7. basic suspended design_slide handouts

8/10/2019 7. Basic Suspended Design_Slide Handouts

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Presentation #7

Bridge Plan & Profile

Bridge

Profile

Step 1: AASHTO Loading

Group 1 = Dead Load + Live Load

Group 2 = (Dead Load + Wind Load)/1.25

Group 3 = (Dead Load + Live Load + 0.3*Wind

oa . Wind Load assumes 100 mph


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Live Loading Step 1: AASHTOLoading

Live Load = 90 psf Dead Load = 22 p/lf

Approximately how many people can stand on your

bridge?

Step 2: Calculate Span length

Maximum of 120 meters using design guide

Step 2: Calculate Span length

Position Foundations

3 meters back from soil slope

1.5 meters from rock

Behind line of angle of internal friction 35 for so il

60 for ro ck

h < 4%.

Add Tiers as necessary

Step 3: Determine Number of Tiers

h

Step 4: Check Freeboard


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Freeboard Required

2 meters for floodplain, 4 meters gorges

Add Tiers as necessary


freeboard

Step 5: Select Walkway Width

Anticipated usage:

Pedestrian

Hand-pull carts

Motorcycles

. meter w t

Step 6: Cable Lookup Tool

Steel Cable Size

- Cable Look-up tool

Breaking strength of available cable

S an of brid e

Width of desired decking

Available on www.bridgestoprosperity.org/resources

Step 6: Cable Lookup Tool

Research available cable breaking strength

Input values and number of cables (redtext)

Modify combinations until desired deck width has

value at least as lon as brid e s an ellow

Step 7: Select Construction Drawings

Use Span and

soil types


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Compile Final Drawings

-

Step 7: Select Construction DrawingsAdd

Plan

and

Profile

Drawings

Step 8: Material Quantities &Cost Estimate

See Design Example

Cable

Cement

Stone

Gravel

an

Re bar

Miscellaneous items

Design Example

Design Example: La Vegas, Yoro, HondurasSite Assessment Survey Information

.

Abney R eadings

Distance Angle Horizontal Vertical Elevation

R 100.00

R - L 70.10 +5.00 69.73 +6.10 106.1

R - 1 66.55 +1.20 66.53 +1.54 101.54

R - 2 56.57 0 56.57 0 100.00

R - 3 48.75 -2.10 48.72 -1.84 98.16

R - 4(hfl) 43.43 -7.00 43.11 -5.29 96.85

R - 5 38.06 -7.50 37.71 -5.19 94.81

R - 6 9.49 100.00

L


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Step 1: Draw Section using Site Survey

.

R R R R

11 1

L

1

2

3

4 (hfl)

5

6

R

RL 1

23 4

5

6

Step 2: Calculate Span Length

Position Foundations


1. Adequate slope angle or adequate distance

Max 35 degrees in soil (or min. 3 meters); Max 60degrees in rock (or min. 1.5 meters)

Right Side: slope angle 41 degrees = NOT OK

Therefore 3.00 m distance from edge of bank, 6.54 m = OK

R

L

WL

HFL



2. Span (l) = 120m

3. Height difference (h) = Eh El < l/25

Allowable height difference (L / 25) 62/25 = 2.48mActual height differenceH = 103.30 103.01 0.29m

H Span/25 OK



2. Sp an (l) = >120m


4 . S ag (bd) = l /20 or l /22

80 m > = l/20;

80 120m = l/22

bd= l/20 = 61.34/20 = 3.06


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Position Foundations: Freeboard



2. Sp an (l) = >120m


4 . S ag (bd) = l /20 or l /22 = 3.06 m

5. Fmin = (4. bd h)

2/16 . Bd

Fmin is the lowest point of the cable. Fmintakes into account heightdifference.

Fmin= (4 . bd h)2/16 . Bd = 2.92

Step 4: Check Freeboard Step 4: Check Freeboard


2. Sp an (l) = >120m


4 . S ag (bd) = l /20 or l /22 = 3.06 m

5. Fmin = (4. bd h)

2/16 . Bd = 2.92 m

6. Freeboard = El Hfl - Fmin > Tower height (3.0 or 1.5 for mountain or valley)

1. Elevation of Fmin = El Fmin= 103.01 2.92 = 100.02. Elevation of Highest Flood Level (Hfl) = 96.85

Fb = 100.09 96.85 =3.24 > 3.0 OK

Step 5: Select walkway width

Community Request

Pedestrian traffic

Bicycle traff ic

Therefore, 1.0 meter deck width adequate

Step 6: Select main cable size

Research available cable breaking strength

Input values and number of cables (red text)

Modify combinations until desired deck width has value at

least as lon as brid e s an ellow


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Using the B2PManual.

Flat or hilly land?Soil or rock?

Span

Left side: Soil slope

Right side: Soil land

61 m bridge in soil:

G120G Dcon



Compile Final Drawings

-

Step 8: Material Quantities

Steel Cable

Cement & rebar

Decking


Steel Cable

Lcable = 1.04 (L + 14 + dlefttower to anchor+ drighttower to anchor)

= .

L=93.60 meters each


Steel Cable

Stone, gravel, Sand, Cement & Rebar

Drawings: quantities in footer


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S teel Cable


Decking

Suspenders

8mm smooth iron. cut each suspender at 2m.

The bridge span x 2 = no. of suspenders required.

ross eams

10 cm x 10 cm x 1.4 meters

Span + 1

D ec k p an el s

6 cm x 20 cm x 2 meters in length

5 across x (Span/length)

Nailers (optional)

Same as deck panels, 1.0 meter length

Span + 1


S teel Cable


Decking

Other mater ials

Tubingfor anchors

2 meters x Number of cables (only 1 anchor)

enc ng

1.5 meters height x 2*Span

Saddles

Use tire rims cut in half

Finishing materials

Asphaltic covering for cables

Nai ls /Screws

Paint for towers

Now your turn!

Questions?

7. basic suspended design_slide handouts

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