Method Statement for Closing Span

Construction, Method Statement
1. INTRODUCTION
1.1 GENERAL

The purpose of this document is to describe the method statement for erecting closing spans in the Ho-Chi-Minh-City Metro Line 1 Project. The closing span is the last span to erect between two completed adjacent spans. The available space for different operations is reduced and work process shall be adapted and carried out differently. Sketch of a typical closing span

Noted : C.S. means closing span 1.2 SCOPE OF WORK This document describes steps to follow for erection of closing spans. It is specific to all closing spans. 13 spans are concerned:  

Span Name length 1 P7-01/S2 20 m 2 P6-01/SG4 35 m 3 P3-01/S2 15 m 4 P2-01/VT04 35 m 5 P10-21/S1 19.49 m 6 P9-01/S2 20 m 7 P7-17/P7-21 35.16 m 8 P11-30/P11-31 35 m 9 P12-49/S1 20 m 10 P13-13/P3-14 35 m 11 P13-66/S1 30 m 12 P14-45/S1 20 m 13 P15-40/HNH1 23.33 m From this table we can extract 3 main categories: 20m / 23.33m / 35m

1.3 DEFINITIONS

LG Launching Gantry SB Spreader Beam MG Main Girder FH Front Head FS Front Support RH Rear Head RS Rear Support HS Hanging System AS Auxiliary Support CG Centre of Gravity WT Winch Trolley PS Pier Segment TS Typical Segment

2. RELEVANT SPECIFICATIONS, STANDARDS AND DOCUMENTS

Method statement of typical erection UMRTL1-CP2-VDGN-CVS-MST-00041 Method statement of launching through station UMRTL1-CP2-VDGN-CWS-MST-00130 Method statement of permanent PT UMRTL1-CP2-VDGN-CWS-MST-00097 Calculation note of Load Transfer UMRTL1-CP2-CSYD-CWS-CAL-00028 Method statement of Span Alignment UMRTL1-CP2-VDGN-CWS-MST-00040

3. METHODOLOGY FOR 35 M SPANS:

The configuration of 35 m spans is described on the sketch below:

The code mark for this category of spans is 1A. This code refers to all U girder spans with length between 33m and 35 m. The sequence of stressing for this span is detailled on the table below:
3.1 PROCESS

• Stage 1 corresponds to stressing sequences carried out while the span is still hanging on the launching girder and transferring span loads from hanging bar to jack. For the stage 1: Sequence of stressing PT and load transfer are as follow (for 35m span): Steps 1 ES1 + tPT Steps 2 ES1 + tPT + 1(50%) Steps 3 ES1 + 10% + tPT + 1(50%) Steps 4 ES1 + 10% + tPT + 1 Steps 5 ES1 + 10% + tPT + 1 + 5 Steps 6 ES1 + 35% + tPT + 1 + 5 Steps 7 ES1 + 35% + tPT + 1 + 5 + 8 Steps 8 ES1 + 60% + tPT + 1 + 5 + 8 Steps 9 ES1 + 60% + tPT + 1 + 5 + 8 + 2 Steps 10 ES1 + 80% + tPT + 1 + 5 + 8 + 2 Steps 11 ES1 + 80% + tPT + 1 + 5 + 8 + 2 + 9 Steps 12 Span SW + stage 1

Noted: spanSW+stage1 means 100% of entire span weight transferred • Stage 2 corresponds to stressing remaining tendons • Stage 3 corresponds to lowering the span. 3.2 PREPARATORY WORKS: • Grout and leveling. • Install under the span steel shims (square tubes filled with concrete). o Interleave type A shims (900x100x100mm) with type B shims (500x100x100mm) until height is 1.2m o Install type C shims (500x100x50mm) • Install lowering jacks (4x3 Jacks HFG506) • Notes: o Steel plates shall be installed at the top and bottom of lowering jacks. o Plywoods shall be installed between shim tubes & pier cap, shim tubes & U-girder. • During the erection of the span, all segments will be hang 2150 mm higher than erected spans. • Perform gluing and temporary PT Operations at this level. Method: Stage 1&2: Stressing • Stressing all the tendons at 2150mm higher than erected span.

Stage 3: Lowering of the span

• The span is supported on the jacks • The span down step by step (2150mm to 150mm higher than erected spans)

• Install the temporary bearings (using shim type A)

• Remove the grout and install lowering jacks on shim type A as per sketch below

• Lower the span step by step ( from 300mm to 150mm higher than pier cap level)

• Remove lowering jacks • Install alignment system

• Remove temporary bearing, install permanent bearings • Align and adjust span to final position

4. METHODOLOGY FOR 20 M SPANS:

The configuration of 20 m spans is described on the sketch below:

The code mark for this category of span is 6A. This code refers to all U girder spans with length between 20 and 22 m. The sequence of stressing for this span is detailed on the table below:

4.1 PROCESS:

• Stage 1 corresponds to stressing sequences carried out while the span is still hanging on the launching girder and transferring span loads from hanging bar to jack. For the stage 1: Sequence of stressing PT and load transfer are as follow (for 20m span): Steps 1 ES1 + tPT Steps 2 ES1 + tPT + 2 (50%) Steps 3 ES1 + 20% + tPT + 2(50%) Steps 4 ES1 + 20% + tPT + 2 Steps 5 ES1 + 20% + tPT + 2 + 10 Steps 6 spanSW + stage1 • Stage 2 corresponds to stressing remaining tendons • Stage 3 corresponds to lowering the span.

