Effect of temperature and galvanization on the compressive strength of cold-formed angles

1990 ◽  
Vol 17 (3) ◽  
pp. 440-451 ◽  
Author(s):  
D. Polyzois ◽  
P. Charnvarnichborikarn ◽  
S. Rizkalla ◽  
C. K. Wong
Keyword(s):  
Compressive Strength ◽  
Material Properties ◽  
Room Temperature ◽  
Slenderness Ratio ◽  
Effect Of Temperature ◽  
Experimental Program ◽  
Ultimate Capacity ◽  
Cold Formed Steel ◽  
University Of Manitoba ◽  
The University

An experimental program was conducted at The University of Manitoba to investigate the effect of subfreezing temperatures and galvanization on the compressive strength of cold-formed steel angles. The study involved the testing of 20 cold-formed angles, 55 × 55 × 4 mm, with a slenderness ratio of approximately 70. Equal numbers of galvanized and ungalvanized angles were tested at various temperatures ranging from −45 to 25 °C. The material properties were obtained through 48 standard tension coupon tests conducted at the same temperature range. The results showed that the capacity of the angles measured at temperatures below −40 °C was approximately 8% higher than the capacity at room temperature. Similar results were obtained during testing of the standard tension coupons where the yield and tensile strengths of the steel used were approximately 10% higher at temperatures below −40 °C than at room temperature. On the average, the ultimate capacity of galvanized angles was approximately 9% higher than that of ungalvanized angles. Although the yield strength of the corner coupons was between 13% and 27% higher than that of flat coupons tested at room temperature, the compressive strength of the full-size angles was influenced mainly by the material properties of the flat regions. A comparison of the measured and predicted capacities using the current Canadian standard and American specification indicated that the Canadian standard overestimated the ultimate capacity of the angles by as much as 37%, while the American specification underestimated the capacity by as much as 45%. Key words: angles, cold-formed, galvanized, temperature, compression, ultimate.

Effect of Temperature on the Material Properties and the Results of Thermal Stress Analysis

2017 ◽  
Vol 729 ◽  
pp. 8-12
Author(s):  
Tae Kyung Kim ◽  
Dong Kwon Oh ◽  
Kwang Ju Lee
Keyword(s):  
Thermal Stress ◽  
Elastic Modulus ◽  
Stress Analysis ◽  
Material Properties ◽  
Room Temperature ◽  
Test System ◽  
Effect Of Temperature ◽  
Air Conditioning System ◽  
Thermal Stress Analysis ◽  
Different Levels

Use of correct values of material properties is important in structural analysis. When incorrect values are used in the analysis, engineers may end up with misleading conclusions. The magnitudes of elastic modulus and strength are usually measured from experiments at room temperature. When these values are used in the thermal stress analysis of structures, the results may not be reliable because the magnitudes of elastic modulus and strength depend on temperature. The temperature distribution of HVAC (Heating, Ventilation and Air Conditioning) system was analyzed. The material properties were measured using MTS810 material test system and MTS 651 environmental chamber at different levels of temperature. They were used in the thermal stress analysis of HVAC system. It was found that the results of thermal stress analysis were significantly different from the results using material properties which were measured from experiments at room temperature.

Characterization of Conventional and Modern Curing Techniques in Concrete

2016 ◽  
Vol 711 ◽  
pp. 1118-1125
Author(s):  
Wasim Khaliq ◽  
Waqas Javaid
Keyword(s):  
Compressive Strength ◽  
Material Properties ◽  
Experimental Program ◽  
Strength Development ◽  
Vital Importance ◽  
Uniform Microstructure ◽  
Curing Methods ◽  
Compressive Strength Development ◽  
Strength And Durability

Appropriate curing of concrete is of vital importance in development of desired material properties in concrete namely compressive strength, durability, and dense uniform microstructure. Improper and intermittent curing is considered as one of the major reasons for concrete failures as evident in the form of cracks that consequently lead to durability issues of structures. An experimental program was designed to study the behavior of concrete under various conventional and modern curing techniques. Numerous cylindrical specimens were tested with different conventional and modern curing techniques to quantify their effects on curing of concrete. Microstructural and compressive strength development analyses at different ages were conducted to monitor the effect of curing methods. This work is helpful in establishing the best curing techniques for attainment of compressive strength and durability in concrete.

The Effect of Temperature on Tensile and Compressive Strengths and Young's Modulus of Oil Shale

1979 ◽  
Vol 19 (05) ◽  
pp. 301-312 ◽  
Author(s):  
P.J. Closmann ◽  
W.B. Bradley
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Young’S Modulus ◽  
Oil Shale ◽  
Room Temperature ◽  
Young's Modulus ◽  
Effect Of Temperature ◽  
Triaxial Tests ◽  
Process Conditions ◽  
Decomposition Pressure

