What is Niches
Niches are a type of metal structure which have an arc shape or gradient ceiling. And they are used for different functions such as factories, workshops, repair shops, and livestock. Salons and restaurants, amphitheaters, hangar. Refrigerator, cellar, some sport salons, etc. these structures are divided into different groups in terms of size, kind of construction, as well as connections.
Different niches and their functions
The grinder plate
They are of oldest these structures. These structures are very similar to truss type but different factors distinct these two kind of structures. In Iran, the construction of truss niches does not have a long term archaism but arrow plate structures have been used in industry of construction of niches in Iran for a long time. Steel is used for making them and currently, a lot of effort is made to decrease the cost of arrow plate niches by changing their designs.
Construction of niches in countries
One of the reasons that these types of structures are not used in other countries is that there are some limitations for their dimensions of aperture, the more the size of the aperture increase, heavier and wider plates should be used in their constructions, so that not only their weights increase extremely but also the cost of their construction will increase. The growth of aperture lessens safety and it is not possible to easily raise the aperture because of an increase in width of metal plates. Therefore, the use of arrow plate niches for structures with raised niches has been almost obsolete. But niches with lowered aperture, still have good functions and it is possible to decrease the final cost.
One of the most important differences of arrow plate niches and truss niches is that for constructing the truss structure exact engineering calculations should be done but for constructing arrow plate niches no especial calculation is needed and this has caused to use it for different functions for a long time.
It is also called truss. HHS truss niches is one of the most functional industrial niches type that a light niches or in them pillars and wide, monolith bars are constituted with standard profile truss connections. The use of these materials not only provides a good strength for the structure but also provides the facility of especial architecture and different shapes for designing the structure.
Final cost of truss2 niches
Their cost is less than other types of niches because they need lighter reinforcement and foundation. In roofs and wall of these structures, ceiling and mural panels, galvanized sheets with different isolators (Aluzinc, fiber glass) or brick and cement covers are used and that ceiling panels are the best option but they are more expensive and ceiling and brick cover is not effective any
more. These structures have many advantages that is why they are used a lot. Their final cost is less that other structures and the final cost of structure skeleton is less. Also, one of the most important feature of this structure is that there is no limitation for its aperture dimensions and it can tolerate extensive amount of weigh and pressure. Also, their design and operation needs shorter period of time and it is possible to install heavy and high tonnage derricks in this type of niches.
UBM
It is considered the newest of this type and its construction has been common in Iran. For their construction galvanized plates are used which are carried raw to the place of construction. There they are shaped and connected with roll forming machines. They are tunnel-like and their roof is quite arc-shaped. Steel is not used in their construction.so their cost is less than other types of these structures. But they have some limitations for making aperture, and they are not suggested for creating any functions. Heavy and high tonnage derricks can’t be installed in them. They are not suitable for other functions such as aviculture as well because their ceiling quality is of polyurethane that is attractor of microbe and bacteria and disinfecting them is not possible too.so if these structures are used for bestial functions, it can a great deal of damage and cause infection and illness to the animals in livestock. Exactly for this reason they are not also used for medical, health, and dietary functions.
Divisions of niches in terms of ceiling and aperture
In terms of their aperture niches are divided into different types such as polygon niches, arc shaped, single span (8), two openings (88), multi-span (888).
In ceiling cover of these structure different materials such as glass wool and fiber glass, sandwich puzzle, inanity, polycarbonate, galvanized plate, foam, rock wool, grid is used
Function of niches
The functions of niches except from large industrial productions also include small domestic niches such as keeping gardening or boating tools, small wooden niches, keeping forage in farms or even entertaining niches that include small, cotton-like space.
Price
Different factors involve in pricing such as the quality of the used material, dimensions, etc. For getting familiar with ways of calculating the price for construction of niches and effective factors on that you can read the article about pricing the construction of niches in this website or through calling us by using the advice of Ralko experts for choosing the best niches suitable for your desired use call us.
Components of niches
The components of niches are certain and they are calculated and designed part by part by engineers. The components of niches are as follows:
Bending frame3 with simple or tangly bearing including pillars, or trusses
Longitudinal rods which are mainly in form of can with pipe
Transverse rods which ceiling braces is part of them
Harness rods
A layer that in size of 6 to 7 meters exist in market.
Braces that are used in form of pre-stressed rebar or profile Flange stay
Her prowess which have the duty of conveying the crane load to pillar Ceiling cover
Walls
The main frame
Pillars and girders are so-called the main frame and also the main girder includes pillars and girder. the main girder4 also so-called kicked.
In our country, pillars and kicked include non-charter cross section. A change in height in term of bar is because of a change in anchor.
One of the points in loading is that because we enter the loads to structure in a linear way, its anchor will be sagittal.
