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NASAs planned mission to the moon wont lift off for more than seven years, but student engineers at Texas A&M University are already designing the systems that could get it safely back to the ground.The students designed a system of parachutes and air Apollo moon missions but much larger) after it enters Earths atmosphere and cushion its
The systems the students presented consisted of three 120-foot parachutes and an array of eight air bags housed between the vehicles heat shield and the capsule itself.
They also designed an array of eight spherical airbags to cushion the capsule when it gets to the ground.The airbags would be stowed between the capsule and the heat shield until needed.Each airbag is actually two bags, one inside the other.The outer bags are
ate as the capsule compresses them so that the capsule wont bounce when it hits.A second, smaller, bag inside each airbag will complete slowing the capsule
The students 2007 design project will be part of the lander that will carry astronauts Dr.William Schneider at email@example.com or 979/458-0116.Texas A&M University Texas A&M University
Mail Stop 3123
College Station, Texas 77843-3123www.mengr.tamu.edu t Org.PAIDTexas 77843Have you Are you getting Whats going on in MECHANICAL ENGINEERING Department of Department of Mechanical Engineering at Texas A&M Your contributions to the Department of Mechanical and our students.To donate, make your check out Department of Mechanical Engineering, Texas A&M University, Mail Stop 3123,
College Station, Texas, 77843-3123, ATTN: Pam Hoestenbach.Mechanical Engineering this year.For more information $ receives new endowmentsdonations it receives from its many friends, former students, and industry.
These gifts help many of our students receive a quality education from the Gladys and William Allison 44 Scholarship in Mechanical EngineeringDon P.Dixon 57 and Sons Scholarship in Mechanical Engineeringschool through participation in organizations or activities such as 4-H, FCA, FFA,
nancial need from the Galveston County area.rst (Hallettsville) or Weimar high schools.
Financial need will be considered..This scholarship will provide one or more scholarships to full-time students in good Jay H.Stafford 46 Scholarship in Mechanical EngineeringWarren Rice, Texas A&M class of 1946, has donated a gift of $50,000 to the department as a small token in recognition of what A&M did for me, said Rice.
t the Mechanical Engineering Excellence Fund.Students Design
System to Return
Astronauts to EarthCalifornia formula car AM The department is in the process of hiring new faculty as part of Texas A&Ms Vision 2020 project.Vision 2020 is designed to guide the university to become a top 10 public university by the year 2020.The new improve the institutions faculty/student ratio, enhance the faculty, and improve the students
New department faculty for fall 2007 are: Texas A&M UniversityTexas A&M UniversityA Few Words...NEW FACULTY: Fall 2007Faculty & Staff AwardsYour Gifts at WorkWenN.K.Anand, professor & Assistant James & Ada Forsyth Endowed Professorship; Charles W.Crawford Service AwardErnest Orlando Lawrence AwardKalyan Annamalai: Associate Editor, Journal of Engineering Gas Turbines & Staff AwardDebjyoti Banerjeeassistant professor : Morris Foster Faculty Professorship: Thomas A.
: NSF CAREER Award: Mervin & Annette Peters Advising AwardIbrahim KaramanDevelopment Professorship I; TEES Won-jong KimDevelopment Professorship II; BP Award for Teaching Excellence; Associate Editor, ASME Journal of associate professor : STLE Fellow: Presidents Award for Academic AdvisingAnastasia Muliana: TEES Select Young
ASME ME Outstanding Graduate Teaching Award: NSF CAREER Award: Association of Former Students Distinguished Teaching AwardBrockett Professorship AwardBrittan Undergraduate Teaching Award: ASHRAE New Investigator Award; NSF Faculty (CAREER) AwardE3 Research LaboratoryJackie Mohrfeld didnt know she would love fact, until she was in college at Texas A&M University, she didnt know anything about
Now she climbs on the pitbox of the No.
33 Camping World Silverado team driven by two-time NASCAR Craftsman Truck Series
A native of Houston, Texas, Mohrfeld attended and graduated from Texas
rst entry in to the racing world was a Texas A&M Formula SAE project.In 2000, the team won its
rst championship in only its second year of competition.As one of a very limited number of female engineers in the garage area of all Its hard to believe is underway.
t Gates faculty rein-Weve featured started in September, we have four new faculty starting in January 2008.
We have faculty
ll for next year.
When the dust is settled This will make us the second largest mechani-hind Georgia Tech.
Demand for our graduates is the strongest it has been in over ten years.
Last academic year,
ll multiple positions.
We M.S./Ph.D.s each year.
The students are get-ting fabulous job offers and many get signing
Our Formula SAE team continued its excel-lent record by winning the West Coast competi-tion in California for the second year in a row.
Each year, we have a new group of students competing.
They have to design, build, and race a new car.
Its quite a remarkable accomplish-ment for these students.
They wouldnt be suc- nancial support of former
In September, we had our
ve the department has grown from 80 to over 150.
