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Phyllis J. Tilley Memorial Bridge in Fort Worth, Texas by Rosales + Partners Architects
March 8th, 2013 by Sanjay Gangal
Article source: Rosales + Partners Architects
The Phyllis J. Tilley Memorial Pedestrian Bridge crosses over the Trinity River connecting Trinity Park to a new trail that terminates in downtown Fort Worth. The bridge has a graceful profile that enhances the serene and beautiful landscape. A steel arch with a span of 163’ (49.5m) supports steel stress ribbon segments and precast concrete planks over the river complementing the adjacent historic Lancaster vehicular bridge.
This 368’ (112m) long steel stressed ribbon/arch combination bridge is the first of its kind in North America. This unconventional structural combination was selected as a result of the site conditions, visual objectives, and the desire of the City of Fort Worth to build a special and memorable structure along the river.
The arch spans the entire river and the steel stressed ribbons sit airily over the rounded arch, appearing to flow toward the abutments. The minimal sag profile of the stressed ribbons creates major tension loads which are balanced against the thrust loading in the opposite direction caused by the steel arch. The balancing of these opposing loads minimizes the required size of the foundations.
A rounded abutment saddle, with its carefully calculated radius was chosen to ensure that bending stresses never exceed a critical level, increasing the durability of the overall bridge structure. Pre-fabricated concrete planks have been anchored directly to the steel stress ribbons to form the bridge walkway, eliminating the need for temporary scaffolding in the river and on the adjacent shorelines.
The absence of vertical support struts reduces horizontal loads created by periodical river flooding. Pedestrians and bicyclists crossing the bridge will experience a smooth, undulating ADA compliant bridge surface. At night, the bridge is illuminated by a combination of white and blue LED lighting for increased safety and aesthetic appeal. This elegant and cost effective bridge has become a visual asset along the Trinity River and a new symbol of the City of Fort Worth.
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