Frame structural systems adopting precast concrete elements can be efficient in raising productivity and quality control as well as being cost effective. In the last years, precast concrete systems with various connection details have been widely used in the construction of frame structures to provide for adequate earthquake resistance. In order to obtain an adequate stiffness and degree of redundancy of the structure against horizontal forces, no simply – supported conditions between precast components (beams and columns) can be used, but correctly designed connection systems must be preferred. In this paper, the results of a full-scale experimental campaign on the beam-column joints of a precast RC multi-story system are described. The experimental tests have been performed on 4-way and 3-way full scale joints subjected to cyclic loadings. The structural system is composed of precast reinforced concrete (RC) beams and multi-story precast RC columns. In the construction phases, the beams usually support precast hollow-core slabs. Then, after the positioning of the negative moment steel reinforcements, each floor is completed with cast-in-place concrete for the slab, the upper part of the beam and the beam-column nodal zone, so providing for an adequate degree of redundancy and earthquake resistance. Hence, in the final configuration, the nodal panel is cast in-situ and connects the precast beams and columns. The experimental tests on the beam-column joints have been performed by imposing quasi-static displacement cycles at the ends of the beams. A constant axial load on the column has been also applied, simulating the vertical load given by the permanent actions. The main objective of the study has been to investigate the cyclic behaviour of the beam-column joints, depending on the amount of stirrups and reinforcement in the nodal zone. The ductility of the connection and the strength degradation for cycles at prescribed values of displacement have been also evaluated. The results shown that the strength of the beam-column nodal zones is sufficiently high to assure the strength hierarchy required by the seismic guidelines for design; the collapse mechanism was in fact due to inelastic deformation at the initial sections of the beams, with no significant damage of the node panels.
Experimental Investigation on a Beam-Column Node of a Multi-Story Precast RC System / C. Mazzotti; L. Vincenzi. - ELETTRONICO. - (2010), pp. 1-8. (Intervento presentato al convegno 14th European Conference on Earthquake Engineering tenutosi a Ohrid, Repubblica di Macedonia nel 30/08/2010 - 3/09/2010).
Experimental Investigation on a Beam-Column Node of a Multi-Story Precast RC System
MAZZOTTI, CLAUDIO;
2010
Abstract
Frame structural systems adopting precast concrete elements can be efficient in raising productivity and quality control as well as being cost effective. In the last years, precast concrete systems with various connection details have been widely used in the construction of frame structures to provide for adequate earthquake resistance. In order to obtain an adequate stiffness and degree of redundancy of the structure against horizontal forces, no simply – supported conditions between precast components (beams and columns) can be used, but correctly designed connection systems must be preferred. In this paper, the results of a full-scale experimental campaign on the beam-column joints of a precast RC multi-story system are described. The experimental tests have been performed on 4-way and 3-way full scale joints subjected to cyclic loadings. The structural system is composed of precast reinforced concrete (RC) beams and multi-story precast RC columns. In the construction phases, the beams usually support precast hollow-core slabs. Then, after the positioning of the negative moment steel reinforcements, each floor is completed with cast-in-place concrete for the slab, the upper part of the beam and the beam-column nodal zone, so providing for an adequate degree of redundancy and earthquake resistance. Hence, in the final configuration, the nodal panel is cast in-situ and connects the precast beams and columns. The experimental tests on the beam-column joints have been performed by imposing quasi-static displacement cycles at the ends of the beams. A constant axial load on the column has been also applied, simulating the vertical load given by the permanent actions. The main objective of the study has been to investigate the cyclic behaviour of the beam-column joints, depending on the amount of stirrups and reinforcement in the nodal zone. The ductility of the connection and the strength degradation for cycles at prescribed values of displacement have been also evaluated. The results shown that the strength of the beam-column nodal zones is sufficiently high to assure the strength hierarchy required by the seismic guidelines for design; the collapse mechanism was in fact due to inelastic deformation at the initial sections of the beams, with no significant damage of the node panels.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