######4.2 PREPARATORY WORKS:

• Grout and leveling. • Install under the span steel shims (square tubes filled with concrete). o Interleave type A shims (900x100x100mm) with type B shims (500x100x100mm) until height is 1.0m o Install type C shims (500x100x50mm) • Install lowering jacks (4x2 Jacks HFG506) • Notes: o Steel plates shall be installed at the top and bottom of lowering jacks. o Plywoods shall be installed between shim tubes & pier cap, shim tubes & U-girder. • During the erection of the span, all segments will be hang 1818 mm higher than station platform. • Perform gluing and temporary PT Operations at this level. Method: Stage 1&2: Stressing • Stressing all the tendons at 1818mm higher than station girder.

Stage 3: Lowering of the span

• The span is supported on the jacks • The span down step by step (2150mm to 150mm higher than erected spans)

• Install the temporary bearings (using shim type A)

• Remove the grout and install lowering jacks on shim type A as per sketch below

• Lower the span step by step ( from 300mm to 150mm higher than pier cap level)

• Remove lowering jacks • Install alignment system

• Remove temporary bearing, install permanent bearings • Align and adjust span to final position

Note: Span with 19.47 m and 15 m long will be erected in the same way of 20 m category. For the span 19.47 m, there is no 2 and 2’ tendons. Therefore, it is possible to erect according to methodology for 20m spans . The code mark for this span is 7A and the sequence of stressing is detailed below:

  Steps 1 ES1 + tPT Steps 2 ES1 + tPT + 3 (50%) Steps 3 ES1 + 20% + tPT + 3(50%) Steps 4 ES1 + 20% + tPT + 3 Steps 5 ES1 + 20% + tPT + 3 + 10 Steps 6 spanSW + stage1 For the span 15m, there is no 2 and 2’ tendons. Therefore, it is possible to erect according to methodology for 20m spans . The code mark for this span is 8A and the sequence of stressing is detailed below:

Steps 1 ES1 + tPT Steps 2 ES1 + tPT + 3(50%) Steps 3 ES1 + 30% + tPT + 3(50%) Steps 4 ES1 + 30% + tPT + 3 Steps 5 ES1 + 30% + tPT + 3 + 10 Steps 6 spanSW + stage1 5. METHODOLOGY FOR 23.33M SPANS :
The configuration of 23.33 m spans is described on the sketch below:

The code mark for this span (23.33 m) is 5A. This code refers to all U girder spans with length between 23 and 25 m. The sequence of stressing for this span is detailed on the table below:

5.1 PROCESS: • Stage 1 corresponds to stressing sequences carried out while the span is still hanging on the launching girder and transferring span loads from hanging bar to jack. For the stage 1: Sequence of stressing PT and load transfer are as follow (for 35m span): Steps 1 ES1 + tPT Steps 2 ES1 + tPT + 2(50%) Steps 3 ES1 + 15% + tPT + 2(50%) Steps 4 ES1 + 15% + tPT + 2 Steps 5 ES1 + 15% + tPT + 2 + 5 Steps 6 ES1 + 35% + tPT + 2 + 5 Steps 7 ES1 + 35% + tPT+2+5+10 Steps 8 spanSW + stage1 • Stage 2 corresponds to stressing remaining tendons • Stage 3 corresponds to lowering the span. 5.2 PREPARATORY WORKS: • Grout and leveling. • Install under the span steel shims (square tubes filled with concrete). o Interleave type A shims (900x100x100mm) with type B shims (500x100x100mm) until height is 1.0m o Install type C shims (500x100x50mm) • Install lowering jacks (4x3 Jacks HFG506). • Notes: o Steel plates shall be installed at the top and bottom of lowering jacks. o Plywoods shall be installed between shim tubes & pier cap, shim tubes & U-girder. • During the erection of the span, all segments will be hang 2300 mm higher than station platform. • Perform gluing and temporary PT Operations at this level. Method: Stage 1&2 : Stressing • Stressing all the tendons at 2300mm higher than station girders.

Stage 3: Lowering of the span

• The span is supported on the jacks • The span down step by step (2150mm to 150mm higher than erected spans)

• Install the temporary bearings (using shim type A)

• Remove the grout and install lowering jacks on shim type A as per sketch below

• Lower the span step by step ( from 300mm to 150mm higher than pier cap level)

• Remove lowering jacks • Install alignment system

• Remove temporary bearing, install permanent bearings • Align and adjust span to final position

6. RESOURCES TO BE USED
6.1 EQUIPMENT TO BE USED

Equipment to be deployed for the installation of closing spans. No. Description Specification Quantity 1 Mobile crane RT880 or equivalent 1 2 Cherry picker 1 3 Harness
4 Setting out instruments
5 Electric tools: Drill, Grinder
6 Chains / Slings / Shackle
7 Safety signs
8 Hammers
9 Jacks
10 Pumps
11 Steel shims
12 Sliding box
13 Sliding rails
14 Jack HFG 506 12 15 Shim tube filled with concrete (type A) 200 16 Shim tube filled with concrete (type B) 432 17 Shim tube filled with concrete (type C) 740 Note: Above stated quantity of equipment could be changed if necessary.  

6.2 MANPOWER TO BE DEPLOYED

Manpower to be deployed for realize the closing span as per detailed organization chart below:

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

7. 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 works of closing spans. 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.

7.1 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 works of closing spans and details the measures to be adopted to minimize or eliminate those risks identified. 7.2 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.  

8. ATTACHMENTS

ATTACHMENT # 1: HAZARD AND RISK ASSESSMENT (HRA)   ATTACHMENT # 2: LOWERING JACK   ATTACHMENT # 3: SKETCH FOR STRESSING   ATTACHMENT # 4: SKETCH FOR REMOVE GROUT   ATTACHMENT # 5: SKETCH OF ACCESS PLATFORM