Oxidized zirconium, a material with a ceramic surface on a metal substrate, and highly cross-linked polyethylene are two materials developed to reduce wear. We measured in vivo femoral head penetration in patients with these advanced bearings. We hypothesized the linear wear rates would be lower than those published for cobaltchrome and standard polyethylene. We retrospectively reviewed a select series of 56 THAs in a relatively young, active patient population utilizing oxidized zirconium femoral heads and highly cross-linked polyethylene acetabular liners. Femoral head penetration was determined using the Martell computerized edge-detection method. All patients were available for 2-year clinical and radiographic followup. True linear wear was 4 lm/year (95% confidence intervals, ± 59 lm/year). The early wear rates in this cohort of relatively young, active patients were low and we believe justify the continued study of these alternative bearing surfaces.
<p>This project included the construction of a new three-span, 170 m-long steel box girder bridge to replace the existing St. George’s Island Bridge over the Bow River. The new bridge is composed of variable depth (arched), rectangular, steel box girders. Flood resiliency and sustainability were major considerations in the design of the bridge. The girders have a curved profile that allows for the majority of the superstructure to sit at least 1 m above the 1:100 year flood level. To minimize the work required over the river, full-depth, full-width, precast concrete deck panels were used. The panel-to-panel and panel-to-girder connections were made with Ultra-High-Performance Concrete (UHPC). Continuity of bridges with full-depth precast panels is usually provided by longitudinal post-tensioning. This was not preferred due to concerns about future deck rehabilitations. Therefore, the design relies on reinforcement splices for continuity. UHPC made it possible to transfer longitudinal forces in relatively short splice lengths. To verify the efficiency of these connections, some of the panels and connecting joints were instrumented with wireless strain gauges to monitor force transfer between adjacent panels. The paper includes a description of the bridge structure (girders and the precast deck panels) and the initial results of the strain monitoring.</p>
<p>The Calgary Airport Trail Tunnel (CATT) is a 620-m-long roadway tunnel constructed under the Calgary International Airport’s (YYC’s) new parallel runway and three associated taxiways owned by The City of Calgary (The City) on land leased from YYC. The CATT was designed according to the Canadian Highway Bridge Design Code (CHBDC). The question arose during the design stage if the tunnel, which is a buried structure, would be subjected to the same temperature effects (range and gradient) given in CHBDC for bridges. To investigate this question for future designs, a system of wireless sensors was installed in the CATT to monitor temperatures with data being collected remotely. The paper includes an overall explanation of the CATT’s design, temperature monitoring instrumentation, and initial findings, including comparisons with temperatures recorded outside the tunnel, and the temperature range and differential provided by the CHBDC.</p>
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