Although the Winter Park Library and Events Center is located just a few miles from Orlando, Fla., and its theme parks, this bold, three-building ensemble is figuratively worlds away. This monumental public landmark boasts angled exterior precast concrete walls and shaded outdoor areas. The buildings splay out dramatically and nearly touch. The rose-colored pigmented architectural precast concrete panels convey a distinctive look, with exterior walls that lean outward as they rise from the base. The convex exterior walls would have been almost impossible to achieve with any other cladding material. The texture, color, aggregates, and concrete matrix for the precast concrete panels were carefully selected for aesthetic value, durability, and low maintenance. The panels were finished with a glass-blast treatment to expose four different types of aggregate in the concrete matrix. This finish creates an appearance that changes with the angle of sunlight.
As part of the extensive revitalization of a 23-acre public park, the new library and events center create a campus that serves as a civic and cultural hub. The three structures are a two-story library, an events center with rooftop terrace, and a portico that ushers visitors from the street and welcomes them into the campus. Each of these three buildings is distinctive in scale and function, but a common aesthetic sensibility unites them.
Large windows bring in abundant natural light and provide sweeping views of the surrounding park. Despite its sprawling size and heavy mass, the vaulted framework elegantly inserts itself into its location on a belvedere overlooking a lake. Inside the two-story library, there is a flexible inner core with moveable walls that includes a community room, a makers’ room, and an archive.
The project team faced challenges associated with the intense sun, wildlife habitats, and native trees that had to be protected. The design team modeled compound, convex exterior walls with a series of scalloping, frond-like patterns that allude to native vegetation. The design modeled innovative ways of moderating intense sunlight. All panels were built using twisting-shaped forms with connection plates set at twisted and varying elevations.
The outward slanting precast concrete panels posed the biggest precast concrete engineering design challenge. The degree of slant varies from the corners to the middle of the building. Construction using these pieces created handling and installation challenges, especially on the corner where all three buildings meet. The team had to carefully review the construction sequencing because parts of the library overlapped with the events center and portico, which restricted access.
Installing panels at an acute angle was a particular challenge. Panels had to be pulled into the building at the bottom, which required a way to “hold” the panels. A model with precise coordinates was sent to a third-party surveyor hired by the erector. To release each panel, every corner of that piece was shot to elevation and plane. Only a few panels could be made with a single mold, as each panel was designed with a different skew or twist or angle, resulting in unique erection picks.
The arches establish the form of the pavilions, with vaulted rooflines and sweeping windows creating a porous relationship between interior and exterior as natural light is drawn deep into the buildings. Given the constantly changing slant and varying radius arch, the angle between the precast concrete panel and building structural steel beams is varied from panel to panel. To reduce the number of different bearing connections, a rolling bearing connection design was used; notably, the rolling bearing connection was also an erection-friendly connection. Lateral connections near the bottom of the panels used a push-pull connection that allowed for easy adjustment of the slant of the panel. This design proved to be very efficient and effective in the field.
The panel types on the buildings are unique. Finite element analysis was performed on each panel type to analyze stress changes during shipping and erection, and to ensure that the precast concrete facade can withstand hurricane-strength winds. Because the design features unique forms with limited repetition, 50 different forms were needed for the three buildings. The finish had to be uniform over a steep incline since the concrete wanted to flow to the lowest level. Radiused and warped shapes required extra attention during the placement of concrete, reveals, and side rails. All production forms were fabricated with stacked plywood cut on a computer numerical control (CNC) machine to ensure accuracy.
Having overcome myriad design and construction challenges, the project team created structures that showcase innovation, engineering, and craftsmanship. The rose-colored precast panels defy gravity with their asymmetrical shapes and placement. This project was possible because of the creativity of the project team and the fluidity of precast concrete.