Rehabilitation of defective connections between two precast concrete segments (experimental and analytical study)

Abstract

Connections in precast concrete elements are essential for improving the structures' utilization, cost, and quality control. Moment connection in beams was one of the easiest ways to achieve good performance of the structures by eliminating the plastic hinges zone. Due to constructing precast elements, some of them can be defective. This paper presents an experimental and analytical study to rehabilitate defective connections between two precast concrete segments. Six simply supported beams with beam-to-beam connections and one simply supported beam without connections, each with dimensions of 200 × 400 × 1600 mm, were fabricated and loaded to failure with a four-point load. The main variables parameters were a) the type of concrete mix in the splice region, two types of concrete were employed: Normal Strength Concrete (NSC) and High Strength Concrete (HSC) b) effect of rehabilitation techniques with using NSC in the connection zone such as; using warped fiber sheets around splice region or Carbon Fiber Reinforcement Polymer CFRP laminates at the tension surface of the tested beams c) effect of rehabilitation techniques with using HSC in the connection zone. Also, a new model was proposed based on some codes and guidelines of beams strengthened with Externally Bonded FRP Systems to calculate the flexure capacity for rehabilitating the beam-to-beam connections. The results indicate that neither casting NSC nor the HSC at the connection region has any effect on increasing the beam's capacity and cannot be used only as a rehabilitation technique in beam-to-beam connection. The fiber sheet warped around the splice region constructed from either NSC or HSC did not significantly increase the beam's capacity compared to rehabilitated beams with casting concrete only in the connection region. The load capacity of the rehabilitated beam with CFRP laminates and warped fiber sheets is increased significantly by about 122 % and 209 % compared to rehabilitated beams with splice regions constructed from NSC and HSC, respectively. The proposed model based on CNR-DT 200 R1/2013 equation gave a good prediction of the capacity of the rehabilitation connection for rehabilitated beams with CFRP laminates and warped fiber sheets.