A big reason for this increase has been due to contact me.
Its a great way to leave a legacy that will help future Aggies reach their dream Former Student Whitaker Receives University of Alabama T.Morris Hackney Leadership Award The University of Alabama College of Engineering announced Dr.Kevin W
Development of the WSDOT Pile Driving Formula and Its Calibration for Load and Resistance Factor Design (LRFD)
Final Research Report March 2005
Department of Transportation Planning and Capital Program Management ghway Administration
Final Research Report Washington State DepartmeHQ Materials Laboratory,Olympia, Washington U.S.Department of Transportation Federal Highway Administration TECHNICAL REPORT STANDARD TITLE PAGE 1.
GOVERNMENT ACCESSION NO.3.
RECIPIENT'S CATALOG NO.
TITLE AND SUBTITLE 5.
REPORT DATE Development of the WSDOT Pile Driving Formula and Its Calibration for Load and Resistance Factor Design (LRFD)6.
PERFORMING ORGANIZATION CODE
PERFORMING ORGANIZATION Tony M.Allen
PERFORMING ORGANIZATION NAME AND ADDRESS 10.
WORK UNIT NO.Washington State Transportation Center (TRAC)
University of Washington, Box 354802 11.
CONTRACT OR GRANT NO.University District Building; 1107 NE 45th Street, Suite 535
SPONSORING AGENCY NAME AND ADDRESS 13.
TYPE OF REPORT AND PERIOD Research Office Washington State Department of Transportation Transportation Building, MS 47370 Research report Olympia, Washington 98504-7370 14.
SPONSORING AGENCY CODE Keith Anderson, Project Manager, NOTES This study was conducted in cooperation with the U.S.
Department of Transportation, Federal Highway Ad16.
ABSTRACT Prior to 1997, WSDOT used the Engineering News Record (ENR) Formula for driving piling to the design capacity.
Washington State Department of Transportation (WSDOT) sponsored research published in 1988 had shown that the ENR formula was quite inaccurate, and that moving toward the Gates Formula would be a substantial improvement (Fragaszy et al.1988).
Hence, in 1996, an in-house study was initiated to update the driving formula used for pile driving acceptance in the WSDOT Standard Specifications.
Recently compiled databases of pile load test results were used as the basis for developing improvements to the Gates Formula to improve pile bearing resistance prediction accuracy.
From this empirical analysis, the WSDOT driving formula was derived.
Once the WSDOT driving formula had been developed, the empirical data used for its development were also used to establish statistical parameters that could be used in reliability analyses to determine resistance factors for load and resistance factor design (LRFD)
The Monte Carlo method was used to perform the reliability analyses.
Other methods of pile resistance prediction were also analyzed, and resistance factors were developed for those methods as well.Of the driving formulae evaluated, the WSDOT formula produced the most efficient result, with a resistance factor of 0.55 to 0.60.
A resistance factor of 0.55 is recommended.
Dynamic measurement during pile driving using the pile driving analyzer (PDA), combined with signal matching analysis (e.g., CAPWAP), produced the most efficient result of all the pile resistance prediction methods, with a resistance factor of 0.70 to 0.80.
KEY WORDS 18.
DISTRIBUTION STATEMENT Pile foundation, bearing, LRFD, design, calibration No restrictions.
This document is available to the public through the National Technical Information Service, Springfield, VA
(of this report) 20.
SECURITY CLASSIF.(of this page) 21.
NO.OF PAGES 22.
PRICE None None 45
The contents of this report reflect the views of the authors, who are responsible for the facts and the accuracy of the data presented herein.
The contents do not necessarily reflect the official views or policies of the Washington State Transportation Commission, Department of Transportation, or the Federal Highway Administration.
This report does not constitute a
TABLE OF CONTENTS EXECUTIVE PILE DRIVING FORMULA DEVELOPMENT11STATISTICAL ANALYSIS AND LRFD 1 Strokedriving resistance relationship piles based on wave equation predictions.
2 Strokedriving resistance relationship fopiles based on wave equation predictions.13
3 Predicted nominal versus measured pile bearing resistance for the WSDOT pile
driving formula based on developed energy..18
4 Predicted nominal versus measured pile bearing resistance for the WSDOT pile
driving formula based on rated energy18
5 Predicted nominal versus measured Modified Gates driving formula based on developed energy.19
6 Predicted nominal versus measured Modified Gates formula based on rated energy..19
7 Predicted nominal versus measured pile bearing resistance for the ENR driving
formula based on developed energy....
