Collaborative Research: Full-culm Bamboo as a Full-fledged Engineering Material

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In its natural full-culm (hollow tube) state, bamboo has evolved to efficiently resist a variety of environmental loads. Its high strength, light weight, fast growth, and low energy and fertilizer requirements all recommend bamboo as a sustainable replacement for conventional materials that are resource and energy intensive. The primary objective of this project is to establish the framework and tools required to standardize the evaluation of the material and mechanical properties of full-culm bamboo and thereby place bamboo on the same footing as timber as a conventional building material. Through such standardization of non-conventional materials like bamboo, the triple bottom line of sustainable development (social equity, ecology, and economy) is advanced in a variety of international contexts, most notably in regard to social equity. In developing regions, standardization of non-conventional building materials serves technical, ecological and social goals empowering rural communities to directly participate in construction of safe and reliable housing as well as to sustainably develop local economies. In particular, this project will advance these goals by leveraging local resources in Puerto Rico and Haiti to sponsor a variety of training and educational activities for U.S. students.This research will consolidate and significantly extend the extant body of knowledge and establish materials- and mechanics-based constitutive models for the behavior of full-culm bamboo as a functionally graded, fiber-reinforced material. Three representations of bamboo behavior will be developed forming the framework and tools required to evaluate the material and mechanical properties of bamboo for engineered applications. First, detailed analytical modeling is key to understanding the engineering properties of bamboo as a functionally graded material. An analytical model will be developed informed by innovative experimental methods focused on establishing through-wall and along-culm variation of fundamental mechanical properties. Second, surrogate representation of difficult-to-obtain engineering properties suitable for field test methods is necessary if broad adoption of full-culm bamboo is to be reliable. The approach taken will leverage the analytical platform developed in order to develop both empirical and mechanics-based representations of engineering design properties that may be obtained from practical field tests. Finally, a new framework for modeling uncertainty in bamboo material and mechanical properties, which can be can be highly variable, will enable reliable calibration of design equations. The approach will include stochastic generation of probability spatial distributions of mechanical properties implemented into the developed analytical model. The project will advance the science of modeling both fiber reinforced and functionally graded materials. Indeed, a better understanding of the naturally evolved optimal design of the bamboo material and culm, including its nonhomogeneity and variability, will inspire optimization of other structural engineering functionally graded materials.