New Plastic Fenders System : Philosophy / Design Approach Session 62

Session 62
Henry Bollmann
FL. Dept. of Transportation CO
New Plastic Fenders System : Philosophy / Design Approach
Topic Description
New standard sheets for fender systems are introduced. The design philosophy, based on energy concepts, is discussed. Use of the
standards and limitations are described.
Speaker Biography
Henry Bollmann is a Senior Structures Design Engineer working in the FDOT Central Office, Tallahasse Fl. Henry received his
MSCE degree from the University of Florida in 1974 and has spent his entire professional career working in many facets of bridge
engineering while focusing on design.
Fender Systems
Henry Bollmann & Jerry Hocking - Structures Design Office
FDOT Design Conference 2006
Structures Design Office
Barge Impact
FDOT Design Conference 2006
Structures Design Office
1
Topics
„ Fender
Purpose
„ Design Guidance & Specifications
„ Standard Index Drawings
„ Heavy Duty Fender System
„ Medium Duty Fender System
„ Light Duty Fender System
FDOT Design Conference 2006
Structures Design Office
Topics
„ Guidance
for Selection of Fender
„ Design
Method and Example
„ Cost Considerations
„ Plastic Pile Bending Test
„ Pile and Wale Capacity Comparison
FDOT Design Conference 2006
Structures Design Office
2
Seabreeze
FDOT Design Conference 2006
Structures Design Office
Seabreeze
FDOT Design Conference 2006
Structures Design Office
3
Concrete and Timber
FDOT Design Conference 2006
Structures Design Office
Clearwater Inlet
FDOT Design Conference 2006
Structures Design Office
4
Boynton Beach
FDOT Design Conference 2006
Structures Design Office
St. George Island
FDOT Design Conference 2006
Structures Design Office
5
Evans Crary
FDOT Design Conference 2006
Structures Design Office
SR 312
FDOT Design Conference 2006
Structures Design Office
6
Purpose of Fender System
In general, a bridge over a navigable
waterway that is under the jurisdiction
of the U.S. Coast Guard will have a
bridge fender system.
„ Primary function is to delineate
channels and redirect aberrant
vessels.
„
FDOT Design Conference 2006
Structures Design Office
Purpose of Fender System
It is considered as a sacrificial
structure.
„ The channel pier is designed for full
ship impact. i.e. Neglecting effect of
fender system.
„
FDOT Design Conference 2006
Structures Design Office
7
Design Guidance and Specifications
„ FDOT
Standard Specifications
„ New
Section 973 – Material
Requirements of Plastic Piles and
Wales
„ New Section 471 – Construction &
Installation of Fender System
„ Modify Section 455-44 – Installation
Requirements of Plastic Piles
FDOT Design Conference 2006
Structures Design Office
Design Guidance and Specifications
„ SDG
Section 3.14 – Fender Systems
„ SDM Chapter 12 – Fender Systems
„ AASHTO – Guide Specification and
Commentary For Vessel Collision
Design of Highway Bridges
„ C3.8
Vessel Collision Energy
„ C7.3.1 Fender Systems
FDOT Design Conference 2006
Structures Design Office
8
New Standard Index Drawings
„
„
„
„
„
Index 21900 – General Notes & Layout
Index 21910 – Heavy Duty Fender System
Index 21920 – Medium Duty Fender
System
Index 21930 – Light Duty Fender System
CADD Cells for Quantities and List of
Variables
FDOT Design Conference 2006
Structures Design Office
Plan and Elevation
FDOT Design Conference 2006
Structures Design Office
9
FDOT Design Conference 2006
Structures Design Office
SS
Bolts
Spacer
Blocks
16” dia.
Piles
FDOT Design Conference 2006
Structures Design Office
10
SS Splice
Plate
SS
Bolts
FDOT Design Conference 2006
Structures Design Office
Piles
„ Pile
Spacing
„ Heavy
Duty Fender – Spacing = 5’- 4”
„ Medium Duty Fender – Spacing = 8’- 0”
„ Light Duty Fender – Spacing = 5’- 4”
FDOT Design Conference 2006
Structures Design Office
11
Piles
„ Pile
Length
„8
feet above MHW
„ MHW - MLW (approx. 4 feet )
„ Channel depth 12 feet
„ Approximate soil embedment 24 feet
„ 48 feet total
„ All
Piles Driven Plumb
FDOT Design Conference 2006
Structures Design Office
Wales
„
Wale lengths and size
„
„
„
16 & 32 feet in length
„ Over lapping joints at splice locations
for greater continuity strength at pile
locations.
10” x 10” square
Stainless steel connection bolts and
splice plates.
