The document discusses the benefits of exercise for mental health. Regular physical activity can help reduce anxiety and depression and improve mood and cognitive function. Exercise causes chemical changes in the brain that may help alleviate symptoms of mental illness and boost overall mental well-being.
Torsional Fatigue Performance of Induction Hardened 1045 and 10V45 SteelsFluxtrol Inc.
Microalloying of medium carbon bar steels is a common
practice for a number of traditional components; however, use
of vanadium microalloyed steels is expanding into
applications beyond their original designed use as controlled
cooled forged and hot rolled products and into heat treated
components. As a result, there is uncertainty regarding the
influence of vanadium on the properties of heat treated
components, specifically the effect of rapid heat treating such
as induction hardening. In the current study, the torsional
fatigue behavior of hot rolled and scan induction hardened
1045 and 10V45 bars are examined and evaluated at effective
case depths of 25, 32, and 44% of the radius. Torsional fatigue
tests were conducted at a stress ratio of 0.1 and shear stress
amplitudes of 550, 600, and 650 MPa. Cycles to failure are
compared to an empirical model, which accounts for case
depth as well as carbon content.
Relations between Structural Damage and Level of External Prestressing Force ...drboon
Prestressed concrete beams can be damaged by overloading beyond cracking stage leading to the reduction of flexural rigidity and excessive deflection. The progressive of damage, crack and permanent deflection can be occurred at the high level of load after cracking. Structural performance of damaged girder can be recovered and improved by external post tension. The level of external prestressing force required in strengthening depends directly on the level of damage due to overloading. This research studied the effect of levels of damage on flexural rigidity, crack and deflection of the test girder. Three levels of damage can be expressed in terms of 0.65, 0.75 and 0.85 times the predicted ultimate load of the test beam. Three levels of external prestressing forces (2, 2.5 and 3 times of the internal prestressing force applied in undamaged reference beam) are applied in strengthening at each level of damage. The results show that reduced flexural rigidity, increased permanent deformation and crack width due to overloading can be recovered by external post tension. Strengthening by means of external post tension can be effectively applied to the damaged beam at the level of damage not more than 0.65 times of predicted ultimate load.
Established a relationship between weld splice length and diameter of the rei...NUR
Reinforcement strength, ductility and bendability properties are important components in the design of reinforced concrete members, as the strength of any member comes mainly from reinforcement. Strain compatibility and plastic behaviours’ are mainly depending on reinforcement ductility. In construction practice, often welding of the bars is required. Welding of reinforcement is an instant solution in many cases, whereas welding is not a routine connection process. Welding will cause deficiencies in reinforcement bars, metallurgical changes and recrystallization of the microstructure of particles. Weld metal toughness is extremely sensitive to the welding heat input that decreases both its strength and ductility.
SLIDING WEAR OF AA6061/CARBON BLACK METAL MATRIX COMPOSITESIAEME Publication
In this study, the effects of carbon black amount on fracture and wear behaviors of AA6061-carbon black metal matrix composites produced by stir casting route were investigated. Wear tests were performed in a pin on type wear apparatus under different loads of 10, 20, 30 N with different sliding speeds of 2, 3 and 4 m/s, at three different sliding distances of 500, 750 and 1000 m. The design of experiments was carried out as per Taguchi technique. Wear rate function was determined in terms of volume fraction, normal load, sliding speed and sliding distance. It was found that there was a good agreement between the theoretical and the experimental value of wear rate. Maximum sliding wear of 68.72% was attributed sliding distance. Sliding wear resistance increases by 42.56% for AA6061/30%CB metal matrix composites as compared to the matrix alloy AA6061
plastic testing ASTM,ISO,IEC
mechanical,chemical,electrical optical testing.
Polymer Testing provides a forum for developments in the testing of polymers and polymeric products and is hence of interest to those concerned with testing rubbers and plastics in research, in production and in connection with the specification and purchase of products.
Torsional Fatigue Performance of Induction Hardened 1045 and 10V45 SteelsFluxtrol Inc.
Microalloying of medium carbon bar steels is a common
practice for a number of traditional components; however, use
of vanadium microalloyed steels is expanding into
applications beyond their original designed use as controlled
cooled forged and hot rolled products and into heat treated
components. As a result, there is uncertainty regarding the
influence of vanadium on the properties of heat treated
components, specifically the effect of rapid heat treating such
as induction hardening. In the current study, the torsional
fatigue behavior of hot rolled and scan induction hardened
1045 and 10V45 bars are examined and evaluated at effective
case depths of 25, 32, and 44% of the radius. Torsional fatigue
tests were conducted at a stress ratio of 0.1 and shear stress
amplitudes of 550, 600, and 650 MPa. Cycles to failure are
compared to an empirical model, which accounts for case
depth as well as carbon content.
