Showing papers by "Mohamed A. ElGawady published in 2010"

Seismic Behavior of Posttensioned Concrete-Filled Fiber Tubes

Abstract: Precast segmental construction technique is an excellent candidate for economic rapid bridge construction in highly congested urban environments and environmentally sensitive regions. This paper presents the seismic behavior of four hybrid segmental columns consisting of precast posttensioned concrete-filled fiber tubes (PPT-CFFTs). A fifth monolithic column was also tested as a reference specimen. The columns were tested under increasing lateral loading cycles in a displacement control. The columns had circular cross section diameters of 203 mm and heights of 1,524 mm each. The parameters investigated included different construction details and energy dissipation systems. The PPT-CFFT columns developed lateral strength and deformation capacity comparable to those of the monolithic reinforced concrete column. However, the PPT-CFFT columns dissipated smaller hysteretic energy compared to that of the monolithic reinforced concrete column. Finally, a simple model was used to predict the backbone curves of se...

Retrofitting of Rectangular Columns with Deficient Lap Splices

Abstract: The cyclic behavior of eight 0.4-scale reinforced concrete column specimens is investigated. The columns incorporated deficient design details to simulate bridge columns built in Washington State prior to 1971. Two columns were tested as reference specimens, five were tested after retrofitting using carbon fiber-reinforced polymer CFRP, and one was tested after retrofitting using a conventional steel jacket. All the specimens were tested under constant gravity load and incrementally increasing lateral loading cycles. The specimens had rectangular cross sections with aspect ratios of 1.5 and 2.0. The parameters investigated included the amount of CFRP reinforcement, different retrofitting jacket configurations, and different retrofitting materials. For the as-built specimens, two modes of failure occurred, namely low cyclic fatigue of longitudinal reinforcement and lap splice failure. For the retrofitted specimens, no lap splice failure was observed. All the retrofitted specimens failed due to low cyclic fatigue failure of the longitudinal bars. The retrofitting measures improved the displacement ductility, energy dissipation, and equivalent viscous damping. In addition, increasing the amount of CFRP reinforcement improved the performance of the test specimens.