Last Updated (11/30/2007)

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DIVISION IV - STRUCTURES (Items 400 to 426)

Table of Contents

ITEM NO. - TITLE AND REQUIREMENTS

400 - EXCAVATION AND BACKFILL FOR STRUCTURES

SPECIFICATION REQUIREMENTS
1) Excavation for structures shall conform to the lines and grades shown on the plans or as directed by the Engineer.
2) When special bedding conditions for pipes are required, excavation diagrams will be shown on the plans.
3) When existing pavement and base are to be cut and restored, the type and thickness of the replaced materials will be as shown on the plans.
4) Bedding will be in accordance with Class C bedding unless otherwise shown on the plans.
5) When cement stabilized backfill is required, the excavation shall be backfilled with cement stabilized backfill to the elevations shown on the plans and measured in accordance with the excavation diagram shown on the plans.
6) The type of aggregate used for cement stabilized backfill will be as shown on the plans or as approved by the Engineer.
7) Structural Excavation may be set up as either a pay item, or as subsidiary.
8) If Structural Excavation is a pay item, quantities for structural excavation of culvert extensions greater than 15 feet and for all other types of structures not listed in Article 400.5. will be shown on the plans.
9) This is a plans quantity measurement Item.

OPTIONAL REQUIREMENTS
1) When flowable backfill is used, it will be measured and paid for as required under Item 401, “Flowable Backfill”.
2) When protection methods for excavation are greater than five (5) feet in depth, they shall be measured and paid for as required under Item 402, "Trench Excavation Protection" or Item 403, "Temporary Special Shoring".
3) When used, concrete seal shall be placed in accordance with Item 420.

REFERENCE ITEMS
(132), (401), (420), (421)

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401 - FLOWABLE BACKFILL

SPECIFICATION REQUIREMENTS
1) Specify the mix design type on plans.
2) Locations and/or areas using flowable backfill must be shown on plans.

REFERENCE ITEMS
(421)

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402 - TRENCH EXCAVATION PROTECTION

SPECIFICATION REQUIREMENTS
1) This Item governs for the excavation protection required for trenches in excess of 5 feet deep.
2) This Item should be utilized for placement of storm drain and other buried, linear structures.
3) Use Item 403 for walls, footings, and other more complex excavation protection.
4) Construction methods are as required by OSHA's Standards and Interpretations.

REFERENCE ITEMS
None

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403 - TEMPORARY SPECIAL SHORING

SPECIFICATION REQUIREMENTS
1) This Item governs for the protection of excavations in excess of 5 feet deep.
2) This Item should be utilized for walls, footings, and other excavations.
3) Use Item 402 for storm drain and other buried linear structures.
4) The plans will show a layout of the shoring, including top of shoring and the minimum protection grade line.
5) The contractor will submit details and design calculations to the Engineer prior to construction.

REFERENCE ITEMS
(423)

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404 - DRIVING PILING

SPECIFICATION REQUIREMENTS
1) Required bearing resistance for piling must be shown on the plans.
2) Embankment at bridge ends will be completed prior to driving of piling.
3) Test piling locations and details for sizes must be shown on the plans.

OPTIONAL REQUIREMENTS
1) When required by the plans, designated piling shall be driven and test-loaded in accordance with Item 405, “Foundation Test Load.”
2) Piling passing through the structural volume of retaining walls shall be subject to the provisions of Item 423, “Retaining Walls.”

PAYMENT AND MEASUREMENT
Subsidiary to the various bid items in the contract.

REFERENCE ITEMS
None

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405 - FOUNDATION TEST LOAD

SPECIFICATION REQUIREMENTS
1) Piling or drilled shafts to be test loaded will be specified on the plans.
2) The Department will furnish jacking equipment, beams, and displacement indicators unless otherwise specified.

OPTIONAL REQUIREMENTS
1) When piling is used, it shall be in accordance with Item 407 (Steel Piling) or 409 (Concrete Piling).
2) When drilled shafts are used, they shall be in accordance with Item 416.

