Three-story, two-bay concrete frames with plain bars under cyclic lateral loading

• Κύριοι συγγραφείς: Palios, Xenophon, Strepelias, Elias, Stathas, Nikolaos, Fardis, Michael, Bousias, Stathis, Chrysostomou, Christis, Kyriakides, Nikolas
• Άλλοι συγγραφείς: Παλιός, Ξενοφών
• Γλώσσα: English
• Έκδοση: Springer 2020
• Θέματα: Reinforced concrete; Smooth bars; Οπλισμένο σκυρόδεμα; Λείες ράβδοι

A 2:3-scale three-story, one-by-two-bay, strong beam-weak column RC frame with plain bars in the columns was subjected to cyclic lateral loading following an inverted triangular heightwise pattern. Column detailing, the testing program and instrumentation focused on the behavior of plain bars and its impact on local and global performance. Chord rotation demands reached 0.055 rads and story drifts almost 5%, causing: a) debonding of FRP overlays applied on the exterior face of joints after their diagonal cracking early in the test, b) residual through-thickness cracks in slabs and torsional ones in transverse beams, as slabs worked as effective flanges of the beams and transferred their in-plane forces to the frame's joints by torsion in the transverse beams. Column deformations were concentrated at flexural cracks at the top and base sections, due to slippage of the plain bars. Hysteresis loops had a shape typical of bond-slip behavior, but without strength decay during load cycling. The dominant role of bar slippage in the reponse did not lead to transfer of bar tension to the hook at the bars' far end: the strains show that wherever the surrounding concrete was in compression, column bars were in compression as well. Lap splices at and/or FRP wrapping of column end regions did not have systematic effects on column behavior. Overall, no adverse effect of the use of plain bars was identified.