FDOT Standard Plans Index 460-477: Thrie - Beam Panel Retrofit (Concrete Handrail)

Design Criteria

Design Criteria AASHTO LRFD Bridge Design Specifications ; Structures Design Guidelines ( SDG )

Design Assumptions and Limitations

Design Assumptions and Limitations This Standard Plan Index is applicable for use along bridges or roadways with design speeds of 45 mph or less and where the existing traffic railing is structurally sound and free of major cracks or spalls. Contact the Structures Design Office regarding potential applications on bridges with higher design speeds. This I ndex is applicable for retrofitting a specific type of existing bridge mounted traffic railing (concrete handrail) which is not based on a crash tested design.

This Index differs from Index 4 6 0 - 476 in that the existing traffic railing stays in place and the retrofit 10 Gauge Thrie - Beam Guardrail panels are bolted directly to the existing railing. In the event that the designs and details presented in this Index do not closely match the existing conditions, and if this Index is ultimately determined to be appropriate for use, the Structures and/or Roadway Engineer(s) may prepare a customized project specific retrofit design based on the bridge railing and guardrail transition designs presented in this Standard as a guide. Cont act the Structures Design Office for guidance in this event.

This Standard Plans Index is intended for retrofitting existing Post and Beam Concrete Handrails (traffic railings) as shown on these and other similar obsolete Design Standard Indexes with geometry and reinforcing as shown: Index 10257 Concrete Handrail (1969 and 1970 with 1975 Revision) Index 10257 - MOD Concrete Handrail (1970 with 1971 and 1973 Revisions) Index 10266 Concrete Handrail (1969 with 1973, 1974 and 1975 Revisions) Index 10276 Concrete Handrail and Light Standard Pilaster Details (1969 with 1973 Revisions) Determine the applicability of this Index to a particular bridge based on a review of the Load Rating of the existing bridge and a comparison of the existing railing geometry to that shown for this. The average weight per linear foot of the retrofit is 20 lb/ft. The Thrie - Beam Trailing End Transition is for use only when a line of guardrail is located outside of the Clear Zone of any opposing Travel Way.

In all other cases, use the Thrie - Beam Approach Transition on each end of each line of guardrail. The treatment of the approach and trailing ends of the retrofit shall consist of the Thrie Beam Approach Transition and Trailing End Transition, respectively, as shown on the Standard Plans Index . The appropriate guardrail treatments beyond the Approach and Trailing End Transitions shall be determined by the Roadway Engineer.

As a minimum, if no other hazards are present, an End Anchorage Assembly Type II shall be provided Standard Plan s Instructions Topic No. 625 - 010 - 003 Index 460 - 477 Thrie - Beam Panel Retrofit (Concrete Handrail) on the trailing end of the retrofit. On approach ends, a Transition Block or Curb is required at the end of the bridge/wingwall if the existing Approach Slab does not have a curb.

A Transition Block is not required on trailing ends of bridges having no opp osing traffic; however, a Curb may be required due to drainage needs. An Index 520 - 001 , Type D Concrete Curb is generally suitable for this application. The Structures Engineer shall identify the locations in the Plans (if any are required) where a Thrie - Beam Expansion Section is to be included in the guardrail.

Evaluate the thermal movements of the existing bridge using the following criteria: If the tota l thermal movement at an individual bridge deck expansion joint is 1½" (¾" in each direction) or less, the Thrie - Beam Guardrail shall span the joint without the use of an expansion section. If the total thermal movement at an individual bridge deck expansi on joint exceeds 1½", a Thrie - Beam Expansion Section must be installed at that location. The total amount of thermal movement at bridge deck expansion joints shall be determined by theoretical calculation and confirmed by field measurements where possible.

…

Payment

Payment Item number Item Description Unit Measure 460 - 72 - 1 Thrie - Beam Panel Retrofit (Concrete Handrail) LF

What your plans must show

Plan Content Requirements for this index — the SPI's checklist for designers.

• - Profile sheet is as follows: "Construct Thrie
• - Beam Panel Retrofit (Concrete Handrail), Index 460
• - 477, from Sta. XX+XX.XX (at or near Begin Bridge) to Sta. XX+XX.XX (at or near End Bridge)." For projects with multiple bridges, a tabular format may be used to convey the necessary information. Also show the appropriate site specific approach and trailing end treatments in the Plans.
• Standard Plan s Instructions Topic No. 625