REFERENCE ITEMS
Required
None
Optional
(404) When driving anchor and test piling is specified.
(416) When construction of anchor and test shafts is specified.

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406 - TIMBER PILING

SPECIFICATION REQUIREMENTS
1) Size, type, length, and details of the timber piling must be shown on the plans.
2) Splices shall be made in accordance with the details shown on the plans.

REFERENCE ITEMS
(404), (492)

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407 - STEEL PILING

SPECIFICATION REQUIREMENTS
1) Type and weight, locations, and lengths of steel piling must be shown on the plans.
2) Need paint note in the General Notes and Specification Data if any painting done is other than that called for in the standard specification.

OPTIONAL REQUIREMENTS
1) When test loading is required, it will be in accordance with Item 405.

REFERENCE ITEMS
Required
(404), (441), (448)
Optional
(446) When Protection System III or IV painting of piling is required.

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409 - PRESTRESSED CONCRETE PILING

SPECIFICATION REQUIREMENTS
1) Size, locations and lengths must be shown on the plans.
2) When test piling is required, locations must be shown on the plans.

REFERENCE ITEMS
(404), (420), (421), (424), (425), (426), (440), (780)

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416 - DRILLED SHAFT FOUNDATIONS

SPECIFICATION REQUIREMENTS
1) Details, sizes, and dimensions must be shown on the plans.
2) When a specific bearing is required, plans should indicate the expected depths and elevations where satisfactory bearing materials will be encountered.
3) Size and shape of bell footings must be shown on the plans, when required.
4) Unless otherwise shown on the plans, drilled shafts may be constructed by the “Slurry Displacement Method.”
5) The quantity of concrete for bell footings must be shown on the plans and is a plans quantity measurement Item.

OPTIONAL REQUIREMENTS
1) When test loading is required it will be in accordance with Item 405.

REFERENCE ITEMS
(420), (421), (440), (448)

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420 - CONCRETE STRUCTURES

SPECIFICATION REQUIREMENTS
1) Class of concrete for each type of structure or unit if not specified by pertinent governing specifications must be shown on plans.
2) Dimensions for expansion joint material or asphalt board material and joint types.
3) Class of silicone joint sealant
4) Strength requirements for staged application of post-tensioning
5) Location of required or permissible construction joints.
6) Indicate requirements for bonding agent (epoxy or grout) for placing concrete against existing concrete.
7) Requirements for re-vibration.
8) Quantities for mass concrete and members designated as mass concrete.
9) Indicate type of bridge deck overlay (asphalt or concrete)

OPTIONAL REQUIREMENTS
1) Mass concrete may be designated on the plans.
2) Any specific construction sequence requirements.
3) Placing sequence, if required, for slabs on continuous steel units.
4) Construction schedule restrictions different from those in the Item.
5) Rate of concrete placement if different from that in the specifications.
6) Concrete placing sequence.
7) Indicate bearing pedestal reinforcing if different from the specifications
8) Indicate type of membrane curing compound, if allowed.
9) Indicate if mass concrete is a plans quantity item or measured in place
10)  Indicate design strength requirements if different from the Specifications.
11) Waterstop requirements that differ from the specs.
12)  Indicate if TxDOT will perform testing for schedule restriction (Contractor-performed testing is the default).
13)  Indicate where welding of reinforcing supports is not allowed.
14)  Indicate depth of holes for dowels if different from this Item.
15)  Indicate if specific type of binding material (e.g., epoxy) is necessary.
16)  Indicate if in-water placement will be allowed.
17)  Indicate texture depth for finish if different from this Item, where a concrete overlay will be placed on the slab.
18)  Indicate if other structural elements not listed in Table 2 are to be a “Plans Quantity” Item.

REFERENCE ITEMS
Required
(400), (421), (427), (438), (440), (448)
Optional
(404) When temporary piling are required to support shoring or falsework.
(426) When constructing post-tensioned structures.
(441) When construction steel structures.

