Bamboo is a building material that lends itself excellently to the construction of sustainable gridshells. Two of the Form Finding Lab’s graduating senior students, Lu Lu and Russell Archer (’16), worked under the guidance of PhD candidate Tim Michiels and Professor Adriaenssens on the analysis of a set of hyperbolic paraboloid (hypar) gridshell roofs in Cali, Colombia. The Form Finding Lab’s team collaborated closely with the design team of Colombian-based Spanish architect Greta Tresserra and her team to improve the structural understanding of gridshells made from locally sourced bamboo. Follow Lu Lu and Russell’s adventure in this video:
Colombia is home to the giant American bamboo species Guadua Angustifolia. Guadua, a type of grass, can grow up to 18m tall and obtain its full height in a mere 6 months. Moreover, it can be harvested and treated for construction purposes after 4 years requiring relatively little effort. The speed of growth of bamboo and the ease of its harvesting is in stark contrast to the time and resources that are required to obtain wooden lattices, a typical material used for gridshell construction. Moreover, architect Tresserra only employs traditional, low-tech joint techniques in order to make expressive and elegant guadua construction accessible to less affluent communities.
Guadua bamboo culms are straight hollow tubes with interspersing nodes about every 20 cm along its length which act as diaphragms. The guadua tubes are thicker than typical bamboo poles, which makes them much stiffer, which is why it makes most sense to employ these straight poles as rectilinear elements in construction. Hypar surfaces, revolutionized by Felix Candela in his concrete shells in Mexico, can be made out of just straight elements, allowing for an elegant forms from simple elements.
Russell’s senior thesis focused on the most important joint in these guadua structures, the fish-mouth connection. Lu Lu performed an in-depth parametric study on one of the hypar structures, allowing to improve the structural behavior of the roof. Lu Lu and Russell, traveled together to Colombia to visit the bamboo structures and optimize their analyses in collaboration with the Colombian team. Tim followed up on this visit, by providing further assistance in Cali on the seismic analysis of these grid shells. Overall, the Form-Finding Lab’s efforts will have an impact in Colombia, as the eventual design of the structures will be optimized using the input of the team. Construction is about to start in the upcoming months!
Author: Tim Michiels