Compression tests of C-FRCM jacket confined hollow section RC columns

Structures ◽  
2021 ◽  
Vol 31 ◽  
pp. 961-969
Author(s):  
Ji-Hua Zhu ◽  
Ju Chen ◽  
Yuan Feng ◽  
Cheng-Bin Liu
Keyword(s):  
Compression Tests ◽  
Rc Columns ◽  
Hollow Section

scholarly journals Evaluation of FRP Bars under Compression and Their Performance in RC Columns

Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4541 ◽  
Author(s):  
Laith AlNajmi ◽  
Farid Abed
Keyword(s):  
Mechanical Properties ◽  
Cross Sections ◽  
Total Force ◽  
Compression Tests ◽  
Rc Columns ◽  
Static Compression ◽  
Compression Members ◽  
Different Diameters ◽  
Glass Frp ◽  
Frp Bars

The behavior of fiber-reinforced polymer (FRP) bars under compression is not fully understood yet due to the limited research in this area. However, the long-term durability, weathering resistance, and exceptional mechanical properties of FRP bars justify the need for their use in compression members. The main objectives of this study are to evaluate the mechanical properties of glass FRP (GFRP) and basalt FRP (BFRP) bars under compression and examine their performances as main longitudinal reinforcements in reinforced concrete (RC) columns. In the first part of this research, a series of static compression tests were conducted on GFRP and BFRP bars of different diameters. The second part of this research numerically investigated the behavior of FRP-RC columns under concentric and eccentric loading using the mechanical properties of the FRP bars obtained experimentally. Nonlinear finite element models were developed to simulate the compressive behavior of the concrete columns reinforced with GFRP and BFRP bars. The FE models were verified with the experimental results conducted previously. The verified FE models are then utilized to conduct a parametric analysis considering two different column geometries and cross-sections, five reinforcement ratios, two concrete compressive strengths, three types of ties materials, and several loading eccentricities to develop a set of interaction diagrams that may provide valuable data for design purposes. The results indicated that the FRP bars could have a significant contribution to the overall capacity of FRP-RC columns by up to 35% of the total force at failure, depending on the reinforcement ratio. The performance of both the GFRP- and BFRP-RC columns was almost similar in terms of capacity, deflection, and bar strength contribution.

scholarly journals Study on the Corroded Hollow Section RC Columns Strengthened by ICCP-SS System

Buildings ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 197
Author(s):  
Chen Ju ◽  
Wang Jun ◽  
Ji-Hua Zhu ◽  
Feng Yuan ◽  
Cheng-Bin Liu
Keyword(s):  
Axial Compression ◽  
Current Density ◽  
Ultimate Load ◽  
Chloride Ions ◽  
Outer Side ◽  
Displacement Curve ◽  
Test Results ◽  
Rc Columns ◽  
Hollow Section ◽  
Impressed Current

In this paper, the behavior of corroded hollow section RC (reinforced concrete) columns strengthened by an Impressed Current Cathodic Protection and Structural Strengthening (ICCP-SS) system was investigated. The Carbon Fabric-Reinforced Cementitious Matrix (C-FRCM) composite serves dual functions in the intervention method. The axial compression behavior of strengthened columns was firstly investigated through axial compression tests. The influence of corrosion ratio and C-FRCM strengthening on the test results, such as failure mode, load–displacement curve, ultimate load, and ultimate strain, were analyzed. Test results showed that the ultimate load of the corroded specimens could be enhanced significantly by C-FRCM, and the ductility of the strengthened specimens was larger than the specimens without strengthening, especially for the specimens with higher corrosion ratios. Secondly, the effects of the ICCP-SS system on the migration and distribution laws of chloride ions (Cl−) in hollow section RC columns were analyzed by the potentiometric titration method. The main parameters include charging time, current density, and salt addition. Results showed that the rebar would have a certain blocking effect on the migration of Cl−, which resulted in that the content of Cl− in the inner side of the rebar was always larger than that of the outer side; and research results also showed that the increase of impressed current density and charge time would reduce the Cl− content on both sides of the rebar, while the impressed current would cause the Cl− near the rebars to constantly move toward the vicinity of CFRP.

