The seismic structural design of a space capsule accommodation requires comprehensive consideration from multiple dimensions, including structural system, material selection, connection methods, foundation design, spatial layout, detail processing, and simulation testing, to ensure structural integrity and occupancy safety during earthquakes.
The structural system is the core of seismic design. Space capsules typically employ lightweight frame structures, such as steel or aluminum alloy frames. These materials possess high strength and good ductility, absorbing energy through elastic deformation during earthquakes and preventing brittle fracture. The frame structure forms an overall force-bearing system based on the principle of triangular stability, distributing seismic forces to various support points and reducing localized stress concentration. For example, some designs utilize mortise and tenon joint structures, enhancing overall rigidity through modular assembly and ensuring the capsule's stability during earthquakes.
Material selection directly impacts seismic performance. Steel structures, due to their light weight and high strength, are the preferred choice for the space capsule's seismic framework, weighing only one-third to one-half of traditional brick-and-mortar structures, significantly reducing inertial forces during earthquakes. Aluminum alloy frames combine lightweight design with corrosion resistance, making them suitable for humid or rainy areas. Regarding the outer shell materials, fiberglass reinforced polymer (FRP) or carbon fiber reinforced polymer (CFRP) materials, due to their high strength and low density, can reduce the weight of the capsule while resisting seismic impacts through fiber-reinforced structures. Some designs also fill the outer shell with graphite EPS insulation material to further enhance structural stability.
The connection method is a key aspect of seismic design. The space capsule's frame nodes require flexible connection technologies, such as special connectors or rubber isolation pads, allowing for structural displacement within a certain range and avoiding breakage due to rigid connections. For example, placing rubber damping pads between the frame and the foundation can effectively absorb the energy transmitted by seismic waves, reducing the impact of earthquakes on the capsule. Simultaneously, the connection between the capsule and the anchoring system must be secure, with each anchor point capable of withstanding several tons of tensile force to prevent displacement or overturning of the capsule due to strong winds or earthquakes.
The foundation design must adapt to different geological conditions. In earthquake-prone areas, the space capsule's foundation must employ seismic isolation technology, such as establishing a seismic isolation zone between the foundation and the capsule, making the capsule and foundation independent and reducing the direct impact of earthquakes on the capsule. For soft soil foundations, piling or enlarging the foundation area is necessary to increase bearing capacity and ensure the capsule does not experience uneven settlement during an earthquake. Furthermore, the foundation design must consider drainage and moisture prevention to avoid structural corrosion caused by groundwater seepage.
Optimized spatial layout enhances earthquake resistance. The interior of the space capsule should avoid complex partitions and adopt an open layout to reduce structural weak points. For example, reinforcing ribs or partitions can enhance the overall strength of the capsule while ensuring unobstructed escape routes. Some designs place heavy equipment such as toilets and kitchens in the middle of the capsule to lower the center of gravity and enhance stability. Additionally, furniture inside the capsule must be fixed to prevent it from tipping over and injuring people during an earthquake.
Attention to detail determines the success or failure of earthquake-resistant design. High-strength sealing strips must be used at capsule joints to prevent rainwater seepage and structural corrosion. Door and window designs must consider earthquake performance, such as using earthquake-resistant glass or metal frames to prevent breakage during an earthquake. Furthermore, the capsule surface must undergo rust prevention treatment, such as galvanizing or spraying anti-corrosion coatings, to extend its service life. Some designs also incorporate seismic bracing inside the capsule to secure pipelines and equipment, preventing them from detaching during earthquakes.
Simulation testing is an essential means of verifying seismic-resistant designs. Finite element analysis software is used to simulate stress conditions under different earthquake magnitudes, optimizing structural design and material selection. For example, the capsule undergoes an 8-degree seismic fortification standard test to ensure its main structure remains largely intact during an earthquake. Some manufacturers also place the space capsule in real earthquake environments for testing, further refining the design based on the test results to enhance seismic performance.
