The floors are constructed of 23-inch-thick waffle slabs with waffle voids spaced 4-foot on center. Voided slabs allow for wider spans between columns; on the San Diego library project, bays spanned 32-feet on center. Further contributing to the streamlined design are the use of in-slab beams, which combined with the aforementioned upturned SMRF beams greatly reduces the occasion of traditional down-turned beams. Morley selected Peri’s Uniportal table system with Multiflex shores to form the soffits of the nearly 350,000 square feet of waffle slabs. Over 2,500 individual fiberglass void forms were provided by MFG Construction Products and installed by Ceco Construction for the more than 14,000 waffle voids.
The building contains a number of unique concrete features. Acting as a focal point of the building interior, spanning through the main lobby with an escalator moving vertically through it, is a 46-foot-tall and 70-foot-wide concrete gravity arch. It requires no mechanical connections for its function of supporting the loads of the five stories above it. Morley considered a multitude of forming scenarios and conducted in-house peer reviews of three “finalists” before settling on a combination of Peri Vario wall forms, GRV radius forms and Multiflex shoring.
The eighth floor reading room has a 60-foot-high ceiling with walls of steel and glass. The structure resembles a lantern and allows for natural daylighting. Supporting the structure are four 6-foot-square columns arranged in a cruciform plan, centered on each wall to create the structure for the diamond-shaped, cast-in-place concrete, steel and glass roof. The beams that support the roof span 58 feet clear in both directions. Peri Multiflex shoring towers were used to shore the roof deck and beams. Covering the reading room is the freestanding, dome-shaped sun shade constructed of a series of eight rib trusses and sails arranged in a scalloped formation, overlaid with fixed perforated steel lattice work.
On the building’s west side, offering views of San Diego Bay, is the ninth floor, 400-capacity Special Events Room. The room’s hybrid roof structure cantilevers 20 feet beyond the west facade supported at center-bay of the overhang by a single 4-foot by 6-foot inclined concrete column leaning out at a 10 degree pitch originating at the fourth floor 90 feet below and culminating 30 feet above the ninth floor. The column supports two precast Grand Beams that are arranged in a pitched V shape, each tied in to a 60-foot spanning beam wall at the room’s eastern side. A series of 20 precast purlins, four tube steel columns and other steel beam work interface with the cast-in-place architectural concrete roof slab and perimeter beam to support the roof.
The library also features the circular-shaped Commission Room, created by what Fleming calls a “miniature modern effigy of Stonehenge” made up of 12 H-shaped concrete columns arranged uniformly in a circle. Each column has a “bent” center so it is not a true H in plan.
In total Morley hired six formwork vendors to answer the challenges of the project. Custom structures such as the gravity arch, Commission Room column forms and Special Events Room roof were unprecedented for Morley and its vendors. Close collaboration with the vendors’ engineering teams was necessary to find the best approach relative to constructability while maintaining sensitivity to the architectural aesthetic. Fleming notes such an approach is vital to good architectural concrete practice, but that such collaborative efforts are common on all Morley projects, not just with vendors but with all who have a stake in the project. “We staff most every job with a full-time engineer and superintendent, often safety engineer and project manager too,” he says. “We find that taking a collaborative, proactive approach at every level of involvement results in superior products, happier clients, and improved bottom lines, even with hard bid public work.”
One of the aspects of the library project that required a high level of planning on Morley’s part was achieving the architect’s vision for the architectural concrete. He wanted the color to be light and consistent with minimal mottling, a matte finish, minimal read of plywood grain and surface imperfections, and minimal tie holes. Another feature he asked for was a readily visible random pattern and non-repeating plywood design, referring to a “collage” or “quilted” effect that added texture and context for the building.