Method Statement for Span Alignment

January 15, 2014

1. INTRODUCTION

1.1 PROJECT DESCRIPTION

The purpose of this procedure is to describe the installation of temporary bearings, span jacks, sliding system & permanent bearings supporting the spans which will be erected by launching gantries using the span by span method for the HCMC Line 1 Metro Project and to describe the process of adjustment of span alignment using sliding system.

1.2 SCOPE OF WORK

This procedure is developed for application in the scope of works and applies to all the spans composing the spans of the viaduct superstructure of the HCMC Line 1 Metro Project and erected by launching gantries using the span by span method.

It also describes the tools, plant, equipment, materials and labour which will be used for this activity together with a risk analysis of the operations.

1.3 GENERAL

To allow the movement caused by metro traffic or weather, each erected span shall be put down on bearings.

However, these bearings, called “Permanent Bearings (PB)”, are not design to support the Launching Gantry’s load. Therefore, it is necessary to install first stronger bearings, called “Temporary Bearings (TB)” during span erection. A total of 4 different types of Permanent Bearings depending on the design of the span:

Type Size (mm) Span description Approx. weight EB1 500 x 850 x 90 35m > Span length > 30m ; Curvature R > 1300m 126.2 kg EB2 450 x 600 x 90 30m > Span length > 25m ; Curvature R > 1300m 79.7 kg EB3 400 x 600 x 90 25m > Span length > 15m ; Curvature R > 1300m 70.7 kg EB4 500 x 850 x 90 Span length > 35m ; Curvature R > 1300m Future 35m station span 126.2 kg Curvature R < 1300m

Note : In drawings in this document, type EB1 is used. The height of the 4 types are the same so the kinematic of installation/ removing stay the same for all.

Before span erection, it’s necessary to remove permanent bearing because it isn’t designed to take LG load.

Temporary bearings are used to sustain the loads from the span, the launching girder and other effects such as wind and construction live loads, segment transporter loads and loads from the drop-in span arrangement, temporarily during the construction stage.

These load effects at the various erection stages may be far in excess of the service loads for permanent bearing and hence temporary bearings are needed.

The load of the span is transferred to the temporary bearings from the launching girder during the permanent prestressing works.

Shim tube 100x50x500mm filled with concrete shall be used as temporary bearing to support the span during erection.

Shim tubes filled with concrete are stacked as required to get the height. The weight of one tube is around 8.3 kg, it is easy to handle by hand so no need any special instruction.

Refer to attachment #4 for more information.

The temporary bearings must be placed at the location as shown on the relevant drawings. Positioning of the temporary bearings in any other location will cause inadmissible stress on the superstructure, pier caps and other substructure elements.

Span jacks + span alignment jacks are used to align the span, longitudinally and transversally. Before the last step (Fully retract the span jack and transfer the load from span jack to permanent bearing), use the transversally and the longitudinally span alignment pushing jacks to adjust and align the erected span.

There are 4 span jacks (SJ): 2 located on the front pier 2 located on the rear pier

For each span jack, there is 1 longitudinal and 1 transversal span alignment pushing jacks to adjust span alignment.

Note : It is possible to reuse by relocating the same pushing jack. Installation of temporary bearings & span alignment system (span jacks + span alignment pushing jacks with sliding box) has to be completed prior to lift any segment of the span.

1.4 DEFINITIONS

General Pushing jacks

LG Launching Gantry TFR Transversal Front (pier) Right (side) pushing jack MG Main Girder TFL Transversal Front (pier) Left (side) pushing jack PB Permanent Bearing TRR Transversal Rear (pier) Right (side) pushing jack TB Temporary Bearing TRL Transversal Rear (pier) Left (side) pushing jack SJ Span Jack LFL Longitudinal Front (pier) Right (side) pushing jack PS Pier Segment LFR Longitudinal Front (pier) Left (side) pushing jack TS Typical Segment LRL Longitudinal Rear (pier) Right (side) pushing jack LRR Longitudinal Rear (pier) Left (side) pushing jack

1.5 WORK-FLOW CHART

The work will be done step by step as describe concisely in the work-flow chart as below:

2. RELEVANT SPECIFICATIONS, STANDARDS AND DOCUMENTS

• Kinematic drawings FVR-TEC-DWG-3240-017

3. INSTALLATION PROCEDURE

3.1 PRELIMINARY CHECKS BEFORE LG SELF-LAUNCHING

Before starting the temporary bearings installation, check that: - The horizontal surface of the bearings and their elements are cleaned of grease and/or dust; - All operatives are fully briefed on the task to be undertaken; - The top of bearing pedestal is at the required level in advance of erection of span.

