Difference between revisions of "751.32 Concrete Pile Cap Intermediate Bents"

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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:
+
In addition, Class B-1 Concrete (Substructure) may also be used in special cases (See Project Manager).  
  
Concrete modulus of elasticity:
+
Modulus of elasticity,
 +
::::::<math>E_c = 33,000\ K_1 \ (w_c^{1.5}) \sqrt{f^'_c}</math>
  
<math>\, E_c = 33000 K_l w_c \sqrt [1.5]{f'_c}</math>
+
Where:
 +
 
 +
:f'<sub>c</sub> in ksi
 +
:w<sub>c</sub> = unit weight of nonreinforced concrete = 0.145 kcf
 +
:K<sub>1</sub> = correction factor for source of aggregate
 +
::= 1.0 unless determined by physical testing
  
Where:
 
{|
 
|<math>\, w_c</math>||= unit weight of non-reinforced concrete = 0.145 kcf
 
|-
 
|<math>\, K_l</math>||= correction factor for source of aggregate = 1.0
 
|}
 
  
 +
Modulus of rupture,
 +
::::::<math> f_r \ = \ 0.24 \sqrt{f'_{c}}</math> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp; LRFD 5.4.2.6
  
{|
+
Where:
|Modulus of Rupture:||For minimum reinforcement,||<math>\, f_r = 0.37 \sqrt {f'_c}</math>
+
:f'<sub>c</sub> is in ksi
|-
 
| &nbsp;||For all other calculations,||<math>\, f_r = 0.24 \sqrt {f'_c}</math>
 
|-
 
|<math>\, \sqrt{f'_c}</math> &nbsp;is in units of ksi|| &nbsp;|| &nbsp;
 
|}
 
  
  
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{|border="0" cellpadding="5" align="center" style="text-align:center" cellspacing="0"
 
{|border="0" cellpadding="5" align="center" style="text-align:center" cellspacing="0"
 
|-
 
|-
|[[Image:751.32 details-part elevation.gif]]||[[Image:751.32 details-part section.gif]]
+
|colspan="2"|[[Image:751.32.3.2 2017.jpg|center|650px]]
 
|-
 
|-
|colspan="2" | (*) 3" (Typ.)
+
!WIDTH="580"|Part Elevation||Part Section
 
|-
 
|-
!Part Elevation||Part Section
+
!colspan="2"|Applicable for both HP piles (shown) and CIP piles
 
|}
 
|}
 +
 
{|border="0" cellpadding="5" align="center" style="text-align:center" cellspacing="0"
 
{|border="0" cellpadding="5" align="center" style="text-align:center" cellspacing="0"
 
|-
 
|-
 
|valign="top"|[[Image:751.32 circled 1.gif]]
 
|valign="top"|[[Image:751.32 circled 1.gif]]
|width="500" align="left"|Use 2'-6" minimum or as determined by the superstructure requirements or the minimum support length required for earthquake criteria (expansion joint bents only) (3" increments).
+
|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) or the minimum beam width required to meet pile edge distance requirement.  
 
|-
 
|-
 
|valign="top"|[[Image:751.32 circled 2.gif]]
 
|valign="top"|[[Image:751.32 circled 2.gif]]
|width="500" align="left"|= 2'-9" (Min.) for Wide Flange and Double-Tee Girders or,<br/> &nbsp;&nbsp;&nbsp;3'-0" (Min.) for Prestressed Girders and Plate Girders.
+
|width="500" align="left"|= 3’-0” (Min.) for Wide Flange, Double-Tee Girders, <br/> &nbsp;&nbsp;&nbsp;Prestressed Girders and Plate Girders.
 
|-
 
|-
 
|valign="top"|[[Image:751.32 circled 3.gif]]
 
|valign="top"|[[Image:751.32 circled 3.gif]]
Line 137: Line 135:
 
|valign="top"|[[Image:751.32 circled 6.gif]]
 
|valign="top"|[[Image:751.32 circled 6.gif]]
 
|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).
 +
|-
 +
|valign="top"|[[Image:751.32 circled 7.gif|24px]]
 +
|width="500" align="left"|Piles shall not be battered.
 
