Retrofit of Rectangular Bridge Columns Using CFRP Wrapping
Author: Endeshaw, Mesay A | Size: 2.19 MB | Format:PDF | Quality:Original preprint | Publisher: Washington State University, Pullman | Year: 2008 | pages: 75
This study investigated retrofitting measures for improving the seismic performance of rectangular columns in existing bridges. Experimental tests were conducted on 0.4-scale column specimens which incorporated details that were selected to represent deficiencies present in older bridges in Washington State. Two unretrofitted specimens were tested to examine the performance of the as-built columns incorporating lap splices at the base of the columns and deficient transverse reinforcement. Five columns were retrofitted with carbon fiber reinforced polymer (CFRP) composite wrapping and one specimen was retrofitted with a steel jacket. The specimens were subjected to increasing levels of cycled lateral displacements under constant axial load. Specimen performance was evaluated based on failure mode, displacement ductility capacity and hysteretic behavior. For retrofitting of rectangular columns, it is recommended that oval-shaped jackets be used whenever possible. Column specimens with oval-shaped jackets of steel and CFRP composite material performed similarly, both producing ductile column performance. Failure in these specimens was due to flexural hinging in the gap region between the footing and retrofit jacket, leading to eventual low-cycle fatigue fracture of the longitudinal reinforcement. Details and procedures for the design of oval-shaped steel jackets are provided in FHWA Seismic Retrofitting Manual for Highway Bridges (2006). Design guidelines for oval-shaped CFRP jackets are given in ACTT-95/08 (Seible et al., 1995). Oval-shaped jackets designed according to these recommendations can be expected to prevent slippage of lapped bars within the retrofitted region. Design guidelines for rectangular-shaped retrofitting using CFRP composite materials are proposed for application to columns with cross-section aspect ratios of 2 or less. While no slippage of the lap splice was observed, it is conservatively recommended that rectangular-shaped CFRP wrapping be used only for the situation where controlled debonding of the lap splice is acceptable.
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Coated Steel Rebar for Enhanced Concrete-Steel Bond Strength and Corrosion Resistance
Author: Chen, Genda | Size: 11.42 MB | Format:PDF | Quality:Original preprint | Publisher: Missouri University of Science and Technology, Rolla | Year: 2010 | pages: 229
This report summarizes the findings and recommendations on the use of enamel coating in reinforced concrete structures both for bond strength and corrosion resistance of steel rebar. Extensive laboratory tests were conducted to characterize the properties of one- and two-layer enamel coatings. Pseudostatic tests were performed with pullout, beam and column specimens to characterize mechanical properties and develop design equations for the development length of steel rebar in lap splice and anchorage areas. The splice length equation was validated with the testing of large-scale columns under cyclic loading. For corrosion properties, ponding, salt spray, accelerated corrosion, potentiodynamic and electrochemical impedance spectroscopy (EIS) tests were conducted to evaluate the corrosion resistance and performance of enamel-coated steel and rebar. Experimental procedures and observations from various laboratory tests are documented in detail. The corrosion performances of enamel and epoxy coatings were compared. It is concluded that a one-layer enamel coating doped with 50% calcium silicate has improved bond strengths with steel and concrete but its corrosion resistance is low due to porosity in the coating, allowing chloride ions to pass through. Based on limited laboratory tests, a two-layer enamel coating with an inner layer of pure enamel and an outer layer of enamel and calcium silicate mixture has been shown to be practical and effective for both corrosion resistance and bond strength. A coating factor of 0.85 is recommended to use with the current development length equations as specified in ACI318-08. The large-scale column tests indicated that the column-footing lap splice with enamel-coated dowel bars had higher load and energy dissipation capacities compared to uncoated dowel bars. When damaged unintentionally, chemically reactive enamel coatings limit corrosion to a very small area whereas epoxy coatings allow corrosion expansion in a wide area underneath the coating.