FDOT Design Conference 2006
Structures Design Office
12
Catwalk
„
Two deck options available
„
„
„
Plastic marine lumber (non-reinforced)
Fiberglass open grating
Width 2’-6”
FDOT Design Conference 2006
Structures Design Office
General Layout Sheet and
Table of Variables
FDOT Design Conference 2006
Structures Design Office
13
Table of Variables
Station
Control
Point
“C”
Skew
Angle
Of
t
fse
Clear
Channel
Dimension “L”
FDOT Design Conference 2006
Structures Design Office
FDOT Design Conference 2006
Structures Design Office
14
Guidance For Selection of
Fender System
„ From
SDG 3.14.3B and 3.14.4C
„ Heavy
Duty Fender System
„ Channel pier strength requirement
from risk analysis exceeds 2500 kips
„ i.e. Two loaded jumbo hopper barges
+ push boat at 4.0 knots
FDOT Design Conference 2006
Structures Design Office
Guidance For Selection of
Fender System
„ Medium
Duty Fender System
„ Channel
pier strength requirement
from risk analysis 1000 to 2500 kips
„ i.e. One loaded jumbo hopper barge +
push boat at 3.6 knots
FDOT Design Conference 2006
Structures Design Office
15
Guidance For Selection of
Fender System
„ Light
Duty Fender System
„ Minor
commercial traffic, pier strength
requirement less than 1000 kips
„ i.e. One unloaded jumbo hopper
barge + push boat at 4.2 knots
FDOT Design Conference 2006
Structures Design Office
Design Methodology
The loss of kinetic energy of the
vessel is transformed into an equal
amount of energy absorbed by the
protective structure. The kinetic
impact energy is dissipated by the
work done by the displacement of the
protective system.
FDOT Design Conference 2006
Structures Design Office
16
Design Methodology
Develop a force versus deflection diagram
via analysis or physical testing. The area
under the diagram is the energy capacity
of the protective system. The forces and
energy capacity of the protective system is
then compared with the design vessel
impact force and energy to determine if
the vessel loads have been safely
resisted.
FDOT Design Conference 2006
Structures Design Office
Design Assumptions
„ Channel
Depth at MHW 12 ft.
„ 8 ft. from MHW to top of pile
„ Weak cohesionless soil
„ Phi
= 30 deg.
„ Subgrade modulus = 20 pci
FDOT Design Conference 2006
Structures Design Office
17
Design Assumptions
„ Coefficient
of friction (mu) between
barge and plastic wale = 0.15
„ Impact angle = 15 deg.
FDOT Design Conference 2006
Structures Design Office
Design Methodology
Governing Equation
η ⋅ KE barge ≤ Work fender
FDOT Design Conference 2006
Structures Design Office
18
Design Methodology
„ Work
done by Fender System
(Absorbed Energy)
„ Increment
load until Pile Nominal
Moment Capacity is reached
„ Find Deflection
1
Work fender
2
⋅
∑
∑ P i ⋅Δ i
FDOT Design Conference 2006
Structures Design Office
FB-Pier Model
Medium Duty Fender
FDOT Design Conference 2006
Structures Design Office
19
Fender Energy
Area = 132 k-f
FDOT Design Conference 2006
Structures Design Office
Barge Energy
Kinetic Energy of Barge (Vessel Energy)
KE
KE
KE
1
2
1
2
⋅M ⋅ V
⋅ CH ⋅
2
W
g
CH ⋅ W ⋅ V
⋅V
2
2
2⋅g
tonne
kip
= 29.18
ft
sec
2
29.2
FDOT Design Conference 2006
Structures Design Office
20
Design Example
Medium Duty Fender
1 loaded jumbo hopper barge => 1900 tons
Push boat => 260 tons
Total Weight W = 1900 + 260 = 2160 tons, 1956 tonnes
n*KEbarge = n*Ch*W*V2 /29.2= Energyfender
n = 0.05 (for mu = 0.15 & angle of impact = 15 deg.)
fig. C3.8C3.8-1 AASHTO – Guide Specification and
Commentary For Vessel Collision Design of Highway
Bridges
FDOT Design Conference 2006
Structures Design Office
Determination of Eta
For:
Mu = 0.15
Alpha = 15 deg.
Graph shows:
Eta = 0.05
0.05
15 deg.
