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Title: Cyclic and Strength Performance of Slab-Beam Superstructure System with UHPC Closure Pour

Author(s): Francisco Chitty

Publication: Web Session

Volume: ws_S22_FranciscoChitty.pdf

Issue:

Appears on pages(s):

Keywords:

DOI:

Date: 3/28/2022

Abstract:
Slab beam superstructures have been used for short-span bridges since prestressed concrete began to be used in the US. Poor joint performance of these superstructures led to recent revisions to design standards; one example being the Florida Slab Beam (FSB). The FSB and other similar slab beam systems include a composite cast-in-place (CIP) reinforced concrete deck and joint between adjacent beams. An optimized joint design has been developed in this research to accelerate the construction times and eliminate the need for a CIP deck by using ultra-high-performance concrete (UHPC) in the longitudinal closure pour to connect the precast members. This presentation will describe large-scale flexure test findings of the developed longitudinal joint with 30-foot length specimens. Two two-beam test configurations with UHPC joints were developed and experimentally tested under strength and cyclic performance with different loading schemes and support conditions, investigating the load transfer mechanisms, and the demand on the precast concrete, joint reinforcement, and joint interface. The joint performed well with no observed joint distress or deterioration in performance through the permit service load testing, more than four million cycles of load, and ultimate strength testing of the two-beam system. Observations from these tests and numerical models were used to guide a subsequent four-beam test configuration, studying cyclic performance under locked-in stress due to beams’ differential camber.