NCEER-89-0013 | 2/28/1989 | 124 pages
TOC: The table of contents is provided.
Keywords: Reinforced Concrete, Stiffening of Structures, Cast-in-Place Reinforced Concrete, Repairs to Concrete Connections, Retrofit of Reinforced Concrete Structures, and Strengthening of Structures.
Abstract: An experimental investigation was performed with the object of evaluating and improving methods of repairing and strengthening beam-to-column connections damaged by earthquakes. Commonly used repair procedures and strengthening details as well as modifications and improvements of those procedures were tested to compare the behavior of damaged and repaired connection subassemblies with that of undamaged subassemblies. These comparisons were made on the basis of restitution or improvement of strength, stiffness, and energy absorption capabilities. Five subassemblies of single beam-to-column connections and six multiple connection subassemblies, each consisting of two exterior and one interior connection with some including a floor slab, were subjected to twelve cycles of a predefined cyclic displacement routine. The specimens were repaired using techniques such as replacement of damaged concrete, enlargement of section, and addition of rolled steel elements. The repaired specimens were then subjected to the same loading history as that used in the original test. Epoxy injection and replacement of concrete restored the strength of specimens to their original level. However, the stiffness and energy absorption capacity of the specimens repaired with epoxy injection could not be restored, primarily due to difficulty in filling all the internal cracks. Specimens strengthened by reinforced concrete and by steel encasement showed increased strength, stiffness and ductility and exhibited desirable failure mechanisms.