3.2 TYPICAL INSTALLATION OF BEARINGS

This section details the typical installation of the different bearings and concerns all the spans with at least one back span already erected. The procedure listed in this document assumes that the permanent bearings are positioned prior to LG reaching the relevant piers. Note: In case of the permanent bearings are not positioned, skip item 3.2.1.

3.2.1 Remove Permanent Bearings (PB)

If the Permanent Bearings are already installed by others, then it’s is required to be removed carefully and stocked securely on top of pier and well protected, prior to the span erection.

Mark with marker the 4 edges of PB on pedestal using an offset guide to assist in identifying the location for the bearing to be returned to.

Note: Do not mark the PB with any solvent based markers.

Sling to be wrapped around PB and connected to a lever block. Connect lever block onto the Front Support’s platform or a piece of bar spanned between the pedestals on the opposite side. Workers pull on the lever block to transfer PB.

Refer to attachment #3, Removal of PB.

3.2.2 Installation of Temporary Bearings (TB)

Clean the pier head pedestal from grease and dust
Put plywood on the pedestal
Put and Stack shim tubes filled with concrete to form the TB as per sketch below
Put plywood on top of shim tubes

3.2.3 Installation of span alignment system

Before span erection: Span Jack (SJ) have to be placed on the pier cap as per sketch.
Clean the pier cap, lift up and install SJ (stroke = 45mm)
Install on top of SJ, 6nos 20mm-high steel plates, then 1no 25mm-thickness steel plate and finally 1no 20mm-high steel plate on top

Note : A 20mm & 25mm-thick steel plate on top of SJ will be required in later stage.

Erect the span: Transfer the span on the jack
Finish stressing phase 2: transfer the span to the temporary bearing

3.2.4 Remove Temporary Bearings & installation of Permanent Bearings

The installation of PB has to be done after self-launching of LG as PB cannot take LG load.

Fully extend SJ (stroke = 45mm): the span weight will be transferred to the SJ
Wing the lock ring of SJ.
Remove carefully TB & plywood by hand.
Install carefully PB using lever block and sling (refer to attachment #3, Installation of PB). On top of PB install 3nos 10mm-thick steel plates by hand (Approx. weight of 1no steel plate = 35 kg).

3.2.5 Adjustment of span alignment

Span alignment will be done by “pushing” transversally and longitudinally. Transverse and longitudinal movement are done using lateral “pushing” jacks. For example :

To move the span to the right (following launching direction), push the span alignment jacks to the right (only 2 pushing jacks are concerned).
To move the span to the left (following launching direction), push the span alignment jacks to the left (only 2 pushing jacks are concerned).
To rotate the span, push 1 span alignment jacks and the opposite one on this other pier.
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- See pictures below
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Note: It is possible and highly recommend to operate the span alignment system at one end at a time.

The control of the alignment will be done by survey. Each segment has 4 survey references, as shown on picture:

FVR will take as reference the survey reference installed on center of each pier and align pier segments survey reference with them. Note : Adjust full span by sliding jacks until within tolerance.

3.2.6 Remove sliding system

Fully retract SJ (stroke = 0mm). The span should come to rest on the steel plate on top of PB.
Remove carefully 1no 20mm-thickness steel plate on top of SJ
Extend SJ (stroke = 40mm), in order to cause 14mm gap above PB steel plate.
Wind SJ ring and transfer loading from hydraulic to ring nut.
Remove carefully 2nos 10mm-thickness steel plates on top of PB
Fully retract SJ (stroke = 0mm). The span should come to rest on the steel plate on top of PB.
Remove carefully 1no 25mm-thickness steel plate on top of SJ
Extend SJ (stroke = 40mm), in order to cause 9mm gap above PB steel plate.
Wind SJ ring and transfer loading from hydraulic to ring nut.
Remove carefully 1nos 10mm-thickness steel plates on top of PB
Double check the span alignment.
- If the alignment is not OK, redo process “3.2.5 Adjustment of span alignment”
- If the alignment is OK, go to next step.
Fully retract SJ (stroke = 0mm)
Span load transfer from SJ to PB retracting 2 SJ on front pier by 2 SJ on rear pier in same time.
Remove carefully the steel plates on top of SJ
Remove carefully SJ

4. RESOURCES TO BE USED

4.1 EQUIPMENT TO BE USED

Equipment to be deployed for the span alignment.

No. Description Specification Quantity Unit Remarks 1 Setting-out instruments 1 set 2 Hand tools 1 set 3 Span Jacks Hi-Force (HFL2502) 1 set Stroke = 45mm 4 Pump Y26 / SPX 554 1 set 5 Chain 1 set 6 Slings 1 set 7 Shackle 1 set 8 Safety signs 1 set 9 Hoisting equipment 1 set 10 Cherry picker 1 set 11 Generators 1 set 12 Spanners 1 set 13 Lever block 1 set

Note: Above stated quantity of equipments could be changed if necessary.