FDOT Design Conference 2006
Structures Design Office
21
Design Example
Medium Duty Fender
1 loaded jumbo hopper barge => 1900 tons
Push boat => 260 tons
Total Weight W = 1900 + 260 = 2160 tons, 1956 tonnes
n*KEbarge = n*Ch*W*V2 / 29.2 = Energyfender
n = 0.05 (for mu = 0.15 & angle of impact = 15 deg.)
fig. C3.8C3.8-1 AASHTO – Guide Specification and
Commentary For Vessel Collision Design of Highway
Bridges
Ch = 1.05 for under keel clearance
FDOT Design Conference 2006
Structures Design Office
Design Example
Medium Duty Fender
n*KEbarge = n*Ch*W*V2 /29.2 = Energyfender
n*KEbarge = 0.05*1.05*1956*V2 /29.2= 132k-f
Solving for velocity: V= 6.12 f/s = 3.62 knots
FDOT Design Conference 2006
Structures Design Office
22
Initial Cost Considerations
„
„
„
There are multiple sources of supply of the
Structural Plastic piles and timbers.
Therefore, there will be competitive bids.
In terms of cost per lineal foot, Structural
Plastic piles are twice the cost of 14”
square prestressed concrete piles.
Total cost of Plastic Fender System is
approximately twice that of the 14” square
concrete pile system.
FDOT Design Conference 2006
Structures Design Office
Initial Cost Considerations
„
However, when comparing cost you must
consider the entire system. For example,
the typical medium-duty structural plastic
system uses approximately 100 - 16” OD
structural plastic piles versus the
traditional prestressed concrete pile
system that uses over 200.
FDOT Design Conference 2006
Structures Design Office
23
Initial Cost Considerations
„
The higher, per lineal foot cost of the
structural plastic piles is offset by 2
factors:
Fewer piles means the material cost is
reduced
„ Fewer piles reduces labor cost (less pile
driving)
„
FDOT Design Conference 2006
Structures Design Office
Life-Cycle Cost Considerations
„
Expect structural plastic members to last
the life of the bridge (75+ years).
Stainless hardware will fail before the
structural plastic piles & timbers.
FDOT Design Conference 2006
Structures Design Office
24
Life-Cycle Cost Considerations
„
In contrast, timber and concrete have a far
shorter service life:
Timber wales offer a maximum service life of
10-15 years
„ Prestressed concrete piles begin failing at the
time of the first significant impact to the fender
system. The prestressed pile cracks on
impact, seawater corrodes steel reinforcing
strands & the concrete begins to spall.
„
FDOT Design Conference 2006
Structures Design Office
Life-Cycle Cost Considerations
„
In contrast, structural plastic fender
systems absorb the energy of these
impacts without requiring any
maintenance. As a result, the structural
plastic fender systems offer a substantially
lower life cycle cost for the State of
Florida.
FDOT Design Conference 2006
Structures Design Office
25
Wale Bending Test
FDOT Design Conference 2006
Structures Design Office
FDOT Design Conference 2006
Structures Design Office
26
10” sq. Plastic Wale
Load-Displacement Curve
24
P = 22.4 k
22
P = 18.5 k
20
18
load (kips)
35 %
My = 58 k-f
My = S*Fy (Fy = 4.5 ksi)
16
Load (k)
Mn = 78.4 k-f
14
12
10
4 – 1.25”
dia. bars
8
6
4
4 – 1” dia. bars
2
0
2
1
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Displacement (in)
displacement (inches)
new wale
old wale 2
old wale 1 initial test
old wale 1 final test
FDOT Design Conference 2006
Structures Design Office
Full-Scale Testing
FDOT Design Conference 2006
Structures Design Office
27
Energy-Absorption Comparison
190 kN
10.5 in
267 mm
42.7 k
FDOT Design Conference 2006
Structures Design Office
Plastic Pile Design
FDOT Design Conference 2006
Structures Design Office
28
Fender Pile Capacities
Moment Capacities
Mn (k-f)
Element
86
% of
Timber
Pile
100
304
353
165
192
110
128
12” dia. Timber Pile
16” dia. FRP
w/16 – 1 1/2” dia. bars
16” dia. FRP
w/16 - 1” dia. bars
14” sq. PS Concrete Pile
w/8 - ½” dia. strand
FDOT Design Conference 2006
Structures Design Office
Fender Wale Capacities
Moment Capacities
% of
Timber
Wale
Element
Mn (k-f)
10” sq. Timber Wale
42
100
10” sq. Plastic Wale
w/4 - 1 1/2” dia. bars
76
181
10” sq. Plastic Wale
w/4 - 1” dia. bars
45
107
FDOT Design Conference 2006
Structures Design Office
29
Questions / Comments
Henry Bollmann, P.E.
Structures Design Office
Florida Department of Transportation
605 Suwannee St., MS 33
Tallahassee, Fl. 32399
[email protected]
FDOT Design Conference 2006
Structures Design Office
30