Mechanical properties

Mechanical properties embrace load bearing capacity and impact resistance. The tiles and grid of a ceiling system are subjected to different loads. All of these possible loads must be considered during the process of planning and designing a ceiling.

  • Load bearing capacity - grid system
  • Load bearing capacity – Suspensions and fixings
  • Load bearing capacity – absorbers
  • Dynamic load bearing capacity - Impact resistance
Functional demands icon

 

Load bearing capacity - grid system

The live load - both static and dynamic - to which the suspension system can be subjected, depends on the demands made on breakage and deformation. In such cases deformation can be a form of deflection or twisting.

Functional demands, Mechanical properties
A form of deformation: Twisted profile
 
Breakage
It is imperative to prevent a ceiling from breakage or collapsing because it has been overloaded. Therefore the recommended maximum allowable load for each ceiling system (see the installation diagrams) is calculated and determined with a multiple safety margin against any kind of failure.
Maximum allowable load can only be applied if the ceiling is complete and has been installed in accordance with the installation diagram. In other words, the prescribed products must be used and all the ceiling tiles must be in place in the grid.
While the grid profiles and hangers constitute the load bearing capacity and strength of the ceiling, the ceiling tiles play an important role in stabilising the profiles sideways. This is especially important when a profile is loaded eccentrically, which often forces it to twist. In light of this, centric loading is always preferable. For example, it is important to install light fittings and other additional components so that the live load will be transferred centrically into the T-profiles.
 
Deflection of grid
When the maximum allowable load of Ecophon ceiling systems is established and determined, it is always deflection, not breakage, that is the decisive factor.
Functional demands, Mechanical properties
A suspended T-profile exposed with load (F) giving a deflection (f).
 
A load on a profile will always cause deflection (f). The deflection is proportional to the load and strongly depends of the span (L) between the supports. If the load (F) doubles, the deflection will double. The deflection becomes, however, even bigger if the distance between two supports doubles. The deflection from a point load will, for example, become eight times bigger.
In the table below, with recommendations for Connect suspension systems and maximum permitted loading of live load, we have taken into account the most important standards: ASTM C635, BS 8290 part 2, DIN 18 168 and SS 81 51 13. The decisive factor has been that deformation should be limited to L/500. When the deflection reaches around L/400 it is possible for the human eye to notice the deformation. The limit L/500 gives, with safety, a ceiling with a smooth appearance.
Example: For the span L=1200 mm the allowed deflection is 2,4 mm.
 
Recommended live load
The recommendations apply to live load in addition to the suspended ceiling's own weight. The live load can be point loads (light fittings, signs etc) located arbitrarily on the suspension system, but separated by at least 1 m. With hangers located more closely together, higher permissible live load than stated in the table can be achieved. Heavier loads must, however, be hung directly from the soffit.
If an actual live load is distributed over an area of 0.36 m² (600x600) or more, the grid is able to take a load 65% bigger than the recommended maximum live load regarding deformation in the table. This is provided the live load is fixed to the grid system. The actual live load must, of course, be considered for hangers and fixings.
Example: A recessed light fitting, 600x600 mm, with a weight of 7 kg is acceptable in a Focus ceiling which, according to the table, are able to carry a maximum live load of 83 N (8,3 kg) if the distributed area is 0,36 m² or more.
 
Recommended load
The above applies provided that the distance from the joint between two main runners to the nearest support point does not exceed ¼ of the allowable distance between suspensions.
Functional demands, Mechanical properties
The joint to nearest support point should not exceed ¼ of the distance between two suspensions.
 
This means that, when the distance between the suspensions are 1200 mm, the coupling point between two main runners has to be less than 300 mm from the support point. The above applies provided that the load will be transferred centric to the T-profile.
 