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421 - HYDRAULIC CEMENT CONCRETE  (with required SP 421---024)

SPECIFICATION REQUIREMENTS
1) The following will need to be shown on the plans or require a plan note:

• A coarse aggregate magnesium sulfate soundness loss other than a maximum of 18% (optional)
• If a value less than 1.0% will be used for the maximum decantation for coarse aggregate (optional)
• For all concrete subject to direct traffic if an acid insoluble value less than 60% will be used (optional)
• If blending of fine aggregates to meet the acid insoluble requirement will not be allowed (optional)
• If a sand equivalent of less than 80 will be used (optional)
• For Class K concrete if fineness modulus values outside the range of 2.60 and 2.80 will be allowed (optional)
• If mortar and grout will be used in the project (required)
• Strength requirements for concrete Classes F, H, K, and HES if used (required)
• Coarse aggregate grade for Class K and HES if used (required)
• If the responsibility of the contractor is waived regarding furnishing and maintaining: (optional)
  • test molds
  • curing facilities
  • maturity meters if used,
  • wheelbarrow or other container acceptable for the sampling of concrete
  • strength-testing equipment in accordance with the controlling test (ie., compression machine or flexural beam breakers)
• If the controlling strength test will not be compressive (optional)
• If the contractor will not be responsible for the handling and transportation of test specimens and the cleaning of molds, if needed (optional)
• When sulfate resistant concrete is required (required)
• TxDOT plant/truck inspection/certification in lieu of NRMCA/professional engineer certification for NON-STRUCTURAL CONCRETE ONLY (optional)
• To allow the use of volumetric mixers for structural concrete (optional)
• To designate the use of high performance concrete classes: C(HPC), F(HPC), H(HPC), and S(HPC) (required)
• Designate an alternate strength over-design requirement other than what is in the specification only for Class K, non-structural concrete and Class C concrete not used for bridge class structures (optional)
• Designate dosage rate of corrosion inhibiting admixture if used (required)
• To waive air entrainment requirements for all concrete classes or individual concrete classes (already waived for Class B and drilled shaft concrete) (optional – refer to Bridge and Pavement Design Manuals)
• To alter target air contents (currently set at 4.0% for pavements and 5.5% for structural concrete) (optional)

PAYMENT AND MEASUREMENT
Subsidiary to the various bid items in the contract.

REFERENCE ITEMS
None

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422 - REINFORCED CONCRETE SLAB

SPECIFICATION REQUIREMENTS
1) The design and details of the reinforced concrete slab will be as shown on plans.
2) Unless otherwise noted, the Contractor has the option of using conventional forms, permanent metal deck forms (PMDF) or prestressed precast concrete panels (PCP) for forms for constructing a cast-in-place slab.
3) Reinforcing steel to be epoxy coated will be shown on plans when required.
4) This is a plans quantity measurement item.

REFERENCE ITEMS
Required
(420), (421), (440)
Optional
(424) When prestressed precast concrete panels (PCP) are allowed.
(426) When prestressed units are used.
(430) When extending structures are shown.

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423 -  RETAINING WALLS

SPECIFICATION REQUIREMENTS
1) Type B backfill will be used for permanent MSE walls unless otherwise shown on the plans.
2) Temporary walls should be designated as such on both the wall layouts and in the bid codes.
3) If a leveling pad embedment of greater than 1 foot is required, it should be clearly required on the retaining wall layout, and the quantity of the wall should be based on the increased embedment.
4) The required surface finish for the walls should be called out in general notes, or on a specific plan sheet.
5) This is a plans quantity measurement Item.
6) Type of wall will be shown on the plans.
7) If MSE or Concrete Block walls are specified, the general notes should include a list of approved systems.
8) If a wall is subject to inundation, the wall layout should show the maximum water level or 100 year flood elevation.  This will set the limits of the Type D backfill.
9) When pipe underdrains are required, they should be shown clearly on the wall layouts, and will be in accordance with Item 556.

