MKP Structural Design Associates (United States)

<p>The White River Bridge will become a key link extending the regional Foothills Trail, which when complete will run more than 48-km through communities and scenic landscapes in the shadow of Mount Rainier. The three-span arch footbridge will become a destination where users can linger over the beautiful White River. It will also provide a much-needed secondary route for emergency vehicles.</p><p>The total bridge length of 174m is divided over three network arch spans. Network arches create a very transparent structure that is very stiff. The crisscrossing hanger pattern of the structure can carry heavy point loads from a fire truck without distressing members. Generous lookouts at the central pier will provide an area for users to linger and take in views of the river.</p><p>Key elements of the design included selection of the preferred geometry of the arch spans, optimization of the hanger pattern, fabrication and construction considerations, and seismic design approach using base isolation of the superstructure atop the supporting piers. The erection sequence of the large spans has been an up-front consideration with every effort to minimize disturbance to the wooded site. User experience and aesthetics are a focus of design, but with equal emphasis on economy and efficiency. This footbridge showcases how all these aspirations can be achieved with the right design approach.</p>

Fibre reinforced plastic, FRP, shear bolt system has been recently developed at the University of Waterloo, Canada. The system can be used to protect existing reinforced concrete slabs against brittle and sudden punching shear failure. The retrofit procedure requires drilling small holes in a slab around the perimeter of a column, inserting bolts into the holes and anchoring the bolts at both external surfaces of the slab. Many existing reinforced concrete slabs had been built without any shear reinforcements. Also, many of these slabs are in corrosive environments, e.g. in parking garages where the use of de-icing salts accelerates reinforcement corrosion and concrete deterioration. Therefore, FRP is an ideal material to be used for such retrofit. The challenge, however, has been the development of mechanical end anchorages for FRP rods that is efficient, aesthetic, cost effective, and that can be applied on-site. In the presented research six isolated slab-column specimens were constructed representing interior slab-column connections in a continuous flat plate slab system. The specimens were subjected to simulated gravity and gravity plus seismic loadings. A new anchorage technique for the FRP rods was developed, which is based on crimping the rod ends with the aluminum fittings. Using this approach, fairly large loads can be resisted by the end-fittings. The developed FRP bolts worked very well improving the performance of the slab-column connections and showing the benefits of using FRP in punching shear retrofit of reinforced concrete slabs.