4.2 MANPOWER TO BE DEPLOYED

Manpower to be deployed for the span alignment works as per detailed organization chart below

Note: - Number of manpower could be changed according to site condition.

4.3 MATERIALS TO BE USED

Materials to be used for the span alignment as per sections are listed below. No. Description Remarks 1 Grease
2 Plywood 3 Steel shims 300x300mm (height = 25 and 20mm) 870x520mm (height = 10mm) Note: Description and sources of materials could be changed according to site condition, subcontractor, schedule, quality, etc.

5. INSPECTION TESTING PLAN

Inspection records will be kept for all critical activities particularly for the positioning of the launching gantry supports, the stroke level and pressure of the supports jacks. Inspection sheets, test reports, material certificates and all the other documents to be collected are listed in the internal ITP.

6. OCCUPATIONAL HEALTH AND SAFETY CONTROL

The Hazard and Risk Assessment (HRA) has been carried out in the form of the Job Safety Analysis (JSA) to include those activities which are specially associated with the installation of TB and sliding system. These are reviewed by the HSE Officer to ensure that all the hazards have been identified and adequate control measures are in place. All personnel shall wear the appropriate PPE at all times.

6.1 JOB SAFETY ANALYSIS (JSA) / HAZARD ANALYSIS & RISK ASSESSMENT (HRA) / SAFE WORK METHOD STATEMENT (SWMS)

The JSA has been completed by the Technical Department and has been reviewed by the HSE Department. It should also be reviewed by the work crew prior to activities being performed. The document has identified the hazards associated with the activities involved in the installation of TB and sliding system and details the measures to be adopted to minimize or eliminate those risks identified. Attachment #1

6.2 TOOLS AND EQUIPMENT

All tools and equipment for the task shall be in safe condition and fit for its purpose. Where applicable, registration papers, certifications shall be produced and tests certificates will be available for inspection.

At the start of each shift, equipment shall be visually checked for mechanical and structural soundness. All equipment shall be carefully examined and all hoses and couplings checked for the leaks and general condition.

7. ATTACHMENTS

ATTACHMENT #1: HAZARD AND RISK ASSESSMENT (HRA) ATTACHMENT #2: SPAN JACK DATA SHEET ATTACHMENT #3: REMOVAL AND INSTALLATION SEQUENCE FOR PERMANENT BEARING

ATTACHMENT #4: TEMPORARY BEARING BY SHIM TUBE FILLED WITH CONCRETE

1. General

Shim tubes 100x50x500 filled with concrete shall be used as temporary bearing. They are stacked as required to get the height as below. The contact area of bearing is 500x500mm.

The compressive strength of concrete at 28 days: 35 MPa

Example of temporary bearing using shim tube filled with concrete

2. Load effect on temporary bearing

2.1. Vertical load V1:

According to the calculation of the launching girder, maximum vertical load transferred to the span through rear support occurs when the launching girder lifts the segment using back feeding method at distance 13m during 37m span erection.

Vertical load transfers to 2 critical temporary bearings including: - Reaction load from launching gantry + weight of segments: refer to calculation report of launching girder as attached in attachment #6, load condition – 7, page 61, the value is 5495 kN. - Half weight of the erected 37m span: The 37m span have 14 segments, weight of one segment is 42 tonnes. Load apply to 2 critical temporary bearings will be 14 x ⁴²⁄₂ = 294 tonnes = 2940 kN - Half weight of transporter 24 tonnes transfers to 2 critical bearings = 120 kN Total vertical load on 2 temporary bearings = 5495 + 2940 + 120 = 8555 kN Vertical load on 1 temporary bearing = ⁸⁵⁵⁵⁄₂ = 4278 kN

2.2. Wind load in transverse direction (wind speed 45m/s):

This load include the wind load from launching gantry transfer to 2 critical temporary bearings through rear support and half of wind load effect onto the erected 37m span.

Wind speed 45 m/s
Wind pressure, p 1.241 kN/m2
Wind load transfer to 2 critical TB is calculated as below:

3. Temporary bearing verification

Vertical pressure checking: Pressure = 1.25x4278x1000/(500x500) = 21.4 MPa < 0.85f’c = 0.85x35 = 29.7 MPa  OK Sliding checking:

Vertical load (kN) Horizontal load (kN) Ratio Conclusion 4278 364 0.09 < 0.2, OK

NOTE: 1.25 : load factor 0.2 : friction coefficient between concrete (U-girder) and steel (shim tube)

ATTACHMENT #5: LAUNCHING GIRDER L91 - CALCULATION REPORT