Brought to you with support fromIn a unique collaborative partnership with Bellevue, Washington-based Su Development—who participated as client, developer, and contractor—Bohlin Cywinski Jackson (BCJ) has completed its second and final phase of development for the SOMA Towers project in Seattle. The team’s shared interest in pairing high design with efficiencies in construction sequencing has resulted in a unique mixed-use development involving two residential towers, a multilayered podium of tiered public plazas, and below-grade parking. The facades of the towers are carefully composed of five-foot window wall modules that utilize a range of clear and frosted glazing. The outcome is a compositional strategy of varied mullion subdivision spacing within each stacked module, visually disrupting a repetitive modular system achieving what Robert Miller, principal at BCJ, called “a real trickery of the eye." The facade is shaped by post-tensioned concrete slab floor plates, whose curvature is a response to structural optimization of cantilevered distances. The architects worked with structural engineers and analysis software to evaluate stresses on the cantilevered slabs early in the design process. The project team would extend cantilever distances on under stressed areas of the slab and shorten distance or add back spans to areas of the slab that were over-stressed. This game of pushing and pulling yielded floor plates with a unique curvature optimized to a material and structural efficiency. Floor plates were further refined through repetition to allow formwork to be reused over many floor levels. Perimeter curvature was rationalized into a faceted geometry corresponding to the roughly five-foot-wide window wall units, which were designed to be installed from the interior side. This allowed for a safer and more cost-effective installation process. One of the challenges of the facade design was in the composition of the elevation, which sought a varied and dynamic grid at odds with the modularity of the construction assembly. The project was designed to prescriptive energy codes, which only allowed for a maximum open area of 40-percent at the time of Phase 1, and 30-percent by the time the second tower was under construction. In order to make the facade feel like it contained more glass, the architects created a matte black spandrel to simulate the aesthetic of glass. The change in energy code standards from Phase 1 and Phase 2 introduced another level of compositional rigor to the project, which sought aesthetic compatibility between the two towers. A horizontal wainscot band located 30-inches above the floor plate also helped to cut down op open glazing percentage. To avoid an unwanted horizontal aesthetic, the architects integrated full height spandrels to the window wall composition to break up the grid. The corners received full height glazing at a slightly wider width than the modular window wall units to accommodate tolerance in the floor slab perimeter geometry. One of the unique details of this project was Bohlin Cywinski Jackson’s treatment of the slab edge. The detailing of the slab edge is a custom extrusion - a channel assembly with an infill panel on the face that performs as a louver composed of 90-degree angles to appear visually crisp. This detail allows a consistent aesthetic that integrates otherwise random vent openings into the compositional logic of the facade. Kirk Hostetter, Senior Associate at BCJ said the detail "articulates the top and bottom of the slab edge, and introduces a crispness to the edge that you don't typically see." Elsewhere, at the main entrance to the podium, a 70-foot circulation “cone” and 80-foot-long suspended leaf-shaped canopy of glass, aluminum, and steel, were also designed with the same approach to construction efficiency. These custom entry components were fabricated and pre-assembled in Taiwan, then disassembled and shipped to the site where they were reassembled. On the unique design process that marries development, client, contractor, and architectural thinking from day one, Miller said "Our buildings conceptually are strong enough that they can take a looser approach to the details. If some details get modified along the way, we can usually work together to make something that works for John Su's business plan and our design ambitions." He concluded, "Su Development has a keen interest in design. The fact that they value design allows us to do our job well. Shared admiration for skill sets and willingness to collaborate is what made this project possible."
Posts tagged with "post-tensioned concrete":
University of Arkansas addition celebrates the future with a contemporary rewrite of Neoclassicism.As head of the architecture department and distinguished professor at the University of Arkansas Fay Jones School of Architecture, Marlon Blackwell was uniquely qualified to oversee the renovation and expansion of the school's home, Vol Walker Hall. To unite the school's landscape architecture, architecture, and interior design departments under one roof for the first time, Blackwell's eponymous firm designed a contemporary west wing to mirror the east bar on the existing Beaux-Arts style building, constructed in the 1930s as the university library. But the Steven L. Anderson Design Center—which tied for Building of the Year in AN's 2014 Best of Design Awards—is more than a container for 37,000 square feet of new studio, seminar, and office space. It is also a teaching tool, a lesson in the evolution of architectural technology writ in concrete, limestone, glass, steel, and zinc. "Our strategy was to create a counterweight to the existing building," explained Blackwell. Rather than a layered steel-frame construction, Marlon Blackwell Architect opted for a post-tensioned concrete structure to convey a sense of mass and volume. "We also wanted to demonstrate what you can do with new technology like post-tensioned concrete, such as introducing a cantilever and introducing a profile that has minimal columns in the spaces," he said. "All of that is a didactic tool for our students to contrast and compare with the load-bearing technology of the existing structure." The exterior of the Steven L. Anderson Design Center also reflects on changes to architectural practice during the last 80 years. "We really wanted to develop a strong profile of the building, in contrast to Vol Walker Hall," said Blackwell. He describes the effect as a figure-ground reversal: where in the older structure the mass of the building is the ground and the windows and ornament act as figure, in the new wing the mass is the figure and the fenestration the ground. To create what Blackwell terms a "condition of resonance" between the Design Center and Vol Walker Hall, the architects engaged Clarkson Consulting to develop an architectural concrete to match the color of a local Arkansas limestone no longer available. They echoed the Indiana limestone on the older wing with panels sourced from a quarry only 50 miles from the original. But instead of grouting the limestone cladding on the new wing, Blackwell chose a limestone rain screen system from Stone Panels. "That allows us to go much thinner but much larger," he said. "Again, we're using the same materials but showing how the advancement of technology allows for a different expression of architecture." The defining feature of the Design Center is the more than 200-foot-long glass and steel curtain wall on the western facade. Knowing that the western exposure would provide the only source of natural light for the new wing, the architects worked to balance the need for light against the threat of solar gain. To complement the existing building, they chose a fascia steel curtain wall custom-fabricated by local company L&L Metal Fabrication. With curtain wall consultants Heitmann & Associates, Blackwell developed a brise soleil comprising 3/4-inch by 18-inch frit glass fins, angled to filter sunlight into the Design Center's 43-foot-deep studios. "What we like about it, too, is that it's one big window," said Blackwell. "It allows it to feel as if we've cut a section right through the building. At night the entire facade becomes a beacon, allowing for a nice interface between the school of architecture and the rest of the community." Other details, including the monolithic concrete pours designed to lighten the Design Center's connection to the ground, and zinc cladding used on the top floor to sharpen the profile of the main body, continue the dialogue between the new structure and its Neoclassical neighbor. "There are a lot of little things that give a tautness to the expression of the new addition, and give it its own identity," said Blackwell. "But at the same time, one of the things we were faithful to was trying to analyze and uncover units of measure and proportion on the old building, and apply that to ours." Perhaps more importantly, the building works as a design school—and Blackwell would know. "There's certainly contrast on the outside," he said. "But there's an almost resonant seamlessness on the inside."