Relations between Structural Damage and Level of External Prestressing Force ...drboon
Prestressed concrete beams can be damaged by overloading beyond cracking stage leading to the reduction of flexural rigidity and excessive deflection. The progressive of damage, crack and permanent deflection can be occurred at the high level of load after cracking. Structural performance of damaged girder can be recovered and improved by external post tension. The level of external prestressing force required in strengthening depends directly on the level of damage due to overloading. This research studied the effect of levels of damage on flexural rigidity, crack and deflection of the test girder. Three levels of damage can be expressed in terms of 0.65, 0.75 and 0.85 times the predicted ultimate load of the test beam. Three levels of external prestressing forces (2, 2.5 and 3 times of the internal prestressing force applied in undamaged reference beam) are applied in strengthening at each level of damage. The results show that reduced flexural rigidity, increased permanent deformation and crack width due to overloading can be recovered by external post tension. Strengthening by means of external post tension can be effectively applied to the damaged beam at the level of damage not more than 0.65 times of predicted ultimate load.
Established a relationship between weld splice length and diameter of the rei...NUR
Reinforcement strength, ductility and bendability properties are important components in the design of reinforced concrete members, as the strength of any member comes mainly from reinforcement. Strain compatibility and plastic behaviours’ are mainly depending on reinforcement ductility. In construction practice, often welding of the bars is required. Welding of reinforcement is an instant solution in many cases, whereas welding is not a routine connection process. Welding will cause deficiencies in reinforcement bars, metallurgical changes and recrystallization of the microstructure of particles. Weld metal toughness is extremely sensitive to the welding heat input that decreases both its strength and ductility.
SLIDING WEAR OF AA6061/CARBON BLACK METAL MATRIX COMPOSITESIAEME Publication
In this study, the effects of carbon black amount on fracture and wear behaviors of AA6061-carbon black metal matrix composites produced by stir casting route were investigated. Wear tests were performed in a pin on type wear apparatus under different loads of 10, 20, 30 N with different sliding speeds of 2, 3 and 4 m/s, at three different sliding distances of 500, 750 and 1000 m. The design of experiments was carried out as per Taguchi technique. Wear rate function was determined in terms of volume fraction, normal load, sliding speed and sliding distance. It was found that there was a good agreement between the theoretical and the experimental value of wear rate. Maximum sliding wear of 68.72% was attributed sliding distance. Sliding wear resistance increases by 42.56% for AA6061/30%CB metal matrix composites as compared to the matrix alloy AA6061
plastic testing ASTM,ISO,IEC
mechanical,chemical,electrical optical testing.
Polymer Testing provides a forum for developments in the testing of polymers and polymeric products and is hence of interest to those concerned with testing rubbers and plastics in research, in production and in connection with the specification and purchase of products.
In the material testing laboratory, Tensile test was done on a mild steel specimen as figure 4 to identify the young’s modulus, ultimate tensile strength, yield strength and percentage elongation. The results were as table 1
Pseudo-In Situ Testing and characterization of Galvanized steelAditya Shankar
-Carried out the characterization of material followed by axial deformation and determined the corresponding strain rates with 99% accuracy
-Calculated the strain rate at different length scales using
X-Ray Diffraction
Electron Back Scattering
Digital Image Correlation
-Observed the moving grain boundary behavior and twinning upon axial deformation of galvanized steel at different deformation conditions
Tensile, Impact and Hardness Testing of Mild SteelGulfam Hussain
The main purpose of this report is to study the mechanical properties and
failure mode of mild steel. Three types of standard tests i.e. tensile test, impact
test, and hardness test were conducted on the standard specimens of mild steel.
From the tests, results were obtained; Tensile strength, Impact strength, and
hardness were calculated. It was observed that Tensile Strength, Impact Strength
and Hardness of MS specimen were 1450.833 N/mm², 29.5 J & 59.25 HRB.
