Author: N. A. Ibraheem (Iraq Ministry of Science & Technology)
4 January 2016
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N. A. Ibraheem (Iraq Ministry of Science & Technology)
A tuned damping solution was developed to mitigate walking induced vibration of joist-framed floors in 25 rectangular, trapezoidal and irregular-shaped rooms in an educational facility. The make-up of the floors was concrete on metal deck, supported by open-web steel bar joists. The floors came in various sizes (800–1200sq.ft) and shapes, with the first resonant frequencies in the 6.5–7.5Hz range. Following the measurement of vibration and finite element analysis of the floors, 50 tuned mass dampers (TMDs) (two for each room) were designed, manufactured and installed to effectively address the vibration challenges of the first structural modes of the floors they were designed for. After installation of the TMDs, the effectiveness of the tuned damping solution was evaluated via further measurements. TMDs effectively dampened the first structural modes of the floors in various rooms and lowered their walking-induced vibration to acceptable levels.
The previous article in the Conservation compendium provided an introduction to common repairs and strengthening of structural timbers in historic buildings. This article continues by illustrating how structural timber fared at the Grade II listed Dunston Staiths in northeast England. The River Tyne has been a major discharge port for coal from the UK’s Northumberland and Durham coalfields for centuries. Staiths were constructed near the mouths of navigable rivers as a means of discharging coal from railway wagons into ships, and the Dunston Staiths were the largest timber structure in Europe at the end of the 19th century. Their repair history has been reasonably well documented and so they provide a good case study for timber deterioration, selection of repair species and strength analysis.
In this article, Phil Burge of SKF (U.K.) Ltd describes how sophisticated bearings systems are helping to keep a variety of cutting-edge civil and structural engineering projects in working order: whether it’s adjusting an enormous telescope, ensuring that a church bell keeps ringing, or moving the immense doors on an aircraft hangar, each comes with a challenge of its own.