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Previous studies have shown that earthquake repair costs can be minimised by using large levels of supplemental damping and uniform damper placement. However, it is not always feasible to achieve this damping due to structural or financial restraints. Iterative damper placement methods may be able to achieve higher levels of damping than simple methods such as uniform damping for the same total damper cost. In this work, six damper placement methods were assessed based on structural and non-structural repair costs. The total damper cost was constrained to be the same in each case. The scope of work was limited to linear fluid viscous dampers, concentric braced frames and regular structures. The iterative methods were found to provide a greater total damping coefficient to the structures than the simple methods. This resulted in a higher supplemental damping ratio and lower repair costs. If upfront funds are limited, or if architectural constraints prevent the placement of dampers in lower storeys, then iterative methods provide the most favourable total-building seismic performance. However, the conclusions should be extended cautiously. Although iterative methods are favourable when the upfront damper investment is strictly limited, in terms of total-building seismic performance, it is advantageous to provide a large damping ratio using uniform damping.

BackgroundThe main risk of capsule endoscopy is retention of the capsule behind a stricture. Passage of an intact Agile patency device (Medtronic, Dublin, Ireland) through the small bowel is widely used to ensure luminal patency, although capsule retention has occurred in patients who have had a reassuring patency study. The device is designed to remain intact for at least 30 hours postingestion, such that loss of signal from the radiofrequency identification tag contained within, or absence of the device on radiological imaging, implies unimpeded intestinal transit.AimTo identify the rate of premature dissolution (MethodsOutcomes of all consecutive patients having an Agile patency device were analysed.ResultsPremature dissolution of the patency device occurred in 5 of 307 patients, an incidence of 1.3%. This was recognised by the detection of a persistent radiofrequency signal after radiological imaging had failed to identify the patency device, prompting a careful search for the radiofrequency tag on the CT scout film. The tag was difficult to detect because of an oblique lie making it appear smaller than its 13×3 mm size and confusion with intra-abdominal or other metallic fragments.ConclusionsIn the absence of radiological evidence of an intact Agile patency device, premature dissolution should be suspected in patients registering a persistent radiofrequency signal and confirmed by identifying the radiofrequency identification tag. Failure to do so might result in false reassurance that capsule endoscopy could be performed without risk of retention.

Previous research has revealed that Eurocode-compliant structures can experience structural and nonstructural damage during earthquakes. Retrofitting buildings with fluid viscous dampers (FVDs) can improve interstorey drifts and floor accelerations, two structural parameters that characterize seismic demand. Previous research focusing on FVD applications for improving seismic performance has focused on structural performance. Structural parameters such as interstorey drifts and floor accelerations are often evaluated. Complexities arise as these parameters are often competing objectives. Other studies use damage indices that are influenced by several assumptions to represent performance. The use of repair costs is a more appropriate measure of total-building seismic performance, and avoids these limitations. This study investigates the application of linear FVDs to improve total-building seismic performance considering repair costs. The energy-based method commonly used to calculate damper coefficients is modified to improve its accuracy. The optimal amount of damping with respect to repair costs (estimated using the FEMA P-58 procedure) is identified as 25–45%. This contrasts with a previously suggested optimal damping of 20–25%, based on structural parameters, that is frequently targeted. This study on the damping-repair cost relationship provides insight when selecting levels of damping for structural designs and retrofits. It also highlights that retrofit methods may be enhanced by using repair costs, rather than structural parameters. The FVD buildings significantly reduce both drift-sensitive and acceleration-sensitive damage. Structural damage is also negligible in the FVD buildings: a major step towards achieving building serviceability following an ultimate limit state level earthquake.