This Week's Featured Presentation
Seismic Repair and Retrofit of Concrete Bridges (ACI Spring 2018 Convention, Salt Lake City, UT) Prestressed precast double-tee (DT) bridges are the most common type of bridges on South Dakota local roads. They are also common in the neighboring states. Longitudinal girder-to-girder joints of many of DT bridges have deteriorated after a few years of service mainly due to insufficient detailing. Twenty joint rehabilitation alternatives were developed and two were selected for bridge system testing: (1) a continuous joint reinforced with wire mesh and filled with latex modified concrete (LMC), and (2) discrete pockets reinforced with steel bars and filled with ultra-high performance concrete (UHPC). A 50-ft long full-scale conventional DT bridge was constructed and tested under AASHTO fatigue loadings. The longitudinal joint of the bridge was subsequently rehabilitated using the two detailing, each was incorporated on one-half of the bridge length. Fatigue and ultimate testing of the rehabilitated bridge showed that the both proposed joint rehabilitation methods are structurally viable.
The presentation highlights the detailing and performance of both conventional and rehabilitated DT bridges, and a summary of findings will be presented.
February 3 - 9
Rapid Repair of Hollow-Core FRP-Concrete-Steel Columns
by Mohamed A. ElGawady, Missouri University of Science and Technology; Ahmed Gheni, Missouri University of Science and Technology; and Sujith Anumolu, Missouri University of Science and Technology
Seismic Repair and Retrofit of Concrete Bridges (ACI Spring 2018 Convention, Salt Lake City, UT) This paper presents a rapid repair technique for a hollow-core fiber reinforced polymer (FRP)- concrete-steel column (HC-FCS). This HC-FCS column consists of a concrete cylinder sandwiched between an outer FRP tube and an inner steel tube. The system has several advantages over conventional concrete construction. Both steel and FRP tubes act as stay-in-place formwork.
Furthermore, the steel tube represents the longitudinal and transverse reinforcement while the FRP tube acts as confinement reinforcement for the concrete cylinder. The system is less susceptible to corrosion as the FRP tube and concrete cylinder protects the steel tube. A HC-FCS column was subjected to cyclic lateral load before and after rapid repair. The virgin column failed due to GFRP tube rupture at drift of 6%. The tested column was rapidly repaired and retested under the same
loading regime. The rapid repair consisted of wrapping the potential plastic hinge region of the column using three layers of glass fiber reinforced polymer (GFRP). To achieve the rapid repair, however, the GFRP was cured using heat treatment for four hours. Once the GFRP cured, high strength grout was injected into the column and the column was retested. The repaired column achieved 95% of the virgin column’s flexural strength and 61% of the virgin column’s stiffness. The repaired column
achieved high lateral drift of 13.2% before the failure.