Title: UHPC Overlays for Suspension Bridges – The Why & How?

Author(s): Vic Perry

Publication: Web Session

Volume: ws_S22_VicPerry.pdf

Issue:

Appears on pages(s):

Keywords:

DOI:

Date: 3/28/2022

Abstract:
Suspension bridges have a unique set of special challenges when it is required to rehabilitate the decks. UHPC has a special set of properties and the ability to uniquely meet these challenges. Engineers and owners when faced with rehabilitating the deck surface of suspension bridges have many conflicting restraints to consider. Suspension bridges are overly sensitive to any increase in dead loads due to the long spans supported by cables. Additionally, they are very flexible and subject to continuous bending and torsion from wind loading and truck traffic. This constant movement and flexing of the deck can cause microcracking allowing the infiltration of salts from both de-icing and salt air (many suspension bridges are over sea water). These challenges make UHPC a suitable material to significantly extend the life of the bridge deck. The placement of concretes on the surface of a suspension bridge also creates a set of unique challenges. Placing a thixotropic UHPC on a sloping deck that is constantly moving from wind across the surface and moving truck traffic can create several placement problems. The workability of the UHPC must be designed so that it is fluid enough to be spread in front of the deck screed, but still stable enough to remain in place after the surface is screeded to grade, all the while the bridge is constantly moving. This presentation will cover the unique properties of a thixotropic UHPC suitable for suspension bridges and show examples of placing an overlay on suspension bridges.