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This report describes a precast concrete bridge bent system that is suitable for high seismic zones. Lateral load tests on both the top (column-to-cap) and bottom (column-to-footing) connections of the system have demonstrated that the connections have strengths and ductilities similar to those of comparable cast-in-place connections. Additional tests on the bottom connection of the system are ongoing, and construction of a demonstration bridge project will begin later this year. The final development of this system is partially funded by the FHWA’s Highways for LIFE Technology Partnerships Program (DTFH61-09-00005).
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Evaluation Of The Orientation Of 90° And 180° Reinforcing Bar Hooks
Author: Podhorsky, Nichole Sneed, Lesley | Size: 5.83 MB | Format:PDF | Quality:Original preprint | Publisher: Missouri University of Science and Technology, Rolla | Year: 2012 | pages: 172
This report describes test results of a study initiated to evaluate the potential influence of hook tilt angle of standard reinforcing hooks on the bond strength of concrete. The topic of the evaluation of the orientation of 90 and 180 degree reinforcing bar hooks in concrete members was identified by the Concrete Reinforcing Steel Institute (CRSI) as high-priority for the reinforcing steel industry. In the test program conducted, a series of single bar and multiple bar specimens was designed and tested to examine bar behavior and potential group effects that may exist in wide flexural members with multiple bars, such as a slab or footing. Using beamend specimens, 90 and 180 degree standard reinforcing hooks were placed at varying angles to compare the angle of tilt and to compare the two hook types. Twelve single bar specimens and twelve multiple bar specimens, each containing either No. 5 or No. 8 standard reinforcing bars,were tested by axially loading the reinforcing bar(s) in tension. Measuring the bar displacement and strain at varying locations along the bar, load-displacement curves obtained were utilized in the analysis of hook tilt. Based on the results, design recommendations for tilted hooked bar anchorages were made. For No. 5 bars and smaller with concrete compressive strength, f’c, greater than 4500 psi, spacing between 0.5 and 2 times the hook length, A, and concrete cover equal to or exceeding the values used in this study, tilting reinforcing hooked bars from vertical at any angle did not compromise the structural integrity. For No. 5 bars and smaller with concrete compressive strength less than 4500 psi, spacing less than 0.5 times the hook length,A, or concrete cover less than the values used in this study, further study is needed. Additionally, further study is needed for bars larger than No. 5.
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dear all,
we have civil engineer positions at an international consultant office in Qatar which required minimum 10 years of experience in construction supervision of infrastructure,tunnel and bridges so if any one interested please let me know through private message
Hello,
For the last few days, I had a few discussions with some of my friends and colleagues which regards the subject question: Should supervisors/mentors transfer their knowledge to their researchers?
I know that persons research is a research done by one individual, but supervisor is there to direct you through the right path. Wouldn't be easier, and thus more productive if he shares some of his own experience to you? Or maybe it isn't so good because it doesn't give you the full opportunity for your own deduction?
I want to see what are your opinions.
