Page 210 - Demo

PRECAST CONCRETE ELEMENTS208 CPI %u2013 Concrete Plant International %u2013 5 | 2025 www.cpi-worldwide.comIn the design of a prefabricated structural system, addressing the interaction between panels and the structural frame is a fundamental aspect that must be carefully considered. The selection of constraints to be installed between the two elements is crucial to ensure effective anti-overturning restraint of the panel and, at the same time, to transmit seismic forces compatible with the structural characteristics. Edilmatic offers a range of structural nodes that include both fixed and sliding connections.The issue concerning the interaction between cladding or infill panels and the seismic-exposed structural frame represents a highly complex and delicate topic within seismic design. This complexity mainly stems from the intrinsic difficulties in predicting and assessing potential adverse effects caused by excessive stiffening of the structure due to the constraint between panels and frame, which could significantly influence the overall behaviour of the building during a seismic event. In particular, the structural node connecting the two elements must be designed with utmost care to, first and foremost, prevent overturning or dangerous deformations of the panel itself, especially in response to static and seismic loads encountered during such events. Regarding the possible transmission of seismic forces in the plane of the panel, two main types of constraints can be adopted: on one side, fixed constraints, which guarantee a rigid and stable connection; on the other, sliding constraints, which allow a certain degree of movement and can absorb seismic energy in a more flexible manner, potentially reducing harmful effects and internal forces throughout the structure. Below, a comparison of these approaches is provided.In the context of seismic actions affecting a building, rigid constraints%u2014commonly referred to as fixed constraints%u2014play a fundamental role in the overall structural response. In this configuration, cladding or infill panels are forced to follow the motion of the structural frame during seismic oscillations. This behaviour results in rigid rotations of the panels in an alternating fashion, synchronized with the motion of the main frame. Essentially, fixed constraints prevent any relative displacement between the panels and the rest of the structure, thereby generating horizontal forces within the frame itself. The magnitude of these forces is directly proportional to the seismic acceleration and the dynamic response of the oscillation. Their intensity also depends on the mass, stiffness, and behaviour of the panels, which%u2014under this configuration%u2014act as integral parts of the oscillating mass of the entire system, contributing to defining the overall vibrational modes and influencing the global seismic response characteristics.During structural modelling, this interaction between panels and frame must be analysed with great care, as panels with fixed constraints actively participate in the building%u2019s vibrational modes. Consequently, the natural modes and frequencies of oscillation of the structure can be altered compared to a model without panels or with constraints that are more flexible. However, in practical applications, it is often considered that such involvement may have adverse effects on seismic performance, particularly regarding structural stiffening and deformation patterns, which can generate high stresses at critical nodes.Design of lateral response connections for precast panels Edilmatic S.P.A., 460202 Pegognaga (MN), ItalyFrame with panels having sliding restraints (a) and fixed restraints (b).a) b)