Fabric strength machine, universal strength machine and Material strength machine mainly used in a variety of materials with its constant speed stretching; tearing, stripping, fixed load, fixed elongation, elastic recovery rate, the top break and other test experiments.http://www.qinsun-lab.com/Products/Property/Strength/Fabric%20Tensile%20Testing%20Machines.html
In the material testing laboratory, a Charpy impact test was performed on three different types (hot,cold,and steel alloy)of steels testing each variety at four different temperatures (32°C(RT), 100°C,0°C and -22°C ). From results (shown below), we determined that the a transition is from ductile failures to brittle failures
Thesis Defense - Debunking the Filipino Students' Stereotypical View of ArtistsAnanda Wisely
"Debunking the Filipino Students' Stereotypical View of Artists"
An Undergraduate Thesis Presented to the Professor of Humanities, Social Sciences and Communications
In the material testing laboratory, Tensile test was done on a mild steel specimen as figure 4 to identify the young’s modulus, ultimate tensile strength, yield strength and percentage elongation. The results were as table 1
Pseudo-In Situ Testing and characterization of Galvanized steelAditya Shankar
-Carried out the characterization of material followed by axial deformation and determined the corresponding strain rates with 99% accuracy
-Calculated the strain rate at different length scales using
X-Ray Diffraction
Electron Back Scattering
Digital Image Correlation
-Observed the moving grain boundary behavior and twinning upon axial deformation of galvanized steel at different deformation conditions
Tensile, Impact and Hardness Testing of Mild SteelGulfam Hussain
The main purpose of this report is to study the mechanical properties and
failure mode of mild steel. Three types of standard tests i.e. tensile test, impact
test, and hardness test were conducted on the standard specimens of mild steel.
From the tests, results were obtained; Tensile strength, Impact strength, and
hardness were calculated. It was observed that Tensile Strength, Impact Strength
and Hardness of MS specimen were 1450.833 N/mm², 29.5 J & 59.25 HRB.
Fabric strength machine, universal strength machine and Material strength machine mainly used in a variety of materials with its constant speed stretching; tearing, stripping, fixed load, fixed elongation, elastic recovery rate, the top break and other test experiments.http://www.qinsun-lab.com/Products/Property/Strength/Fabric%20Tensile%20Testing%20Machines.html
In the material testing laboratory, a Charpy impact test was performed on three different types (hot,cold,and steel alloy)of steels testing each variety at four different temperatures (32°C(RT), 100°C,0°C and -22°C ). From results (shown below), we determined that the a transition is from ductile failures to brittle failures
Thesis Defense - Debunking the Filipino Students' Stereotypical View of ArtistsAnanda Wisely
"Debunking the Filipino Students' Stereotypical View of Artists"
An Undergraduate Thesis Presented to the Professor of Humanities, Social Sciences and Communications
Page 6 of 8Engineering Materials ScienceMetals LabLEEDS .docxbunyansaturnina
Page 6 of 8Engineering Materials Science
Metals Lab
LEEDS BECKETT UNIVERSITY
SCHOOL OF THE BUILT ENVIRONMENT & ENGINEERING
Course: BSc (Hons) Civil Engineering BEng (Hons) Civil Engineering
HND Civil Engineering
Laboratory Experiment:
Stress-Strain Behaviour of Mild Steel and High Yield Steel bars.
Associated Module(s)
Level 4 Engineering Materials Science
Object of Experiment
To investigate the stress-strain behaviour of the above materials.
Theory/Analysis
A knowledge of the behaviour of structural steel under load is essential to ensure structural collapse does not occur and that serviceability requirements are achieved. In these respects the following mechanical properties of a material are required:-
1. The yield stress, σy (or 0.2% proof stress)
2. The Elastic (or Young’s) Modulus, E
3. The maximum tensile strength, σmax
4. The stress at failure, ie the fracture stress, σf
5. The % elongation at failure
Apparatus
1. 500kN Denison Testing Machine
2. Extensometer and Denison extension gauge (measures cross head movement)
3. Grade 250 plain round mild steel bar, 20mm diameter
Characteristic strength = 250 N/mm²
Conforms to BS 4449.
4. Grade 460 deformed high yield steel.
Reinforcing bar, T16, 16mm diameter.
Characteristic strength = 460 N/mm²
Conforms to BS 4449.
Method
Each of the bars in turn is placed in the jaws of the testing machine.
The 50mm extensometer is attached to the bar and zeroed.
Load is applied and recorded in increments up to failure. For each load increment, extension readings from the extensometer and the Denison extension gauge are noted.
At the yield point, the extensometer is removed to prevent damage to it and readings continue on the Denison extension gauge.
The load at failure and the manner of failure are noted.
See the Figure below showing the Test Setup.
(
L
G
values; L
G
= 100 mm for the plain
round
bar, and L
G
= 80 mm for the deformed
high yield
bar
) (
L
G
,
gauge length of the samples
) (
P = the tensile force applied to bars from Dennison testing machine
) (
P
) (
Extension of the sample bars is measured by:
the
Dennison (on-board) extension gauge which monitors cross-head
movement
. This effectively gives sample extension readings from the start of the test (P = 0) through to failure.
