7 5 ok CW2C CANTILEVER SPAN

Preparation works Installation of Rail beam Installation of Main truss Installation of Transverse beam/truss Installation of Transverse beam/truss Installation of Lower deck form Install

METHOD STATEMENT OF CANTILEVER SPAN CONSTRUCTION

TABLE OF CONTENTS

1 FLOW CHART FOR CANTILEVER CONSTRUCTION

2 ASSEMBLING PROCEDURE FOR FORM TRAVELER

3 CONSTRUCTION OF GIRDER

4 SAFETY CONTROL

1 Flow Chart for Cantilever Construction:

Assembly of Form Traveler

Setting of Formwork

Disassembly of bracket Construction of K0, K1 segment by bracket

Construction of segments

Disassembly of Form traveler and Formwork

Center closure Side closure

2 Assembling Procedure for Form Traveler

Flow Chart procedure for assembling of Form traveler is shown below

Preparation works

Installation of Rail beam

Installation of Main truss

Installation of Transverse beam/truss

Installation of Transverse beam/truss

Installation of Lower deck form Installation of Platform

Adjustment of Lower deck form

Installation of External form

Adjustment of External form

Installation of Top slab form

Construction work

3 Construction of Girder

3.1 K0, K1 segment by Bracket

Assembly of Supporting

Installation of form for bottom slab

Installation of External form for web

Assembly of re-bar for bottom, web

Casting Concrete

Assembly of Internal supporting

Curing, Chipping

Assembly of re-bar for bottom slab, web

Installation of Internal form

Assembly of re-bar and PC for top slab

Casting Concrete

Curing, Chipping

Prestressing

Removal of formwork

3.2 K2 segment – K9 segment by Form Traveler

3.3 Work Sequence for Cantilever construction by Form Traveler

a Survey Works:

1 Preparation:

The surveyor shall check the whole survey points and coordinates network

Setting of Form traveler

Assembly of re-bar and PC (bottom slab & web)

Installation of internal form

Curing

Prestressing works

Launching form traveler to next segment

Setting of Formwork

Assembly of re-bar and PC (top slab)

Casting concrete

Removal of inner form

Removal of outer form

Provide marking point for centerline of the form traveler by offsetting from the end of the old cast segment, the longitudinal centerline of the form traveler shall match to the centerline of the bridge/pier

3 Set rail beam in its exact layout base on dimension of the form traveler

4 After the rail beams confirm its exact location, the form traveler can start

assembling

b Assembling Form traveler and Formworks

Work sequence:

1 Preparation works:

1.1 Prepare all necessary materials and equipments to be used for form

traveler erection

1.2 Assemble all necessary formworks & structures on ground for easy installation

1.3 All form surfaces shall be cleaned and applied with the approved form

release oil

1.4 Before installation, the location of the form traveler shall be located

determined by the survey

2 Installation and assembling of Form traveler:

2.1 Installed the rail beam and fixed it with PC bars passing through the top

slab of box girder Installed the main beam (I1000) and fixed it with PC bar passing throught the rail beam

2.2 Main cantilever truss shall be set by the use of crane then check the

vertical position Main truss shall be fixed to rail beam

2.3 Main cantilever truss must be supported temporary by chain block or

lever block for easy adjustment to attain its vertical alignment

2.4 Install the transverse beams and all necessary structural supports for

Main cantilever truss

2.5 Installed all necessary PC bars and supports prior for installation of

formworks

Install the lower deck form; it shall be fixed and supported by the PC bars

or high tensile stress bar provided before installation Set the elevation of the deck forms to its exact elevation by using hydraulic jacks After confirming the condition of the lower deck form the external side deck form shall be installed

2.6 Install the external side deck form, this form shall be supported by the

PC bars provided at the top portion and fixed at the bottom by the adjustable support or jacks for horizontal adjustment

2.7 When external forms were set, the dimension of the box girder should

be check by the survey Considering its exact position, level, and alignment according to the planned pre-camber calculation

2.8 Install the top slab bottom forms and fixed it with the PC bars provided 2.9 Define the level of formwork prior for the installation of rebars

