PREFABRICATED SPACE FRAME SYSTEM
TECHNICAL SPECIFICATIONS
1. GENERAL
1.1. SCOPE
Scope of the work covers design, fabrication, and erection of the steel space frame with pre-determined area, geometry and features described as per architectural drawings.
1.2. SUBMITTALS
DESIGN CALCULATIONS
Space frames are highly hyper static systems. Design calculations shall be made by means of computers. Software used for the design shall execute the analysis by using Matrix – Displacement (Stiffness) Method. Connections on the joints shall be defined so as not to transfer bending moments due to transmission of the loads by pin connected connections with bolts. Loads on the structure shall be transferred via the nodes. The design analysis may include the following loading criteria according to the project and contract conditions;
a) Dead loads (space frame, purlins & cladding)
b) Live load.
c) Wind load.
d) Seismic load.
e) Service loads (A/C ducts, catwalks, suspended ceiling, concentrated loads, etc.)
f) Snow load if applicable.
g) Temperature variation
Design calculations shall be prepared in accordance with current design rules of the DIN, EN, AISC, and BS or equivalent internationally accepted standards.
1.2.2. DRAWINGS
1.2.2.1. SHOP DRAWINGS
A. Layout details, section properties and identification of all the components.
B. Accurately dimensioned layout of space frame showing the related distances with walls, columns, beams or slabs of the substructure on which the space frame is to be erected.
C. Details and all other information to show provisions for horizontal expansion and contraction of space frame at the supports.
D. Details of supports and anchoring to the substructure.
E. Purlin system plan and details.
2.2. SPACE FRAME COMPONENTS
TUBES:
All the tubes, whose sections are determined according to the tension and compression forces as per the design calculations shall be seamed tubes produced from S235JR (St37-2), S275JR ( St44-2), S355J2G3 ( St52-3) quality steel sheets with high weldability property conforming to EN10025 standards.
Steel Quality |
Yield Stress |
Tensile Stress |
Elongation After Fracture |
S235JR (St37-2) |
235 N/mm2 |
340-470 N/mm2 |
24% |
S275JR (St44-2) |
275 N/mm2 |
410-580 N/mm2 |
20% |
S355J2G3 (St52-3) |
355 N/mm2 |
510-680 N/mm2 |
20% |
Tubes produced in conformance with the DIN 2440, DIN 2441, DIN 1626, EN 10219 standards ranging from Φ26.9mm and Φ323.9mm diameter according to the design shall be used. Hot forged and/or machined cones of the same material quality of the tubes shall be welded on each end by semi-automatic gas shielded arc welding process.
NODES & CONES:
Nodes starting from Φ50mm diameter (Φ50,60,75,90,110,130,160,200,240,280,300,380...) shall be produced with C45 or AISI / SAE 1050 quality material in conformance with the EN 10083-2 standard, with hot forging in normalized condition and/or machining production techniques. Required bolt connection holes shall be drilled and tapped with digitally / manually controlled drilling machines.
BOLTS:
All bolts shall be produced with the materials in conformance with EN 10083-1 standard and shall have ISO metric treads conforming to DIN 13-1. Strength classification shall be 6.8, 8.8 or 10.9 in compliance with the requirements of EN ISO 898-1.
Bolt Quality |
Yield Stress |
Tensile Stress |
Elongation After Fracture |
Space frame bolt 8.8 |
640 N/mm2 |
800 N/mm2 |
12% |
Space frame bolt 10.9 |
900 N/mm2 |
1000 N/mm2 |
9% |
Purlin system bolt 6.8 |
480 N/mm2 |
600 N/mm2 |
- |
SUPPORTS:
Supports shall be produced with C45 or AISI / SAE 1050 quality material in conformance with the EN 10083-2 standard, with hot forging and/or machining production techniques. Required bolt connection holes shall be drilled and tapped with digitally controlled drilling machines. Support flanges shall be of S235JR (St37-2) material in conformance with EN 10025. Teflon plates with low friction coefficient shall be placed under the moveable supports.
2.3. PURLIN STOOLS AND PURLINS (if necessary)
PURLIN STOOLS:
Slope of the roof shall be provided by means of purlin stools. Connection of the purlin stools to the nodes shall be made by means of bolts.
PURLINS:
Purlins shall have sufficient width to receive cladding shall be spaced as required to provide appropriate support for cladding. Purlins shall be from S235JR (St37-2) quality steel with rectangular hollow section /or channel or built-up sections in dimensions required by the design.
2.4. PROTECTION AGAINST CORROSION AND FINISHINGS
a) Nodes and supports shall be electro plated with average 25 micron thick zinc in conformance with ISO 2081.
b) Bolts shall be coated with Delta Protect or Dacromet in conformance with ISO 10683, which consist of aluminum and zinc particles stocked in inorganic titanium and provides highest resistance against corrosion. This process meets the requirements of DIN 50021.
c) Tubes, purlins and purlin stools shall receive electrostatic polyester powder coating of average 70-80 microns and shall be baked in oven at 200 °C. If required, tubes and purlins can be hot dip galvanized in conformance with EN ISO 1461, EN 1179 prior to powder coating.
d) Sleeves shall be hot dip galvanized in conformance with EN ISO 1461, EN 1179.
3. PRODUCT DELIVERY, HANDLING AND STORAGE
Space Frame components shall be handled, delivered and stored in such a way that;
A. Materials to be free from scratches, other damages and corrosion
B. Not to require a large storage area
C. To facilitate handling and segregation
D. Each package, box or crate to be labeled to identify components in type and quantity and provide reference codes.
Contractor shall hold the responsibility for protection of the materials stored at site or completed space frames as per manufacturer’s recommendations, to prevent damage or deterioration whilst current or subsequent works are executed.
4. ERECTION
4.1. CONTROL AND CONVENIENCE OF THE SUB STRUCTURE
As required by quality procedures and instructions, prior to erection, our engineers shall check the general site conditions and particularly the condition of the substructure on which space frame system is to be erected. All deviations, from the approved shop drawings and all other unsatisfactory conditions, to be brought to the attention of the Engineer. At the same time appropriate Contractor to be notified about the conditions detrimental to the proper and timely completion of the work and requirements necessary to correct them. Erection shall commence as soon as the unsatisfactory conditions are corrected.
4.2. ERECTION
Erection shall proceed in strict accordance with the manufacturer’s approved erection drawings and general “Work safety and workers health” regulations, all bolts shall be tightened correctly in a way that no bolt will remain loose and there will be no slack in the connection. All the components of the space frame are prefabricated to match their position in the system and to be in true line and level with configurations as shown on the erection drawings. So, no force shall be placed on the member and the bolts shall not be forced during the erection to prevent secondary stresses. Temporary supports shall be placed to ensure the stability of space frame, as may be required during the erection according to the design controls of the erection sequences. Site welds of the supports shall be made by the experienced, welders upon completion of the erection and arrangement of the support allowances for movement. Touch up paint work of the scratched and damaged surfaces shall be made with matching air drying touch up paint provided by the manufacturer.
4.3. HAND OVER OF THE JOB
Upon completion of all the erection woks, the space frame shall be handed over to the client with the “Practical completion and hand over report” which is to be duly signed by the manufacturer and the client.
4.4. WARRANTY OF PROJECT
A written guarantee shall be issued to the owner warranting that all works described in the contract documents have been completed in accordance with the contract documents, for a period of one (1) year from the date of completion.
