This structural design project required a light-weight roof to cover a 80ft by 100ft courtyard which is surrounded by four wings of Heyden Library at MIT. Our team conducted form-finding process and optimized the geometry in terms of strain energy with constraints on column location, truss depth, and minimum blockage of windows and incoming sunlight from above. With respect to structural analysis, hand-calculation and Finite Element Analysis (FEA) were performed and compared. The final design is super light-weight and includes a complete set of detail designs.
Per code, the existing surrounding building is unable to carry lateral loads that the roof structure may be submitted to. We hence needed to include columns in our design and to design the structure against both vertical and lateral loadings. The surrounding building has one level below ground where twelve columns are carrying the courtyard. Also, under each of these columns lies a pile foundation, making them the only existing structural elements that are able to carry the roof structure. Thus, in order to limit project costs and disturbance to the existing structure, we constrained the columns of the roof structure to end on top of these columns.
The finite element analysis has been performed through a GSA model. It contains 18 load cases, defined per ASCE 7-05, chapter 2 (ASD category). For snow loading, 14 asymmetric loading configurations have been considered, which explains the large number of total load cases. In the table above, highlighted load cases correspond to asymmetric ones.
The gravity load path is simple and effective. It consequently helps to achieve a light and cost-effective structure.
The structure has been conceived to efficiently resist any seismic or wind load, following the inverted pendulum principles for both directions.
Heyden Library Roof Design Project
Team: Benjamin Jacot, Mark Membreno, Yu Zhang
The structure sizing and materials are based on the forces from structural analysis and AISC. All the members satisfied the buckling check and strength check.
By the end of this project, we also proposed detailed construction process, and provided details of the connections.