Abstract The analysis of underground oil-shale recovery processes requires knowledge of the mechanical properties of oil shale at various temperatures. The tensile strength, compressive strength, and Young's modulus are of special importance. The variation of these properties with temperature is important when assessing the strength of underground columns and confining walls for process cavities. This paper presents the results of an experimental study to quantify this temperature dependence. We found that both tensile and compressive strengths of oil shale show a marked decrease in strength as temperature increased, for a given richness. For example, for 15.6 gal/ton oil shale, the tensile strength at 400 deg. F is only 28% of its room temperature value. For 19.2 gal/ton shale, the compressive strength at 400 deg. F with 500-psi confining pressure is 43% of its value at room temperature. At a given temperature, both the tensile and compressive strengths decrease as richness increases, although the rate of decrease diminishes at richnesses of about 42 gal/ton and higher. Equations are developed to permit estimates of the various parameters involved. The compressive Young's moduli show a considerable decrease with temperature. At 400 deg. F the modulus is reduced to 51% of its room temperature value. Introduction In-situ processes for recovery of oil from nahcolite-bearing oil shale usually involve some heating or pyrolysis of the shale. Wet processes (steam, hot water) also involve dissolution of nahcolite to generate pore space and to create permeability. If the leaching of nahcolite is conducted at a sufficiently high temperature, some stress will develop in the rock beyond the heated cavity boundary because of CO2 generation and possibly water vapor, as follows. 2NaHCO3 goes to Na2CO3 + H2O + CO2. When the decomposition pressure of nahcolite is high enough, the rock tends to fracture ("popcorn effect"). Rubbling of the formation then can occur. To predict conditions suitable for fracturing and rubbling, we need to know how the rock tensile strength varies with temperature. McLamore measured the oil-shale tensile strength as a function of orientation of stress. So far as we know, no measurements of tensile strength as a function of temperature have been reported for oil shale. We also need to know the variation of nahcolite decomposition pressure with temperature. This pressure variation was measured by Templeton. The variation of Young's modulus, compressive strength, and Poisson's ratio also have been reported for various richnesses. Logan and Heard studied the compressive Young's modulus and thermal expansion as functions of richness. Compressive strength of oil shale has been studied extensively. This parameter was measured as a function of oil-shale richness for various confining pressures in triaxial tests at temperatures up to 300 deg. C (572 deg. F). The effect of temperature on rocks other than oil shale has also been studied. Knowledge of the compressive strength is important when assessing the possibility of failure of underground supporting walls in mines or with process cavities. Since the reacted oil shale probably will support the walls or the roofs of the process cavities very little, the strength of the supporting walls and roof under process conditions will determine the tendency for subsidence or intercavity communication. SPEJ P. 301^

Effects of Connecting Plates on Cold-Formed Steel Wall Plate System

2016 ◽  
Vol 858 ◽  
pp. 38-43
Author(s):  
Ng Ling Ying Adeline ◽  
Wei Hui Hii
Keyword(s):  
Failure Mode ◽  
Material Properties ◽  
Experimental Investigations ◽  
Ultimate Capacity ◽  
Pull Out ◽  
Modes Of Failure ◽  
Cold Formed Steel ◽  
Yield Capacity ◽  
Mode Failure ◽  
Plate System

The paper presents experimental investigations on cold-formed steel (CFS) wall plate system. The behavior and the modes of failure of the system under uplift were studied. The parameters tested were the presence of gaps and the thickness of connecting plates. Results showed that samples with and without gaps at the supports experienced the same failure mode. Failure began with the yielding of connecting plates followed by the buckling of C-channel. Similar ultimate capacity was also obtained for samples with and without gaps. When connecting plates of different thicknesses were used to connect the wall-plate, different modes of failure were observed. Instead of yielding in the connecting plates, screw pull-out was observed in the connection before the C-channel buckled. Besides, it was observed that the ultimate capacity of the system was reduced when thicker connecting plates were used. It is not conservative to estimate the capacity of screwed connection according to the design standard and it is proposed that the capacity of the wall plate system is taken as the yield capacity of the connecting plates of the same material properties.

The 1-MeV Electron Microscope Installation at the University of Colorado

1973 ◽  
Vol 31 ◽  
pp. 8-9 ◽  
Author(s):  
Mircea Fotino
Keyword(s):  
Electron Microscopy ◽  
Developmental Biology ◽  
Transmission Electron Microscopy ◽  
Electron Microscope ◽  
National Institutes Of Health ◽  
Experimental Program ◽  
University Of Colorado ◽  
Transmission Electron ◽  
The University ◽  
Research Resources

A new 1-MeV transmission electron microscope (Model JEM-1000) was installed at the Department of Molecular, Cellular and Developmental Biology of the University of Colorado in Boulder during the summer and fall of 1972 under the sponsorship of the Division of Research Resources of the National Institutes of Health. The installation was completed in October, 1972. It is installed primarily for the study of biological materials without many of the limitations hitherto unavoidable in standard transmission electron microscopy. Only the technical characteristics of the installation are briefly reviewed here. A more detailed discussion of the experimental program under way is being published elsewhere.

