Shapes of Prestressed Concrete Bridges for Aesthetic Construction
Following are the different shapes of prestressed concrete bridges for aesthetic construction:- Shape of superstructure
- Shape of pier
- Underside appearance of a bridge
- Creating shadows
Shape of Superstructure for Aesthetic Prestressed Concrete Bridges
Depend on structural needs the dimensions of bridge superstructures are established. The Seventh Street Bridge in Fort Lauderdale as shown in Figure-1 is considered as an example of superstructure shape and how it provided aesthetic appearances will be discussed. Due to its attractive appearances, the form of closed box girder of the Seventh Street Bridge in Fort Lauderdale is determined. The aesthetic appearance of the closed girder box is originated from perfectly regular surfaces of continuous level planes. There is a cantilever at the tip of the girder box that provides pleasing shadow effects. There are long spans over land on both sides of the river joining to the major span crossing the Intra-costal waterways. The bridge sculptural shapes and the smooth underside improve the attractiveness of green areas and parks underneath the bridge. There are other examples of bridges that their superstructure shapes provide aesthetically appealing appearances such as shown in Figure-2.
Fig.1: Seventh Street Bridge in Fort Lauderdale
Fig.2: The Unique Box Shape of Tampa’s Lee Roy Selmon Crosstown Expressway Expansion was an Economical Solution to Achieving Aesthetic Goals.
Shape of Pier for Aesthetic Prestressed Concrete Bridges
Generally, the shape of piers is extremely significant element for producing attractive lines and shadows and slender piers with taper at the top create graceful connection with super structure for example San Antonio Y bridges that is shown in Figure-3. Generally, the connection and relation and environmental effects of the cross-sectional shape of piers need to be considered sufficiently. There are number of pier shapes that have been utilized for different situations and at the same time provided aesthetical appearances for example elliptical shape that give classic appearance as in Figure-4. Not only do elliptical shapes provide aesthetical appearances but also it may decrease the drag condition of hurricane wind condition. Twin wall cast in place concrete pier is another shape which withstands unbalanced loads on foundations and offer aesthetic appearance, as shown in Figure-5. It is possible to improve visual appeal of a bridge by introducing monolithic connection between pier and super structure if omitting bearing is permitted.
Fig.3: San Antonio Y Bridge, Subtly Shaped Pier
Fig.4: Elliptical Pier Shape Provides Aesthetical View and Deduce Wind Drag
Fig.5: Twin Wall Cast in Place Concrete Pier
Underside Appearance of a Bridge
It is substantially significant to take all visual vantage points such as tourists or passengers travel underneath the bridge, pedestrians, and passenger in the cars goes underneath or over the bridge into consideration during the design of the structure. All travelers have special view of the bridge and value the visually appealing of the structure. Broad Way Bridge which is shown in is a compelling example for underside aesthetic appearance. This bridge is seen by travelers and pedestrians in the park close to the river and special attention was paid to this visual vantage point. The elliptical pier of the bridge covered with glass mosaic tile on which large dolphins and manatees are painted. The manatees and dolphins are painted in such a way that provides a sense of movement to those who see the piers. Finally, well designed lightings are applied for the piers which not only improve aesthetic appearance of the pier but also illuminate the murals at the evening. Figure-6 exhibits an esthetical appearance to the piers and show visual attractiveness to the viewers.
Fig.6: Mosaic Tile Provide Attractive Scene to the Views
Creating Shadows for Aesthetic Prestressed Concrete Bridges
To generate shadows that enhance aesthetic view of the bridge through shapes and contour feature of bridge elements, both natural lighting and artificial lighting need to be assessed. The latter might include both aesthetic lighting and roadways lighting that utilized for safety purposes. It is important to consider the whole bridge structure while establishing shadows to improve bridge visual appealing because all elements of substructure and superstructure need to work with each other to produce shadows that continuously changing. This change is generated when the condition of lighting is changed and exceptional effects will be created during movement of light source and the shadows it creates change. The sun light is a source that moves continuously over time during day, thus different feature of the bridge, which exposed to natural sunlight, will be seen differently during the day. The major part of the bridge that creates shadows is the superstore. A convenient space can be created under the bridge for the travels through constructing long slim piers. Moreover, it is possible to improve underside bridge view by creating patterns longitudinally which cast into the superstructure. These longitudinal patterns make aesthetically shadowing effects. The changes in the slope of the vertical web of piers lead to generate depth illusion. The application of vertical lines on the piers by curved or chamfered edges are so significant that help the piers to appear attractively, more graceful, and the piers will mix with surrounding environment. An example of using vertical line utilization is Blue Parkway Viaduct that it’s cross sectional shape is octagonal and its aesthetic appearances are improved by concave faces, and the bridge mix with mountain.
Fig.7: Blue Bridge Parkway Viaduct
Read More: Aesthetics Consideration of Long Span Prestressed Bridges at Conceptual Design Phase