PREFABRICATED SPACE STEEL FRAME SYSTEMS TECHNICAL SPECIFICATIONS
PREFABRICATED SPACE STEEL FRAME SYSTEMS TECHNICAL SPECIFICATIONS
A-) METHOD OF CALCULATION:
As the Prefabricated Space Frame System is highly hyperstatic, the system is designed by means of computers without requiring any simplifying aceeptance. The computerprogram operates with the Matrix-Displacement system. Once the analysis outputs of a project are received, the x,y,z displacements of the nodal points, bar forces, selected strut cross- sections, reactions at support and tensions at the bars of that project can be calculated. The loads are transported into struts (junction piece) via spherical hubs on the nodal points. In this case the junction pieces receive only axial stress or tensile force. Loading perpendicular to strut axis that will create moment on the space system struts is not allowed. External loads should be prevented from being laid on any elements other than nodal points.
Production and Assembly projects are prepared via computer in accordance with data obtained beforehand. Details of supporting and anchorage related to the wall, column, floor and contiguous buildings, with which the Prefabricated Space Frame System is supported, are given.
Load criteria that are taken in Space Frame System Statics calculation:
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Dead Loads
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Live Load
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Service Loads
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Snow Load
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Wind Load
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Seismic Load
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Temperature Influence
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-
Space Frame System
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Purlin system
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Coating
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Ventilation
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Lighting
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Wireways
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Suspended Ceilings
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Catwalks
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Installment Loads
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Point concentrated load
The loads are calculated according to TS 498, however it can beincreased in proportion that the management desires by taking the climate conditions into account according to the region.
B-) ELEMENTS THAT COMPOSE PREFABRICATED SPACE FRAME SYSTEM
1-) STRUTS:
In space frame system, struts, whose diameters and wall thicknesses are determined according to the forces that are detected in consequence of calculations, are welded ortensile materials with TSE certification, low-carbon according to DIN EN 10222-1 and DIN EN 10025, highly weldable, in the steel quality of St 37-2 or St 52-3.
Table – 1
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Steel Quality Tensile Stress
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St 37-2 37-45 kg/mm²
St 52-3 52-62 kg/mm²
Yield Stress
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24 kg/mm²
36 kg/mm²
The struts are produced in diameters between ¾” and 8”according to the forces that are detected in consequence of calculations and in conformity with TS 301/2 and DIN 2440. No other load is laid on the struts than tensile and pressure force. (Purlin, installment, catwalk, wireway etc.) The struts are not drilled in order not to create statically weak areas.
Table – 2
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Nominal Diameter Outside Diameter Wall Thickness
inch/mm mm mm
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¾” .........20 26,9 2,65
1” ..........25 33,7 3,25
11/4” .....32 42,4 3,25
11/2” .....40 48,3 3,25
2” ..........50 60,3 3,65
21/2” .....60 76,1 3,65
3” ..........80 88,9 4,05
4” .........100 114,3 4,50
5”..........125 139,7 4,85
6”..........150 165,1 4,85-6,30
8”..........200 219,0 5,60-6,30-8,00
2-) ADAPTERS (CONICS): The adapters that are welded to both strut edges are used in transmitting the tensile and pressure forces. The adapters are welded to both strut edgesvia gas metal arc welding in conformity with DIN 18800-1- 7 and DIN 18808. The adapters are processed with St 37, SAE J403 material with steel quality 1010 or 1020 and cut a bolt thread by being drilled from their edge axes according to bolts. The conic heads and strut material will be made of same quality materials. Their lengths can be extended asmuch as required for the securely transmitting of the excessive loads on nodal points. This characteristic gains importance in large openings.
3-) SPHERICAL HUBS : Spherical hubs are the nodal elements produced in hollow form with hot steel forging technique from SAE J403 material with steel quality 1020 or 1030. They are the points, where junction pieces linked with bolts, drillable from desired angle and on which the loads are transmitted. Their diameters are variable between 60 mm to250 mm according to the specifications of the project they are used and the loads they take. Screwing of struts to spherical hubs is conducted by opening maximum 18 bolt holes in spherical hubs. In the production of spherical hubs the material is given the spherical form with hot steel forging technique in hollow form and oxide layer on the surface is cleaned with sanding method. They allow loads to work as completely tensile or pressure according to the junction system.
Being approved in consequence of quality control, the spherical hubs are subjected to hot-dip galvanized coating in 80 micron thickness and painted with polyester electrostatic powder paint if desired.