A Discussion on Numerical Simulation of Axial Reinforcements in RC and RCFT Columns

2013 ◽  
Vol 859 ◽  
pp. 186-190
Author(s):  
Alifujiang Xiamuxi ◽  
Akenjiang Tuohuti ◽  
Akira Hasegawa
Keyword(s):  
Numerical Simulation ◽  
Reinforced Concrete ◽  
Numerical Simulations ◽  
Nonlinear Analysis ◽  
Element Model ◽  
Beam Element ◽  
Displacement Curve ◽  
Compression Tests ◽  
Nonlinear Analyses ◽  
Rc Columns

In numerical simulations of reinforced concrete (RC) columns with ADINA, when the REBAR element model is applied to simulate the reinforcement, the load-displacement curve of RC is similar to that of concrete, without reflecting the contribution of reinforcement. Therefore, employing another element model-BEAM element model for reinforcement, nonlinear analyses of RC columns are carried out and compared against the REBAR element model. The nonlinear analysis of reinforced concrete filled steel tubular (RCFT) columns, then, is performed with the BEAM element model. Meanwhile, the axial compression tests of concrete, RC and RCFT columns are also conducted to validate the nonlinear analysis. Comparing the results of nonlinear analysis against the results of experiment, it is concluded that the BEAM element model can simulate the reinforcement more reasonably than REBAR element model and can be applied to the nonlinear analysis of RCFT columns.

Experimental Investigation of RC Columns Confined with Ni-Ti Shape Memory Alloys Wires versus CFRP Sheets

2020 ◽  
Author(s):  
Khaled Abdelrahman ◽  
Raafat El-Hacha
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Nickel Titanium ◽  
Superior Performance ◽  
Heating Process ◽  
Compression Tests ◽  
Rc Columns ◽  
Cfrp Sheets ◽  
Confinement System ◽  
Cfrp Confinement

The critical need to enhance existing strengthening methods with more efficient and effective ones has led to the evolvement of smarter and innovative class of materials termed Shape Memory Alloys (SMA). The SMA’s possess unique characteristic properties that lie in their ability to undergo large deformations and return to their undeformed shape through stress removal or heating process. Limited research studies conducted using SMA’s have shown high potential for their use in building industry. Results presented in this research study are from an experimental study that investigated the compressive behaviour of uniaxial concentrically loaded Nickel – Titanium (Ni-Ti) SMA-spirally confined RC columns and compared with RC columns confined with conventional CFRP sheets. The compression tests revealed that actively confining the concrete column with Ni-Ti SMA spiral wires increased the performance of the concrete dramatically. Additionally, the active Ni-Ti SMA-confinement system exhibited superior performance compared to the conventional passive CFRP-confinement system.

Electron Microscopy of Shock Loaded Polycrystalline Beryllium

1974 ◽  
Vol 32 ◽  
pp. 506-507 ◽  
Author(s):  
J. M. Galbraith ◽  
L. E. Murr ◽  
A. L. Stevens
Keyword(s):  
Electron Microscopy ◽  
Wave Propagation ◽  
Structural Change ◽  
Single Crystal ◽  
Diffraction Pattern ◽  
Shock Loading ◽  
Slip Systems ◽  
Compression Tests ◽  
X Ray Diffraction ◽  
X Ray

Uniaxial compression tests and hydrostatic tests at pressures up to 27 kbars have been performed to determine operating slip systems in single crystal and polycrystal1ine beryllium. A recent study has been made of wave propagation in single crystal beryllium by shock loading to selectively activate various slip systems, and this has been followed by a study of wave propagation and spallation in textured, polycrystal1ine beryllium. An alteration in the X-ray diffraction pattern has been noted after shock loading, but this alteration has not yet been correlated with any structural change occurring during shock loading of polycrystal1ine beryllium.This study is being conducted in an effort to characterize the effects of shock loading on textured, polycrystal1ine beryllium. Samples were fabricated from a billet of Kawecki-Berylco hot pressed HP-10 beryllium.

Dislocations in alumina deformed by prismatic slip

1978 ◽  
Vol 36 (1) ◽  
pp. 606-607
Author(s):  
J. Cadoz ◽  
J. Castaing ◽  
J. Philibert
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Basal Slip ◽  
Prismatic Slip ◽  
Compression Tests ◽  
Thin Sections ◽  
Burgers Vector ◽  
Maximum Deformation ◽  
Transmission Electron ◽  
Mechanical Thinning

Plastic deformation of alumina has been much studied; basal slip occurs and dislocation structures have been investigated by transmission electron microscopy (T.E.M.) (1). Non basal slip has been observed (2); the prismatic glide system <1010> {1210} has been obtained by compression tests between 1400°C and 1800°C (3). Dislocations with <0110> burgers vector were identified using a 100 kV microscope(4).We describe the dislocation structures after prismatic slip, using high voltage T.E.M. which gives much information.Compression tests were performed at constant strainrate (∿10-4s-1); the maximum deformation reached was 0.03. Thin sections were cut from specimens deformed at 1450°C, either parallel to the glide plane or perpendicular to the glide direction. After mechanical thinning, foils were produced by ion bombardment. Details on experimental techniques can be obtained through reference (3).

