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MAKING A DIFFERENCE One Bridge at a Time Kelley C. Rehm, P.E Kelley C. Rehm, P.E October 2, 2012
MAKING A DIFFERENCEOne Bridge at a Time
Kelley C. Rehm, P.EKelley C. Rehm, P.EOctober 2, 2012
WHO AM I? Education
University of Kentucky University at Buffalo
V d bilt U i it Vanderbilt University
Professional Bridge Engineer Professional Bridge Engineer Kentucky Transportation Cabinet American Association of State Highway and
T i Offi i lTransportation Officials Board Member of Bridging the Gap Africa
FINDING A HERO…
HOW I GOT INVOLVED… Connection with Harmon Parker Appointment to Board of Directors Planned Surveying and Inspection Trip to Kenya Construction Trip - 2012
REFERENCE MANUALS
Helvetas Bridges to Prosperity AASHTO Pedestrian Bridge Guidelines Other Local Manuals
BRIDGE FACTS
THE BRIDGES… “Suspended” Hanging Bridgep g g g Typically 40-60 meter spans Typically 20 - 32mm Cable (donated)
5 1 0 lk .5m – 1.0m walkway Steel Cylinder Towers – concrete filled Concrete = M10 or M20 Grade Concrete M10 or M20 Grade
1450psi to 2900 psi Low strength mix with no quality control – mixed
with aggregates found onsitewith aggregates found onsite Eucalyptus Wood Deck – 2 meter lengths 12mm rebar used as hangers Fencing for safety
EXAMPLES OF STANDARD DESIGN ANDCONSTRUCTION
DO
CU
This is the largest suspension footbridge in East Africa at 112
Signature Bridge in Africa
UM
EN
TA
R
Africa at 112 meters long. It is the only bridge of its kind in Africa
RY
The Galana River Bridge cost $200,000 and took a year and a half t b ildto build.
SURVEY
Survey StationTopo Point
distance (m)
Angle Theta (radians) remarks
Horizontal Distance
Vertical Distance Elevation
Starting point a L 5 0.0610865244.990673
9920.30524
27 100.31
h 7 0.005817182 cross over trail6.999881
562 0.04072 100.04
SURVEY
Abney Level
h 7 0.005817182 cross over trail 562 0.04072 100.04
b 3.3 ‐0.500327719 mid slope2.895503
813
‐1.58305
33 98.42
c 5.2 ‐0.491601073average water
level4.584206
753
‐2.45459
74 97.55‐y
Yard Stick Measuring Tape
d 31 ‐0.09599310930.85728
2152.97121
83 97.03Changed Survey
Point
d a 31 0.08144869830.89723
1532.52211
89 99.553.147970 1.14576
103
104
105
hmar
k
e 3.35 0.349065853.147970
281.14576
75 98.18
100
101
102
103
) -N
OT
to B
enc
high water mark
97
98
99
Ele
vati
ons
(M)
A liAvg. water level
960 5 10 15 20 25 30 35 40 45 50 55Horizontal Distance (m)
ANALYSISAASHTO Pedestrian Load = 90 lb/ft^2
Steel Tower – AISC Manual
Anchor Analysis – Pull out, Overturn, SlidiSliding
ANCHORSANCHORS
ANCHORS
TOWERS AND FOUNDATIONSTOWERS AND FOUNDATIONS
“FABRICATION SHOP”
DECK AND HANGERS
PROBLEMS
No Soil Testing!g Cable is Used (breaking strength is re-tested) Concrete strength is low Aggregates are often substandard Steel strength is questionable Welds and Fabrication is questionable (on site
shop)
TIA! This Is Africa!
MY TRIPS September 2011 – Survey and Planningp y g
August 2012 – Construction
Maasi Mara – Game Reserve Area
CONTRACTORS
CONSTRUCTION TRIP – AUGUST 2012
UB SENIOR PROJECT - REQUEST FORUB SENIOR PROJECT REQUEST FORPROPOSALS
LOCATION AND SPECIFICS OF THE BRIDGE
The Organization’s priorities are: The Organization s priorities are:
Cost effective design using locally available g g ysteel, welding and concrete
Construction methods easily accomplished with local untrained labor
Simple constructible design
TERRAIN
Highly Erodible Soilg y Visual Identification Only – Silty Sand High Grazing – little ground cover
DESIGN CRITERIA
B id U d Wid h h d i b id h ld b Bridge Use and Width: the pedestrian bridge should be designed for two way walking traffic or one (1) meter width. The bridge should not be designed for livestock or motor vehicle passage. The bridge should have a p g gminimum of two (2) meters of ‘freeboard’ clearance above the predicted high water mark.
