What is the difference between a single-layer reticulated shell and a double-layerreticulated shell?

 The differences between single-layer reticulated shells and double-layer reticulated shells are as follows:

Structural Configuration
  Single-layer reticulated shell: Composed of a single layer of members, with the members directly connected to form a grid structure. The node configuration is relatively simple, typically employing rigid connections that allow the members to bear not only axial forces but also bending moments and shear forces.

  Double-layer reticulated shell: Consists of upper and lower parallel layers of members connected by web members, forming a truss-like structural system. The nodes are generally hinged, and the members primarily bear axial forces. Its configuration is relatively complex, requiring more members and nodes to ensure structural stability and load-bearing capacity.

Structure

Single-layer mesh shell: composed of one layer of rods, the rods are directly connected to form a mesh structure, the node structure is relatively simple, usually rigid nodes, which enables the rods to withstand bending moment and shear force in addition to axial force.

Double-layer mesh shell: It consists of two layers of parallel rods connected through the web, forming a truss-like structural system. The nodes are usually articulated, and the rods are mainly subject to axial force, and the structure is relatively complex, which requires more rods and nodes to ensure the structural stability and load carrying capacity.

Mechanical Properties

Load carrying capacity:

    Single-layer mesh shell: within reasonable design and appropriate span, it can bear certain load, but due to its fewer rods, the redundancy of the structure is relatively low, and the resistance to local loads and accidental damage is weak.

    Double-layer mesh shell: Due to the fact that there are two layers of rods that are jointly loaded and the web rods can effectively transfer the load, its load carrying capacity is relatively strong, the redundancy of the structure is high, and in the case of failure of local rods, it can still maintain a certain load carrying capacity through the concerted work of other rods.

Stability:

    Single-layer mesh shell: relatively poor stability, especially in the case of large span, easy to instability, more sensitive to initial defects and geometric nonlinearities, the design and construction process needs to strictly control the geometric accuracy and quality of the structure to ensure its stability.

    Double-layer mesh shell: It has better stability, and its truss structure form makes the mutual constraints between members stronger, which can effectively resist the deformation and instability caused by external loads, and it is more suitable for large-span structures.

Steel consumption

Single-layer mesh shell: Due to the relatively simple structure and small number of bars, the steel consumption is relatively small and economic under the condition of meeting the same span and load requirements. However, in order to ensure the stability in large-span structure, it may be necessary to adopt larger cross-section bars, thus increasing the steel consumption.

Double-layer mesh shell: the structure is more complex, need more rods and nodes, the amount of steel is usually more than single-layer mesh shell, but in the case of large span and high load, its advantage is that it can be reasonably designed to use smaller cross-section of the rods to meet the requirements of structural strength and stability, so as to control the increase in the amount of steel consumption to a certain extent.

Construction Difficulty

Single-layer mesh shell: the construction is relatively simple, the installation and connection of the rods are more convenient, the rods can be prefabricated in the factory and then assembled at the site, the construction speed is faster, and the requirements for construction equipment and technology are relatively low.

Double-layer mesh shell: due to its complex structure, the number of rods, installation precision requirements, the construction is relatively more difficult, requires more professional construction team and equipment, the construction process needs to carry out accurate measurement and positioning to ensure that the position of the upper and lower layers of rods is accurate and the connection is reliable, the construction period is relatively long.

Application Scenarios

  Single-layer reticulated shell: Suitable for building roofs with smaller spans and lighter loads, such as small exhibition halls, cultural activity centers, and industrial workshops. It can also be used for buildings with special architectural requirements, such as adopting unique curved shapes to create novel architectural images.

  Double-layer reticulated shell: Widely used in large-span, large-space buildings such as large sports stadiums, exhibition halls, and airport terminals. It can meet the requirements of large usable spaces and high loads, and its good stability and load-bearing capacity make it widely applicable in complex building structures.