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Rodney Turner
Structural Engineer
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Which are the Methods or Reference codes for the casting of Precast Piers for Metro Construction particularly?

Which are the methods or reference codes for the casting of precast piers for metro construction particularly?

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Wilma Caldwell
Architectural technologist

Two types of precast concrete pier systems were developed in this research. The first system is an emulation of current cast-in-place reinforced concrete pier designs, hereafter referred to as the cast-in-place (CIP) emulation pier system. The second system uses a combination of vertical, unbonded post-tensioning tendons and bonded mild steel reinforcing bars to reinforce the pier, hereafter referred to as the hybrid pier system. 

Descriptions of the two systems and their expected behavior during an earthquake are presented below.

 The columns and crossbeam in a CIP emulation pier are fabricated out of precast concrete and connected in the field to facilitate rapid construction. 

The proposed CIP emulation pier system is shown in Figure 1.2. The foundations and diaphragm of the pier are constructed out of cast-in-place concrete. The columns are reinforced with mild steel reinforcement. The cross beam can be pre-tensioned to reduce the congestion of the reinforcement and improve the capacity of the cross beam to withstand transportation and erection loads. The connections are facilitated by extending the reinforcing bars out of both ends of the columns. The bars extending from the bottom of the column are embedded into the top portion of the cast-in-place foundation. The reinforcing bars extending from the top of the column fit into openings in the cross beam, which are filled with grout to complete the connection. Hieber et al. (2005b) presented several potential details for the column-to-footing and column-to-cross beam connections. 

The connections of the precast columns to the foundation and the columns to the cross beam are designed to be stronger than the columns. Therefore, plastic hinges are expected to form at the ends of the columns during an earthquake, as shown in Confining the inelastic deformations to these regions will result in satisfactory performance, provided that the columns are appropriately confined so that they exhibit little strength degradation at large deformation demands. Because the columns are weakest, they will yield first, and the other components of the pier will remain elastic and relatively undamaged during an earthquake. This practice is commonly referred to as capacity design.

The hybrid precast pier system is reinforced with a combination of mild steel reinforcement and unbonded post-tensioning. A schematic of the proposed hybrid system is shown in As with CIP emulation piers, the columns and cross beam of the pier are precast concrete, while the foundations and diaphragm are cast-in-place concrete. The precast components are similar to those used in the CIP emulation system, except that a duct is installed in the center of the column for the post-tensioning tendons. A corresponding opening is fabricated in the cross beam. 

The post-tensioning contributes to the moment capacity of the columns, allowing the required number of mild steel reinforcing bars to be decreased. This decrease reduces congestion of the column-to-cap beam connection, making the components easier to fabricate and to erect. The anchors for the post-tensioning are located in the cast-in-place concrete of the foundations and diaphragm. 

For typical column lengths, furnishing the post-tensioning tendons without requiring splices should not be a problem. Hieber et al. (2005b) presented potential details for the column-to-footing and column-to-crossbeam connections. Corrosion of the post-tensioning tendons is a concern in the design of hybrid piers. A corrosion protection system is envisioned consisting of a combination of epoxy coated strand, plastic sheathing, and/or grease. Future work would be required to finalize the corrosion protection system and develop methods for inspecting the post-tensioning. 7 Figure 1.4: Hybrid Precast Concrete Pier System The hybrid piers are expected to perform differently than CIP emulation, and cast-in-place reinforced concrete piers during an earthquake. Only a portion of the mild steel reinforcement in the precast columns of a hybrid pier extends into the footing and crossbeam. 

This causes the interfaces between the column and footing and column and crossbeam to be the weakest portion of the pier. Consequently, the majority of deformation during an earthquake will be concentrated at these interfaces. The deformation is expected to be dominated by one large crack at the top and bottom of the columns, and the overall behavior of the pier is expected to be similar to rocking blocks, as little cracking is expected to occur in the precast components, and plastic hinges should not form.

The interface regions of the piers must be detailed to withstand large deformations. For example, the mild steel reinforcement is unbonded in the interface region to reduce the peak strains and prevent the bars from fracturing. 

The ends of the columns are also heavily confined to reduce damage to the columns caused by high local compressive stresses. The post-tensioning in the columns is designed to remain elastic during an earthquake. After an earthquake, the post-tensioning will provide a recentering force and reduce residual displacements. 

The mild steel is intended to yield and to dissipate energy, reducing the maximum deflection. The proportion of post-tensioning reinforcement to mild steel reinforcement can be adjusted to balance the maximum and residual displacements

Hi, In the construction of metros, the contract must be utilised the the the Indian Standard System of units and the court's values in the empirical units were not be used unless the engineer is given consent. while all the standard course and technical specifications are practised must be of the latest edition which included the applicable official amendments. The contractor makes a well of all the relevant Indian Standard course and Indian road Congress codes which are applied. Nowadays priority order is IRS, IRC IS, BS, DIN.

Peter Smith
Heating and ventilation engineer

Hi, Following are some Codes used in Pune metro constructions(INDIA).

  1. IRS
  2. IRC
  3. IS
  4. AASHTO

Indian Railway Standards(IRS)

IRS – Bridge Rules for loading (Min. of Railway)

IRS – Code of practice for Steel bridges.

IRS – Code of practice for plain, reinforcement and prestressed concrete for general Bridge construction, latest revision.

