Various aspects of space frames and their erection using sliding method

Various Aspects Of Space Frames And Their Erection Using Sliding Method

Space frames have gained unprecedented popularity as durable and reliable construction units suitable for a wide range of structures. Today these units are being increasingly used to erect column free structures that offer the advantage of efficient utilization of space besides being economical. The popularity of space frame units, understanding their various aspects is of utmost importance.

Structural Details Of Space Frames Space frames are basically long spanning, three-dimensional late like structures that are made up of linear elements. These structures are based on

the rigidity of the triangle with the elements exposed only to linear tension and compression even when they are connected by relatively rigid joints. This not only minimizes the influence of bending and torsion movement but also enhances the sturdiness of the units.

Different Types Of Space Frames A space frame manufacturer generally classifies these units into two main categories as discussed below.

On The Basis Of Curvature: As the name suggested this category includes the space frame units that have different curvatures. This category is further divided into following three subcategories.  Flat Covers: These space frames are made up of planar substructures with the planes channeled through horizontal bars while the diagonals support the shear forces.  Barrel Vaults: These vaults are comprised of a cross section of a simple arch. These space frames generally do not require to be backed by tetrahedral modules or pyramids.  Spherical Domes: As the name suggests, these Space frame units are spherical in shape and hence require the backing of tetrahedral modules and pyramids along with additional support from a skin.

On The Basis Of Grid Layers: These types of space frame units are categorized according to the number of layers that comprise the unit. This category consists of the following three subcategories.  Single Layer: In this type of structural units all the elements are located in a single layer on the surface that is to be approximated.  Double Layer: As the name suggests, these space frame units consists of two parallel layers located a specific distance. All the elements are organized along these two layers, while diagonal bars are used to connect the nodes of the two layers in different directions in space.  Triple Layer: These are three layered space frame units that are generally flat except in some rare cases. The three layers are connected by diagonal bars, which are greater in number in units that are not flat.

Main Components Of Space Frames The space frames are comprised of two main components namely the members and the joints, each of which is described in brief as follows.  Members: These axial elements feature circular or rectangular sections and are designed to only tension or compression. A space grid generally comprises of long tension members and short compression members.  Joints: Joints are the most important component of space frames both in terms of functionality and aesthetic appeal. They comprise of a total of 20 to 30% of the weight of space frames and have a deep impact on the strength, stiffness, safety and economy of the structure, which is why the joints needs to be designed with great care and after considering a variety of factors.

Sliding Method Of Erection Another factor that plays a critical role in enhancing the aesthetic appeal and long life of a structure is the method of erection used for establishing the space frames. For large span structures using the sliding method of space frame erection is generally preferred as it simplifies the process of setting the roof in its final place in an accurate and perfect manner.

The assembling of the roof structure is done temporarily on a stage, after which the roof is slid into its position by sliding it over a rail. The rail is settled into the temporary supports or perimeter beams, while the roofing units are slid with the help of oil jacks and winches. The multiple roofing units are thus slid into position one by one and are assembled successively as each unit slides in. Alternatively, the engineers might choose to assemble the entire roof together, once all the roofing units have been put in their proper place.

Using the sliding method for erecting roofing structure space frames brings down the construction time and cost as the setting up of the roof can be carried out simultaneously with the building construction going underneath.

Using this technique is extremely simple and does not require the use of any special lifting or erecting machinery or equipments, such as cranes, hydraulic lifts or other such equipments.

However, in order to ensure perfect accuracy and precision in setting the roofing structure, the engineers need to first study the process through computer simulation. It is also important to monitor the entire process quite closely to attain a perfect setting. In this respect the sliding method can be quite demanding and might even require reinforcement to attain the required accuracy desired for the structure.