2.10 Assembled and installed external end forms

1.1 Install the lower transverse rebars of bottom slab.

1.2 Install the longitudinal bars for bottom and fixed to transverse rebars

by a tie wire

1.3 Install the stirrups and longitudinal bars for the web Web stirrups shall

be temporarily supported by a rebar until all longitudinal bars installed 1.4 Install the upper rebars for the bottom slab

1.5 Install the lower rebars for top slab.(Same procedure as bottom slab) 1.6 Install the upper rebar for top slab and rebars for parapet Install the

transverse tendons, transverse tendons shall be fixed and kept in correct position by using rebar spacers or by hanging using tie wire Install longitudinal tendons, it shall be supported by steel racks and fixed with tie wire

1.7 Assemble and install the internal side forms Fixed internal forms by

using tie rod

1.8Final checking for box girder dimension and elevation shall be done

immediately prior for casting

2 Cleaning inside formworks:

2.1 Before casting, cleaning inside forms shall be done

2.2 All waste of tie wires, dust, and rust shall be removed 2.3 Use air compressor for cleaning

3 Installation of necessary block out:

3.1 Install the block out for drainage inlet

3.2 Install the pipe sleeves or block out for PC bars to be used for fixing the

form traveler

d Preventive measures for rebars and forms:

1 For long time waiting for next step, exposed rebar shall be treated by applying

cement grout to prevent rust

2 Forms shall be treated in case there is a gap in between, this gap shall be filled with cement paste

3.4 Curing, Finishing, and Construction joint:

1 Concrete curing:

After casting, cover the fresh concrete by vinyl sheet For exposed surfaces such as slab and other structure it must be covered for a period of 7 days

2 Finishing Concrete:

Immediately after placing concrete, top deck surface shall be struck-off with templates to provide proper transverse section and shall be hand finished smooth to the concrete levels Finishing shall slightly but uniformly roughened

by broom

3 Surface Treatment for Construction Joint:

Before the installations of end forms for construction joint Rugasol F shall

be applied for the surface of the end forms This retarder is used to delay the settlement of the concrete surface without affecting the strength of the concrete After removal of end forms, the surface of construction joint could

be treated easily by spraying water pressure

3.5 Pre-stressing

3.6 Grouting Works

3.7 Measuring cast block:

For defining the level in this stage data must accepted by the Engineer The differential between the design and actual level should be attested in measuring segment deflection in early morning

All measurement must keep going until the forms adjustment meet the requirement and raging from allowable limit

4 Safety Control

1 General Safety Provisions

a Safety protection for staff:

All workers should wear Personal Protective Equipment (PPE) during working and safety belt when required

b.Safety Protection for Equipment:

Concrete pumps, especially its condition, tremie pipes and elbow pipes and truck mixers shall be regularly maintained and checked by sub-contractors before mobilization Spare parts such as tremie or elbow pipe shall be stocked on site for emergency cases

c Safety rail on working platforms:

Working platforms and safety rails shall be provided on high working area for workers to prevent accident of falling down according to local safety regulations

d Safety nets shall be provided underneath the form traveler

e Prepare lighting system for emergency use or in night operation

b.A numbers of hand lights shall be provided in case the electricity shut down

3 During placing concrete

a Communications between pump operators and person-in-charge in placing concrete shall be closely done with walky-talky receiver or loud microphone, if the operator cannot see concreting place

b When the concrete pump shifts to another location, the tip of the hose shall be covered so that the remaining concrete inside the discharge hose will not fall down on workers

c Workers shall not stand under the boom and discharging hose

4 Safety measures before and during Pre stressing works:

Before pre stressing:

1 PC strands, PC bars, hydraulic jacks, and other materials to be used shall be periodically checked and the equipment must maintained its good condition

2 If unsuitable condition is found, material and equipment shall be replaced immediately

3 Provide working platforms for workers for good working convenience

4 All equipment to be used must be calibrated by the local authorized calibration

5 When jack already set for pre stressing Provide safety board in front of extended

strand to prevent accident, just in case if the strand suddenly cut during stressing

6 All work shall be done by skilled and well-trained workers