Method Statement for Precast Segment Production Short Line Pier Mould

Construction, Method Statement
1. INTRODUCTION
1.1 PURPOSE OF THE DOCUMENT

The purpose of this procedure is to define the sequence of operations to be carried out for the mould preparation & operation works of the Short Line Pier mould, including general arrangements, construction methodologies, technical solutions and other works, and ensures that all works will be conducted safely in accordance with the drawings and the project specifications.

1.2 PROJECT DESCRIPTION

Ho Chi Minh City Urban Railway Construction Project – Ben Thanh – Suoi Tien section (Line 1), contract Package 2 consists of approximately 12 km long of elevated viaduct structures, erected by span-by-span Method.

Figure 1: General layout - Precasting yard 

1.3 SCOPE OF WORK

The purpose of this document is to clarify, step by step, the procedure for the mould preparations & operations, described in the casting sequence for Short Line Pier segments.

1.4 REFERENCES

All reference documents are intended to refer to the last issued revision. • Specifications - Clause 12.4.1 “Precast segment casting” Section 12-3 of 19 from Outline construction specification – Package 2: Civil (Elevated & Depot) - “Standard specifications for concrete structures – 2007, Materials and construction” from Japan Society of Civil Engineers, regarding the stripping strength required to reach. • Method Statement - HCMC-261-CSYD-CWS-MST-00012 “General precasting works at precasting yard” - HCMC-261-CSYD-CWS-MST-00016 “Geometry control for short line casting method” - HCMC-261-CSYD-CWS-MST-00018 “Casting sequence for Short Line Pier segments” - HCMC-261-CSYD-CWS-MST-00020 “Segment concreting works” - HCMC-261-CSYD-CWS-MST-00021 “Segment curing” - HCMC-261-CSYD-CWS-MST-00022 “Segment marking” - HCMC-261-CSYD-CWS-MST-00023 “Segment lifting & handling works”

1.5 DEFINITIONS

All relevant definitions have been given in Section 1.5 “Definitions” of the Method Statement “General precasting works at precasting yard” HCMC-261-CSYD-CWS-MST-00012 • Lifting frame for segment Also called “Spreader beam”, the lifting frame that is required for the lifting and transporting of the complete segment from the mould either to the finishing area or storage area. The lifting frame shall be designed so that there is no permanent distortion of the segment either during lifting, transport or placing on trailer prior to deliver on site.   • Lifting frame for rebar cage Lifting frame that is required for the lifting and transporting of the fabricated rebar cage from the rebar jig area to the mould. The lifting frame shall be designed so that there is no permanent distortion of the rebar cage either during lifting, transport or placing. • Mould release agent Chemical product which provide quick, clean and easy stripping of moulds and formwork, and ensure high quality stain-free concrete. • Debonding agent Product which is applied on the match-cast segment face prior to cast the new segment.

2. SAFETY & ENVIRONMENTAL RISKS
2.1 HAZARD ANALYSIS & RISK ASSESSMENT

Hazards Analysis and Risks assessment are carried out and attached in each method statement. This document will identify all the hazards to ensure adequate control measures and strategies are in place to mitigate as much as possible the risks (Appendix A). All personnel carrying out the work will be properly trained by experienced supervision. Besides, all personnel shall wear the appropriate PPE (Personal Protective Equipment), such as Safety shoes, safety helmet and safety harness if required.

2.2 TOOLS AND EQUIPMENT

All tools & equipment shall be in safe condition before utilisation and fit for its purpose.

2.3 EMERGENCY RESPONSE

In the event of an accident/incident, response will carried out in the appropriate procedure, such as: • Remedial Actions, proposing actions to ensure that the Accident/Incident will be fully fixed, as required, managed by the Responsible within a target date. • Preventive Actions, proposing actions to ensure that the Accident/Incident will never happen again, including for example: Toolbox Meeting (TBM) held by the Safety Officer to ensure that Site Team (Workers, Supervisors & Engineers) fully understand methods & risks. Prestart and Toolbox talk will reinforce safety requirements prior to commencement of the work.  

3. CONSTRUCTION RESOURCES

In principle every type of work involves the following resources:

3.1 PERSONNEL

The personnel involved are such as: • Precasting yard Manager • Segment casting Superintendent • Site engineers • Quality engineers • Safety officers • Supervisors • Plant Operators (Tower cranes & Gantry Cranes) • Riggers • Workers

3.2 PLANT AND TOOLS

The following equipment shall be used for all precasting works: • Short Line Pier (SLP) mould • Gantry cranes 50 & 10T • Tower crane TC#1 (6.89ton – 50m) • Spreader beam • Others lifting frames (rebar cage, soffit table) • Electrical tools • Chains / slings / shackles • Chain blocks • Generator set • Air compressor & compressed air network Note that this list only provides a preliminary overview of resources which can be possibly used and does not necessarily prevent personnel to use other equipment plants and tools.