An extensometer gauge. This is accurate only over the initial linear-elastic phase of the test.
) (
P
)
Each student should prepare and submit a laboratory report, the results and discussion sections are outlined below:a) Results and Calculations
Readings of load (P), against extension (e), have been recorded for each specimen tested and provided to you (appended at the end of this laboratory briefing document).
Knowing the original bar diameters (d), load data can converted to stress (σ) by dividing each load reading by the appropriate cross sectional area.
Strain values are determined by dividing the extension (e) data by the appropriate gauge length for each bar (LG); the g.
SCR and TTR modeling using shell and beam elements to deal with local interests, such as touch-down compression or buckling. Two examples are presented. The FEA tool employed is ABAQUS. Videos can only be seen when downloaded.
Experimental Investigation of Axial Capacity and Energy Absorption of SFRC Co...IJMERJOURNAL
ABSTRACT: This paper presents the results of the experimental study on the axial compressive behavior of steel fiber reinforced concrete (SFRC) wrapped with fiber reinforced polymer (FRP). A total of 18 concrete cylinders were tested under axial compression. The effects of steel fiber parameters were investigated which includes fiber aspect ratio (AR) and fiber volume fraction (VF). The concrete cylinders were divided into groups of confined and unconfined ones. In accordance with previous study, it was found that, FRP confined cylinders showed greater axial stress than that of unconfined specimens. Although the presence of steel fiber increases the peak axial stresses for both confined and unconfined group of specimens, but no significant change of peak axial stress (and peak strain) has been observed in both confined and unconfined group due to increase of fiber volume ratio. But with the increase of fiber aspect ratio, the peak axial stresses of both unconfined and FRP-confined cylinders were found to slightly decrease. It was also observed that, concrete specimens reinforced with internal steel fiber absorbed much higher energy than that of unreinforced ones.
Axial Capacity Enhancement of CFRP Confined Columns Made of Steel Fiber Reinf...IOSRJMCE
Results of the experimental study on the axial compressive behavior of steel fiber reinforced concrete (SFRC) wrapped with fiber reinforced polymer (FRP) have been presented in this paper. A total of 18 concrete cylinders were tested under axial compression. The effects of steel fiber parameters were investigated which includes fiber aspect ratio (AR) and fiber volume fraction (VF). The concrete cylinders were divided into groups of confined and unconfined ones. In accordance with previous study, it was found that, FRP confined cylinders showed greater axial stress than that of unconfined specimens. Although the presence of steel fiber increases the peak axial stresses for both confined and unconfined group of specimens, but no significant change of peak axial stress (and peak strain) has been observed in both confined and unconfined group due to increase of fiber volume ratio. But with the increase of fiber aspect ratio, the peak axial stresses of both unconfined and FRPconfined cylinders were found to slightly decrease. It was also observed that, concrete specimens reinforced with internal steel fiber absorbed much higher energy than that of unreinforced ones.
We offer a comprehensive range of Strength of Material Lab Equipment, which are widely used in Schools, Colleges and Universities.
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BEHAVIOR OF SLENDER COLUMN SUBJECTED TO ECCENTRIC LOADINGijiert bestjournal
This paper focuses on Behavior of slender column su bjected to eccentric loading. Six slender,reinforced concrete columns with slenderness ratio equals to 15;the compressive strength of the concrete were ranged from 60 to 100 MPa. Slender co lumn were subjected to eccentric axial load with load-eccentricity:depth ratio of 0.15. Three columns were reinforced with six bars having a nominal strength of 415 MPa and other three were re inforced with same number of bars having strength equals to 500 MPa with longitudinal steel ratio equals to 4%. The test results were compared with the values predicted using IS 456-200 0. These test,enabled the provision for slender columns in the code to be checked against e xperimental values,have indicated that IS 456-2000 are very safe and uneconomical design docu ment for HPC slender column.
Forklift Classes Overview by Intella PartsIntella Parts
Discover the different forklift classes and their specific applications. Learn how to choose the right forklift for your needs to ensure safety, efficiency, and compliance in your operations.
For more technical information, visit our website https://intellaparts.com
Sachpazis:Terzaghi Bearing Capacity Estimation in simple terms with Calculati...Dr.Costas Sachpazis
Terzaghi's soil bearing capacity theory, developed by Karl Terzaghi, is a fundamental principle in geotechnical engineering used to determine the bearing capacity of shallow foundations. This theory provides a method to calculate the ultimate bearing capacity of soil, which is the maximum load per unit area that the soil can support without undergoing shear failure. The Calculation HTML Code included.
