Seismic Performance of Unitized Glazed Façades: A Parametric Study

Glass-aluminum façade systems, especially unitized curtain walls, are commonly used in high-rise buildings for their flexibility and aesthetic openness. However, the glazed surfaces of buildings suffer from severe brittle fracturing and posing a glass failure risk, particularly with regard to façade partitions; these pose significant issues when subjected to seismic forces. This thesis seeks to explore the numerical approach for evaluating the seismic performance of these systems. This study is based on the “Influence of Design Variables on Seismic Performance of Unitized Curtain Walls: A Parametric Experimental Study” by Bianchi et al. (2024) in collaboration with Permasteelisa Group and TU Delft, which analyzed inter-story drift imposed onto full scale glazing units. In this work, the in-plane seismic response of façade panels due to inter-story drift was modelled using SAP2000 with a Finite Element Method (FEM) approach. Frame elements represented the aluminum structures, shell elements for the triple-glazed units and silicone connectors were modeled as nonlinear spring elements. A study on structural performance included changes to geometry parameters of the connectors, dimensions of the panel and boundary restraint conditions. The numerical analyses for these parameters cover multiple indicators: integrated frame displacement, rotational strain of the glazing panel, distribution of bending moments in aluminum members and stress distribution both in glass and frame components. Moreover, international regulations from Eurocode 8, ASCE 7-16, NZS 1170.5, JASS 14 and AAMA guidelines were also reviewed to understand the contextual design practices and performance criteria within a specific region. These codes capture several paradigms of designing a system which may span from force-based approaches to displacement-driven methods with varying degrees of deformation compatibility emphasis. The results indicate that façade seismic performance is not only reliant on material strength but also influenced by connector configuration, panel geometry and boundary conditions which will aid in guiding the glazing systems towards future performance-based design objectives.