Roof jacks Roof jacks

To form ceilings in concrete structures, including concrete slabs and block beams, roof jacks are used. Roof jacks are produced in various lengths based on order requirements, and the usable dimensions of roof jacks typically range from 3 meters to 5.5 meters. For heights greater than this, the use of alternative methods and supports is necessary Use triangular struts or hammerhead struts. A ceiling jack at a height of 3.5 meters has a load capacity of 1.5 tons.

It is desirable to calculate a ceiling jack with a standard height of 1 meter and a diameter of 5 centimeters.

k=1m . l=300cm
s=kl/r=(1×300)/(1∙76)=170∙45

ce=√((2π^2 e)/fy=131∙4)

kl/r=170∙45>ce=131∙4

Fa=(π^2 e)/〖f∙s(kl/r)〗^2 F∙s=1∙92

fa=π^2 E→1∙92×(170∙〖45〗^2 )=371∙5kg

P=1∙4ton
p=fa×A→371∙5×3∙73≈1385

The pipe thickness in ceiling jacks up to a height of 3.5 meters is 6 (male) pipes with a thickness of 2mm and 5 (female) pipes with a thickness of 2.5mm. For jacks with higher heights, it is preferable to use 2.5mm thickness for male pipes and 3mm thickness for female pipes to adjust the height of the ceiling jack, holes are placed on the 5 (female) pipe at a distance of 10 centimeters from each other. This allows for optimal use of the minimum and maximum height of the ceiling jack. The adjustment of the centimeter height of the jack under the concrete structure is done using a spring-loaded pin and the ceiling jack’s nut. Therefore, the durability of the jack nut under hammer blows or load pressure is of great importance. The material of the nuts of the jacks produced in this collection is ductile iron, and they are provided with a warranty for being unbreakable.

Roof jacks

Calculating the number of ceiling jacks:

Usually, one ceiling jack is used for every square meter of the ceiling, provided that the concrete pressure per square meter does not exceed 1.5 tons. Otherwise, there is a risk of bending the male pipe of the ceiling jack. To ensure there are no issues when using ceiling jacks in tall concrete structures, it is necessary to increase the number of jacks. Instead of using them per square meter, the jacks should be spaced 80 centimeters apart from each other, and additional bracing should be used for extra security.

Ceiling jacks are produced in three different types due to their use in various situations:

  • Cross braced ceiling jack (teedar)
  • U shaped ceiling jack
  • Simple ceiling jack without a cross (plain), with the ability to install a movable cross

The crosses for ceiling jacks produced by Arta Bani Sanat Company are made of (50*30) profiles with a length of 75 centimeters, and the cross arms are made from (20*20) profiles. The approximate weight of the 3.4-meter cross-arm jack from this company is 15 kilograms.

Proper maintenance, careful handling, and lubrication of the jacks after the completion of each project increase the useful life of the ceiling jacks.

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