Rice University’s recently completed projects, McMurtry and Duncan Residential Colleges, are featured on the cover of the January/February 2010 issue of Texas Architect. The residential complex includes seven buildings that provide students with housing, dining facilities, kitchen servery and upstairs formal meeting rooms, and master’s houses. The article, written by Fernando Brave, does an excellent job of describing and illustrating the new additions to the Rice campus environment.
With that, I would like to describe the “behind-the-scenes” and under-the-ground elements that made this project an engineering challenge from day one.
The structural foundation system for the entire project was designed using drilled and under-reamed piers founded at a depth of about 20 feet below existing grade. There is a new connecting underground utility tunnel that links all of the structures with MEP services and connects to the existing tunnel system on campus. Construction started with the two dormitories and even though Civil drawings indicated where the underground utilities were supposed to be, other existing utilities were found during pier construction. As a result, we designed below-grade transfer girders with a few additional piers to redirect the weight of the five-story building columns into the ground.
Because of the expansive soils found throughout the site, the ground floor slabs were all structural, two-way flat slab designs, isolated from potential movement of clayey material that can swell or shrink with the change in moisture content from seasonal conditions or underground utility issues. Load-bearing CMU walls, starting at the 2nd floor, continue to support a structural, two-way slab design. The finish surfaces of the load-bearing CMU walls and concrete slab structure are exposed to view and required strict quality control to insure a quality finish and uniform coloration. Fly ash mixed with concrete, is a pozzolan product that can make the concrete stronger, improve durability, and make the concrete more resistant to chemicals. This was an important aesthetic issue since the concrete surfaces were to be left exposed. A common percentage of fly ash added to concrete is around 25% but on this project, 50 to 70 percent fly ash content was used because of its performance qualities. Fly ash is also a cost-effective resource and when added to concrete, the amount of cement that is necessary can be reduced.
The dining halls each have their unique shape but common structural framing elements. Duncan’s dining hall is rectangular with interior, turned solid timber columns supporting, turned and tapered branches supporting the wood roof structure. The exterior perimeter framing supports the roof structure and consists of wood flitch columns, detailed to be an integral part of the window system. McMurtry’s dining hall is a circular design with twelve solid wood turned columns, 10 inches in diameter. Glue-laminated flitch beams with a 1 inch steel plate, along with an outer tension ring and inner compression ring were designed to create this column-free space that is 74 feet across in diameter. Both structures utilize a high strength cabling and bracket system that is nearly invisible to the eye to provide lateral bracing for the structures. Perimeter grade beams were designed to incorporate the below-grade mechanical distribution system that heats and cools the spaces.
The center structure to the project is the kitchen/servery where the students from both colleges interact at mealtime. The exposed concrete ceiling structure is also a structural, two-way slab system and designed to integrate the lighting system and decorative recesses. The 2nd floor structure is supported by 18 inch diameter concrete columns in the servery area and by load-bearing CMU walls in the kitchen area. The second floor has a couple of libraries and private dining rooms for school functions. The roof structure consisted of shallow steel framing members to create large open spaces for meeting.
The Master’s houses have the same foundation system and were constructed with load-bearing metal stud walls. Some flitch columns and glue-laminated beams were used to lighten the structure and provide large, uninterrupted interior spaces.
Communication and an overall understanding of cooperation among the contractor, their subcontractors and design professionals made this project a success.