Vocabulary - Loads
Static load
The weight of the ceiling itself and the weights of items attached to the ceiling e.g. light fittings, loudspeakers, ventilation grills, signs and so on.
Dynamic load
Mechanical impacts, for example contact from balls in gymnasiums or water pressure when the ceiling is being cleaned with high pressure hoses.
Own weight (g)
The weight of the ceiling system itself (including the tiles, the total suspension system and all mounting details). This is always a static load.
 
Functional demands, Mechanical properties
Suspended T-profile with different loads.
Live load 
All loads added to the "naked" ceiling system. Live loads can be static or dynamic and embrace:
  • Uniformly distributed load (q) from light fittings, signs, pressure differences, cleaning, etc.
  • Point load (F) from light fittings, signs, impact, cleaning, etc.
  • Normal force (N) Force caused by impact, abrasion, cleaning and/or installation work. A dynamic load.
Design load
The own weight of the suspended ceiling and the actual live loads the ceiling is designed for.

 

Load bearing capacity – Suspensions and fixings

The chosen suspensions and fixings, such as hangers, direct fixing brackets, screws etc. must be able to carry the design load (the own weight of the suspended ceiling and actual live load) with at least factor three of the safety limit set against breaking. This means that suspensions and fixings used to support a ceiling must be able to carry, without collapsing, a load at least three times the load that they will be imposed to. All Connect adjustable hangers and direct fixing brackets meet these demands, providing the installation is carried out according to Ecophon installation diagrams and the maximum live load for the ceiling system has been respected.
The load bearing capacity (maximum allowable load) for Connect suspension and fixing products can be found in section Connect grid and accessories. The maximum allowable live load and the required minimum load bearing capacity of the fixings and the hangers for each individual ceiling system can be found in the installation diagrams.
Example: For Ecophon Master A the maximum allowable live load is 40 N (4 kg). The minimum load bearing capacity for the hangers and fixings must not be less than 160 N (16 kg), included a safety margin of at least three against breaking.

 

Load bearing capacity – absorbers

The basic rule is that loads must not be imposed on the absorbers. Light fittings, ventilation components etc. located in the suspended ceiling should be supported by the suspension system or be hung directly from the soffit.
Functional demands, Mechanical properties
The loading on the tile must be distributed evenly around the rim of the aperture.
 
However, Ecophon absorbers in 600x600 mm and 1200x600 mm sizes can take small loads, such as halogen spotlights. For absorbers that are 20 mm or thicker, e.g. Focus or Master, a maximum of 500 g applies, with a largest aperture diameter of 100 mm. The equivalent for 15 mm absorbers, e.g. Gedina, is 300 g.
Tiles wider than 600 mm and longer than 1200 mm must not be subjected to loads.

 

Dynamic load bearing capacity - Impact resistance

Dynamic load bearing capacity and impact resistance are measurements indicating how well single ceiling products or complete ceiling systems are affected by dynamic live loads, e.g. abrasion and impact.
Dynamic live load can be a separate blow from a ball or stick. It can also be recurrent, for example an object that is being pushed forward and backwards along a surface for a certain period of time. Another example of a dynamic live load is the pressure difference for a ceiling that may occur in a room due to opening and closing of doors and windows or due to changes in the ventilation systems.
The test method and evaluation scheme for ball impact resistance used by Ecophon is described in Annex D of the European standard EN 13964:2004 Suspended ceilings – requirements and test methods.
The test method in EN 13964 is mainly based on the old German standard DIN 18 032 part 3. However, the EN 13964 allows classifications in three classes (1A, 2A and 3A). The classification achieved depends on the choice of impact velocity of the ball.
It is the complete ceiling system that is being tested (including all components as hangers, profiles, fixing devices and tiles). In the test a handball is fired towards the ceiling with a special ball gun apparatus. The ceiling should be hit 36 times from three different angels. The method can also be used for evaluating wall panel systems.


Smart connecting

Modern ceiling installations require access and servicing during their entire life span. Connect accessories permit ready access to the ceiling void without any necessary interference to the system. Every single component has a well adjusted bearing capacity so that the system as a unit meets stringent demands.