IRS – Code of practice for the design of substructures and foundation of bridges. Indian Roads Congress (IRC) Standards (with Latest Revisions, Addendum &Corrections) IRC 5: 1985 Standard Specifications and Code of Practice for Road Bridges, Section I – General Features ofDesign IRC 6: 2000 Standard Specifications and Code of Practice for Road Bridges, Section II – Loads and Stresses IRC 10: 1961 Recommended Practice for Borrow pits for Road Embankments Constructed by ManualOperation IRC 18: 1985 Design Criteria for Prestressed Concrete Road Bridges (PostTensioned Concrete) IRC 19: 1977 Standard Specifications and Code of Practice for Water BoundMacadam IRC 21: 1987 Standard Specifications and Code of Practice for Road Bridges Section III – Cement Concrete (Plain and reinforced) IRC 22: 1986 Standard Specifications and Code of Practice for Road Bridges, Section VI – Composite Construction for RoadBridges IRC 24: 1967 Standard Specifications and Code of practice for Road Bridges, Section V – Steel Road Bridges IRC 36: 1970 Recommended Practice for the Construction of Earth Embankments for Road Works IRC 37: 1984 Guidelines for the Design of FlexiblePavement IRC 45: 1972 Recommendations for Estimating the Resistance of Soil below the maximum Scour Level in the Design of Well Foundations ofBridges IRC 48: 1972 Tentative Specifications for Bituminous surface Dressing using Pre-coated Aggregates IRC 75: 1979 Guidelines for the Design of HighEmbankments IRC 78: 2000 Standard Specifications and Code of Practice for Road Bridges, Section VII (Parts 1 and 2), foundations and substructure Standard Specifications and code of practice for Road Bridges, SectionIX – Bearings Part I & II: Bearings (Metallic and elastomeric) IRC 87: 1984 Guidelines for the Design and Erection of False Work for RoadBridges IRC: SP 11 1958 Handbook of quality Control for Construction of Roads and runways. IS: Codes: National building code SP 7: 1983 Bureau of Indian Standards IS 73: 1992 Paving Bitumen IS 215: 1995 Road Tar IS 217: 1988 Cutback Bitumen IS 226: 1975 Structural steel (standard quality) IS 269: 1989 33 grade Ordinary Portland Cement IS 278: 1978 Galvanised steel barbed wire for fencing IS 280: 1978 Mild Steel wire for general engineering purposes IS 281: 1991 Mild Steel siding door bolts for use with padlocks IS 383: 1970 Coarse and fine aggregates IS 432: 1982 Mild steel and medium tensile steel bars and hard-drawn steel wire for concrete reinforcement (Part 1) Mild steel and medium tensile steel bars (Part 2) Hard-drawn steel wire IS 455: 1989 Portland slag cement IS 456: 2000 Code of practice for plain and reinforced concrete IS 457: 1957 Code of practice for general construction IS 515: 1959 Natural and manufactured aggregates for use in mass concrete IS 516: 1959 Method of test for the strength of concrete IS 650: 1991 Standard sand for testing cement IS 800: 1984 Code of practice for general construction in steel structures IS 814: 1991 Covered electrodes for manual metal arc welding of carbon and carbon manganese steel IS 815: 1974 Classification coding of covered electrodes for metal are welding of structural steel IS 823: 1964 Code of procedure for manual metal arc welding of mild steel IS 875: 1987 Code of practice for design loads (other than earthquake) for buildings and structures IS 1077: 1992 Common burnt, clay building bricks IS 1080: 1986 Design and construction of shallow foundation in soil (other than the raft ring and shell) IS 1161: 1979 Steel tubes for structural purposes IS 1239: 1990 Mild steel tubes, tubular and other wrought steel fittings (Part 1) Mild steel tubes (Part 2) Mild steel tubular and other wrought steel pipe fittings IS 1322: 1993 Bitumen felts for waterproofing and damp-proofing IS 1343: 1980 Code of practice for Prestressed concrete IS 1489: 1991 Portland Pozzolana Cement IS 1732: 1989 Dimensions for round and square steel bars for structural and general engineering purposes IS 1785: 1983 Plain hard-drawn steel wire for prestressed concrete (Part 1) Cold-drawn stress-relieved wire (Part 2) As drawn wire FOREIGN STANDARDS ASTM D-297 Methods for Rubber Product Chemical Analysis ASTM D-395 Compression set of vulcanized rubber ASTM D-412 Tension testing of vulcanized rubber ASTM D-429 Adhesion of vulcanized rubber-metal ASTM D-573 Accelerated ageing of vulcanized rubber by the oven method ASTM D-624 Tear resistance of vulcanized rubber ASTM D-797 Young’s Modulus in flexure of elastomer at normal and subnormal temperature ASTM D-1149 Accelerated Ozone cracking of vulcanized rubber ASTM D-1559 Test for resistance to plastic flow of bituminous mixtures using Marshall Apparatus ASTM D-2166 Test methods for Unconfined Compressive Strength of Cohesive Soils ASTM 0-2172 Extraction, quantitative, of bitumen from bituminous paving mixtures ASTM 0-2240 Indentation hardness of rubber and plastic using a Durometer ASTM 0-2434 Test methods for the permeability of Granular Soils ASTM 0-3080 Method for the direct shear test of soils under consolidated drained condition ASTM E-11 Specification for wire cloth sieve for testing purpose AASHTO OM 57-80 Materials for embankments and sub-grade AASHTO OM 147-67 Materials for aggregate and soil (1980) base and surface courses AASHTO OM 282-80 Joints sealants, not poured, elastomeric type, (ASTM: D 3406) for Portland cement cure rate of pavements