# 751.34 Concrete Pile Cap Non-Integral End Bents

## 751.34.1 General

### 751.34.1.1 Material Properties

Concrete
Class B Concrete (Substructure) ${\displaystyle \,f'_{c}}$ = 3.0 ksi
${\displaystyle \,n}$ = 10

Class B-1 Concrete (Substructure) may also be used in special cases (See Project Manager). The following equations shall apply to both concrete classes:

Modulus of elasticity,

${\displaystyle E_{c}=33,000\ K_{1}\ (w_{c}^{1.5}){\sqrt {f_{c}^{'}}}}$

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,

${\displaystyle f_{r}\ =\ 0.24{\sqrt {f'_{c}}}}$       LRFD 5.4.2.6

Where:

f'c is in ksi

Reinforcing Steel
Minimum yield strength, ${\displaystyle \,f_{y}}$ = 60.0 ksi
Steel modulus of elasticity, ${\displaystyle \,E_{s}}$ = 29000 ksi

## 751.34.2 Design

### 751.34.2.1 Limit States and Factors

In general, each component shall satisfy the following equation:

${\displaystyle \,Q=\sum \eta _{i}\gamma _{i}Q_{i}\leq \phi R_{n}=R_{r}}$

Where:

 ${\displaystyle \,Q}$ = Total factored force effect ${\displaystyle \,Q_{i}}$ = Force effect ${\displaystyle \,\eta _{i}}$ = Load modifier ${\displaystyle \,\gamma _{i}}$ = Load factor ${\displaystyle \,\phi }$ = Resistance factor ${\displaystyle \,R_{n}}$ = Nominal resistance ${\displaystyle \,R_{r}}$ = Factored resistance

Limit States

The following limit states shall be considered for abutment 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 6.5.4.2 and LRFD 5.5.4.2
For all other limit states, ${\displaystyle \,\phi }$ = 1.00

Loads from stringers, girders, etc. shall be applied as concentrated loads applied at the centerline of bearing. Loads from concrete slab spans shall be applied as uniformly distributed loads.

Loads from stringers, girders, etc. shall be applied as concentrated loads applied at the centerline of bearing. Dynamic load allowance (impact) should be included for the design of the beam. No dynamic load allowance should be included for foundation design.

For wings with detached wing walls, no portion of the bridge live load shall be distributed to the detached wall. The detached wing wall shall be designed as a retaining wall. The weight of the barrier or railing on top of the wall shall be included in the dead load.

Collision

Collision shall be designed if abutments are located within a distance of 30.0 feet to the edge of roadway, or within a distance of 50.0 feet to the centerline of a railway track and conditions do not qualify for exemptions given in EPG 751.2.2.6. If designed for, the collision force shall be a static force of 400 kips assumed to act in any direction in a horizontal plane, at a distance of 4.0 feet above ground.

Temperature

The force due to expansion or contraction applied at bearing pads are not used for stability or pile bearing computations. However, the movement due to temperature should be considered in the bearing pad design and expansion device design.

Wing with Detached Wing Wall

When Wing Length, L, is greater than 22'-0", use maximum of 22'-0" rectangular wing wall combined with a detached wing wall.

 * Detached wing wall shown is for illustration purpose only. Design detached wing wall as a retaining wall. Report Pile Cut-off Elev. and Minimum Galvanized Penetration (Elev.) (See Foundation Data).

Section A-A

Detail B

 (*) Detached wing wall shown is for illustration purpose only. Design detached wing wall as a retaining wall. (**) Use retaining wall design.

### 751.34.2.3 Design Assumptions

 (1) Beam The beam shall be assumed continuous over supports at centerline of piles. One half of the dead load of the approach slab shall be included in the beam design.
 (2) Wing and Backwall (a) Vertical Loads The minimum steel placed horizontally in wings shall be #6 bars at 8" centers, each face. These bars should be adequate to support the wing. See figure below.