Best regards
freequo
Contents
1 Introduction
1.1 The phenomenon of fatigue
1.2 Basic tests
1.3 Terms and definitions
1.4 Fatigue strength of unwelded material
1.5 Methodological aspects and stress assessments
1.6 Nominal stress assessment for fatigue resistant joints
1.7 General references to relevant literature
2 Fatigue strength for infinite life of welded joints in
structural steel 36
2.1 Simply loaded joints 36
2.2 Multiply loaded joints 59
2.3 Influence of mean stress
3 Fatigue strength for finite life and service fatigue strength
of welded joints 66
3.1 Fatigue strength dependent on number of cycles 66
3.2 Load spectra 74
3.3 Fatigue strength with load spectra 82
3.4 Manufacturing measures for increasing fatigue strength
4 Fatigue strength of welded joints in high tensile steels and
aluminium alloys 98
4.1 Welded joints in high tensile steels 98
4.2 Welded joints in aluminium alloys
5 Fatigue strength of welded components, design 10 Structural stress, notch stress and stress intensity
improvements 105 approach for assessment of fatigue strength ofspot welded
5.1 General aspects and welded components in structural joints 299
steel engineering (bar structures) 105 10.1 Development status of local approaches 299
5.2 Welded components in shipbuilding (bar to plate 10.2 Basic loading modes at weld spot 300
structures) 127 10.3 Elementary mechanics of tensile shear and cross
5.3 Welded components in tank, boiler and pipeline tension loading 302
construction (circular shell and plate structures) 136 10.4 Structural stresses at weld spot 305
5.4 Appropriate design with regard to fatigue strength 150 10.5 Notch stresses at weld spot 308
10.6 Stress intensity factors at weld spot 311
6 Fatigue strength of spot, friction, flash butt and stud 10.7 Local stress parameters for common weld spot
welded joints 153 specimens 314
6.1 Spot welded joints 153 10.8 Assessment of load carrying capacity of weld spots in
6.2 Weldbonded joints 160 structural components 322
6.3 Friction welded and flash butt welded joints 161
10.9 Effect of residual stresses and hardness distribution 324
6.4 Stud welded joints 161
10.10 Large deflections and buckling 327
7 Design codes, assessment of nominal and structural stress 163 10.11 Crack initiation with local yielding and crack
7.1 Codes based on science, empirical knowledge and propagation 331
tradition 163 10.12 Local fatigue strength of weld spot 333
7.2 Dimensioning for fatigue in accordance with the 10.13 Combination of spot welding and bonding 341
7.3 Scoudrveesy, aosfsethsesmdeesnitgonfcnoodmesinal stress 116664 @ Corrosion and wear resistance of welded joints 343
7.4 Design loads, load spectra, loading classes 168 11.1 General aspects 343
7.5 Notch classes and quality of manufacture 172 11.2 Corrosion resistance 343
7.6 Permissible stress, safety factor, multiaxiality hypothesis 189 11.3 Wear resistance 347
7.7 Assessment of structural stress 200
12 Example for the development of a fatigue resistant welded
8 Notch stress approach for assessment orratigue strength of structure 349
seam welded joints 208 12.1 Introduction, general outline, requirements 349
8.1 General fundamentals of the method 208 12.2 Development procedure, numerical and experimental
8.2 Elastic notch effect of welded joints with regard to simulation 350
fatigue strength for infinite life 214
8.3 Elastic-plastic notch effect of welded joints with Bibliography 356
regard to fatigue strength for finite life and service
fatigue strength 262
Index 375
9 Fracture mechanics approach for assessment offatigue
strength ofseam welded joints 277
9.1 Principles of the approach 277
9.2 Crack propagation equations 279
9.3 Input parameters of the fracture mechanical strength
or life evaluation for welded joints 287
9.4 Application for assessment of fatigue strength for
finite and infinite life 293
9.5 Application for assessment of safety, residual life,
fitness-far-purpose and backtracing of failures 295
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Hi guyz, i am starting my masters in structure and foundation engineering from HERIOT WATT university in UK..through their distant learning program.
Please shed some light on this topic. I want to have your opinion.
I did my bachelors from NUST (Times higher education ranking: 351-400)
Heriot watt ranking (351-400) & 42nd in UK
Another option was university of surrey having same worldwide ranking but 26th ranking in UK.
but its 67% more expensive than heriot watt.
In USA i liked UNIVERSITY OF SOUTHERN CALIFORNIA having top 11th position in the world but its really very expensive. It is about 300% more expensive than heriot watt..
so i have selected now the university of heriot watt based on the budget, ranking and subject.
Input your data in INPUT sheet and get outputs in SAP2000 sheet.
I'm waiting for your opinion.
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The Windows Calculation Companion
• Capable of more than 400,000 different conversions.
• More than 60 additional calculation modules included.
• Includes a periodic table with pertinent information on each element.