|}
 
|}
 +
 +
====751.32.3.2.1 Sway Bracing====
 +
 +
(Use when specified on Design Layout or when required by design.)
 +
 +
[[Image:751.32.3.2.1 steel bearing.jpg|center|675px]]
 +
 +
 +
 +
[[Image:751.32.3.2.1 alternate.jpg|center|675px]]
 +
 +
 +
Guidance for use of sway bracing for steel bearing pile:
 +
 +
(1) 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).
 +
 +
Note: In case of a large number of piles, see the Structural Project Manager.
  
 
=== 751.32.3.3 Encased Pile Cap Bent===
 
=== 751.32.3.3 Encased Pile Cap Bent===
  
Consideration shall be given to [http://epg.modot.org/index.php?title=751.1_Preliminary_Design#751.1.2.19_Substructure_Type EPG 751.1.2.19 Substructure Type] before using this type of structure.
+
Consideration shall be given to [http://epg.modot.org/index.php?title=751.1_Preliminary_Design#751.1.2.20_Substructure_Type EPG 751.1.2.20 Substructure Type] before using this type of structure.
  
 
{|border="0" cellpadding="5" align="center" style="text-align:center" cellspacing="0"
 
{|border="0" cellpadding="5" align="center" style="text-align:center" cellspacing="0"
 
|-
 
|-
|[[Image:751.32.3.3.1.jpg|center|750px]]
+
|[[Image:751.32.3.3 part elev 2017.jpg|center|700px]]
|-
 
!'''Part Elevation'''
 
 
|-
 
|-
|[[Image:751.32.3.3.2.jpg|center|300px]]
+
|[[Image:751.32.3.3 part section.jpg|center|300px]]
 
|-
 
|-
 
!'''Part Section'''
 
!'''Part Section'''
Line 156: Line 172:
 
|-
 
|-
 
|valign="top"|[[Image:751.32 circled 1.gif]]
 
|valign="top"|[[Image:751.32 circled 1.gif]]
|width="500" align="left"|Use 2'-6" minimum or as determined by the superstructure requirements or the minimum support length required for earthquake criteria (expansion joint bents only) (3" increments).
+
|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) or the minimum beam width required to meet pile edge distance requirement.  
 
|-
 
|-
 
|valign="top"|[[Image:751.32 circled 2.gif]]
 
|valign="top"|[[Image:751.32 circled 2.gif]]
|width="500" align="left"|= 2'-9" (Min.) for Wide Flange and Double-Tee Girders or,<br/> &nbsp;&nbsp;&nbsp;3'-0" (Min.) for Prestressed Girders and Plate Girders.
+
|width="500" align="left"|= 3’-0” (Min.) for Wide Flange, Double-Tee Girders,<br/> &nbsp;&nbsp;&nbsp;Prestressed Girders and Plate Girders.
 
|-
 
|-
 
|valign="top"|[[Image:751.32 circled 3.gif]]
 
|valign="top"|[[Image:751.32 circled 3.gif]]
Line 173: Line 189:
 
|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).
 
|}
 
|}
 
  
 
== 751.32.4 Reinforcement ==
 
== 751.32.4 Reinforcement ==
Line 179: Line 194:
 
=== 751.32.4.1 Typical Pile Cap Bent ===
 
=== 751.32.4.1 Typical Pile Cap Bent ===
  
{|border="0" cellpadding="5" align="center" style="text-align:center" cellspacing="0"
+
[[image:751.32.4.1 2020.jpg|center|600px]]
|-
 
|[[Image:751.32 reinforcement-part elevation.gif]]
 
|[[Image:751.32 reinforcement-section thru beam.gif]]
 
|-
 
!Part Elevation||Section Thru Beam
 
|-
 
|colspan="2"|&nbsp;
 
|-
 
|[[Image:751.32 reinforcement-part plan.gif]]
 
|&nbsp;
 
|-
 
!Part Plan||&nbsp;
 
|}
 
  
 
