Improvement of punching strength of flat plates by using carbon fiber reinforced polymer (CFRP) dowels

Erdoğan, Hakan
Due to their practical application, flat-plates have been commonly used slab type in constructions in recent years. According to the investigations that were performed since the beginning of the 20th century, the vicinity of the slab-column connection is found to be susceptible to punching failure that causes serious unrepairable damage leading to the collapse of the structures. The objective of this study is to enhance the punching shear strength of slab-column connections in existing deficient flat plate structures. For this purpose, an economical and easy to install strengthening method was applied to ¾ scale flat-slab test specimens. The proposed strengthening scheme employs the use of in house-fabricated Carbon Fiber Reinforced Polymer (CFRP) dowels placed around the column stubs in different numbers and arrangements as vertical shear reinforcement. In addition, the effect of column aspect ratio on strengthening method was also investigated in the scope of this study. Strength increase of at least 30% was obtained for the CFRP retrofitted specimens compared to the companion reference specimen. Three-dimensional finite element analyses of test specimens were conducted by using the general purpose finite element analyses program. 3-D finite element models are successful in providing reasonable estimates of load-deformation behavior and strains. The experimental punching shear capacities and observed failure modes of the specimens were compared with the estimations of strength and failure modes given by punching shear strength provisions of ACI 318-08, Eurocode-2, BS8110-97 and TS500. Necessary modifications were proposed for the existing provisions of punching shear capacity in order to design CFRP upgrading.
Citation Formats
H. Erdoğan, “Improvement of punching strength of flat plates by using carbon fiber reinforced polymer (CFRP) dowels,” Ph.D. - Doctoral Program, Middle East Technical University, 2010.