Blast response of structural envelope elements : LG windows and CFS roof trusses

Abstract

[EMBARGOED UNTIL 5/1/2025] Building safety continues to be a concern due to the increasing number of explosion threats targeting civilian and government buildings. Building envelope elements, such as walls, windows, and roof truss systems, are particularly vulnerable during an external blast event. Although recommendations for blast design of wall systems, including cold-formed steel (CFS) studs, concrete, CMU, and tilt-up precast/prestressed panel wall systems, have been developed through extensive research, there is limited understanding of the blast response and resistance of windows and roof truss systems. Therefore, in this dissertation, the blast response and resistance of these two critical structural envelope elements, namely laminated glass (LG) windows and CFS roof trusses, were evaluated numerically and experimentally to predict their performance under blast loads. The static resistance function of different LG panels was experimentally evaluated. Numerical models were developed and validated using experimental data to predict the response of LG systems under static and dynamic loading conditions. An elasto-damagebased model using the VUMAT user subroutine in Abaqus was developed to capture the brittle failure in the glass. Furthermore, the validated numerical models were used to investigate the effect of different design parameters. Tests were conducted using two types of polymeric interlayer materials used in LG panels, such as, PVB and SG6000, under quasi-static loading rates to develop engineering stress vs. strain responses and identify key parameters. The longitudinal engineering strain throughout the tests was measured using digital image correlation techniques, and strain localization curves were produced at key loading points to gain a better understanding of laminated glass behavior under quasi-static loading conditions. For the CFS truss systems, numerical models were developed and validated using experimental results of full-scale truss systems. The validated models were used to predict the static resistance function of different roof truss systems. The research findings will contribute to the development of engineering-level blast-resistant analytical and design recommendations for CFS roof truss systems. The results of this dissertation will improve the existing blast design methods for predicting the dynamic response and dynamic reactions of LG panels and CFS roof truss systems used as structural envelope elements under blasts, which will enhancing building safety under extreme loading caused by explosion threats.