WINTER PARK LIBRARY & EVENTS CENTER

Background

As part of the extensive revitalization of a 23-acre public park, the new Library & Events Center creates a campus that is in harmony with the unique tropical ecology of the site and redefines the role of the public library in the 21st century. This new civic and cultural hub, envisioned as a space for intergenerational community empowerment and edification, replaces existing library and civic center buildings. The new campus is conceived as a micro-village of three pavilions, each of a different scale and function but which share a common formal language. These pavilions include a two-story library, an events center with rooftop terrace, as well as a new welcome portico (porte cochère) that ushers users from the street and unifies the three structures.

During the early stages of design, the architect looked to the site’s history, climate, and context, which included research into regional structures such as other civic and public buildings. To further elevate the rich architectural history of stone and masonry structures, and to contribute to innovations in engineering, there were two aspects of the project that needed to be defined: 1) the building of these forms, and 2) identifying a unifying system that tied the buildings into a cluster of systems.

The site constraints required creative, efficient use of space for the buildings, the raised belvedere that the structures sit atop, and for parking.

During the conceptual phase of design, the team evaluated several structural and envelope systems including concrete and steel, cast-in-place concrete, and precast concrete cladding.

This state-of-the-art library and events center boasts angled exterior precast concrete walls and shaded outdoor areas. The buildings splay out dramatically and almost touch according to the library’s Architect of Record. “Through proximity, geometry, and form, the buildings create public, shaded outdoor environments conducive to social interaction. Precast concrete helps define the outdoor space as a special room.”

From arrival, to the library, to the events center are variations of the same motif of form and texture that is guided by biophilic design principles. The rose-pigmented architectural precast concrete panels give the trio of pavilions a distinctive look, with outer walls that lean outward as they rise from the base.

Through a well-coordinated effort, the precaster fabricated these complex panels, which frame the arched openings on each facade.

The buildings’ precast concrete facades are resilient to tropical storms and require minimal maintenance, while active and passive design strategies, including solar panels, deep overhangs and shading elements, tilted glass for greater reflection of direct sunlight, and high thermal mass, contribute to energy savings and reduction.

The quality and durability of the compound, 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.

Inspired both by local fauna and the region’s vernacular architecture, the structures’ graceful arches carved from the outward-sloping concrete facades establish the form of the pavilions, with vaulted rooflines and sweeping windows creating a porous relationship between interior and exterior, drawing natural light deep into the buildings. The diverse program includes flexible floorplates for both the library and events center, encouraging cross-pollination and maximizing adaptability for each.

As an ensemble, the Library & Events Center comes together as a space of social gathering, intellectual nourishment, and enhanced connection to its natural tropical context.

At the grand opening ceremony the Executive Director of the Library commented, “It’s a once in a generation project, creating a dynamic learning environment through amazing enhanced indoor and outdoor spaces.”

Design Challenges

Designing for a tropical, hurricane-prone environment was a big learning curve and yet a wonderful challenge. There were also challenges associated with unstable soil conditions, intense sun, wildlife habitats, and native trees that had to be protected. References to the Florida flora reacting to its environment became evident in the design. The design team modeled compound, convex exterior walls with a series of scalloping, frond-like patterns that allude to the native vegetation. The design modeled innovative ways of moderating intense sunlight.

Challenging Production Aspects

• All panels were built using twisted/warped shaped forms

• All connection plates were set at twisted/warped and varying elevations

• A bull float was used to vibrate the concrete so as not to let the aggregate and mix run from one side to the other following the form’s shape

3D modeling was used to build the project prior to constructing the steel structure, which helped the coordination of compounding angles. Meticulous planning and attention to detail are credited to very few field connection issues.

The biggest test of the general contractor’s expertise was coordinating the connection points from the precast concrete to the steel structure. When precast concrete wall panels lean away from the structure, it is difficult to check and coordinate the connections.

The outward slanting precast panels also posed the biggest precast engineering design challenge. The degree of slant varies from corner to middle of the building. The outward slanted panels create handling/erection challenges especially on the corner where all three buildings meet and overlap. The bottom of the outward slanting panels formed an arch with varying radius, which was challenging in panel analysis. The panel types on the buildings are unique. Finite element analysis (FEA) was performed on each panel type to analyze stress changes during shipping, erection, and to ensure the precast façade can withstand Florida hurricane winds.

Jobsite Challenges

• As oak trees are native to this region, and are rarely removed or even trimmed to accommodate new construction, extra precaution was taken on site when the precast erector was maneuvering around the oak trees on site.

• Because of unstable soil conditions, limestone rock was spread out and compacted along the crane path to facilitate crane tracking.

• The three buildings did not have complete 360-degree access. The GC and precaster met multiple times about sequencing as it was crucial since parts of the library hung over the events center and Porte Cochere.

• Installing panels at an acute angle was a challenge. Panels had to be pulled into the building at the bottom, which required a way to “hold” the panels while a come-along was used. Virtually no panels were set with a hand-held level or measuring stick. A model with precise coordinates was sent to a third party surveyor hired by the erector. In order to release each panel, every corner of that piece was shot to elevation and plane.

• Despite fewer panels being made with the same mold, each one was designed with a different skew or twist or angle, resulting in unique erection picks.

Innovations

Due to constantly changing slant and varying radius arch, the angle between the precast panel and building structural steel beams varied from panel to panel. This necessitated bearing connections to be different from panel to panel. To reduce the different bearing connections, a rolling bearing connection design was used which 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.

• Precast concrete panels were produced with unique forms with limited repetition. The panels for the three structures required 50 different forms

• Finish had to be uniform over a steep incline, as the concrete wanted to flow to the lowest level.

• Radiused/warped shapes required extra attention to the placement of concrete, reveals, and side rails

• All production forms were fabricated with stacked plywood cut on CNC machine to ensure accuracy

• All panels required complex connections

• Corbel supports were placed on steep angles

• Bolted connections were utilized in various places to help with in/out adjustments.

• Ensure proper access to install overlapping panels while maintaining continuous flow during the construction of three separate structures.

High Performance

• Improved thermal performance/reducing energy consumption

• High thermal mass contributes to energy savings and reduction. The deep overhangs of the precast walls provide shading elements. Improved storm resistance

• The pavilion structures are resilient to tropical storms Increased service life/durability

• The precast concrete wall panels require minimal maintenance.

The entire project team with exception of the lead design architect is located within 50 miles of the site, reducing transportation costs.

With active and passive design strategies, the project exceeds its energy reduction goals, including energy recovery wheels in highly ventilated spaces, variable and highly efficient compressors on package rooftop units, and LED lighting. Other energy reduction goals were met or exceeded with the deep overhangs for direct shading, tilted glass to reflect direct sunlight and reduce solar load, insulation in and on the precast concrete to reduce direct heat loss, and a structure with high thermal mass to absorb heat and humidity. 62 solar panel modules have a total of 25.1 KW capacity (annual production estimated to be 37,865 KWH).

Photos via GATE Precast Company