WZQ Bridge Design Competition 2010 HANDRAIL TRUSSES: SIMPLY SUPPORTED BETWEEN ABUT-
6m LONG ‘W-SHAPED’ TRUSS MODULES SPLICED TOGETHER
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BAMBOO TRUSS BRIDGE ·
HANDRAIL BRACING AND FLOOR BEAMS AT 3m cts
HIGH WATER LEVEL
EXISTING ROCKS
EXISTING BRIDGE CAN BE USED DURING CONSTRUCTION
HEIGHT OF DECK ABOVE HWL = 1m
WATER LEVEL VARIANCE = 4m
ABUTMENT A: 4m X 4m X 2m HIGH GABION ROCK BASKET
ABUTMENT B: GABION ROCK BASKET CUT LIGHTLY INTO ROCK
SPAN = 21m N.T.S.
N.T.S.
SIDE ELEVATION
NOTE: ALL BAMBOO MEMBERS SOURCED LOCALLY, TO BE 70100mm dia. X 15mm THICK MOSO BAMBOO
TRUSS CHORDS & STRUTS: DOUBLE D BAMBOO MEMBERS
MARINE-GRADE PLYWOOD GUSSET PLATES (IMPORTED)
PLAN
HANDRAIL BRACING AT 3m cts: SINGLE BAMBOO MEMBERS LASHED TO HANDRAIL DECK SURFACE: HEAVY DUTY WIDEWEAVE BAMBOO MAT
TRUSS HEIGHT = 1.5m
DECK BEAMS: TRIPLED BAMBOO POLES PROTRUDE LATERALLY, SUPPORTING BRACING STRUTS
DECK JOISTS SIDE-BYSIDE BAMBOO POLES BRIDGE WIDTH = 2m N.T.S.
TYPICAL SECTION
ISOMETRIC
WZQ Bridge Design Competition 2010
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HANDRAIL TRUSSES • •
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BAMBOO TRUSS BRIDGE ·
DECK SURFACE
DESIGN FEATURES
TRUSSES FABRICATED EITHER ON OR OFF SITE IN ‘W-SHAPED’ MODULES POLES ARE BOLTED THOUGH GUSSET PLATES, LASHED AND INTERNALLY REINFORCED AROUND BOLTS TO PREVENT SPLITTING. ALL MEMBERS DOUBLED UP (SIDE-BYSIDE) TO ‘SANDWICH’ IMPORTED PLYWOOD GUSSET PLATES SIMPLY-SUPPORTED BETWEEN ABUTMENT BASKETS. , ALLOWING WETTING/DRYING SHRINKAGE AT ONE END. TEMPORARY ROPE STAYS CAN BRACE DURING CONSTRUCTION
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LOCALLY-SOURCED, DURABLE MATERIALS WITH LOW EMBODIED CARBON: BAMBOO, PLYWOOD, LOCAL RIVER STONES
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SIMPLE, MODULAR, CAN BE LIFTED MANUALLY IN PLACE AND MAINTAINED BY UNSKILLED WORKERS WITH MINIMAL DIRECTION
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TRUSS IS EFFICIENT, HAS A HIGH STRENGTH/WEIGHT RATIO & IS SAFE FOR USERS
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HEAVY DUTY 5mm THICK WIDE-WEAVE BAMBOO MAT OR EQUIVALENT, LOCALLY AVAILABLE MATERIAL.
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IMPORTED IN 3m LONG PANELS (DOUBLED OR TRIPLED IN THICKNESS IF NECESSARY.
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TIED AND/OR BOLTED THROUGH DECK JOISTS DOWN TO DECK BEAMS FOR USE AS OVERALL LATERAL BRACING
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ROWS OF BAMBOO POLES LASHED TOGETHER USING BAMBOO LASHING OR ROPE.
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SPANNING 3m (LONGITUDINALLY) BETWEEN DECK BEAMS
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3-6m LONG PANELS SPLICED TOGETHER USING BAMBOO OR ROPE LASHING
LOW COST PER METRE LENGTH, WITH FAST CONSTRUCTION TIME ENTIRE STRUCTURE CLEAR OF WATER FLOW REDUNDANCY IN DESIGN: TRUSS MEMBERS DOUBLED OR TRIPLED IN CASE OF FAILURE OF SINGLE POLE
6 2 DECK JOISTS 5 HANDRAIL BRACING 4 •
BRACES HANDRAIL AGAINST COMPRESSION BUCKLING AND TRANSFERS LATERAL HANDRAIL LOAD TO DECK BEAMS
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SINGLE BAMBOO POLE TIED & THROUGHBOLTED TO HANDRAIL AND DECK BEAMS. BAMBOO LOCALLY-REINFORCED AT CONNECTIONS WITH GROUT
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MIDDLE POLE STOPPED SHORT TO ALLOW ‘SANDWICHING’ OF BRACING MEMBER.
ABUTMENTS
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LARGE STEEL CAGE ‘GABION BASKETS’ FILLED WITH ASSORTED RIVER STONES CUT INTO HILLSIDE. ABUTMENT A TO BE CUT SUBSTANTIALLY INTO STEEL EARTHCAGE TO PREVENT LARGE ‘GABIONEROSION BASKETS’ FROMWITH RIVER FLOW RIVER STONES FILLED ASSORTED ABUTMENT NOTCHED INTO ROCK FOR CUT INTOB HILLSIDE. MECHANICAL ‘KEYING’ ON ABUTMENT ABUTMENT A TO BE CUT SUBSTANTIALLY POSITION INTO EARTH TO PREVENT EROSION FROM RIVER FLOW
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DECK BEAMS STRUCTURAL ANALYSIS • •
ASSUMED LIVE LOAD = 4kPa (PEOPLE & LIVESTOCK) GSA MODEL ANALYSED (SHOWN BELOW) : LL DEFLECTION = 200mm
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3NO. BAMBOO POLES LASHED & WEAVED TOGETHER SPANNING 2m BETWEEN HANDRAIL TRUSSES BOTTOM CHORDS, EXTENDING OUTWARDS TO SUPPORT BASE OF HANDRAIL BRACING.
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CONNECTIONS LASHED WITH MULTIPLE BAMBOO STRANDS
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NOT CONNECTED AT NODES FOR EASE OF CONSTRUCTION.
A = 8010mm2 E = 12E3MPa CHORD PROPERTIES
ABUTMENT B NOTCHED INTO ROCK FOR MECHANICAL ‘KEYING’ ON ABUTMENT POSITION OVERALL LATERAL STIFFNESS AND TORSIONAL STIFFNESS NOT CALCULATED. DEFLECTION SLIGHTLY EXCESSIVE, HOWEVER, CONNECTION STRENGTH WILL ULTIMATELY GOVERN MEMBER DESIGN.