751.32 Concrete Pile Cap Intermediate Bents: Difference between revisions
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In addition, Class B-1 Concrete (Substructure) may also be used in special cases (See Project Manager). | In addition, Class B-1 Concrete (Substructure) may also be used in special cases (See Project Manager). | ||
Modulus of elasticity, | Modulus of elasticity, |
Revision as of 13:36, 10 February 2012
751.32.1 General
751.32.1.1 Material Properties
Concrete | |||
---|---|---|---|
Typically, shall consist of: | |||
Class B Concrete (Substructure) | Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \, f'_c} | = 3.0 ksi | |
Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \, n} | = 10 |
In addition, Class B-1 Concrete (Substructure) may also be used in special cases (See Project Manager).
Modulus of elasticity,
Where:
- f'c in ksi
- wc = unit weight of nonreinforced concrete = 0.145 kcf
- K1 = correction factor for source of aggregate
- = 1.0 unless determined by physical testing
Modulus of Rupture: | For minimum reinforcement, | Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \, f_r = 0.37 \sqrt {f'_c}} |
For all other calculations, | Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \, f_r = 0.24 \sqrt {f'_c}} | |
Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \, \sqrt{f'_c}} is in units of ksi |
Reinforcing Steel
Minimum yield strength, | Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \, f_y} | = 60.0 ksi |
Steel modulus of elasticity, | Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \, E_s} | = 29000 ksi |
751.32.2 Design
751.32.2.1 Limit States and Factors
In general, each component shall satisfy the following equation:
Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \, Q = \sum \eta_i \gamma_i Q_i \le \phi R_n = R_r}
Where:
Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \, Q} | = Total factored force effect |
Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \, Q_i} | = Force effect |
Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \, \eta} | = Load modifier |
= Load factor | |
Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \, \phi} | = Resistance factor |
Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \, R_n} | = Nominal resistance |
Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \, R_r} | = 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, Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \, \phi} = 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). |
751.32.3.2.1 Sway Bracing
(Use when specified on Design Layout or when required by design.)
STEEL BEARING PILE | CAST-IN-PLACE PILE |
Guidance for use of sway bracing:
(1) | Omit sway bracing if less than 10'-0" (Cast-In-Place piles only). |
(2) | When angle slope of bracing becomes less than 15° to the horizontal, omit the diagonal angles and use the horizontal angles only (except on four pile bents, then use alternate shown above). |
(3) | Piles shall not be battered unless approved by the Structural Project Manager or Structural Liaison Engineer. |
Note: In case of a large number of piles, see the Structural Project Manager.
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 |