Part Section Thru Backwall and Wing
 Note: The minimum steel (horizontally) in the corner haunch at the junction of the wing and backwall shall be #6 bars at 8" cts. "".

(*) See Live Load Surcharge, LS

Equivalent Fluid Pressure and Live Load Surcharge

Limits of Earth Pressure and Surcharge

## 751.34.3 Details

### 751.34.3.1 Front Sheet

 Notes: The following are details and dimensions for the plan view on the Front Sheets. Details for unsymmetrical roadways will require dimensions tying Centerline Lane to Centerline Structure. Pile arrangement shown is for illustrating dimensions and should not be considered as a recommended pile arrangement.

Non-Integral End Bents
Steel piles shown, CIP piles similar.

### 751.34.3.2 Wide Flange Beams, Plate Girders and Prestressed Girders

For epoxy coated reinforcement requirements, see EPG 751.5.9.2.2 Epoxy Coated Reinforcement Requirements.

 (1) When the total length of a beam and backwall exceeds 60'-0", use a keyed construction joint at or near CL bent as shown, preferably located at 1/4 point between piles. Maximum key length equals 18". For multiple keys make total key length equal to H/3 or d/3. (2) Slope top of beam one inch when using expansion devices. (3) Wing layout length shall be rounded to the next higher foot. See the profile sheet for length of wing to fill face. (4) See Design Layout for maximum slope of spill fill. (5) Provide a minimum of 8" cl. from outside edge of pile to face of beam. (6) Length determined by superstructure requirements or the minimum support length required for seismic criteria. (7) Dimensions are based on a 2.0% sloped deck. Subtract 1/8” for a 3/16” per foot sloped deck. (8) Based on 8 ½” slab. Adjust for different slab thickness.
Expansion Device (*) End pile edge distance is to be 18” and provide a minimum of 8” clear from outside edge of pile to outside face of beam. (*) End pile edge distance is to be 18” and provide a minimum of 8” clear from outside edge of pile to outside face of beam.
 Length determined by superstructure requirements or the minimum support length required for seismic criteria.

 (*) When total length of beam and backwall exceeds 60'-0", show a keyed construction joint at or near the centerline of bent as shown, preferably located at the 1/4 point between piles. Unless required by design or stage construction, this construction joint shall be shown as optional on the plans and may be eliminated at the contractor's discretion.

Section Thru Bents Two Rows of Piles
 3'-6" min. (1" Increments). Dimensions may be increased for superstructure requirements or the minimum support length required for seismic criteria. When this dimension is less than 6", make the front face vertical. Use 18" min. thickness. 4'-0" min. (1" Increments). Check clearance of anchor bolt well to top of pile. Increase beam depth, if needed. Slope top of beam 1" when using expansion device only. Apply protective coating to the backwall, top of beam cap and front face of beam cap when using expansion devices in accordance with Sec 711, Concrete Bents and Piers (Urethane or Epoxy). (*) Provide a minimum of 8" clear from outside edge of pile to face of beam.

Dimension D
 Note: Pile arrangements shown is for illustrating minimum dimensions only and should not be considered recommended arrangements.
 End pile edge distance is to be 18". Max. pile spacing = 12'-0". Pile spacing increments to be dimensioned as computed (1" increment). Provide a minimum of 8" clear from outside edge of pile to outside face of beam. Show on plans. For exceptions to these dimensions, see the Structural Project Manager. (*) Provide a minimum of 8" cl. from outside edge of pile to face of beam. Steel piles shown, CIP piles similar. Left advance shown, right advance similar.

Typical View of Beam For epoxy coated reinforcement requirements, see EPG 751.5.9.2.2 Epoxy Coated Reinforcement Requirements.

 Top of curtain wall shall not obstruct bottom of slab. If necessary slope top of curtain wall. Elevation A - Wing elevation is determined at this point for bridges on grade.

### 751.34.3.3 Wing Brace Details

The wing brace dimensions will only vary on the wing with obtuse angle. Wing brace dimensions shown are minimum dimensions. The wing with the acute angle will always be 18" minimum.