Constructing lunar bases is crucial as lunar missions progress towards utilization and exploitation. The challenging lunar environment, with its unique characteristics and limited resources, requires special materials, structures, and construction methods. Inflatable structures offer great potential for lunar construction due to their advantages in transportation, stowage, construction, and reliability. This paper proposes a rigidizable inflatable lunar habitat that maintains its shape even after air leakage, enhancing safety, durability, and fixability. The membrane material adapts to different requirements during transportation, construction, and service, achieved through solid-state actuation of shape memory polymer (SMP) for stiffness variation, allowing multiple moves and ground tests. This work comprises three parts: 1) system: design concept and construction processes, 2) material: design and characterization of restraint and rigidization materials, and 3) structure: numerical validation of structure properties. Finite element analysis, based on material models obtained through dynamic mechanical analysis (DMA) and tensile tests, demonstrates the effectiveness of including an SMP rigidization layer in preventing collapse and enhancing dynamic properties. This paper not only proposes a new system, but also provides material design methods and requirements, along with structural validation techniques. Findings validate the feasibility of rigidizable inflatable lunar habitats, applicable in extreme environments, also in temporary buildings, space structures, and soft robotics.

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The utilization of coral aggregate concrete (CAC) in marine construction has drawn the attention of engineers and researchers in recent years. Due to the high content of chloride in CAC induced by coral aggregates and sea water, reinforcing CAC with traditional material, i.e., steel, can cause serious corrosion-related durability problems. Replacing steel with corrosion-resistant fiber-reinforced polymer (FRP) has been considered a promising solution. This paper provides insight into the bond behavior between CAC and FRP bars. In total 30 pull-out tests were conducted. The investigated variables included the concrete matrix, FRP bar type, bar diameter, and thickness of concrete cover. Based on the test results, discussions on the bond failure modes, influencing factors of bond strength and bond stress-slip relationship were presented. For splitting failure mode and pullout failure mode, empirical bond stress-slip models were proposed respectively. Adopting the failure criterion of CAC proposed in a previous study, a mechanical model for bond strength under pullout failure mode was developed. Comparisons with test results validated that the proposed models provide reasonable predictions for the bond properties between GFRP bars and CAC.@en

The design of FRP profile-concrete composite sections, including beams and decks, is usually governed by the shear strength of the FRP profiles. However, analytical methods that can precisely predict the shear capacity of the composite sections have not been well developed, because there is lack of knowledge of the FRP-concrete composite action and distribution of shear stress along the FRP. This paper investigates the shear behaviors of FRP-concrete composite sections and develops formulae to predict the shear capacity of the composite sections. First, flexural tests of three FRP-concrete composite beams were conducted to investigate the shear failure mode and interface behaviors. All the beams failed in FRP shear fracture along horizontal direction. Then, push-out tests were used to determine the slip property for the FRP-concrete interface which reveals that FRP stay-in-place form and steel bolts can ensure full and partial composite action, respectively. Based on the experimental study, closed-form equations to compute the maximum shear stress are derived and validated against experimental data in this paper and literature. Finally, simple yet reliable equations of shear capacity are derived and recommended for engineers to design the FRP-concrete composite sections.

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