Automobile Management System Project Report.pdfKamal Acharya
The proposed project is developed to manage the automobile in the automobile dealer company. The main module in this project is login, automobile management, customer management, sales, complaints and reports. The first module is the login. The automobile showroom owner should login to the project for usage. The username and password are verified and if it is correct, next form opens. If the username and password are not correct, it shows the error message.
When a customer search for a automobile, if the automobile is available, they will be taken to a page that shows the details of the automobile including automobile name, automobile ID, quantity, price etc. “Automobile Management System” is useful for maintaining automobiles, customers effectively and hence helps for establishing good relation between customer and automobile organization. It contains various customized modules for effectively maintaining automobiles and stock information accurately and safely.
When the automobile is sold to the customer, stock will be reduced automatically. When a new purchase is made, stock will be increased automatically. While selecting automobiles for sale, the proposed software will automatically check for total number of available stock of that particular item, if the total stock of that particular item is less than 5, software will notify the user to purchase the particular item.
Also when the user tries to sale items which are not in stock, the system will prompt the user that the stock is not enough. Customers of this system can search for a automobile; can purchase a automobile easily by selecting fast. On the other hand the stock of automobiles can be maintained perfectly by the automobile shop manager overcoming the drawbacks of existing system.
CFD Simulation of By-pass Flow in a HRSG module by R&R Consult.pptxR&R Consult
CFD analysis is incredibly effective at solving mysteries and improving the performance of complex systems!
Here's a great example: At a large natural gas-fired power plant, where they use waste heat to generate steam and energy, they were puzzled that their boiler wasn't producing as much steam as expected.
R&R and Tetra Engineering Group Inc. were asked to solve the issue with reduced steam production.
An inspection had shown that a significant amount of hot flue gas was bypassing the boiler tubes, where the heat was supposed to be transferred.
R&R Consult conducted a CFD analysis, which revealed that 6.3% of the flue gas was bypassing the boiler tubes without transferring heat. The analysis also showed that the flue gas was instead being directed along the sides of the boiler and between the modules that were supposed to capture the heat. This was the cause of the reduced performance.
Based on our results, Tetra Engineering installed covering plates to reduce the bypass flow. This improved the boiler's performance and increased electricity production.
It is always satisfying when we can help solve complex challenges like this. Do your systems also need a check-up or optimization? Give us a call!
Work done in cooperation with James Malloy and David Moelling from Tetra Engineering.
More examples of our work https://www.r-r-consult.dk/en/cases-en/
Vaccine management system project report documentation..pdfKamal Acharya
The Division of Vaccine and Immunization is facing increasing difficulty monitoring vaccines and other commodities distribution once they have been distributed from the national stores. With the introduction of new vaccines, more challenges have been anticipated with this additions posing serious threat to the already over strained vaccine supply chain system in Kenya.
Hybrid optimization of pumped hydro system and solar- Engr. Abdul-Azeez.pdffxintegritypublishin
Advancements in technology unveil a myriad of electrical and electronic breakthroughs geared towards efficiently harnessing limited resources to meet human energy demands. The optimization of hybrid solar PV panels and pumped hydro energy supply systems plays a pivotal role in utilizing natural resources effectively. This initiative not only benefits humanity but also fosters environmental sustainability. The study investigated the design optimization of these hybrid systems, focusing on understanding solar radiation patterns, identifying geographical influences on solar radiation, formulating a mathematical model for system optimization, and determining the optimal configuration of PV panels and pumped hydro storage. Through a comparative analysis approach and eight weeks of data collection, the study addressed key research questions related to solar radiation patterns and optimal system design. The findings highlighted regions with heightened solar radiation levels, showcasing substantial potential for power generation and emphasizing the system's efficiency. Optimizing system design significantly boosted power generation, promoted renewable energy utilization, and enhanced energy storage capacity. The study underscored the benefits of optimizing hybrid solar PV panels and pumped hydro energy supply systems for sustainable energy usage. Optimizing the design of solar PV panels and pumped hydro energy supply systems as examined across diverse climatic conditions in a developing country, not only enhances power generation but also improves the integration of renewable energy sources and boosts energy storage capacities, particularly beneficial for less economically prosperous regions. Additionally, the study provides valuable insights for advancing energy research in economically viable areas. Recommendations included conducting site-specific assessments, utilizing advanced modeling tools, implementing regular maintenance protocols, and enhancing communication among system components.
