SPACE FRAMES:MODULAR CONSTRUCTION

TECHNOLOGYPREPARED BY:

SHERYL

SEM VI

KMEA COLLEGE OF ARCHITECTURE

• A space frame or space structure is a truss-like, lightweight rigid structure constructed from interlocking struts in a geometric pattern.

• span large areas with few interior supports.• Inherent rigidity of the triangle; flexing loads ( bending moments ) are transmitted as

tension and compression loads along the length of each strut.• Simplest form – horizontal slab of interlocking square pyramids and tetrahedral built

from aluminium or tubular steel struts.

SPACE FRAMES

HISTORICAL BACKGROUND

• Space frames were independently developed by Alexander Graham Bell around 1900 and Buckminster Fuller in the 1950s.

• Bell – using them to make rigid frames for nautical and aeronautical engineering, with the tetrahedral truss being one of his inventions.

• Fuller – architectural structures and his work had greater influence.

APPLICATIONS

• For a platform overhead structure that spans large distances without need for internal load bearing support.

• New and imaginative applications are being demonstrated in the total range of building types , such as sports arenas

exhibition pavilions, assembly halls, transportation terminals, airplane hangars, workshops, and warehouses.• Also used on mid and short span enclosure

as roofs , floors, and exterior walls.

ADVANTAGESlightweight The material is distributed spatially in such

a way that the load transfer mechanism is primarily axial; tension and compression.Consequently, all material in any given element is utilized to its full extent.Aluminium decreases considerably their self-weight.

Mass productivity Can be built from simple prefabricated units, which are often of standard size and shape.Easily transportedRapidly assembled on site.Therefore it can be built at lower cost.

stiffness Sufficiently stiff in spite of its lightness.This is due to its three-dimensional character and to the full participation of its constituent elements.

versatility Possess a versatility of shape and form and can utilize a standard module to generate various flat space grids, latticed shell, or even free-form shapes.

STRUCTURAL BACKGROUND

• A long spanning three dimensional structure• Rigidity of the triangle• Composed of linear elements subject only to

axial tension or compression• The influence of bending moment is

insignificant.• The span-depth ratio varies from 12.5 to 25, or

even more.• The depth can be relatively small when

compared with more conventional structures.

TYPES OF SPACE FRAMES

Flat covers Barrel vaults Spherical domesComposed of planar substructures.The plane are channelled through the horizontal bars and the shear forces are supported by the diagonals.

This type of vault has a cross section of a simple arch form.Usually does not need to use tetrahedral modules or pyramids as a part of its backing

Usually require the use of tetrahedral modules or pyramids and additional support from a skin.

ACCORDING TO THE NUMBER OF GRID LAYERS

Single layer Double layer Triple layerAll elements are located on the surface to be approximated.

Organised in two parallel layers with each other at a certain distance apart.The diagonal bars connecting the nodes of both layers in different directions in space

Placed in three parallel layers , linked by the diagonals.Almost always flat.This solution is to decrease diagonal members length.

COMPONENTSMembers Joints Axial elements with circular or rectangular sections , all members can only resist tension or compression.The space grid is built of relatively long tension members and short compression members.

A trend in which the structural elements are left exposed as a part of the architectural expression.

Connecting joints- both functional and aesthetic.joints have a decisive effect on the strength and stiffness of the structure and compose around 20-30 percent of the total weight.

SPACE FRAME CONNECTIONS

DESIGN CONSIDERATIONS FOR DOUBLE LAYER

MERO SPACE FRAME SYSTEM• The Mero connector, introduced in 1948 by Dr,

Mongeringhausen , proved to be extremely popular and has been used for numerous temporary and permanent buildings.

• Its joint consist of a node that is a spherical hot-presses steel forging with flat facets and tapped holes.

• Members are circular hollow sections with cone-shaped steel forging welded at the ends, which accommodate connecting bolts.

• Originally developed for double-layer grids.

• Due to the increasing use of non-planar roof forms- load bearing space frame integrated with the cladding element.

• A new type of joining system called Mero Plus System was developed so that a variety of curved and folded structures are possible.

METHODS OF ERECTION

Scaffold method Block Assembly method Lift-up methodIndividual elements are assembled in place at actual elevationsMembers and joints or prefab subassembly elements are assembled on their final position.Full scaffoldings usually.Sometimes partial scaffolding are used if cantilever erection.Elements fabricated at the shopTransported to the construction site, and no heavy lifting equipment is required.

Divided on its plan into individual strips or blocks.These units fabricated on the ground level. Then hoisted upon into its final position and assembled on the temporary supports.Suitable for double layer grids.

The whole space frame is assembled at the ground level so that most of the work can be done before hoisting.Increased efficiency and better quality.

Space frame To accommodate large unobstructed areas

Satisfying the requirements for lightness, economy and speedy construction

Its great structural potential and visual beauty

Demand for large space with minimum interference from internal supports

Difficulty of the complicated analysis of such a system has contributed to its limited use

APPLICATIONS : Sport arenas

Exhibition pavilions

Assembly halls

Transportation terminals

Airplane hangars

Workshops

Warehouses

Long span,mid and short span enclosures as roofs, exterior walls , and canopies.

SINGLE AND DOUBLE LAYER• a flat or a curved surface.• Earliest form is single-layer grid.• By adding intermediate grids and including rigid

connection to the joist and girder framing system.

• The major characteristic of grid construction is the omnidirectional spread of the load as opposed to the linear transfer of the load in an ordinary framing system.

• Since such load transfer is mainly by bending, for large spans the bending stiffness is increased most efficiently by changing to a double-layer system.

• The load transfer mechanism of a curved surface from the grid system that is primarily membrane-like action.

LOAD TRANSER planar structures and space frames

• In a planar system, the force due to the roof load is transferred through the secondary elements, the primary elements, and then finally to the foundation.

• Ina space frame system, there is no sequence of load transfer, and all elements contribute to the task of resisting the roof load in accordance with the three-dimensional geometry of the structure.

LOAD TRANSFER• Designing a roof structure for a square

building.

• A complex roof composed of planar latticed trusses. Each truss resists the load acting on it independently and transfers the load to the columns on each end.

• Latticed trusses are laid orthogonally to form a system space latticed grids that will resist the roof load through its integrated action as a whole and transfer the loads to the columns along the perimeters.

• Since the loads can be taken by the members in three dimensions, the corresponding forces in space latticed grids are usually less than in planar trusses and hence depth can be decreased in a space frame.

LOAD TRANSFER• Designing of a circular dome.

• A complex of elements like arches, primary and secondary beams and purlins which all lie in a plane. Each of the elements constitutes a system that is stable by itself.

• An assembly of a series of longitudinal, meridional and diagonal members, a form of latticed shell.

ADVANTAGES• Lightweight

• distributed spatially, load transfer mechanism is primarily axial- tension or compression.

• steel, aluminium.

• Prefabricated , easily transported and rapidly assembled. Can be built at a lower cost.

• Sufficiently stiff.

• versatile

DOUBLE-LAYER GRIDS