{|border="0" cellpadding="3" align="center" cellspacing="0"
 
{|border="0" cellpadding="3" align="center" cellspacing="0"
 
|-
 
|-
|valign="top"|Note:||width="500pt" align="left" valign="top"|Locate #4 bars "[[Image:751.32 reinforcement--4 bar under bearing.gif]]" under bearings where required to maintain a 6" maximum spacing of combined stirrups. (#4 bars "[[Image:751.32 reinforcement--4 bar under bearing.gif]]" are not required for Double-Tee Structures.)
+
|valign="top"|Note:||width="550pt" align="left" valign="top"|Locate #4 bars "[[Image:751.32 reinforcement--4 bar under bearing.gif]]" under bearings where required to maintain a 6" maximum spacing of combined stirrups. (#4 bars "[[Image:751.32 reinforcement--4 bar under bearing.gif]]" are not required for Double-Tee Structures.)
 
|-
 
|-
|&nbsp;||width="500pt"|When an expansion device is used at an intermediate bent, all reinforcement located entirely within the beam or extending into the beam shall be epoxy coated.
+
|&nbsp;||width="550pt"|For epoxy coated reinforcement requirements, see [[751.5 Structural Detailing Guidelines#751.5.9.2.2 Epoxy Coated Reinforcement Requirements|EPG 751.5.9.2.2 Epoxy Coated Reinforcement Requirements]]. Details of [[751.13 Expansion Devices#751.13.1.4 Details of Substructure Protection|protective coating and sloping top of beam to drain]] shall be used when below an expansion device.
|}
 
 
 
 
 
{|border="0" cellpadding="5" align="center" style="text-align:center" cellspacing="0"
 
 
|-
 
|-
|rowspan="2"|[[Image:751.32 reinforcement under bearings-part elevation.gif]]
+
|&nbsp;||width="550pt"|When dimension “B” is required to be greater than 15” to clear piles by 1 ½”, typical when HP14 and CIP14 or larger diameter piles are used, add intermediate longitudinal bar(s) between piles. The spacing between intermediate bar(s) and full length bars shall not be greater than required by crack control provisions. Ends of intermediate bar(s) shall be hooked.
|[[Image:751.32 reinforcement under bearings-part plan.gif]]
 
|-
 
|width="200pt" align="left"|* #4 Bars ([[Image:751.32 reinforcement--4 bar under bearing.gif]]) not required for Double-Tee structures
 
|-
 
!colspan="2"|Reinforcement Under Bearings
 
|-
 
|colspan="2"| &nbsp;
 
|-
 
|colspan="2"|[[Image:751.32 transverse beam steps.gif]]
 
|-
 
!colspan="2"|'''Transverse Beam Steps - Over 3"'''<br/>'''or Steps Accumulating Over 3"'''
 
 
|}
 
|}
  
  
 +
[[image:751.32.4.1.3.jpg|center|700px]]
 +
[[image:751.32.4.1 longitudinal.jpg|center|500px]]
 +
::::(1) 6” (Max.), add #6 bars as needed.
 +
::::(2) 9” (Max.), add #6 bars at each face as needed.
 +
::::(3) Location 2 development length, f'c = 3 ksi:
 +
:::::::::::21" (uncoated)
 +
:::::::::::32" (epoxy coated)
  
{|border="0" cellpadding="5" align="center" style="text-align:center" cellspacing="0"
+
See [[751.5 Structural Detailing Guidelines#751.5.9.2.8 Development and Lap Splices|EPG 751.5.9.2.8]] for development and lap splice lengths not given or lengths for scenarios other than those shown. Provide standard hooks if required.
|-
 
|colspan="2"|[[Image:751.32 reinforcement at end of beam-part plan.gif]]
 
|-
 
!colspan="2"|Part Plan
 
|-
 
|colspan="2"| &nbsp;
 
|-
 
|colspan="2"|[[Image:751.32 reinforcement-longitudinal beam steps.gif]]
 
|-
 
!Over 3" thru 12"||Over 12"
 
|-
 
!colspan="2"|Longitudinal Beam Steps
 
|}
 
  
 
=== 751.32.4.2 Encased Pile Cap Bent===
 
=== 751.32.4.2 Encased Pile Cap Bent===
Line 239: Line 220:
 
Supplemental details for encased pile cap bents are provided.
 