Overview of the fundamental roles in Hydropower generation and the components involved in wider Electrical Engineering.
This paper presents the design and construction of hydroelectric dams from the hydrologist’s survey of the valley before construction, all aspects and involved disciplines, fluid dynamics, structural engineering, generation and mains frequency regulation to the very transmission of power through the network in the United Kingdom.
Author: Robbie Edward Sayers
Collaborators and co editors: Charlie Sims and Connor Healey.
(C) 2024 Robbie E. Sayers
Immunizing Image Classifiers Against Localized Adversary Attacksgerogepatton
This paper addresses the vulnerability of deep learning models, particularly convolutional neural networks
(CNN)s, to adversarial attacks and presents a proactive training technique designed to counter them. We
introduce a novel volumization algorithm, which transforms 2D images into 3D volumetric representations.
When combined with 3D convolution and deep curriculum learning optimization (CLO), itsignificantly improves
the immunity of models against localized universal attacks by up to 40%. We evaluate our proposed approach
using contemporary CNN architectures and the modified Canadian Institute for Advanced Research (CIFAR-10
and CIFAR-100) and ImageNet Large Scale Visual Recognition Challenge (ILSVRC12) datasets, showcasing
accuracy improvements over previous techniques. The results indicate that the combination of the volumetric
input and curriculum learning holds significant promise for mitigating adversarial attacks without necessitating
adversary training.
Saudi Arabia stands as a titan in the global energy landscape, renowned for its abundant oil and gas resources. It's the largest exporter of petroleum and holds some of the world's most significant reserves. Let's delve into the top 10 oil and gas projects shaping Saudi Arabia's energy future in 2024.
1. AHSANULLAH UNIVERSITY OF SCIENCE
AND TECHNOLOGY (AUST)
Paper Title
“Investigation of axial capacity of RC columns made of
steel fiber reinforced concrete (SFRC)”
1
Presented by
Romana Akhter
Department of Civil Engineering
Ahsanullah University of Science
and Technology (AUST),
Dhaka 1208, Bangladesh
Co-Partners:
Kazi Shahriar Islam
Rufaka Tabasum
2. Presentation Outline
I n t r o d u c t i o n
O b j e c t i v e
E x p e r i m e n t a l P r o g r a m
a n d S t r a t e g y
E x p e r i m e n t a l D a t a
A n a l y s i s
F i n i t e E l e m e n t M o d e l i n g
a n d A n a l y s i s
V a l i d a t i o n o f F E r e s u l t s
E v a l u a t i o n o f F a i l u r e
P a t t e r n s
C o n c l u s i o n
2
5. Types of steel fiber
Introduction
According to ASTM A 820/A 820M – 06, five general types of
steel fibers are identified based upon the product or process
used as a source of the steel fiber material, these are,
Type I: cold-drawn wire,
Type II: cut sheet,
Type III: melt-extracted,
Type IV: mill cut,
Type V: modified cold-drawn wire
5
7. 7
Fibers distribute
randomly and act
as crack
arrestors.
changing concrete
from a brittle material
to a ductile one, in
addition to improving
toughness and
rigidity
Increases the
ductility by
arresting crack and
prevents the
propagation of
cracks by bridging
fibers.
zone a: Free area of
stress
zone b: Fiber bridging
area
zone c: Micro-crack area
zone d: Undamaged area
Introduction
8. Objective
8
To study the compressive behavior of SFRC RC columns
due to different aspect ratios of steel fiber, i.e. 40, 60 and
80
To investigate the compressive and tensile behavior of
SFRC RC columns of two different cross-sections
To examine failure patterns of RC columns made of
SFRC.
To construct FE models for plain concrete and SFRC in
the FE platform of ANSYS 11.0 and also to validate the
models with the experimental results.
9. 9
Important properties of steel fibers for fiber selection
Type of fiber
Shape of fiber
Aspect ratio (ratio of length to diameter, l/d)
Quantity of steel fiber (volume ratio in %)
Orientation of fiber
Experimental program and
strategy
10. 10
Selection of shape
Stress-strain curves for steel fiber
reinforced mortars in tension
(ACI 544.4R-88)
Experimental program and
strategy
11. 11
Materials
Sand
Stone
Cement
Water
Steel fiber
Experimental program and
strategy
Cement type OPC (Ordinary Portland Cement)
Coarse Aggregate Size 1 in passing and 3/4 in retain (50%)
3/4 in passing and 1/2 in retain (50%)
C:FA:CA 1:1.5:3
W/C 0.5
Slump 1in (25mm)
Fiber Volume 1.5%
Fiber Aspect ratio 40, 60 and 80
Fiber type End enlarged
Fiber Tensile strength 160000 psi (1100 MPa)
Fiber cross section Circular
Fiber diameter 1.18 mm
Concrete comp. strength 3700 psi (25.5 MPa)
Type of coarse aggregate Stone
12. 12
Testing and Data Acquisition
A digital universal testing machine (UTM) of capacity 1000 kN is
used in this experiment. This is a displacement controlled
machine. Load and displacement value can be measured from this
UTM.