Effect of Temperature on ADP-Induced Platelet Aggregation

1973 ◽  
Vol 29 (01) ◽  
pp. 183-189
Author(s):  
C. A Praga ◽  
E. M Pogliani
Keyword(s):  
Platelet Aggregation ◽  
Incubation Period ◽  
Room Temperature ◽  
Important Variable ◽  
Practical Significance ◽  
Effect Of Temperature ◽  
Induce Platelet Aggregation ◽  
Cuvette Holder ◽  
Exact Temperature

SummaryTemperature represents a very important variable in ADP-induced platelet aggregation.When low doses of ADP ( < 1 (μM) are used to induce platelet aggregation, the length of the incubation period of PRP in the cuvette holder of the aggregometer, thermostatted at 37° C, is very critical. Samples of the same PRP previously kept at room temperature, were incubated for increasing periods of time in the cuvette of the aggregometer before adding ADP, and a significant decrease of aggregation, proportional to the length of incubation, was observed. Stirring of the PRP during the incubation period made these changes more evident.To measure the exact temperature of the PRP during incubation in the aggre- gometer, a thermocouple device was used. While the temperature of the cuvette holder was stable at 37° C, the PRP temperature itself increased exponentially, taking about ten minutes from the beginning of the incubation to reach the value of 37° C. The above results have a practical significance in the reproducibility of the platelet aggregation test in vitro and acquire particular value when the effect of inhibitors of ADP induced platelet aggregation is studied.Experiments carried out with three anti-aggregating agents (acetyl salicyclic acid, dipyridamole and metergoline) have shown that the incubation conditions which influence both the effect of the drugs on platelets and the ADP breakdown in plasma must be strictly controlled.

Centres for Health Evidence Demonstration Project

2013 ◽  
Author(s):  
Tracy Stewart ◽  
Denise Koufogiannakis ◽  
Robert S.A. Hayward ◽  
Ellen Crumley ◽  
Michael E. Moffatt
Keyword(s):  
Evidence Based Practice ◽  
Demonstration Project ◽  
Evidence Based ◽  
Research Opportunities ◽  
University Of Alberta ◽  
Information Usage ◽  
University Of Manitoba ◽  
The University ◽  
Hospital Wards ◽  
Support Evidence

This paper will report on the establishment of the Centres for Health Evidence (CHE) Demonstration Project in both Edmonton at the University of Alberta and in Winnipeg at the University of Manitoba. The CHE Project brings together a variety of partners to support evidence-based practice using Internet-based desktops on hospital wards. There is a discussion of the CHE's cultural and political experiences. An overview of the research opportunities emanating from the CHE Project is presented as well as some early observations about information usage.

HAYNES STELLITE ALLOY No. 98M2

Alloy Digest ◽  
1960 ◽  
Vol 9 (7) ◽  
Keyword(s):  
Fracture Toughness ◽  
Compressive Strength ◽  
Physical Properties ◽  
Room Temperature ◽  
Base Alloy ◽  
Heat Treating ◽  
The Other ◽  
Stellite Alloy ◽  
Cobalt Base Alloy ◽  
Cobalt Base

Abstract HAYNES STELLITE 98M2 Alloy is a cobalt-base alloy having higher compressive strength and higher hardness than all the other cobalt-base alloys at room temperature and in the red heat range. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and compressive strength as well as fracture toughness. It also includes information on heat treating, machining, and joining. Filing Code: Co-22. Producer or source: Haynes Stellite Company.

scholarly journals Green Biosynthesis of Silver Nanoparticles Using Leaf Extract of Carissa carandas L. and Their Antioxidant and Antimicrobial Activity against Human Pathogenic Bacteria

Biomolecules ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 299
Author(s):  
Reetika Singh ◽  
Christophe Hano ◽  
Gopal Nath ◽  
Bechan Sharma
Keyword(s):  
Silver Nanoparticles ◽  
Pathogenic Bacteria ◽  
Leaf Extract ◽  
Room Temperature ◽  
Xrd Analysis ◽  
Antibacterial Activities ◽  
Effect Of Temperature ◽  
Human Pathogenic Bacteria ◽  
Carissa Carandas ◽  
Antioxidant And Antimicrobial Activity

Carissa carandas L. is traditionally used as antibacterial medicine and accumulates many antioxidant phytochemicals. Here, we expand this traditional usage with the green biosynthesis of silver nanoparticles (AgNPs) achieved using a Carissa carandas L. leaf extract as a reducing and capping agent. The green synthesis of AgNPs reaction was carried out using 1mM silver nitrate and leaf extract. The effect of temperature on the synthesis of AgNPs was examined using room temperature (25 °C) and 60 °C. The silver nanoparticles were formed in one hour by stirring at room temperature. In this case, a yellowish brown colour was developed. The successful formation of silver nanoparticles was confirmed by UV–Vis, Fourier transform infrared (FT-IR) and X-ray diffraction (XRD) analysis. The characteristic peaks of the UV-vis spectrum and XRD confirmed the synthesis of AgNPs. The biosynthesised AgNPs showed potential antioxidant activity through DPPH assay. These AgNPs also exhibited potential antibacterial activity against human pathogenic bacteria. The results were compared with the antioxidant and antibacterial activities of the plant extract, and clearly suggest that the green biosynthesized AgNPs can constitute an effective antioxidant and antibacterial agent.

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