Browsing by Subject "Buildings -- Protection"
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Item Concrete block masonry construction to resist severe winds(Texas Tech University, 2001-08) Al-Menyawi, Yahya MohammedUnreinforced masonry is a common construction system for low-rise commercial buildings. It is often used as load-bearing wall system in large low-rise buildings such as malls, warehouse and industrial buildings. Failure of such construction type is prevalent during severe windstorm events such as tornadoes, hurricanes and severe thunderstorms. Resistance of masonry construction to wind depends on the out-of-plane strength of the exterior walls. Out-of-plane strength of unreinforced masonry walls depends mainly on the wall modulus of rupture (MOR). The statistical analysis of previously published investigations gives a mean value of the MOR of 55.5 psi with a COV of 26%. Wind-induced load is probability-based and involves variables of wind speed, terrain exposure, building enclosure type, and pressure direction. The Monte Carlo Simulation using 1,000 observations of the MOR and the wind-induced loads is used to determine the probability of failure of walls. For a wall of 10-in. thickness and 15-ft height of a partially enclosed building located in terrain exposure C in Lubbock, Texas, the probability of failure is 94% in 50-year life of the building. A target probability of failure of 1.5% in a 50-year life is ascertained from the current practice of masonry wall design. Failure strength of intermittently reinforced walls is determined using yield-line theory analysis. A mathematical methodology to relate the target probability of failure to the intermittent reinforcement spacing is introduced. It is found that a wall with intermittent reinforcement placed at a spacing equal to the wall height would survive in areas with design wind speeds up to 120 mph.