The production of pillars and bar is that they are primarily in form of sheets and they are cut based on the segment and then they are welded to one another.
From the bottom, pillars are welded to pillar page and from the top they are welded to kicked. Of course in limited cases especially in terms of pipe segments, the welded connections are used.
The wall post pillars
The wall post pillars are included in minor pillars and they are placed in primary and final part of the niche for decreasing the level of wind catching of the major pillars and making mustaband* for the surrounding walls and also for connecting the entrance and exiting doors of the vehicles.
Lining
We can consider lining as the side support.
The longitudinal components are horizontal that connect two in row frames in multiple points in a symmetrical way. These components are often made with canes and pipes. These components cause the energy to convey from one frame to the other and connecting frames to one another, in
fact, lining as the side support cause the increase of member’s capacity which length is usually between 5 to 8 meters.
Flange stay
For preventing the side twisting of the bar wings in spots where the lowered wings is under pressure, the pressing wing is restrained to hader layer in frames part with help of flange stay which is made of cornerstone or sheet.
Important points in designing the niches
Heavy designed or made niches
Due to some reasons such as decrease in waste of sheets, more profit, or the feeling of unsafety about the niches that they will make, sometimes the creators are interested in making the cross- sections stronger than the presented design. For instance, they increase the height of the pillars or the number of bolts or they intensify their width or they increase the length of the bars. In the meantime, although the design is now stronger, some points should be considered:
According to the fact that the amount of power attraction in bending frame5 is based on a difficult matrix, and it is possible that by a segment becoming stronger more energy be attracted, according to this it is necessary to take
some control so that the empowerment of inner member energy in comparison to the seen energy isn’t dangerous. For instance, the attraction of more anchor to the ending parts of the bar may need larger twisters in connecting bars to pillars.
with welding and overstated intensification, the pillar’s footage with different stepheners can cause that attraction of anchor in a connection which is supposed to be joint and cause rupture in pillar footage or the sheet at bottom of the pillar or bolts or destruction of the foundation.
The prediction of niche for future
It is better to add an extra niche. Experience has showed that addition of a niche (twins or a small niche) to an existing niche or to a niche which is being designed usually not only won’t it add any additional load to it but also through considering its restrains and creating reversed anchor in its pillar, it will improve the situation in terms of tension and replacement.
But for niches which are supposed to be designed in a twins’ form or in multiple twins’ form or with a childish niche, but currently the employer wants to construct one of them, and later with financial support will construct the other parts, the case is different, and since during the years when the niche is used single, if it pressured by the pressure of maximum load of wind or snow that was designed for it, it may not have the seen function in design and be destructed.
In these cases, firstly, the single niche which is supposed to be designed should be separately modeled and analyzed and evaluated.
If the tension6 of the niche solely is more than the accepted limit, it is necessary to intensify it, but if simply in the single condition its replacement be extended from the accepted limit, to a certain extent which relies on the benefactor departments, and this measure depends on the devotion of the employer we can ignore its replacement.
Two or three-dimension analysis
The doctor preferred the two-dimension technique.
Mr. tahooni agree more with the three-dimension analysis.
The analysis of niche using three-dimension analysis becomes complicated and relies on the ceiling braces and even the pressuring members take energy.
For controlling the displacement of niche and the use of dependent capacity of the frame, the three- dimension model is needed.
In three dimensional model the first and the final frame in comparison to other frames and existence of wind pillars and shooting horseshoe portal and coil and even wall and the first and second frame having less distance can be used for minimizing the displacement. Badband can be used in first and last frame for their more restraint. The foundation of these two frames should be designed for more wind power.
According to the decrease of niches replacement, and with the decrease of effect of –p it is possible that the niche’s tensions become less than two-dimensional. But considering that the analysis may not be exact or may not function well, it is better not to use this method for decreasing the tension.
But solely this method can be used for displacement so that no especial danger is made.
In three-dimensional analysis for controlling niche’s displacement, it is better to limit the number to something like doubled size of allowed displacement size so that functionality of niche is assured.
In forms of two-dimension analysis, out of page tensions such as twisting resulting from longitudinal power of derrick or bending surrounding the weak orientations of the girder and pillars is not seen.
Types of coverage of niches ceiling
For constructing niches sandwich panels can be used in covering the ceiling and the walls. Depending on the type of use in the niches celling, three panels can be used as is explained below:
Using sandwich panel with polystyrene insulation foam7
Using the made panel made with galvanized sheet and fiber glass Using the made panel made with aluminum sheet
The three proceeding cases have their own advantages and disadvantages and each of them can be called ceiling sandwich panels because they have layered structures. For choosing among these three types for the ceiling of your niches our suggestion is the use of polystyrene sandwich panel. Polystyrene is the newest internal foam for panels which being refractory, being waterproof, spit and thermal standard insulation are of its advantages.