Novel antiseismic, sustainable structural system of reinforced concrete

Edit Hook

STICK.S represents the conclusions of a two-year research and development (R+D) dissertation for the MA in architecture. Inspired by the morphological performance of the human body structural system, this project seeks to define a holistic architectural strategy which uses novel geometric parameters for building structure design in order to increase the building mechanical, structural and sustainability performance. The investigation setting takes advantage of seismically vulnerable areas in order to propose and evaluate the new design technique for concrete structures fabrication. In fact, the whole research development can be resumed as a bio-structural solution which involved analogical translations of parameters into architecture for the formulation of an efficient design solution. Such a proposal rethinks the way we design and build towards a performance-based design strategy capable of adapting to some determined natural hazards factors, such as earthquakes implications, while reducing the material waste and the energy demand that it implies for fabrication.

Key Differentiators

To Wilfredo, inefficiency becomes both an unsafe and unsustainable practice. For his thesis he uses the human body’s structural system composed by bones and muscles to optimize the design parameters for RC structural system. With the principles defined in his thesis, Wilfredo is proposing the evolution of the current and inefficient structural system. The design of the novel structural system was based in the parameters of morphology adaptation of human bones. The system, named STICK.S or the Stick System as a reference to a lightweight structural system, employs the femur as the adaptation model for columns and beams.STICK.S extrapolates the adaptation parameters of the skeleton to the concrete building structure in order to encourage better use of material resource. STICK.S mimics the bone morphology to minimize structural material use for components such as columns and beams in order to maximize the material performance. In fact, each structural component is designed emulating the bone Wolff’s Law, which implies that material resource is adapted to the structure diagram of force and is applied just where it is needed. That parameter permits to subtract up to 30 percent of the concrete use for each component without compromising its load resistance. Also serves to decrease almost 118 lbs. of CO2 per component.

Biomimicry Story

The femur is the strongest human bone and its hollow cylinder design provides maximum strength with minimum weight. Those essential features represent ideal parameters for the reduction of earthquake intensity on a building structure. In addition, the bone’s anatomy reflects the common stresses it encounters in order to adapt its morphology to its common mechanical stress. In order to achieve the bio-structural adaptation, STICK.S used hollow-shaft columns and beams whose morphology was adapted to its bending moment diagram. The resulting non-prismatic form helps the proposed frame to respond better than conventional prismatic frame to the lateral loads normally produced during an earthquake.STICK.S becomes a custom Special Moment Resisting Frame (SMRF). Like the bones in the human skeleton, each column and beam are precisely designed according to its specific load condition and its own bending moment diagram. The hollow-shaft parameter reduces about 0.32 cubic meters (11.18 ft3) of reinforced concrete, besides reducing 761 kg and up to 118 lbs of CO2 by structural component (column or beam). Also, because the RC frame is adapted to its common stresses by lateral loads, the deflection was greatly reduced in comparison with a conventional RC frame under the same load conditions. The form, as the result of the diagram of force, directly abstracted from the bones' morphology paradigm, makes the proposed frame almost three times stiffer than a conventional one. In further analysis, the frame base shear (seismic intensity) was greatly reduced by 35 percent.In conclusion, because of the human skeleton parameters were adapted to the conventional structure system, which encourages the efficient concrete utilization and the building weight reduction, the building seismic vulnerability was significantly reduced, increasing its adaptation to the site characteristics. Adaptation reflects in efficiency which becomes the key to better structural performance and the building relevant sustainable output.

Challenges Solved

Earthquake tragedies, such as those in Japan and Lorca, Spain in 2011, demonstrate that even the most prepared and alert urban territories could be seriously affected by the strike of a large earthquake and its many implications. Even the strongest construction materials, such as reinforced concrete, become vulnerable because of the scourge of the seismic wave. Although, a lot of investigations study the mechanical properties of concrete material and retrofitting techniques for reinforced concrete (RC) structures, there isn’t significant research about RC structural system and its seismic adaptation. This preoccupation guided Architect Wilfredo Méndez (AIT) to propose his Master of architecture thesis, "Principles of a Biotectonic Culture," at the School of Architecture, University of Puerto Rico.The thesis is a structural design guide based on principles of biological adaptation for reinforced concrete morphologies. Using biomimicry as the theoretical platform, Wilfredo sought to define structural design strategies that reduce the seismic vulnerability of RC structures. He used Puerto Rico as his case study because the geographical similarity to many other territories in the Caribbean and Latin America.

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