10-10 Torr). Finally, it has been interfaced with a VAX 3200 work station by Kirkland. This permits, for example, the acquisition of bright field (or energy loss) images and dark field images simultaneously as quantitative arrays in perfect registration.

Enhanced information from biological materials through technological improvements in cryo-electron microscopy

1992 ◽  
Vol 50 (1) ◽  
pp. 788-789
Author(s):  
Marc J.C. de Jong ◽  
Wim M. Busing ◽  
Max T. Otten
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
Biological Materials ◽  
Electron Crystallography ◽  
Cryo Electron Microscopy ◽  
Transmission Electron ◽  
The Many ◽  
Technological Improvements ◽  
Beam Damage

Biological materials damage rapidly in the electron beam, limiting the amount of information that can be obtained in the transmission electron microscope. The discovery that observation at cryo temperatures strongly reduces beam damage (in addition to making it unnecessaiy to use chemical fixatives, dehydration agents and stains, which introduce artefacts) has given an important step forward to preserving the ‘live’ situation and makes it possible to study the relation between function, chemical composition and morphology.Among the many cryo-applications, the most challenging is perhaps the determination of the atomic structure. Henderson and co-workers were able to determine the structure of the purple membrane by electron crystallography, providing an understanding of the membrane's working as a proton pump. As far as understood at present, the main stumbling block in achieving high resolution appears to be a random movement of atoms or molecules in the specimen within a fraction of a second after exposure to the electron beam, which destroys the highest-resolution detail sought.

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