• Scientific/Financial calculator with scrollable tape and integrated help.
• Material density class giving metric and Imperial densities of more than 600 common materials.
• Geometry class providing helpful hints for solving common geometric problems.
• Custom Conversion class for adding conversions that might not be included in ProKon .
• All conversion info can be printed or copied to clipboard and file.
• Comprehensive help is available throughout the program.
• Excellent teaching tool for anyone learning the metric system.
• Compatible with Windows 95/98/ME, Windows NT, Windows 2000, Windows XP, Windows Vista, and Windows 7
• Conversion results can be displayed graphically.
• Windows XP Themes enabled.
• New Installation Utility based on InnoSetup
• Beginning with v10.0u, ProKon is compatible with Windows XP 64-Bit, Vista 64-Bit. and Windows 7 64-Bit
ProKon (short for Professional Converter) is a 32-bit & 64 bit Microsoft Windows program that is intended to perform numerical conversions between the various units used in the scientific and business community. Early versions of ProKon were capable of performing this, and only this, function. As the program has evolved, many things have been added so that the current version is capable of doing much, much more. Following is a complete description ProKon and what ProKon is capable of doing for you. ProKon is intended for use with Windows 95, Windows 98, Windows ME, Windows NT, Windows 2000, and Windows XP. ProKon cannot be used with Windows 3.11 or earlier versions. There is a 16-bit version of ProKon available (called SICon) that is capable of this.
The primary use for ProKon is to convert numerical data to/from various units of measurement. While focusing on conversions between the metric and Imperial (English) systems of measurement, it is capable of performing conversions between many other units, foreign, ancient, and archaic. ProKon's capabilities have grown to the point that it is capable of performing well over 400,000 different unique conversions. You would have a difficult time finding a measurement unit that is not already included in ProKon. Even if you could, ProKon has the capability of storing any special conversion units that you might come up with in a special "Custom" conversion class.
The conversions in ProKon are grouped into various "Classes". Each class contains units that would logically fit in the Class description. Examples of classes are Mass, Length, Viscosity, Density, Concentration, Light, Temperature, Area, etc. In all, there are 26 Classes to select from. Each of the units contained in any Class can be converted to any of the other compatible units in the Class. Selection of a pair of units for conversion presents a calculation window in which calculations can be performed. Calculations are performed 'dynamically', meaning that as values are entered under one unit, the converted value is updated instantaneously to the other unit. Either conversion value may be edited to dynamically display results - useful for 'what if' calculations. All data shown can be printed, or copied to Windows clipboard and file.
ProKon also contains a Periodic Table of the Elements. Selecting the Periodic Table class shows the complete periodic table of the elements. Any element may be selected to bring up a window showing pertinent data on that element. Such things as atomic number, atomic weight, density, oxidation states, melting point, boiling point are shown along with descriptive text on the element giving reactivity, uses, sources, prevalence, toxicity, etc. All data shown can be printed, or copied to Windows clipboard and file.
A Class titled 'Material Density' gives density of over 600 common materials. Approximate density is given in both metric and Imperial (English) units. Densities are available for materials from acetylene to flint to mahogany to zirconium. Again, all data shown can be printed, or copied to Windows clipboard and file.
A 'Geometry' Class gives a folder of common geometric formulae. Each page of the folder shows a keyed graphic of a geometric figure along with various formulae that can be used to perform calculations pertinent to that figure. Very useful for finding that formula that you learned in school but 'forgot'.
A 'Constants' Class contains a folder of various types of numerical constants used in the scientific and academic communities. These lists are a valuable reference tool for constants used in chemistry, physics, mathematics, etc.
