Graduate Thesis Or Dissertation


Direct Shear Interface Friction and Linear Motion Shaking Response of Ecoroofs Public Deposited

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  • Ecoroofs have become more prominent in recent years. However, there is currently no enforceable standard or building code for the design and construction of ecoroofs across the United States (Kraupa, 2014). Further research is needed to determine how ecoroofs respond to roof motion and to develop an appropriate design standard.The work herein attempts to examine the complete ecoroof system and its response when subjected to motion. Direct shear interface testing was performed to determine the coefficient of friction at the interface between each layer of the ecoroof. The interfaces were tested under both dry and submerged conditions for soil depths of 100 mm (4 in), 300 mm (12 in), and 900 mm (36 in) to model both extensive and intensive soil conditions. These coefficients of friction tell at which interface the system is most susceptible to sliding, and at what point this sliding will begin. When root barrier is used, its interfaces are critical to sliding. When root barrier is excluded from the ecoroof system, the insulation board Tremco drain mat & filter fabric interface is most susceptible to sliding.Additionally, a shake table was designed and built to subject model ecoroofs to linear motion. Model ecoroofs of varying soil densities, moisture conditions, and slopes were subjected to haversine acceleration pulses. The goals of this testing were to access the potential for soil decoupling from the roof, to determine the extent of this decoupling, to determine how decoupling is impacted by roof slope, soil density, and moisture conditions, and to determine which intensity measure or measures best predicted the observed decoupling. It was determined soil decouples from the roof when velocity exceeds a critical threshold. The magnitude of decoupling is greatest under submerged soil conditions, greater for loose than for dense soil placements, and generally increases with increasing roof slope. Such information is paramount in the development of an ecoroof design standard to ensure public safety.
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