University of Guilan Concrete Research 2008-4242 16 3 2023 09 23 Evaluation of the behavior of moment frames without stirrup in the joint core and improved by the method of enlargement of the joint core Evaluation of the behavior of moment frames without stirrup in the joint core and improved by the method of enlargement of the joint core 55 65 6772 10.22124/jcr.2023.23940.1614 FA Ali Golafshar Assistant Professor, Department of Civil Engineering, Semnan Branch, Islamic Azad University, Semnan, Iran Journal Article 2023 04 22 Many of the existing reinforced concrete structures have inappropriate details in the reinforcement, which causes problems such as low lateral displacement capacity, low energy consumption, strength deterioration, and occurrence of mechanisms in undesirable places in the structure. One of these problems is the weakness in the shear resistance of the joint core due to the lack of transverse reinforcement in the joint core. In this research, the effect of using the method of enlarging the joint core in improving the behavior of joints without transverse reinforcements in the joint core has been investigated. For this purpose, after conducting experimental studies on the control and improved connections and validating their numerical model, the control and improved concrete frames of 4 and 8 stories have been modeled in OpenSees software, and their lateral behavior has been analyzed using non-linear static analyzes under Uniform lateral loading and incremental cyclic loading were compared and evaluated. The results of the studies indicate the use of the studied improvement method in connections stirrups in the core increases the bearing capacity, reduces pinching, increases energy disipation and forms a flexural hinge in the beam. Many of the existing reinforced concrete structures have inappropriate details in the reinforcement, which causes problems such as low lateral displacement capacity, low energy consumption, strength deterioration, and occurrence of mechanisms in undesirable places in the structure. One of these problems is the weakness in the shear resistance of the joint core due to the lack of transverse reinforcement in the joint core. In this research, the effect of using the method of enlarging the joint core in improving the behavior of joints without transverse reinforcements in the joint core has been investigated. For this purpose, after conducting experimental studies on the control and improved connections and validating their numerical model, the control and improved concrete frames of 4 and 8 stories have been modeled in OpenSees software, and their lateral behavior has been analyzed using non-linear static analyzes under Uniform lateral loading and incremental cyclic loading were compared and evaluated. The results of the studies indicate the use of the studied improvement method in connections stirrups in the core increases the bearing capacity, reduces pinching, increases energy disipation and forms a flexural hinge in the beam. https://jcr.guilan.ac.ir/article_6772_809e4f5dc14397bb6f1e83af04292e28.pdf