3.3 MATERIALS

• Concrete (Provided by Sumitomo Corporation) • Rebar cage (equipped with corrugated PT duct and spacer blocks) • Mould release agent • Debonding agent

4. CONSTRUCTION SEQUENCE
4.1 DESCRIPTION

Listing of mould for the production of pier segments: • Short Line Pier #1 (SLP #1) • Short Line Pier #2 (SLP #2)
• Short Line Pier #3 (SLP #3) • Short Line Pier #4 (SLP #4)

4.2 COMPONENTS

Each Short Line Pier mould has the following components:

Figure 2: Short Line Pier mould - Transversal section

  1. Soffit table (typical segment) 1 Nos
  2. Soffit table (pier segment) 2 Nos
  3. Manipulator with 4 hydraulic vertical & horizontal jacks 1 Nos
  4. External side forms (left & right) 1 Set
  5. Inner forms (left & right) 1 Set
  6. Portal frame for inner forms (including the roof) 1 Set
  7. Fixed bulkhead (with supports, Stairs & platforms) 1 Nos
  8. Hydraulic system (for inner forms) 1 Set  

Figure 3: Short Line Pier mould – Longitudinal section

Figure 4: Short Line Pier mould - Plan view 

4.3 SEGMENT PRODUCTION – DAILY CYCLE

The following sub-sections outline the process which typically accomplishes the pier segment production cycle in hourly basis, with the Short Line Pier mould. • Survey of as-built geometry. • Confirmation of as-built data within tolerance • Confirmation of demoulding strength • Remove inflatable tubes (also called “satujo”) • Remove anchorage bolts • Strip inner forms & shift portal frame on rail behind the fixed bulkhead • Marking of segment (ID number, Span No, date of casting & arrow). Refer to the method statement “Segment marking” HCMC-261-CSYD-CWS-MST-00022 • Lower / strip & shift external side forms • Break bond between cast segment ES1 (or ES1’) and Match Cast (M/C) typical segment S1 (or S1’) • Move M/C typical segment S1 (or S1’) to lifting position • Lift M/C typical segment S1 (or S1’) to finishing area • Break bond between cast segment ES1 (or ES1’) and fixed bulkhead • Move cast segment ES1 (or ES1’) to lifting position but do not lift. • Lift soffit table for pier segment ES1 (or ES1’) to be cast (placing 300mm away from fixed bulkhead) • Clean external side forms & apply the mould release agent (mould oil) • Clean inner forms & apply the mould release agent (mould oil) • Adjust bearing downstand at ES1 (or ES1’) soffit table including restrainer recess • Bolt anchorages to fixed bulkhead • Place the pre-checked rebar cage on soffit table for pier segment ES1 (or ES1’) • Shift soffit table for pier segment ES1 (or ES1’) with rebar cage to cast position • Lift soffit table for typical segment S1 (or S1’) to 300mm away from match-cast position • Lift typical segment S1 (or S1’) to soffit table for match-cast • Apply debonding agent to match-cast segment face • Shift typical segment S1 (or S1’) to match-cast position • Position & pre-close the external side forms • Connect PT duct to anchorages, bursting reinforcement, align PT duct with supports including inserts at bottom slab and webs • Inspection with SCC/GS prior to inner forms closure • Shift on rail the portal frame to casting position & close inner forms • Install inserts at top flange of segment (inserts for handrails, others..) • Final closure of mould • Final survey Refer to the method statement “Geometry control for short line casting method” HCMC-261-CSYD-CWS-MST-00016 • Inflate “Satujo” • Final inspection before casting / Cleaning of workstation • Cast pier segment & concrete finishing (floating) Refer to the method statement “Segment concreting works” HCMC-261-CSYD-CWS-MST-00020 • Cure pier segment Refer to the method statement “Curing of segments” HCMC-261-CSYD-CWS-MST-00021 • Transfer cured segment to finishing area, after lifting strength concrete required reached Refer to the method statement “Segment liftings & handling works” HCMC-261-CSYD-CWS-MST-00023 • Segment finishing works Refer to the method statement “Segment finishing works” HCMC-261-CSYD-CWS-MST-00024 • Remedial works for segment (if needed) Refer to the method statement “Segment remedial works” HCMC-261-CSYD-CWS-MST-00025 • Storage of segment Refer to the method statement “Segment storage and stacking” HCMC-261-CSYD-CWS-MST-00026 • Load segment on trailers for site delivery Refer to the method statement “Segment delivery and transportation” HCMC-261-CSYD-CWS-MST-00027

4.4 MOULD OPERATIONS FOR SHORT LINE PIER SEGMENT

 

5. ACTIVITY HOLD POINTS

All Activity hold points will be identified in the Inspection & Test Plan (ITP).

6. INSPECTION & RECORDS

All Inspection / Check-lists & documents records will be identified in the Inspection & Test Plan (ITP).

7. ATTACHMENTS
7.1 HAZARD ANALYSIS & RISK ASSESSMENT