MEDIOS DE PROTECCIÓN COLECTIVA

4.3.1 Moment Connections

Components can be connected with a joint that can transmit moment and shear using the following methods. See section 5.2.1.3 for grouting procedure.

• Embedded Mechanical Couplers as shown in Figure 4.3.1-1 .

2V:1H (TYP)

CONSTRUCTION JOINT CONSTRUCTION JOINT

4" ØWEEPER (TYP OPTIONAL CONSTRUCTION JOINTS APPROXIMATE EXISTING GROUND A FLOWABLE GROUT BED (3" MIN.) STRUCTURAL FILL (2' THICK) BEARING SEAT FILL LINE GRANULAR BACKFILL

Figure 4.3.1-1 Stem Joint Detail

The most common connector is a grouted sleeve for mild reinforcing that can develop in excess of 125% of the specified yield strength of the bars. See ACI 550.1R-01, Emulating Cast-in-

Place Detailing in Precast Concrete Structures.

For grouting sequence see section 5.2.1.3.

• Cast-in-place closure pours Closure pours are also effective; however

speed of construction is compromised. This is often used for horizontal moment joints.

MECHANICAL GROUTED SPLICES

6" x 6" PLASTIC SHIM AT

EACH END OF ABUTMENT COMPONENT 8"

2" STEM WIDTH

FILL WITH APPROVED FLOWABLE NON-SHRINK HIGH STRENGTH GROUT 1 1/2 " 6" TOE FOOTING HEEL FOOTING 2'

NARROW CLOSURE POUR WITH GROUTED SPLICERS PRECAST SECTION

Figure 4.3.1-2 Cast-In-Place Closure Pour

• Post Tensioning with match-cast components. See Figure 4.3.3-1.

The designer shall address shear transfer through moment connections.

Post Tensioning may be used for complex structures (tall piers), or to eliminate closure pours for horizontal moment connections (integral abutment stems, pier caps, etc.). In these cases the components are match cast against each other during production and an epoxy adhesive is placed between the components during installation. See Figure 4.3.1-2.

Shear transfer can be accommodated by the use of grouted shear keys within the joint, keyed pockets, or by providing additional reinforcement across the joint (shear friction design).

Separate unit Placing units together Units connected

Figure 4.3.1-2 Example of sections that were match cast for a tight fit. The right photo shows the sections held together by the use of an epoxy adhesive.

4.3.2 Shear Connections

Certain components may need to be connected with a joint that only transmits shear using the following methods:

Vertical shear joints are typically used in tall vertical wall joints and transverse joints in one- • Vertical Grouted Keys as shown in Figure

Figure 4.3.2-1 Footing Joint Detail

Figure 4.3.2-2 Detail of a Vertical Joint in Wall

• Horizontal Grouted Keys as shown in Horizontal shear joints are typically used in column to bent cap. Shear transfer can be developed by means of a grouted shear key within the confines of the joint.

Figure 4.3.2-3 Horizontal Grouted Joint

• Reinforced Dowels as shown in Error! Not a valid bookmark self-reference..

Shear transfer can be developed by means of steel reinforcing bars or grouted mechanical splices designed for shear friction. An example

Bent Shear Key Mechanical Splice Column Horizontal Grouted Joint 1" CHAMFER (TYP) WITH APPROVED NON-SHRINK GROUT 1 ½ " 1" 3 ½ " 1 ½" D 6 ½" 6 ½" 1 ½"

SHEAR KEY FILLED APPROVED NON-SHRINK GROUT 1 (TYP 1" (TYP 3 ½ 1 ½ W 1/3 1/3 1/3

typical approach slab. Other state details will vary. For instance, some states do not require a concrete overlay and others place the approach slab at the roadway surface.

Figure 4.3.2-4 Beam End Detail with Approach Slab

4.3.3 Pile Connections

Integral abutment pile connections can be achieved by providing a blockout in the precast component. This connection should be designed to develop the full moment capacity of the pile. Refer to Figure 4.3.3-1.

The connection for pile supported spread footings can be achieved by providing a blockout or recess in the precast component. This connection may be designed to develop the full moment capacity of the pile. The connection will also depend on the need to prevent uplift on the piles. See Figure 4.3.3-2 and Figure 4.3.3-3.

BEARING PAD 1'-0" 9" 4" 10 ½" ½ " JOINT FILLER BEAM BOX OVERLAY CONCRETE L C BRG JOINT MATERIAL CLOSED CELL EXPANSION

FILL VOID WITH AN APPROVED GROUT ROADWAY SELECT MATERIALS BURIED APPROACH SLAB SLEEVE #5 ANCHOR DOWEL ½” CLOSED CELL FILLER MATERIAL

The designer should refer to individual state construction specification tolerances.

The size of the blockouts needs to accommodate pile driving tolerances.

Abutment & Wing Shear Reinforcement

C Brg. Match cast joints

quantity and location vary as required Galvanizeddeformed anchor sleeve Galvanized corrugated fill/vent sleeve refer to design considerations

Galvanized thread bar post tensioning refer to design considerations Slope to Approach Slab Bridge

Galvanized metal duct with deformations refer to design

considerations Abutment and Wing

segment mild reinforcement for temperature shrinkage, handling, and wing parapets

Pile

L

Redundant Void Location to be filled

Figure 4.3.3-1 Typical Integral Abutment Details

2" gap over pile Leveling bolt 1'-0“

Min.

Tapered grout port at each pile

Extend grouted dowels from Pile into footing

Precast concrete pile

Figure 4.3.3-2 Conceptual Elevation Pile Supported Precast Footing With Uplift On Piles

Note: Steel pile details are similar. Weldable reinforcing steel bars can be field welded to the pile web after installation.

Figure 4.3.3-3 Conceptual Elevation Pile Supported Precast Footing Without Uplift On Piles

4.3.4 Anchoring Devices

Certain components will need to be connected to others with pre-embedded anchoring devices. Pre-embedded anchoring devices will require additional quality control measures in the precast plant to ensure the anchored component fits up to the anchoring component.

To ensure accurate anchor layouts, anchor templates should be used. Another recommendation is to dimension anchor locations using running dimensions all measured from a common point.

In general, field drilling of anchors is not recommended.

Examples of anchored components are: • Bridge rail connections

Bridge rail will require anchors to be previously embedded in the precast component or bridge deck. Depending on the type of rail, different measures should be employed to ensure a durable connection. Figure 4.3.4-1 shows the detail used to anchor the Northeast Precast Rail. See Section 3.5.

Though not required, having the same precast plant fabricate both the anchored component and the anchoring component will better ensure that each will fit up to the other.

There is a high potential for conflicts with internal reinforcements. If field drilling is used, care should be taken in the layout of reinforcement to prevent conflicts.

2" gap over pile Leveling bolt 1'-0“

Min.

Grout port at each pile

Precast concrete pile

A precast concrete rail system may require measures such as:

• Setting the rail on a raised pedestal. Water and other corrosive materials will flow along the edge of the pedestal and not seep in the joint of the rail and the deck sections. • Stainless steel anchoring bolts.

• Beam Bearing Assemblies

The preferred method for supporting precast

ertain conditions may require the use of bea

ight tolerances or other construction concerns ma

Bearings and bearing assemblies for precast beams