PSI - Issue 66

Albena Doicheva et al. / Procedia Structural Integrity 66 (2024) 433–448 Author name / Structural Integrity Procedia 00 (2025) 000–000

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Keywords: larges deformations, crack on the face of the column, beam-column connection, limite state, shear force, cantilever beam, reinforced concrete

1. Introduction The beam-column connection is a key element in the frame structures. The transfer of forces from the beams to the columns under dynamic actions can threaten the integrity of the connection. To ensure the strength of the joint, adequate design, is necessary, which must be based on full knowledge of the magnitudes of the forces passing in the beam-beam and column-column direction. Over the last 6 decades, hard work has been done to develop a uniform procedure for the determination of shear force. The first definition is given in Hanson and Connor (1967). This is a horizontal force transferred at the midheight of a horizontal section of a beam-column connection. Experimental and analytical studies follow. With these, various variables are set and their influence on the response of frame joint is investigated Park and Paulay (1975), Paulay (1989), Javad et al. (2018), Gombosuren and Maki (2020), Hayat et al. (2021), Kim and LaFave (2007), Bonacci and Pantazopoulou, (1993), Alaee and Li (2017), Ramaglia et al. (2022), Zhuang et al. (2024), Kalogeropoulos et al. (2024). In Eurocode 8 (2004), that part of the shear force that is transferred from the beam to the column is determined on the basis of capacitive design. This is the force that is absorbed by the longitudinal reinforcing bars when the steel yield. We find the same acceptance in Barbagallo et al. (2023). Nowadays, capacitive methods are proposed with additional consideration of the participation of the concrete section and stirrups in the joint, Shiohara (2001), Fardis (2021), Floridia et al. (2023). In Nicoletti et al. (2023) a graphical method (called monograms) is proposed, which allows to determine the geometric dimensions of the beam-column joint and hoop amount so that the Italian technical code (NTC18) for beam-column joint verifications are satisfied. In Angiolilli et al. (2023) investigated a beam-column joint model from the facade of an old building designed under the conditions of the 1960s and 1970s. The experimental results are compared with a 3D model, allowing to vary the material characteristics of the used building materials. Control of the shear force at the joint based on the friction between the elements and the energy dissipation under cyclic loading is proposed in Pagnotta et al. (2023). A machine-trained variable-angle truss model for predicting the shear capacity of RC members with transverse reinforcement is proposed in De Domenico et al. (2023). However, all these approaches do not give an answer to the question, of how big the shear force actually is. In this study, the forces leaving the beam will be determined as the result of a specific load applied to a specific beam of specified dimensions and material characteristics of its composite elements. Determining the exact magnitude of the forces entering the beam-column connection will allow the exact magnitude of the shear force to be determined. The appearance of a crack between the beam and the column, and its growth, will allow to follow the variation of the shear force in the limit stage. The obtained results for the magnitude of the shear force will be compared with those given in the literature and prescribed in Eurocode 8 (2004). 2. Materials In 1967, Hanson and Connor defined the shear force as the sum given in Equation (1).

j C C C V T C C V T T V ′ ′ ′ = + + − = + − S

(1)

where S C , S C ′ and T , T ′ are the compressive and the tensile forces in the bottom and top longitudinal reinforcing bars in the beam passing through the connection, respectively; C C and C C ′ are the compressive forces in concrete on the bottom and top edge of the beam; C V is the column shear force. The forces are shown in Fig. 1.