Application of regularization methods to damage detection in large scale plane frame structures using incomplete noisy modal data

This paper presents an approach for detecting local damage in large scale frame structures by utilizing regularization methods for ill-posed problems. A direct relationship between the change in stiffness caused by local damage and the measured modal data for the damaged structure is developed, based on the perturbation method for structural dynamic systems. Thus, the measured incomplete modal data can be directly adopted in damage identification without requiring model reduction techniques, and common regularization methods could be effectively employed to solve the developed equations. Damage indicators are appropriately chosen to reflect both the location and severity of local damage in individual components of frame structures such as in brace members and at beam-column joints. The Truncated Singular Value Decomposition solution incorporating the Generalized Cross Validation method is introduced to evaluate the damage indicators for the cases when realistic errors exist in modal data measurements. Results for a 16-story building model structure show that structural damage can be correctly identified at detailed level using only limited information on the measured noisy modal data for the damaged structure.

Numerical and experimental studies of a substructural identification strategy

For structural health monitoring it is impractical to identify a large structure with complete measurement due to limited number of sensors and difficulty in field instrumentation. Furthermore, it is not desirable to identify a large number of unknown parameters in a full system because of numerical difficulty in convergence. A novel substructural strategy was presented for identification of stiffness matrices and damage assessment with incomplete measurement. The substructural approach was employed to identify large systems in a divide-and-conquer manner. In addition, the concept of model condensation was invoked to avoid the need for complete measurement, and the recovery process to obtain the full set of parameters was formulated. The efficiency of the proposed method is demonstrated numerically through multi-storey shear buildings subjected to random force. A fairly large structural system with 50 DOFs was identified with good results, taking into consideration the effects of noisy signals and the limited number of sensors. Two variations of the method were applied, depending on whether the sensor could be repositioned. The proposed strategy was further substantiated experimentally using an eight-storey steel plane frame model subjected to shaker and impulse hammer excitations. Both numerical and experimental results have shown that the proposed substructural strategy gave reasonably accurate identification in terms of locating and quantifying structural damage.

I wanna be a protocol: online media and electronic structures of kinship

Heidegger famously identified Modernity with a technological leveling of being to a single order of a “standing reserve.” In a radically different tone, Gilles Deleuze articulated a single “plane of immanence” within which ontological distinctions between mind and body, God and world, interiority and exteriority become indiscernible. Taking such philosophical declarations as points of departure, this panel will consider how a collapse of ontological distinction emerged as a thematic and structural trope in literary and cinematic modernisms. We hope to consider how writers and film-makers of the 20th c. utilize the resources of their media to ask “the question of being” that troubled their philosophical contemporaries and heirs. In this vein, we will examine how these modernist ontologies of immanence describe the crisis of a subject saturated and eclipsed by a world which comprises her while also remaining strange or opaque. Papers will ask what is lost with the departure of a distinctly human sense of “being” and how the historical arrival of an alternative ontological order may be evident in the lived experience of modernity. In this sense, the relationship to departures and arrivals becomes the modern subject’s suspicion that he is unable to do either vis á vis the world.