Influence of Performance and Design of Structural Silicone Joints on the Resilience of Curtain Wall Units Exposed to Seismic Impacts
Presented on August 5, 2020 at Facade Tectonics 2024 World Congress
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Overview
Abstract
Facade failure due to seismic event represents a potential hazard to people and can cause serious damages to buildings with consequent high-cost remedial works. As a result, interest in the design of buildings and facades to resist seismic loads and displacements has increased. Current standards and literature recognize the benefits offered by Structural Sealant Glazing (SSG) systems to enhance the performance of unitized curtain walls exposed to seismic impacts but no precise criteria are available for the seismic design of the structural silicone joints. This paper proposes a design concept to evaluate the effect of forces and displacements imposed to the structural joints due to panel seismic racking; referring to the design philosophy developed by Japanese Standard, the concept is engineered based on three performance levels associated to different design requirements, which aim at balancing costs and risks with no compromise on safety. Tensile and shear tests performed on sealant H-bars and Hockman cycle tests simulating accelerated life cycles at different deformation rates are used to exploit the deformation capability of the joints correlated to residual strengths. The comparison of different structural sealants enables an even more active use of structural silicone joints for improving the resilience of specific curtain wall units.
Authors
Viviana Nardini
Market Field Engineer Facade / Insulating Glass
nardini.viviana@ch.sika.com
Florian Doebbel
Business Development Manager, Facades
Sika Corp.
doebbel.florian@us.sika.com
Introduction
Past earthquakes have focused the attention on the performance of facades and architectural glazing, revealing their seismic vulnerability. Two major concerns related to their performance during and after a seismic
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Seismic Design Requirements for Glazed Curtain Walling in Building Codes
Even if an increased attention is arising on the seismic response of glass facade systems, only limited guidelines are provided to design and evaluate architectural glazing systems exposed to earthquake
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Benefits Offered By SSG Systems in Areas Prone to Earthquake
Captured glazed systems in unitized curtain walling typically consist of glass panels retained to a main frame by mechanical means able to transfer the loads acting on the glass panels
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Concept for Seismic Design of SSG-Joints In Unitized Curtain Walling
Even if the benefits offered by SSG systems in CW exposed to earthquake are widely recognized, no official regulation currently provides clear seismic design criteria or performance levels to ensure
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Conclusions
Even if the benefits offered by Structural Sealant Glazing systems in unitized curtain walling exposed to earthquake are widely recognized, current available standards provide very poor guidelines to assess the
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References
EN 1998-1, Eurocode 8: Design of Structures for Earthquake Resistance – Part 1: General Rules, Seismic Actions and Rules for Buildings (2004).
ASCE 7-10, Minimum Design Loads for Buildings and Other Structures (2010).
AAMA 501.6-09, Recommended Dynamic Test Method for Determining the Seismic Drift Causing Glass Fallout from a Wall System (2009).
AAMA 501.4-09, Recommended Static Testing Method for Evaluating Curtain Wall and Storefront Systems Subjected to Seismic and Wind Induced Interstorey Drift (2009).
FEMA E-74, Reducing the Risks of Nonstrcutral Earthquake Damage – A practical Guide (2012).
JASS 14, Japanese Architectural Standard Specification – Curtain wall, AIJ (1996).
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EOTA ETAG002-1, Structural Sealant Glazing Systems – Part 1, 2012.
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Nardini, V., Doebbel F.: Concept for Seismic Design of structural Silicone Joints in Unitized Curtain Walling. Conference Proceedings, Glass Performance Days 2015 – Tampere, Finalnd, 26-31 (2015).
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