Experimental investigation of Corner RC Beam-Column Joints Subjected to Unidirectional and Bidirectional Lateral Loading

Document Type : Original Article

Authors

Seyyed Ahmad Nezami ¹

Ahmad Shooshtari ²

Jalil Shafaei ³

¹ Department of Civil Engineering, Ferdowsi University of Mashhad, Mashhad, Iran

² Civil Engineering Department,, Ferdowsi University of Mashhad, Mashhad, Iran

³ Department of Civil Engineering, Shahrood University of Technology, Shahrood, Iran

10.22067/jfcei.2025.93466.1356

Abstract

The most important aspect of the stability of reinforced-concrete (RC) buildings against lateral movements caused by earthquakes is maintaining the elastic behavior of the joint area. Therefore, the most important task in the seismic resistant system of the moment frame is the beam-column joints. In this research, the seismic behavior of the corner joint substructure under the influence of bi-directional loading is evaluated experimentally. The studied asymmetrical joints include three categories: 1-with seismic details according to the ACI318-19 standard, 2-without seismic details, due to the absence of transverse reinforcement in the joint area and 3- Has second-class weakness and also insufficient bond length of the beam bottom bars in the joint area. By applying half of the demand ductility of the primary direction in the orthogonal direction, the seismic performance of the frame in the primary direction changes due to the entry of the corner joint area space into bidirectional interactions. On average, in the joints under the studied joints under limited bidirectional loading, the maximum force that can be tolerated by the specimen is reduced by 10% compared to the unidirectional loading. If the bidirectional loading is applied in equal proportions in two orthogonal directions, not only does it reduce the force capacity of the corner joints by an average of 32%, but also the initial stiffness of the specimen, the effective stiffness in drift by 1.75%, the energy dissipation capacity and the ductility are reduced by 54%, 40%, 35% and 23%, respectively, compared to the unidirectional loading condition.

Keywords

Beam-Column Joints

Reinforced Concrete Structures

Bidirectional Lateral Loading

Corner Joint

Experimental Evaluation

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