Also available from within ProKon is ProKalc, a pop-up combination scientific/financial calculator with a scrolling tape. The ProKon calculator is capable of performing all of the standard math operations +, -, X, /, as well as such things as logarithms, natural logs, trigonometric functions, hyperbolic functions, powers, roots, factorials, combinations, permutations, reciprocals, percentages, etc. Financial calculations such as present value, future value, loan calculations, profit/loss, interest, currency conversions, dividend, and investments can be performed. A 10-location, non-volatile memory that is saved between sessions in included. Although very intuitive and easy to use, integrated help is available for all calculator functions. All or a portion of the calculator tape can be printed or sent to clipboard or file. The ProKon calculator features 15-digit accuracy with no rounding errors.
The 'Miscellaneous' Classes actually offers 62 additional modules, some of which give access to databases of information on various topics. Others allow calculation of various types of data that are not true 'conversions' but that are, nevertheless, quite useful. Modules available are: a module for inorganic chemicals that gives data such as formula weight, density, physical form, melting point, boiling point, etc. on a very large number of inorganic chemicals, a nutritional database that gives nutritional data on a large number of food items, for instance, calories, fat content, carbohydrate content, etc. A 'Standard Sieve' module gives information such as sieve opening size, standard sieve number, wire size, etc. on the standard sieve series and a 'Wire/Sheet Gauge' module gives wire diameter and sheet thickness in both metric and Imperial units. A 'Number Base Conversion' module allows conversion of decimal, binary, octal, or hexadecimal values between the various systems and an 'Electrical Calculation' module allows calculation of various electrical properties such as ohms, volts, watts, energy cost, and electric motor properties. A 'Meteorological' module allows calculation of numerous 'weather' related values such as relative humidity, dew point, wind chill index, etc. Recent additions to Miscellaneous for contractor or engineering type work include a Concrete module that allows calculation of various information needed by contractors and those involved in calculating quantities of concrete required for concrete pours, a Lumber module allowing calculation of data related to board feet requirements, a Paint module which calculates paint requirements and theoretical paint coverage, a Twist Drill Size module giving a database of info, and a Gauge module giving thickness and diameter requirements of various systems of wire and sheet gauge. A graphical and interactive Resistor/Capacitor module allows calculation of resistance or capacitance values through a point-and-click interface. Other modules include an Irrigation module which allows calculation of irrigation requirements such as time to irrigate, amount of irrigation water required, area or quantity of water required, a Roman Numerals module which allows calculation of Roman numerals from decimal value and which allows simple math performed on Roman numerals, a Fractions module allowing conversion to and from fractions and decimals, and a Formula Weight calculator module which allows calculation of chemical formula weight by simply entering a chemical formula. To go on, there's a Sound module, an architectural symbol database, and a module that allows currency conversions to and from approximately 220 currencies from around the world. The currency rate conversion module allows for instant updates of the currency conversion factors database from the internet. These rate factors are current within a day and come to you compliments of ShowMe Software. To round out the Miscellaneous class is a module that allows calculation of various 'solution' parameters such as the amount of material required to dissolve in an existing solution to obtain a solution of a given strength or the amount of water to add to a solution of given strength to reduce its strength. Look below for a comprehensive list of the various modules available.
With the latest version, the Miscellaneous Class has been split into Miscellaneous I and Miscellaneous II. In addition, several new modules have been added. These include a Paper module that allows the calculation of various paper measures. Also added are a Metal Hardness, a Mixed Density, A Numbers by Name, a Metric Prefix module, Traffic Marking calculation, and a water vapor permeability module.
Also in the latest version are two new menu items called Find and GoTo. Both of these menu items can be found in the main menu item titled Locate. The Find menu shows a list containing all of the units contained in ProKon that are located in the various unit conversion modules. The list of units is searchable to make it easy to locate a unit in the list. This list of units is useful if you're not sure which module a specific unit might be located in. Selecting a unit from the Find list will take you directly to the module containing that unit. The GoTo menu item shows a list of all of the modules contained in ProKon. The Goto list is also searchable and allows the user to go directly to any module in ProKon, including those modules normally accessed from the Miscellaneous I and Miscellaneous II screens.
Private Note:
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