In this experiment displacement rate of 0.5mm per minute is
applied.
Lateral displacements/strain are measured by analyzing the
image histories obtained from high definition video camera and
employing an image analysis technique which is called Digital
Image Correlation Technique (DICT).
Experimental program and
strategy
21. Finite Element modeling and
analysis
21
FE element
SOLID65 is used to model the concrete and also SFRC. The solid is
capable of cracking in tension and crushing in compression. The
element is defined by eight nodes having three degrees of freedom at
each node; translations in the nodal x, y, and z directions. The element
is capable of plastic deformation, cracking in three orthogonal
directions and crushing. In concrete applications, the element is also
applicable for reinforced composites, such as, fiberglass and in this
case fiber reinforced concrete (FRC). The geometry and node locations
for this type of element are as follows:
FE element
LINK8 is a spar. The 3-D spar element is a uniaxial tension-compression
element with three degrees of freedom at each node: translations in the
nodal x, y, and z directions. As in a pin-jointed structure, no bending of the
element is considered. Plasticity, creep, swelling, stress stiffening, and large
deflection capabilities are included. The geometry and node locations for this
type of element has shown below:
22. Finite Element modeling and
analysis
22
Properties for FE
model
Specimen
Unit
CSSCCON CSSC40 CSSC60 CSSC80
Elastic
Modulus
2200000 1936000 1936000 1936000 psi
Density 0.083 0.094 0.094 0.094 lb/in3
Ultimate uniaxial
tensile strength
558 884 1215 918 psi
Poisson’s
Ratio
0.3 0.3 0.3 0.3 -
Displacement
boundary
condition (-y
direction)
1.0 1.0 1.0 1.0 mm
Shear Transfer
Co-efficient for
Closed crack
0.5 0.5 0.5 0.5 -
Shear Transfer
Co-efficient for
Open crack
0.3 0.3 0.3 0.3 -
FE input data
Properties for FE
model
Specimen
Unit
CSCCCON CSCC40 CSCC60 CSCC80
Elastic
modulus
2200000 2200000 2200000 2200000 psi
Density 0.083 0.094 0.094 0.094 lb/in3
Ultimate uniaxial
tensile strength
558 884 1215 918 psi
Poisson’s
ratio
0.3 0.3 0.3 0.3 -
Displacement
boundary
condition (-y
direction)
1.0 1.0 1.0 1.0 mm
Shear Transfer
Co-efficient for
Closed crack
0.5 0.5 0.5 0.5 -
Shear Transfer
Co-efficient for
Open crack
0.3 0.3 0.3 0.3 -
Properties for FE model Reinforcement Unit
Density 0.283 lb/in3
Yield stress 72,500 psi
Teng. Modulus 3,000 psi
Poisson’s ratio 0.3
Elastic modulus 30000000 psi
23. Finite Element modeling and
analysis
23
Finite Element modeling requires optimum mesh size for better analysis.
A suitable mesh size helps to achieve sufficient accuracy and also saves
time.
FE mesh analysis
24. Finite Element modeling and
analysis
24
Geometry of FE models
Volume
With Reinforcement
Boundary Condition
32. Conclusion
32
It was observed that steel fibers, up to approximately 1.5% by volume, can
partially substitute for the transverse reinforcement in RC columns and
hence could result in improved constructability.
It was also observed that fibers transform the cover spalling from a sudden
mechanism to a gradual mechanism. The addition of fibers, however, did
not prevent bar buckling from occurring.
The FE models showed similar analyses result compared to experimental
outcomes which ensures good agreements
The failure patterns are also similar which validated the FE models.
The addition of steel fibers in reinforced concrete columns can lead to
improvements, including an increase in peak load-carrying capacity of the
column and a significant improvement in the post-peak response of the
column.
FE analyses have shown conservative results in most of the cases
compared to experimental result which indicate sufficient factor of safety
and also ensure a reliable FE model.