B id T S d d d t i b id i f Bridge Type: Suspended pedestrian bridge using four (4) cable design approximately 35 meter span
Design criteria: The bridge should be designed Design criteria: The bridge should be designed according the Bridges to Prosperity Suspended Bridge manual with live loadings from the AASHTO LRFD Pedestrian Bridge Design Guide ( http://bridgestoprosperity.org/resources/technical-
resources/ )
PRELIMINARY PROFILE
Sultan Hamud Preliminary Profile
106107108109
MA
RK
y
9899
100101102103104105106
RO
M B
EN
CH
M
L
R
929394959697
0 10 20 30 40 50 60
on (
m)
-NO
T F
high water level
Ele
vati
o Horizontal Distance (m)
K Rehm P EK.Rehm, P.ESeptember 4, 2011
CONSTRUCTION
Remote area – rough roadway Materials and construction equipment transported
by a 4-wheel drive Land RoverBtGA d t t li t BtGA owns and can transport a gasoline generator, a small batch concrete mixing drum and a steel welder.
Cement purchased and transported from Nairobi Cement purchased and transported from Nairobi Steel purchased in Nairobi and fabricated on site or
in the “shop” Water from stream or local wells Aggregate may be mined on site or trucked in in
small batchessmall batches
DELIVERABLES FOR THE PROJECT
The following will be required for Preliminary g q yDesign: Geotechnical Investigation
Include discussion on soil strength assumptions and Include discussion on soil strength assumptions and innovative ways to determine soil type and strength by visual means.
Structural Design Structural Design Discussion of various bridge structure types that may work
in this profile Comparative merits and deficiencies of each type Comparative merits and deficiencies of each type Constructability issues related to each type Costs associated Fabrication/Erection discussion Fabrication/Erection discussion Recommended Structure Type
DELIVERABLES FOR THE PROJECT
The following will be required for Final Design:g q g
Final Design Calculations in Mathcad electronic files. Mathcad files should be easy to replicate (ie – text
and references should be included).
Final Standard Drawings in electronic format to include: Profile, Deck and hanger details, Anchor details,
Tower foundation details, Tower fabrication details,
Construction and QA/QC planCo st uct o a d Q QC p a Quantity Estimate
ELEMENTS OF THE PROPOSAL
Part 1 – Letter of Transmittal. Part 2 – Key Personnel (resumes) Part 3 – Organization and Management of the project.
Include the following:Include the following: Describe how the project will be organized within the
design team as well as communication with the Organization.
Describe how the team will accomplish the work: Innovative Design Ideas Identification and approach to the stages of the project Communication plan (report frequency etc ) Communication plan (report frequency, etc.)
Part 4 – Phase schedule. Schedule for preliminary design delivery Schedule for final design delivery Schedule for final design delivery
Part 5 – Software.
REFERENCES FOR THE PROPOSAL Bridging the Gap Africa References American Associations of State Highway and Transportation Officials (AASHTO) (2010), LRFD Guide American Associations of State Highway and Transportation Officials (AASHTO) (2010), LRFD Guide
Specifications for Design of Pedestrian Bridge. Washington, D.C.
AISC Manual of Steel Construction, (1998) Load and Resistance Factor Design, Volume 1. Chicago, IL. Section 5.
Bang, A.L. (2009) Cable- Suspended Pedestrian Bridge Design for Rural. Masters Thesis, University of Colorado Colorado.
Bridges To Prosperity (2009) Bridge Design Manual – Volume 1-3. Denver, Colorado. Common Soil Coefficients – website accessed August 2011.
http://environment.uwe.ac.uk/geocal/foundations/founbear.htm Helvetas (2006) Short Span Trail Bridge Standard: Suspended Type Volume ) Switzerland Helvetas, (2006) Short Span Trail Bridge Standard: Suspended Type, Volume ), Switzerland. I.T. Transport, Ltd. (2004) FOOTBRIDGES: A Manual for Construction at Community and District Level.
United Kingdom. Stone, L. J. (2006) Suspension Canyon and Gully Crossing for Small Scale Community Aqueducts: A Design
Guide Based on Experience and Observations from Peace Corps, Dominican Republic. Masters Thesis, Michigan Technological University.
Websites www.bridgingthegapafrica.org http://krehm.posterous.com (blog) http://bridgestoprosperity.org/resources/technical-resources/ http://www.nepaltrailbridges.org/ (Helvetas partnership)
MORE INFORMATION
www.bridgingthegapafrica.org
My Blog: Kelley in Kenya http://krehm posterous com http://krehm.posterous.com
www.Causes.com
Contact Me: Kelley Rehm [email protected] I have reports and references for your use!
HOW TO GET STARTED… Brainstorming!g
FUNDRAISING
How Much Do We Need Just to Build the Bridge?g
$10,000 to $15,000
What if we want to bring a construction team to Africa?Africa?
Travel costs for each team member = $2500 Cost of Bridge Total $30,000 to $35,000
QUESTIONS?
