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Colonizing other planets, like Mars, marks a significant milestone in the pursuit of a multi-planetary existence. Millions of people would settle on Mars in self-sufficient bases. Colonizing Mars is a long-term mission that demands self-sufficient, secure habitats and comprehensive planning. Importing structures, such as inflatable structures, from Earth is cost-prohibitive, making the utilization of in-situ resources and onsite construction the most viable approach for preparing the required buildings. Studies have shown that it is possible to produce and craft several kinds of binders and concretes with appropriate mechanical behavior using Martian soil composition; however, determining the optimal option for onsite construction remains a challenge. This study investigates available cement/concrete options for onsite construction on Mars from a structural engineering perspective, taking into account the available resources and technologies. In this regard, the observations and data provided by Martian landers, rovers, orbiters and methods such as Viking-1 & 2, Pathfinder, Spirit, Opportunity, Curiosity, Mars Express, Ultraviolet–visible/Near-infrared reflectivity spectra and Alpha particle X-ray spectrometer were used to obtain a comprehensive and detailed investigation. Eleven types of Martian cement/concrete based on the in-situ resources, soil composition, and available technologies were compared based on the criteria and indices defined in accordance with the structural engineering point of view to select the best practical option for onsite construction. These criteria encompass factors such as mechanical behavior, Martian structural loads, raw material accessibility, available sources, energy required for production, water requirement, curing and hardening time, possibility of using 3D printers, byproduct usefulness, conditions required for hardening and curing, importation requirements from Earth, production complexity, long-term durability and behavior under galactic cosmic rays (GCRs) and solar energetic particles (SEPs). The pros and cons of each cement/concrete option are thoroughly assessed, considering the harsh conditions on Mars. Additionally, the study highlights extra considerations that are crucial for onsite construction on Mars. To determine the best practical option for onsite construction and sustainable colonization, the proposed cements/concretes were compared using multi-scale spider/radar diagrams and a quantitative point of view. This perspective was enabled by assigning weights to each criterion through expert consultation, experimental data, and literature review, ensuring that the diagrams accurately reflect the features of each concrete mix. This comprehensive investigation aims to provide valuable insights into selecting the most suitable cement/concrete for onsite construction on Mars, considering the structural engineering perspective and the long-term goal of sustainable colonization. • The Martian soil composition is investigated using data from Martian landers and orbiters. • Eleven types of Martian concrete/cements are proposed based on available resources and technologies. • Structural engineering criteria and indices are defined to select the best option for onsite construction. • The best practical option for onsite construction is determined using multi-scale spider/radar diagrams. [ABSTRACT FROM AUTHOR]

Near-fault earthquakes have different properties compared to far-fault earthquakes. Due to the phenomenon of forward directivity in near-fault earthquakes, the component perpendicular on fault has pulses with longer periods and wider range than the parallel component. Seismic isolators as the types of damping systems prevent structure to enter into non-linear range through their deformation. In this study, Single Degree of Freedom Structures (SDOFS), which are connected to FPS and DCFP isolators, was analyzed under time history implementing the records of near-fault and far-fault earthquakes. In addition, base shear, displacements, and acceleration incurred on the foundation of upper structure were examined. The obtained results indicated that in comparison with DCFP isolator, FPS isolator transfers less base shear on its structure in near-fault earthquake, whereas in comparison with FPS isolator, DCFP isolator transfers less displacements on its structure in near-fault earthquake. In addition, it transfers smaller acceleration on its foundation in near-fault and far-fault earthquakes. [ABSTRACT FROM AUTHOR]

A new bending connection between a steel beam and concrete-encased composite column (CEC S) with a bolted flange plate is proposed which maintains the integrity of the column and allows for the interchangeability of the beam for improvement of the connection. The confinement of the steel plates and the central steel core (H-section column) is provided by reinforced concrete and cover plates, thus lateral torsional and local buckling of the through plate (TP) and the central core is prevented. Three full-scale samples of the proposed exterior connection with variable TP thickness and different bending capacities under lateral cyclic and constant axial loads in the column were tested. The moment contribution in the components and seismic behavior of the connection were studied. The load transfer to the panel zone occurred through four components in the bending plane; TP, concrete performance, tensile studs, and side plates. The average share of the resistant elements which is immediately behind the front plate were determined as 56%, 26%, 12.50%, and 5.5%, respectively. The internal panel zone remained undamaged and the stresses were below the yield limit, so that the plastic hinge could occur outside the connecting members in the beam. In general, the specimens with sufficient pre-tensioning in the connection bolts had stable hysteresis curves and less pinching. In addition, these specimens showed acceptable energy dissipation that provided a high ductility index. • Integrity of the column and continuity of the longitudinal reinforcement in the internal panel zone • No requirement for transverse reinforcement in the region of the internal panel zone • The confinement of the through plate and the central steel core by reinforced concrete and cover plates • Determination of moment contribution of the connection components using analytical method and experimental tests • Showing acceptable cyclic behavior and appropriate energy dissipation [ABSTRACT FROM AUTHOR]