Difference between revisions of "751.32 Concrete Pile Cap Intermediate Bents"
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− | |width="500" align="left"|Use 2'-6" minimum or as determined by the superstructure requirements or the [[751.9 LFD Seismic#751.9.2.3 Minimum Support Length|minimum support length]] required for | + | |width="500" align="left"|Use 2'-6" minimum or as determined by the superstructure requirements or the [[751.9 LFD Seismic#751.9.2.3 Minimum Support Length|minimum support length]] required for seismic criteria (expansion joint bents only) (3" increments). |
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− | |width="500" align="left"|Use 2'-6" minimum or as determined by the superstructure requirements or the minimum support length required for | + | |width="500" align="left"|Use 2'-6" minimum or as determined by the superstructure requirements or the [[751.9 LFD Seismic#751.9.2.3 Minimum Support Length|minimum support length]] required for seismic criteria (expansion joint bents only) (3" increments). |
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|width="500" align="left"|Minimum of 3 piles at 10'-0" cts., maximum spacing (1" increments). | |width="500" align="left"|Minimum of 3 piles at 10'-0" cts., maximum spacing (1" increments). | ||
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== 751.32.4 Reinforcement == | == 751.32.4 Reinforcement == |
Revision as of 14:23, 3 November 2011
751.32.1 General
751.32.1.1 Material Properties
Concrete | |||
---|---|---|---|
Typically, shall consist of: | |||
Class B Concrete (Substructure) | = 3.0 ksi | ||
= 10 |
In addition, Class B-1 Concrete (Substructure) may also be used in special cases (See Project Manager). The following equations shall apply to both concrete classes:
Concrete modulus of elasticity:
Where:
= unit weight of non-reinforced concrete = 0.145 kcf | |
= correction factor for source of aggregate = 1.0 |
Modulus of Rupture: | For minimum reinforcement, | |
For all other calculations, | ||
is in units of ksi |
Reinforcing Steel
Minimum yield strength, | = 60.0 ksi | |
Steel modulus of elasticity, | = 29000 ksi |
751.32.2 Design
751.32.2.1 Limit States and Factors
In general, each component shall satisfy the following equation:
Where:
= Total factored force effect | |
= Force effect | |
= Load modifier | |
= Load factor | |
= Resistance factor | |
= Nominal resistance | |
= Factored resistance |
Limit States
The following limit states shall be considered for bent design:
- STRENGTH – I
- STRENGTH – III
- STRENGTH – IV
- STRENGTH – V
- SERVICE – I
- FATIGUE
See LRFD Table 3.4.1-1 and LRFD 3.4.2 for Loads and Load Factors applied at each given limit state.
Resistance factors
- STRENGTH limit states, see LRFD 5.5.4.2
- For all other limit states, = 1.00
751.32.3 Details
751.32.3.1 Front Sheet
Note: | The following are details and dimensions for the plan view of a typical pile cap bent on the front sheet of the bridge plans. Details and dimensions for an encased concrete pile cap bent are similar. |
Details for unsymmetrical roadways shall require dimensions tying Centerline Lane to Centerline Structure. |
751.32.3.2 Typical Pile Cap Bent
(*) 3" (Typ.) | |
Part Elevation | Part Section |
---|
Use 2'-6" minimum or as determined by the superstructure requirements or the minimum support length required for seismic criteria (expansion joint bents only) (3" increments). | |
= 2'-9" (Min.) for Wide Flange and Double-Tee Girders or, 3'-0" (Min.) for Prestressed Girders and Plate Girders. | |
Check the clearance of the anchor bolt well to the top of pile. Increase the beam depth if needed. | |
If the depth at the end of the beam, due to the steps, exceeds 4'-6", the beam bottom should be stepped or sloped. | |
Use 3/4" drip groove where expansion device is located at bent. Continue to use 1-1/2" clear to reinforcing steel in bottom of beam. 3/4" drip groove shall be formed continuously around all piling at 3" from edge of beam. | |
Minimum of 3 piles at 10'-0" cts., maximum spacing (1" increments). |
751.32.3.3 Encased Pile Cap Bent
Consideration shall be given to EPG 751.1.2.19 Substructure Type before using this type of structure.
Part Elevation |
---|
Part Section |
Use 2'-6" minimum or as determined by the superstructure requirements or the minimum support length required for seismic criteria (expansion joint bents only) (3" increments). | |
= 2'-9" (Min.) for Wide Flange and Double-Tee Girders or, 3'-0" (Min.) for Prestressed Girders and Plate Girders. | |
Check the clearance of the anchor bolt well to the top of pile. Increase the beam depth if needed. | |
If the depth at the end of the beam, due to the steps, exceeds 4'-6", the beam bottom should be stepped or sloped. | |
Height by design. Embed encasement 2 ft. (min.) below the top of the lowest finished groundline elevation, unless a greater embedment is required for bridge design. | |
Minimum of 3 piles at 10'-0" cts., maximum spacing (1" increments). |
751.32.4 Reinforcement
751.32.4.1 Typical Pile Cap Bent
Part Elevation | Section Thru Beam |
---|---|
Part Plan |
* #4 Bars () not required for Double-Tee structures | |
Reinforcement Under Bearings | |
---|---|
Transverse Beam Steps - Over 3" or Steps Accumulating Over 3" |
Part Plan | |
---|---|
Over 3" thru 12" | Over 12" |
Longitudinal Beam Steps |
751.32.4.2 Encased Pile Cap Bent
Supplemental details for encased pile cap bents are provided.
Part Elevation |
Part Section |
Part Plan |