Supplemental details for encased pile cap bents are provided.
  
{|border="0" cellpadding="5" align="center" style="text-align:center" cellspacing="0"
+
[[image:751.32.4.2 part elev 2020.jpg|center|700px]]
|-
+
 
|[[image:751.32.4.2 part elev.jpg|center|750px]]
 
|-
 
|align="center"|'''Part Elevation'''
 
|}
 
  
{|border="0" cellpadding="5" align="center" style="text-align:center" cellspacing="0"
+
[[image:751.32.4.2 part section 2020.jpg|center|500px]]
|-
+
{|border="0" cellpadding="3" align="center" cellspacing="0"
|[[image:751.32.4.2 part section.jpg|center|450px]]
 
 
|-
 
|-
|align="center"|'''Part Section'''
+
|valign="top"|Note:||width="500pt" align="left" valign="top"|When dimension “A” is greater than 18” add intermediate longitudal bar(s) between piles. Ends of bar(s) shall be hooked. Keep 3” minimum clearance between the pile and intermediate bar(s) and do not show on the plans.
 
|}
 
|}
  
 
{|border="0" cellpadding="5" align="center" style="text-align:center" cellspacing="0"
 
{|border="0" cellpadding="5" align="center" style="text-align:center" cellspacing="0"
 
|-
 
|-
|[[image:751.32.4.2 part plan.jpg|center|650px]]
+
|[[image:751.32.4.2 part plan Dec 2011.jpg|center|650px]]
 
|-
 
|-
 
|align="center"|'''Part Plan'''
 
|align="center"|'''Part Plan'''
Line 264: Line 240:
 
|valign="top"|Note:||width="500pt" align="left" valign="top"|Locate #4 bars "[[Image:751.32 reinforcement--4 bar under bearing.gif]]" under bearings where required to maintain a 6" maximum spacing of combined stirrups. (#4 bars "[[Image:751.32 reinforcement--4 bar under bearing.gif]]" are not required for Double-Tee Structures.)
 
|valign="top"|Note:||width="500pt" align="left" valign="top"|Locate #4 bars "[[Image:751.32 reinforcement--4 bar under bearing.gif]]" under bearings where required to maintain a 6" maximum spacing of combined stirrups. (#4 bars "[[Image:751.32 reinforcement--4 bar under bearing.gif]]" are not required for Double-Tee Structures.)
 
|-
 
|-
|&nbsp;||width="500pt"|When an expansion device is used at an intermediate bent, all reinforcement located entirely within the beam or extending into the beam shall be epoxy coated.
+
|&nbsp;||width="500pt"|For epoxy coated reinforcement requirements, see [[751.5 Structural Detailing Guidelines#751.5.9.2.2 Epoxy Coated Reinforcement Requirements|EPG 751.5.9.2.2 Epoxy Coated Reinforcement Requirements]]. Details of [[751.13 Expansion Devices#751.13.1.4 Details of Substructure Protection|protective coating and sloping top of beam to drain]] shall be used when below an expansion device.
 
|}
 
|}
  
  
 
[[Category:751 LRFD Bridge Design Guidelines]]
 
[[Category:751 LRFD Bridge Design Guidelines]]

Revision as of 09:33, 17 April 2020

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).

