Date of Award
Master of Science
Civil, Construction, and Environmental Engineering
Cladding systems are conventionally designed to provide buildings with environmental protection against wind, temperature, humidity, moisture, etc. Recently, researchers have proposed to leverage these systems to provide additional protection against manmade (e.g., bombs) and natural (e.g., earthquakes, hurricanes) hazards. This can be achieved, for example, by redesigning the connection cladding-structure to provide energy dissipation capabilities. While promising, these strategies are typically effective against single types of hazards. Here, we propose to utilize a novel semi-active damping system connecting cladding to the structure. This system is based on a variable friction mechanism. By varying the normal force applied on the friction plates through a system of moving toggles, it is possible to mitigate vibrations over a wide frequency range, therefore making it useful to mitigate different types of hazards, or multi-hazards. In a passive mode, i.e. unactuated, the device is designed to provide very high stiffness and friction resistance to provide blast mitigation capabilities.
The objective of this thesis is to enable a holistic integration of such device within the structural design process by developing performance-based design procedures. The study will focus on the passive mode of the device, which will provide a stepping stone for the development of performance-based design procedures for its semi-active, i.e. actuated, capabilities. The proposed performance-based design procedure consists of: 1) determining the design performance criteria, including the blast properties and allowable distance cladding-structure; 2) selecting design properties for the cladding connection, including stiffness and damping; and 3) designing the impact rubber located between the structure and the cladding in order to prevent the cladding from impacting the structure.
In this work, we first describe the novel semi-active device in the context of cladding systems designed for blast resistance. It is followed by a description of the proposed performance-based design procedure, which includes the derivation of different models to simply the derivation of key equations. These equations are then used to provide design guidance. The proposed design procedures are verified and validated on a single degree-of-freedom model, on a two degree-of-freedoms model, and on a realistic four stories structure. Results show that the design methodology can be applied for the semi-active connection utilized in a passive mode against blast load.
Lu, Sijia, "Performance-based design prodedure for a novel semi-active cladding connection applied to blast mitigation" (2017). Graduate Theses and Dissertations. 16171.