REFERENCE ITEMS
Required
(110), (132), (400), (420), (421), (440), (445) 
Optional
(424) When formed precast elements are required.
(458) When waterproofing is required.
(556) When pipe underdrains are required.

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424 - PRECAST CONCRETE STRUCTURES (FABRICATION)

SPECIFICATION REQUIREMENTS
1) If shop drawings for nonstressed members are desired, note accordingly on the plans.
2) Designate the class of concrete on the plans.
3) If air entrained concrete is necessary, note accordingly on the plans.
4) Note if any concrete performance tests other than compressive strength cylinders (if not already included in a special provision) are required.  i.e. concrete permeability.
5) Designate desired chamfers or radii on the plans.
6) Designate any unique surface finishes on the plans.
7) Note any finished product tolerances that are not listed in this Item.
8) Reference Item 424 for fabrication on wall panel plans if 424 is the preferred fabrication specification.
9) Note that an inspection laboratory and laboratory equipment are required unless otherwise directed by the Department.
10)  This is a plans quantity measurement Item. 

PAYMENT AND MEASUREMENT
Subsidiary to the various bid items in the contract.

REFERENCE ITEMS
(420), (421), (425), (426), (440), (504)

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425 - PRECAST PRESTRESSED CONCRETE STRUCTURAL MEMBERS

SPECIFICATION REQUIREMENTS
1) Dimensions for panel bedding strips will be shown on the plans
2) This is a plans quantity measurement Item

3) Include the following in General Notes when Texas Girders are used;

For bridges with Type Tx28, Tx34, Tx40, Tx46, Tx54, Tx62 and/or Tx70 prestressed concrete girders, the contractor can submit an alternate design for approval using other TxDOT prestressed concrete girder shapes . Alternate designs must be signed, sealed, and dated by a Licensed Professional Engineer and submitted to the Engineer for review and approval. 

For alternate designs, use the same live load as the original design and adhere to the current versions of the AASHTO LRFD Bridge Design Specifications and the TxDOT LRFD Bridge Design Manual. 

Alternate bridge designs can differ from the original design only by type of girder used. Do not raise the roadway grade or lower the structure bottom chord elevation to accommodate the alternate girders. No other change to the original design is allowed except as necessary to accommodate the alternate girders. Substructure re-design may be necessary to accommodate the alternate girders. No additional compensation will be made for these alternate designs or for any increase in quantities required to accommodate the alternate designs, including quantities paid for under other Items.

REFERENCE ITEMS
Required
(420), (421), (424), (426), (427), (434), (440)
Optional
(442) When structural steel is required.

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426 - PRESTRESSING

SPECIFICATION REQUIREMENTS
1) Class of concrete will be shown on the plans.
2) Total tension will be shown on the plans for pretensioning.
3) Post-tensioned tendons will be grouted or ungrouted, as required by plans.
4) Concrete strengths for stressing and staged loading of post-tensioned structural elements will be specified on the plans.
5) Elastomeric bridge bearings will be in accordance with Item 434, including measurement and payment.
6) This is a plans quantity measurement Item.  

OPTIONAL REQUIREMENTS
1) When precast units are allowed or required, they will be in accordance with Item 424.
2) When joint sealants and fillers are allowed or required, they will be in accordance with DMS-6310.
3) When structural steel is allowed or required, it will be in accordance with Item 442.
4) Special requirements for vertical grouting, when used, need to be included.
5) If testing is desired to more accurately estimate friction losses for prestressing steel in ducts, specify an “in-place friction test.”
6) For segmental construction, specify “duct connection pressure field test” for internal tendons after erection and before grouting.
7) If calculation adjustments for elongation are required from an apparent modulus derived by testing, specify a “bench test.”
8) When post-tensioning of precast units is not measured and paid for as specified in Item 425, note it on the plans.  

REFERENCE ITEMS
Required
(420), (421), (434), (440), (442)
Optional
(445) When galvanized steel pipe is required

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