Hi everyone, thank you for having me here. Its an honor to be here. I have been chosen for giving you a presentation on
I’ve arranged the topic into some components which will help us to understand the subject clearly.
To understand a topic clearly one must know the answer of three important questions, What? Why? And How? The first question is, what?
It is a composite material, it means steel fiber reinforced concrete.
We can see some different shapes of steel fiber
In this slide we can see 5 types of steel fiber according to ASTM, based on their product or process by which these are produced. These are
Here are some pictures of SF. These are straight, hooked end, crimped, paddled, irregular, ordinary duoform.
Now we go to the next question. That is why? Why we will use SFRC instead of PC? Plain Concrete is a brittle material. It is weak in tension and SFRC has various advantages over PC. These are
When steel fibers are added to a concrete mix. Here we can see that at zone a….
the objective of the study are:
Above all to provide the construction industry of Bangladesh with reliable experimental data and validated FE modeling about this engineering material.
Now we r going to move to our last question. How? At first we have to select fiber. To select fiber there are some important properties. These are
Here we can see stress strain curve. The curve shows the tensile strength of mortars using different type of fibers and performance of end enlarged fibers are distinctly better compared to other fiber and according to ASTM classification we have chosen Type V: Modified cold drawn wire. For better handling and workability we have selected fibers with aspect ratios 40, 60, 80.
The materials we have used in this research are:
This is how we have collected data. With the help of utm of capacity 1000kN we have tested all specimens. It’s a displacement controlled machine. The rate is 0.5mm per min. to collect data we have used high definition video camera, this process is called DICT means...
This is the experimental strategy and reinforcement layout of this research. We have used only 4-8mm longitudinal rod and no tie bar is used.
There are some experimental works photos. This is how we work in the laboratory.
After testing specimens ,data analysis is necessary and This is how we test Compressive specimens
The compressive strength of SFRC made of steel fibers having aspect ratio 40 is found 17.6% increased with respect to control specimen (normal concrete without fiber). But in case of steel fiber aspect ratio 60 and 80 reduced compressive strength is observed. This is due to the length (original and effective) of these fibers are significantly larger and evenly distribution of concrete mix may not be accomplished. But in case of ductility which is one of the major concern of this investigation is increased about 5, 3.6 and 3 times for steel fiber aspect ratio 40, 60 and 80 respectively.
This is how we test tensile specimens
Compared to the plain concrete, the tensile capacity of steel fiber reinforced concrete with steel fiber of aspect ratio 40, 60 and 80 is increased 58%, 117.5% and 64.1% respectively. Beside this the ductility also enhanced 15, 9.2 and 13 times for steel fiber aspect ratio 40, 60 and 80 respectively. So it can be easily said that steel fiber is more effective to increase the tensile strength compared to compressive strength.
To investigate the axial capacity the square and circular columns are casted with only longitudinal rebars and no tie bars are used. The axial capacities are enhanced 6%, 12% and 21% for SFRC square RC columns with SFAR (steel fiber aspect ratio) 40, 60 and 80 respectively compared to control column (CON) and ductility enhanced 2, 3 and 4 times respectively
In case of SFRC circular RC columns axial capacities are enhanced 27%, 24% and 20% respectively and ductility enhanced 3, 4 and 2 times respectively.
Before start modeling we have to know the FE elements. We have used two elements. The 1st one is solid65 which is used to build model and it is capable of cracking in tension and crushing compression just like concrete. The another element is link8 which is a spar. It shows same behavior like steel.
To build FE model we have to give some input data. The in put data for solid65 in case of square column these are, in case of circular column these are and the in put data for link8 are
After building models we have to mesh them. Finite Element modeling requires optimum mesh size for better analysis.
Some geometry view of FE models.
FE analyses have shown similar stress strain pattern compared to experimental stress strain pattern.
From this graphical relationship it is seen that FE analysis by ANSYS 11.0 satisfactorily demonstrates the accuracy of the FE model of plain concrete as well as SFRC.
After analysis the cracks it is found that all cracks are vertical. It is observed that in case of plain concrete sudden spalling has occurred and pc specimens are splited out. And no. of cracks of SFRC RC columns are less than plain concrete RC column both in case of square column and circular column.
In the both cases square and circular columns the experimental failure pattern is quite similar to the ANSYS model failure pattern which validates the FE modeling and analysis. So there remains a good agreement as well as it can be used in future SFRC model of different fiber volume and different shape.
In this we can see the stress contour of square column and circular column for plain concrete as well as SFRC.
Based on the experimental investigation and FE analysis, the following conclusions can be made.