Performance of Partially Grouted, Minimally Reinforced CMU Cavity Walls against Blast Demands. I: Large Deflection Static Resistance under Uniform Pressure

This paper presents the results of large-deflection resistance testing of partially grouted single-wythe and multiwythe insulated masonry walls. Three design sections were evaluated under uniform pressure in a vacuum chamber test, as follows: (1) 150-mm (6-in.) standard block masonry wall reinforced with 10-mm (No. 3) rebar at 80-cm (32-in.) maximum spacing; (2) 200-mm (8-in.) standard block masonry wall reinforced with 13-mm (No. 4) rebar at 120-cm (48-in.) maximum spacing; and (3) a cavity wall consisting of 200-mm (8-in.) standard reinforced concrete masonry unit (CMU) wythe, a 100-mm (4-in.) clay facing brick veneer with 50-mm (2-in.)-thick extruded polystyrene rigid board insulation, and a 25-mm (1-in.) air gap between the structural wythe and the veneer. Each test panel was 3.5-m (136-in.) wide x 3.0-m (116-in.) high with only the cells containing reinforcement grouted. Displacement at several locations through the height and width of each panel were recorded as each test panel was loaded to collapse. Interior and exterior videography was also used to record the progression of cracking and failure. The failure mechanisms demonstrated the expected tension cracking due to flexure and a ductile flexural response was observed with rotations up to approximately 20 degrees. The resistance function results were plotted and assessed against the resistance definitions assumed by commonly used blast design methodologies, and it was demonstrated that the flexural design resistances used in blast analysis single degree of freedom methodology are conservative. Furthermore, since the 200-mm (8-in.) thick singlewythe wall and the veneer wall had the same structural wythe designs, the stabilizing effects provided by the clay brick veneer and cavity wall components was demonstrated. The resistances and failure modes will subsequently be compared in the companion paper against those encountered in full-scale blast tests involving the same masonry panel designs. (C) 2014 American Society of Civil Engineers.