عنوان مقاله [English]
Within the past few decades, researchers and designers have become more interested in utilizing the hybrid structures consisting of the reinforced concrete and steel members. This combined system benefits its own advantages from both steel and concrete characteristics. One of these systems is the RCS; Reinforced Concrete Column Steel beam. A moment frame consists of Reinforced Concrete columns (RC) and Steel beams (S).
In this research, two samples of this type of connection whose experimental models were established by Alizadeh et al. (2000) were used. Both specimens were tested under quasi-static reversed cyclic loading and simulated using a nonlinear three-dimensional finite element method analyzed by the ABAQUS software. After verifying the FEM models, some special joint details were simulated for investigating the effect and the performance of the steel band plates, FBPs, EBPs, WFBPs, ABPs , steel doubler plates and the stirrups in joint. Lateral load story drift response, the cracking pattern of the joints, shear strains at the joints, non-linearization of steel beam were studied in the considered models. The results indicated that the performance of the models depended directly on the joint detailings, the effectiveness of the shear keys, and the amount of the confinement provided for the panel zone region.
Engineered cementitious composites (ECC) are a class of high-performance fiber reinforced cement composite with strain hardening and multiple cracking properties. Therefore, replacing the connection column with strong and flexible concrete, such as engineered concrete, increases the seismic behavior of this type of connections. Therefore, composite concrete was replaced by the column concrete in the modeled joints for further investigations.
The comparative results indicated that the application of the ECC in columns, beam-column joints, in parts or as a whole, in composite systems can greatly improve their seismic behavior. In addition, the use of ECC, allowed the reduction and even the elimination of the steel transverse reinforcements in the connection. This indeed simplifies the joint detailing, especially when the beams are framing into the same column from different directions.
Finally, a model of RCS connection with ECC is presented, which in addition to simpler detailing scheme in the joint area, has also a favorable seismic behavior.