4-) BOLTS : The bolts are ISO gearwheels conforming with the designated DIN 13 in variable diameters and quality in accordance with the load transmitted by the strut, on which it is used. They are produced in 8.8 and 10.9 quality conforming with DIN 267 terms. Bolt heads are shaped proprietarily according to inner diameter of spherical hubs. The lengths of the bolts can be altered when desired according to the loads; any operation (drill etc.) on the bolt that will weaken the intersection is not allowed and they transmit the load directly to nodal points.
Table – 3
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Bolt Quality 8.8 10.9
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to permanent strain) Tensile Strength
64 kg/mm² 90 kg/mm²
80 kg/mm² 104 kg/mm²
Minimum ultimate deterioration % 12 9
5-) SUPPORTS : They are designed as fixed support, spring support and movable support in accordance with the project. To procure the oiliness in movable supports teflon plates are used. Teflon plate thicknesses are determined according to the loads.
C-) PURLINS AND PURLIN STOOLS:
1-) PURLINS : Space frame system is mounted on the roof via purlin junction pieces in order to create appropriate surfaces for the coating type that will be made on the SpaceFrame System and to provide required roof pitch. Accordingly they are selected from box profiles or profiles with various cross sections. The purlins are made of ST-37 material.
2-) PURLIN STOOLS: Purlins are used for providing the desired pitch. Purlin junction pieces are linked to upper head hubs for the roof coating according to the form of the roof, tolower head hubs for the side coating via bolts. An adapter is found on one edge of the stools, which allows them to be bolted to the hub, and U-element that is bended from 2 or 3 mm sheet metal is found on the other edge. The length of the purlin stool varies according to the roof pitch.
D-) PROTECTION AGAINST CORROSION:
1-) APPLICATION OF POLYESTER BASED ELECTROSTATIC POWDER PAINT
Space frame system struts first will be cleansed from oil and rust in special baths. Then the struts are painted with polyester based electrostatic powder paint in a manner thatwill create a film layer in 80 micron thickness and hardened by being baked in an oven with 2000C heat. The struts are not drilled in order to prevent the increasing of corrosion.
The spherical hubs can be painted with polyester based electrostatic powder paint if desired over the hot-dip galvanized coating in 80 micron thickness.
Purlins and purlin stools are painted with 80 micron polyester based electrostatic powder paint after the required surface cleaning is carried out.
Bolts and washers are electro-galvanized in 20 micron thickness.
Polyester based electrostatic powder paint creates an even andbright film layer. The color of this paint is selected from the RAL catalogue. Matt, semi-matt, semi-gloss and high gloss surfaces can be obtained in various tonalities. As the electrostatic powder point is highly resistant against impacts, they are much more long-lasting than wet paints and other paints made in building sites. Electrostatic powder paint is resistant to temperatures between -350C and +280 0C and also to ultraviolet light. It is highly resistant against wear.
E-) ASSEMBLY:
Before starting the assembly authorized staff member checks the site, where the space frame system will be built, the supports and axles and takes it over from the employer.He/she reports the obstructive or inconvenient situations, if there is any, to the employer and asks for help for repair. Assembly of the space frame system is conducted inaccordance with the assembly plan and under the responsibility and surveillance of the authorized staff member, who will be constantly present on the assembly site. In the assembly process the system is temporarily supported, required camber is provided to the system and general safety of the system is assured in accordance with the instructions of the authorized staff member responsible for the assembly; and thus the assembly is completed by ensuring that junctions are made in a way that no loose bolts are left and all space frame system elements are in their axels.
Assembly methods:
a) The space frame system is mounted in the ground and then lifted up via cranes.
b)) Single member or a group of three st f members assemble the system in desired height.
c)) Both methods are used togeth .
Below are the applied DIN-ISO norms and equivalent TSE standards:
DIN 2440, 2441, 2458
TS 301/2, 301/3, 416/1: Methods of Strut Manufacturing
DIN 1055 (TS 498): Specification on Loads for Structures
DIN 18801, DIN 18800-1: Calculation Rules and Building Styles in High Steel Structures DIN 4100 (DIN 18800-1-7olarak değişti): Welded steel structures under static loads DIN 4114 (DIN 18800-2-3 olarak değişti):
Method of Calculation and Specifications on Stability Conditions in Steel Structures Şartnameler
DIN4115 (DIN 18801- 18808 olarak değişti):
Permission Principles, Manufacturing and Dimensions in Light Steel Structures made of Struts
Manufacturing and dimensions
DIN 55976 (DIN EN ISO 12944) (TSE 914): Painting Principles
DIN 17100 (DIN EN 10222-1, DIN EN 10025 olarak değişti): Material Norms