The standard includes steel truss beams that are construction steel beam by manual welding or spot welding, as well as crocheting. The standard does not include steel girders integrated with the lower steel wing.
A beam is a piece made of steel and concrete that forms a T-shaped section by placing blocks on it as a cover concrete mold (poured in a grid).
There are two types of truss beams:
A beam with a permanent mold (clay) which is called a shoe beam.
Beam without permanent mold (concrete)
Truss is a truss made of steel truss and concrete heel. The grid beam truss is a prefab structure of lower, upper and transverse tensile bars (zigzag) that are welded or hooked to each other in the form of a truss and.
provide the necessary strength for carrying and its components. they do. The prefabricated truss consists of the following components:
1) The bottom bars in the first stage of beam loading, the bottom bars of the truss must be able to withstand the tensile force (resulting from the bending anchor) caused by the weight of the dead load of the roof in the distance from the axis to the axis of the beams.
they are loaded in three stages, in the first stage of load They bear the load caused by transportation, and in the second stage, the load caused by the roof concreting components, which is the dead weight of the roof (the weight of the block beams and in-situ concrete).
and the loads during execution between the main supports and the beams. And in the third stage, the load bearing process resulting from the dead and live loads after processing the cover concrete has sufficient resistance.
while the live opening of each building is suitable for itself and has the approval of the supervising engineer and the accounting engineer. (residential, commercial, office)
2) Hot-rolled steel products are packed in a simple or ribbed or round section in the form of branches or coils. Treads are ridges that are created longitudinally and transversely on the surface of the rebar during rolling. The free distance of the joists should not be more than 75 cm.
the thickness of the covering concrete of the upper part of the joists should not be less than 5 cm, the width of the joists should not be less than 10 cm, and the total height should not be more than 3.5 times their minimum width.
Due to its high weldability, A2 rebar can be used in grades 9, 10, and 12. If necessary, A3 type rebar can be used in grades 14, 16, and 18. Welding must be done in a roofed hall and from The rectifier device with 160 to 190 amperes in different sizes should be used.
The appearance of the concrete part of the beam, which is the seat of the blocks, must be at least 15 mm and be healthy and smooth, and the head of the reinforcing bar must be visible from the surface of the heel concrete. Moving the beams during production must be done 72 hours after concreting.
if using the Special features that accelerate the setting of concrete, the above time can be reduced, the amount of negative rise of the beam 1 cm in length, and also the lateral complexity of the beam should not be more than 1 cm in length.
Definition of a beam with an open web (metal)
Based on the scientific methods and technology of design, production and implementation in the field of steel beams with open life, it is a prefabricated member that plays a role as a simple two-headed special truss for uniform distribution and transfer from the roof to the support.
These beams include an integrated combination of a self-standing metal beam and a concrete slab that acts as a T-shaped beam, which is used to fill the gaps between the beams from a temporary or permanent form (cement block) or from light pieces (plasto). foam) is used.
Steel beams with open life have various advantages as follows:
No need for candles
Due to the dynamic and static properties of steel and its special design, the steel beam with an open life has the ability to support its own weight, permanent or temporary molds.
the pressure caused by pumping and the weight of wet concrete. For this reason, the construction of the roof with steel beams with open life does not require piling, and as a result, the construction of the roof at different heights is possible.
Considering that there is no need for piling in the roofs of open steel beams, several roofs can be prepared one after the other and concreting operations can be done at the same time, thus reducing the overhead costs (concrete pump cost – worker’s wages) and Waste of time is reduced.