Effect Of Elevated Temperatures On Complete Concrete Deformation Diagrams

2019 ◽  
pp. 9-14
Keyword(s):  
Experimental Data ◽  
Elastic Modulus ◽  
Elevated Temperatures ◽  
Peak Load ◽  
Relative Deformation ◽  
Deformation Characteristics ◽  
Compression Tests ◽  
Strain Behavior ◽  
Different Temperatures ◽  
Deformation Diagrams

The analysis of the previous results of the study on concrete stress-strain behavior at elevated temperatures has been carried out. Based on the analysis, the main reasons for strength retrogression and elastic modulus reduction of concrete have been identified. Despite a significant amount of research in this area, there is a large spread in experimental data received, both as a result of compression and tension. In addition, the deformation characteristics of concrete are insufficiently studied: the coefficient of transverse deformation, the limiting relative compression deformation corresponding to the peak load and the almost complete absence of studies of complete deformation diagrams at elevated temperatures. The two testing chambers provided creating the necessary temperature conditions for conducting studies under bending compression and tension have been developed. On the basis of the obtained experimental data of physical and mechanical characteristics of concrete at different temperatures under conditions of axial compression and tensile bending, conclusions about the nature of changes in strength and deformation characteristics have been drawn. Compression tests conducted following the method of concrete deformation complete curves provided obtaining diagrams not only at normal temperature, but also at elevated temperature. Based on the experimental results, dependences of changes in prism strength and elastic modulus as well as an equation for determining the relative deformation and stresses at elevated temperatures at all stages of concrete deterioration have been suggested.

Our Surgical Strategy for Thoracic Outlet Syndrome

2018 ◽  
Vol 1 (2) ◽  
Author(s):  
Yasuhiro Nakajima
Keyword(s):  
Brachial Plexus ◽  
Thoracic Outlet Syndrome ◽  
Vascular Compression ◽  
Compression Tests ◽  
Provocation Tests ◽  
Diagnosis Method ◽  
Tunnel Syndrome ◽  
Electrophysiological Examination ◽  
Sensory Neural ◽  
Plexus Block

Surgical treatment for thoracic outlet syndrome (TOS) is a very controversial surgery because objective diagnosis, such as image and electrophysiological examination, is very difficult. Clinical provocation tests including brachial plexus compression tests, such as Morley and Roos, and vascular compression tests, such as Wright and Eden ,are not high in specificity and are likely to be positive even in healthy persons and patients with carpal tunnel syndrome. We place emphasis on the laterality of latency and amplitude in the sensory neural action potential (SNAP) of the medial antebrachial cutaneous nerve and ulnar nerve. After enough stretching exercises of scapular stabilizers and brachial plexus block, we always select surgery. In this presentation, I would like to show our diagnosis method and treatment strategy including surgery.

Determining elastic properties of sedimentary strata in terms of limestone samples by laser ultrasonics

2020 ◽  
pp. 125-134
Author(s):  
I. A. Shibaev ◽  
V. A. Vinnikov ◽  
G. D. Stepanov
Keyword(s):  
Physical And Mechanical Properties ◽  
Laser Ultrasonics ◽  
Compression Tests ◽  
S Waves ◽  
Static Modulus ◽  
Enhance Efficiency ◽  
Static Modulus Of Elasticity ◽  
Static Elastic Moduli ◽  
Non Destructive ◽  
Moduli Of Elasticity

Geological engineering often uses geomechanical modeling aimed to enhance efficiency of mining or performance of structures. One of the input parameters for such models are the static elastic moduli of rocks. This article presents the studies into the physical and mechanical properties of rocks-limestone of non-metamorphic diagenesis. The precision measurements of Pand S-waves are carried out to an accuracy of 0.2% by laser ultrasonics. The static moduli of elasticity and the deformation characteristics of rocks are determined in the uniaxial compression tests by the standards of GOST 21153.2-84 and GOST 28985-91, respectively. The correlation dependence is found between the static and dynamic elasticity moduli in limestone samples. The found correlation allows drawing the conclusion that the static modulus of elasticity can be estimated in non-destructive tests, which largely simplifies preliminary diagnostics of samples in case of limited number of test core.

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