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An experimental study was conducted to investigate the effectiveness of strengthening the intersection of flanged concrete block shear walls using surface-bonded composite laminates. A total of 15 specially designed flange-web intersecting wall specimens were tested using four different retrofit schemes. Tests included wall intersections reinforced with unidirectional laminate with the fibers oriented perpendicular to loading direction (90°), and bi-directional laminate with orientations of (90°/0°), (90°/0°) 2, and (45°/135°) to the applied load direction. The behavior of each specimen type is discussed with respect to its failure mode, strength, and deformation characteristics. Results showed that the composite laminates significantly increased the shear strength of concrete block shear wall intersections. In addition, the fiber orientation influenced the failure mode and controlled the development of the post-peak deformation capacity of the flange-web intersection. The improved post-peak behavior demonstrated the benefits of retrofitting concrete block wall intersections for strength enhancement. The retrofit scheme resulted in 100%—400% increase in strength compared to non-retrofitted specimens constructed with traditional steel joint reinforcement.

Friction and wear are major concerns in the performance and reliability of micromechanical (MEMS) devices. While a variety of lubricant and wear resistant coatings are known which we might consider for application to MEMS devices, the severe geometric constraints of many micromechanical systems (high aspect ratios, shadowed surfaces) make most deposition methods for friction and wear-resistance coatings impossible. In this program we have produced and evaluate highly conformal, tribological coatings, deposited by atomic layer deposition (ALD), for use on surface micromachined (SMM) and LIGA structures. ALD is a chemical vapor deposition process using sequential exposure of reagents and selflimiting surface chemistry, saturating at a maximum of one monolayer per exposure cycle. The self-limiting chemistry results in conformal coating of high aspect ratio structures, with monolayer precision. ALD of a wide variety of materials is possible, but there have been no studies of structural, mechanical, and tribological properties of these films. We have developed processes for depositing thin (

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We report a hybrid atomic layer deposition (ALD) / molecular layer deposition (MLD) approach that produces a new class of hybrid organic-inorganic films. These novel films have very low densities, yet display typical ALD characteristics: controllable linear growth, conformality, low roughness, and uniform composition. The etch behavior of these materials indicates that they are completely removed in acidic solutions. Due to their low density and high carbon content, the new hybrid materials are promising as protective coatings and sacrificial layers in MEMS/NEMS devices.