8 Comparison of wave equation and WSDOT driving formula for 18-inch diameter
steel piles using a steam hammer with a rated energy of 25 ft-tons.25
9 Comparison of wave equation and WSDOT driving formula for 18-inch diameter
mmer with a rated energy of 27.5 ft-tons..26
10 Comparison of wave equation and WSDOT driving formula for 18-inch diameter
hammer with a rated energy of 36 ft-tons....27
11 Predicted nominal versus measured piresults at EOD.
STATIC ANALYSIS DESIGN PROCEDURESStatic analysis methods are simplified analytical techniques used to model the very complex soil-structure interaction between driven piles and the surrounding soils.The analysis techniques that are presented in this manual have been selected because they have been proven to provide reasonable agreement with full scale field results.The techniques that will be presented here include the Meyerhof Method and the Nordlund Method for piles founded in cohesionless soils, the Alpha () Method and the Effective Stress Method for cohesive soils, and the Nottingham Schmertmann Method when CPT data is available.These methods have also been selected for presentation because they are relatively straightforward to use, and are the techniques that are recommend by the Federal Highway Administration (FHWA-HI-97-013).It is strongly recommended that prior to using any of the static methods presented in this chapter that the user be familiar with the limitations of that analytical technique.In conjunction with static analysis, it is also recommended that static load tests be conducted to further calibrate the empirical models for the regional geology, to perform wave equation analysis and to perform dynamic monitoring during installation.These tools are essential in assuring that the design objectives are accomplished.4.2 SOIL/PILE INTERACTION The ultimate capacity of a pile is limited by the structural capacity of the pile (Chapter 3) and the capacity of the surrounding soil to support the loads transferred from the pile.This transfer of stress between the soil and pile is quantified by two components: the resistance that is developed along the shaft of the pile ( = shaft resistance) and the resistance that is developed at the bottom (toe) of the pile ( = toe resistance).The process of driving piles affects the soil/pile interaction.The effects of this installation disturbance on the soil/pile interaction is briefly explained here.Timber piles are considered to be a displacement type pile (versus a non-displacement pile (i.e., H pile).
In cohesionless soils, displacement piles disturb a zone around the pile by a lateral distance of 3
5.5 pile diameters and 3
5 diameters below the tip of the pile (Broms, 1966).Figure 4-1 shows the limits of this pile disturbance.For loose cohesionless soils, the disturbance from driving the displacement pile increases the relative density of the soil.
This increased relative density increases the capacity of single piles and pile groups and is a major advantage of timber piles driven into cohesionless soils.The pile driving process can, also in addition to increasing the density of loose cohesionless soils, generate high positive porewater pressures in saturated loose to medium fine sands.Positive pore pressures temporarily reduce the soil shear strength and the pile capacity; as the pore pressure dissipates, the pile capacity increases.This phenomenon is called pile set up and is generally quicker for sands and silts than for clays, because these types of soils are more permeable than clays, and pore pressures dissipate more rapidly.
In dense cohesionless soils, the disturbance from the pile driving may decrease the relative density of the surrounding soil.In these dense soils, the increase in horizontal stress in the soil adjacent to the pile during driving may be lost by relaxation.
This phenomenon occurs as the negative pore pressure generated during the driving dissipates.
The negative pore pressure occurs because of the dilation of the dense sand into a lower relative density.
The negative pore pressure temporarily increases the soil shear strength by effectively increasing the normal stress on the failure surface.As the negative pore pressure dissipates, the shear strength and Figure 4 - 1
Compaction of Cohesionless Soils During Driving of Piles (Broms, 1966) For cohesive soils, the soil pile interaction is different than for cohesionless soils.Soft, normally consolidated clays have a zone of disturbance around the pile both laterally, and at the toe of the pile, of approximately one pile diameter (Figure 4-2).The process of driving displacement piles in cohesive soils typically generates high positive pore water pressure.
This increase in pore water pressure temporarily decreases the shear strength of the soil and the load carrying capacity of the pile.
Reconsolidation of the cohesive soil and dissipation of the excess pore pressure results in an increase in shear strength and pile capacity.This is commonly referred
to as pile setup.4.2.1 Load Transfer The ultimate bearing capacity () of a timber pile in homogeneous soil is the sum of the shaft reisistance ( ) and the toe resistance (
The shaft resistance may be expressed as the product of the unit shaft resistance (shaft surface area (), and the toe resistance may be expressed as the product of the unit toe ) times the area of the toe ().
Equation 4-1 may be rewritten in unit resistance The equations presented here assume that both the pile toe and shaft have moved a sufficient distance with respect to the adjacent soil to simultaneously mobilize the ultimate shaft and toe resistance.It should be noted that the displacement needed to mobilize the shaft resistance is generally smaller than that required to mobilize the toe resistance.Figure 4 - 2
Disturbance of Cohesive Soils During Driving of Piles (Broms, 1966)Figure 4-3 shows the typical load transfer profiles for piles.The axial load in the pile is a combination of the shaft resistance and toe resistance.Figure 4-3a shows the case when no shaft resistance is developed and the ultimate capacity of the pile is developed through toe resistance.
Figure 4-3b shows the load transfer profile for the case where uniform shaft resistance is developed along the length of th