Structural Insight of Persian Bathhouse Architecture for Designing Greenhouses on Mars

摘要

The Lut Desert of Iran looks as one of the regions on Earth more similar to the Mars landscape. Close to that area, there are vernacular adobe architectures dating back to the ancient Silk Road, two thousand years old, which were built by primitive construction methods but with complex geometry. Among all city structures, bathhouses represent the unique example of an introverted architecture that has a profound commonality with greenhouse closed-systems. Bathhouse not only isolated active interior life from the outer world but also insulated the temperature and humidity from the extreme environment of the Lut Desert. It usually also had a closed clean water system, open-air water flow circulation, and water reservoir and safe power access, all features that should be present in a greenhouse design concept for Mars. The main architectural feature of the Persian bathhouse architecture is the presence of one or more domes as a roof system. These masonry domes are characterized by ease of construction and use of local materials, absolutely consistent with the in-situ resources utilization requirements for building on Mars. Indeed, this research focuses on exploring the feasibility of using the bathhouse structural system for designing a regolith dome structure-a shelter to provide micrometeoroid and radiation shielding for a greenhouse infrastructure on Mars. The analysis has been developed through an innovative computational design model that begins with embedding the geometrical information given by the Persian domes. Consequently, it optimizes each structural element to withstand the harsh Martian environment, minimizing the cross-section while considering the minimum thickness required to provide the micro-meteoroid and radiation protection. The finite element analysis considered different inner pressurization loads from 27.6 kPa (4psi), the airlock pressure in the pre-breathing phase, to 101.3 kPa (14.7 psi) that is currently used for the ISS pressure to obtain an earth-like environment. This research selects five Persian arches for analyzing their structural performance. The domes originated by each different arch structures are highly representative of this Persian architecture typology. Among all various dome construction methods, the Karbandi (stellar vault or ribbed dome) style dating back to the third century has been chosen, as it is the most common one among various bathhouses. Converting arches to the ribbed vault morphs the shape of the dome pattern. The span of 20 m is considered as one of the input parameters. The results of the analyzed Karbandi domes have been compared with the optimum hemispherical geometry highlighting their high structural performance after the optimization and a geometric pattern that might lead to a more innovative architecture on Mars.