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,

      LRFD 5.4.2.6

Where:

f'c is in 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


Load Modifiers

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 details-front sheet plan of int bent.gif

751.32.3.2 Typical Pile Cap Bent

751.32.3.2 2017.jpg
Part Elevation Part Section
Applicable for both HP piles (shown) and CIP piles
751.32 circled 1.gif 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) or the minimum beam width required to meet pile edge distance requirement.
751.32 circled 2.gif = 3’-0” (Min.) for Wide Flange, Double-Tee Girders,
   Prestressed Girders and Plate Girders.
751.32 circled 3.gif Check the clearance of the anchor bolt well to the top of pile. Increase the beam depth if needed.
751.32 circled 4.gif If the depth at the end of the beam, due to the steps, exceeds 4'-6", the beam bottom should be stepped or sloped.
751.32 circled 5.gif 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.
751.32 circled 6.gif Minimum of 3 piles at 10'-0" cts., maximum spacing (1" increments).
751.32 circled 7.gif Piles shall not be battered.

751.32.3.2.1 Sway Bracing

(Use when specified on Design Layout or when required by design.)

751.32.3.2.1 steel bearing.jpg


751.32.3.2.1 alternate.jpg


Guidance for use of sway bracing for steel bearing pile:

(1) 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).

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 751.1.2.20 Substructure Type before using this type of structure.

751.32.3.3 part elev 2017.jpg
751.32.3.3 part section.jpg
Part Section
751.32 circled 1.gif 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) or the minimum beam width required to meet pile edge distance requirement.
751.32 circled 2.gif = 3’-0” (Min.) for Wide Flange, Double-Tee Girders,
   Prestressed Girders and Plate Girders.
751.32 circled 3.gif Check the clearance of the anchor bolt well to the top of pile. Increase the beam depth if needed.
751.32 circled 4.gif If the depth at the end of the beam, due to the steps, exceeds 4'-6", the beam bottom should be stepped or sloped.
751.32 circled 5.gif 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.
751.32 circled 6.gif Minimum of 3 piles at 10'-0" cts., maximum spacing (1" increments).

751.32.4 Reinforcement

751.32.4.1 Typical Pile Cap Bent

751.32.4.1 2020.jpg
Note: Locate #4 bars "751.32 reinforcement--4 bar under bearing.gif" under bearings where required to maintain a 6" maximum spacing of combined stirrups. (#4 bars "751.32 reinforcement--4 bar under bearing.gif" are not required for Double-Tee Structures.)
  For epoxy coated reinforcement requirements, see EPG 751.5.9.2.2 Epoxy Coated Reinforcement Requirements. Details of protective coating and sloping top of beam to drain shall be used when below an expansion device.
  When dimension “B” is required to be greater than 15” to clear piles by 1 ½”, typical when HP14 and CIP14 or larger diameter piles are used, add intermediate longitudinal bar(s) between piles. The spacing between intermediate bar(s) and full length bars shall not be greater than required by crack control provisions. Ends of intermediate bar(s) shall be hooked.


751.32.4.1.3.jpg
751.32.4.1 longitudinal.jpg
(1) 6” (Max.), add #6 bars as needed.
(2) 9” (Max.), add #6 bars at each face as needed.
(3) Location 2 development length, f'c = 3 ksi:
21" (uncoated)
32" (epoxy coated)

See EPG 751.5.9.2.8 for development and lap splice lengths not given or lengths for scenarios other than those shown. Provide standard hooks if required.

751.32.4.2 Encased Pile Cap Bent

Supplemental details for encased pile cap bents are provided.

751.32.4.2 part elev 2020.jpg


751.32.4.2 part section 2020.jpg
Note: When dimension “A” is greater than 18” add intermediate longitudal bar(s) between piles. Ends of bar(s) shall be hooked. Keep 3” minimum clearance between the pile and intermediate bar(s) and do not show on the plans.
751.32.4.2 part plan Dec 2011.jpg
Part Plan
Note: Locate #4 bars "751.32 reinforcement--4 bar under bearing.gif" under bearings where required to maintain a 6" maximum spacing of combined stirrups. (#4 bars "751.32 reinforcement--4 bar under bearing.gif" are not required for Double-Tee Structures.)
  For epoxy coated reinforcement requirements, see EPG 751.5.9.2.2 Epoxy Coated Reinforcement Requirements. Details of protective coating and sloping top of beam to drain shall be used when below an expansion device.