Development of Blast Resistant Panels and Wall Systems Made of Engineered Cementitious Composites and Light-Gauge Steel Sheets

Abstract

This thesis outlines experimental and numerical research that was performed for the fulfillment of doctoral requirements at the Civil Engineering Department of the University of Ottawa. The thesis research is aimed at developing blast-resistant cementitious panels reinforced with light-gauge steel sheets and blast-resistant wall systems consisting of the panels and the supporting hollow steel sections (HSS) acting as studs. It consists of experimental and numerical components. The experimental research involves large-scale tests of panels and walls under simulated blast loading using the shock tube facility of the University of Ottawa. The numerical research involves finite element analysis (FEA) using LS-Dyna software to simulate blast loads and the behaviour of panels under these loads. The numerical research also includes a parametric study for investigating the blast resistance of various panel configurations that are not included in the experimental program. Four different types of panels were included in 16 panel tests. They consisted of two layers of engineered cementitious composites (ECC) with either 1.5 mm or 3.0 mm thick steel sheets sandwiched in the middle. The panel layers were connected by means of self-drilling screws as shear connectors to ensure composite action, spaced at either 100 mm or 200 mm. Each panel was 510 mm (20 inches) wide, 2080 mm (82 inches) tall, and 15 mm (5/8 inch) thick to keep the weight approximately equal to 50 kilograms, which facilitates easy installation. The panels were tested in three different configurations: first, they were tested as panels only without any HSS studs; second, connected to vertically placed hollow steel sections (HSS) that were relatively flexible; third, they were connected to vertically placed HSS that were at the front and back of the panels for increased strength and rigidity. A fifth set, consisting of only 1.5 mm and 3 mm steel sheets, was also tested to assess the contribution of ECC to panel behaviour. The results of the shock tube tests indicated that the panels are suited for use as blast-resisting elements with significant ductility. The panels with 100 mm connector spacing performed better than those with 200 mm connector spacing due to the enhanced composite action. The wall systems consisting of the panels and the HSS studs resulted in increased blast resistance for use in increased threat scenarios. In the analytical phase of research, the finite element models were first validated against shock tube test data. Using the validated models, a parametric finite element study was performed by varying the model parameters. This parametric study included specimens with HSS members and 3 mm steel sheets without the ECC layers; panel-only specimens with higher contact explosion strength; panel-only specimens with thicker ECC layers; partition wall type panel-HSS-panel specimens; and a ballistic penetration model for ECC-steel-ECC panels and steel sheet panels. The results of the experimental and analytical research indicate that 15 mm thick panels with 3 mm thick steel sheets provide significant protection against blast loads when used in conjunction with HSS members. The partition wall type panels with HSS members as main vertical structural elements, enclosed by an ECC-Steel-ECC panels on both sides, provide an attractive alternative to existing blast mitigation strategies for creating a blast-resistant enclosure with the added advantage of ease and speed of installation stemming from their lightweight.