Cyclic performance of emulative precast beam to column con-nection with corbel using dowel bar

Summary

The objective of this study is to examine the seismic performance of exterior and interior types of an emulative precast beam to column connection, constructed with grouted steel dowel bar and cast-in-situ concrete under quasi-static reversed cyclic loading. The dowel bar connection between the precast structural elements is achieved by inserting the dowel bar into the column corbel's holes and the precast portion of the beam. To secure the dowel bar's anchorage, these holes are packed with non-shrinkage grout and then cast-in-situ concreting is done in the joint core and the entire upper segment of the precast beam. In the past, particularly after an earthquake in the Emilia-Romagna region of Italy in May 2012 (Ercolino, Magliulo, & Manfredi, 2016), witnessed damage to precast reinforced concrete structures was more likely to occur in the precast beam-column joint section. Hence, it’s essential to improve the performance of the beam-column joint to withstand all possible lateral load combinations, which are to be included in the design and detailing of the precast structural components. This study analyzed an eight-story RC frame building for earthquake loading using Staad.Pro software. The exterior and interior types of proposed beam-column connections were designed and detailed using the design forces and moments computed by the Staad.Pro analysis, in accordance with the Indian standard codes (IS 456, 2000), (IS 1893, 2016)and (IS 13920, 2016). The beam-column joint behavior under quasi-static cyclic loading was studied using one-third scaled-down test specimens, i.e., monolithic (MBC-EJ & MBC-IJ) and emulative beam-column (EBC-EJ & EBC-IJ) exterior and interior joints. In that proposed emulative connection, the structural continuity and compatibility between the precast elements were achieved through the corbel with the dowel bar and cast-in-situ concreting. The test specimen’s ultimate and yield load carrying capacity, energy dissipation capacity, stiffness degradation, and ductility parameters were determined based on the obtained load-displacement hysteresis relationship. Based on the findings, the precast exterior joint specimens (EBC-EJ) were found to be 14.36% more ductile and 13.23% more energy dissipative than monolithic exterior joint specimens (MBC-EJ). Similarly, precast interior joint specimens (EBC-IJ) outperformed monolithic interior joint specimens (MBC-IJ) by 6.27% more ductility and 16.86% more energy dissipation. Therefore, the experimental results confirmed that using grouted dowel bars and wet concreting in the joint area enhances rigidity and structural continuity, as well as improves the ultimate strength of precast connections to a level that closely resembles typical monolithic beam-column joints.