Guidelines Concerning Expansion Joint Selection And Design

Product description

An expansion joint (dilation joint, from Latin dilatare: to expand, to extend) is a purposefully created slit in a building or structure, the task of which is to allow individual components of the structure to work independently of the rest. Separate components transfer loads, deformations and movements by themselves. Expansion joints are executed to protect the structure from:
- concrete contraction and temperature differences that can cause cracks or fractures of a reinforced steel structure,
- unequal setting
- concrete creep.

The following types of expansion joints are known:

  • structural joints - they separate a part of the building forming one complete whole with respect to statics, manufacture technology and foreseen site use, or stem from its grand proportions. They are used if a foundation method is changed, a building's structural arrangement is changed or load differences are great. They separate all structural components across one section, from the foundation to the roof,
  • thermal expansion joints - they work to contract or expand and protect the building against cracks arisen as a result of temperature changes. They act to eliminate the influence of large stresses from thermal deformations of individual building components,
  • anti-vibration expansion joints - in most cases associated with industrial structures, where they are supposed to protect the site or its constituent components against the influence of vibrations (dynamic and/or acoustic influences) from foundations and the framework profiles on which machines are placed. Similar properties and a similar requirement of use for a structure may be imposed by virtue of a building's location in the area of influence of seismic waves caused by earthquakes or mining damage,
  • expansion joints allowing unequal structure setting - the phenomenon of setting stems from mechanical properties of soil, and in particular, from its compression ability, or the ability to reduce its volume under the influence of load. If the soil conditions change under the foundations, within the outline of the building's silhouette, then its subdivision into individually working parts is substantiated from the economic point of view. One needs to remember that expansion joints should be designed in buildings along their entire height, from the foundation to the roof.


A national annex to Polish standard PN-EN 1992-1-1 indicates the maximum distances between expansion joints.

Table no. NA.1
Structure type Distance between expansion joints djont
in metres
Structures subject to outside temperature variations
a) non-reinforced walls
b) reinforced walls
c) reinforced concrete framework structures
d) uninsulated roofs, cornices

5
20
30
20
Heated, multi-storey buildings
a) internal walls and ceilings, concreted monolithically in one line
as above - concreted in sections not exceeding 15 m in length, 
with spaces left over for later concreting
c) internal pre-cast walls with external pre-cast walls
d) as above - with external walls of aerated concrete
e) as above - with light outside walls, lengthwise part providing rigidity in the central part of the building
f) as above - with fixing walls in the end parts of the building
g) pre-cast framework structures and monolithic structures with reinforcement in the central part of the building
h) monolithic framework structures with walls providing rigidity in the end parts - as appropriate

30
as in the case of internal pre-cast walls
50
40
70
50
as in the case of internal pre-cast walls
as for a) or b))
Heated single-storey reinforced concrete walls without walls providing rigidity or only in central part, with outside walls of low rigidity not experiencing cracking in case of deformations in their plane - depending on structure height h
a)  h≤5m
b)  5 c)  h  ≥  8  m


60
10 + 10h
90
Massive walls, if no special processes are used to reduce hardening heat and contractions depending on thickness
a) b = 0,3 m ÷ 0,6 m
b) 0,6 m < b ≤ 1,0 m
c) 1,0 m < b ≤ 1,5 m
d) 1,5m < b ≤ 2,0m

 

Possible directions of movement of building parts connected through expansion joints

Structures and their individual component parts are subjected to actions of various forces that are the result of the building setting, temperature and humidity variations, as well as static and dynamic loads. These forces then cause changes in tension of components that can lead to the emergence of irreversible changes in the parts or contribute to cracking, or, in the extreme cases, to fractures of the material.
In order to reduce the possibility of emergence of permanent or their spreading to other parts of the building is simplified by independent static work. This requirement is fulfilled by the designed structure divisions - expansion slits..

With respect to the choice of an appropriate expansion profile, the following criteria should be considered: expansion slit width, height of installation of the profile in the structure, profile type (overlay profile or profile installed before the execution of floor finishing work), type of coverage of the surface with the expansion slit, volume and intensity of the loads to which the profile will be subjected during use, sanitary requirements and resistance to aggressive chemical compounds.

Very important is also the information concerning the type of tyres of the transport vehicles used on site. Singular loads exerted on the expansion profile with a small vehicle diameter or their small width, made of i. e. hard polyamide or vulkollan, are very high. Even in case of comparably narrow slits, they must be appropriately robust.

For industrial floor expansion profiles offered by Betomax, comprehensive strength tests were conducted according to load values for forklift trucks per norm PN-EN 1991-1-1 and for loads from vehicle traffic according to standard DIN 1072.


Below the tables, norm loads are indicated, to which a profile may be subjected, and according to which it is chosen.

Deflex floor profile load table
Load type According to norm 
Vehicle type Maximum static vertical load from vehicle axle
[kN]
Area of tyre adherence to surface [cm]
Separation between components anchoring the profile to the grounda [cm]
Distance from last anchor to profile end [cm]

PN-EN 1991-1-1
DIN 1055






Forklift truck
26
20/20 30
15

PN-EN 1991-1-1
DIN 1055
40
20/20 30
15

PN-EN 1991-1-1
DIN 1055
63
20/20 30
15

PN-EN 1991-1-1
DIN 1055
90
20/20
30
15

PN-EN 1991-1-1
DIN 1055
140
20/20 30
15

PN-EN 1991-1-1
DIN 1055
170
20/20 30
15

DIN 1072


Goods truck
40
20/30
30
15

DIN 1072
30
20/26
30
15

DIN 1072
20
20/20
30
15

DIN 1072
50
20/40
30
15

DIN 1072
100
20/60
30
15

particular situation Pallet lifter 10
2/3
30
15

PN-EN 1991-1-1
Light vehicle
≤ 30 kN
10
20/20
30
15

The image below shows the action of vertical loads (pressure) on expansion profile structures.

One of the most important parts of an industrial building is its floor. It constitutes the main interior finishing component, allowing easy and safe movement of people, means of transport and appropriate storage of materials.

Under operating conditions, the floor is subjected to numerous destructive factors stemming mainly from static and dynamic loads (often characterised by great intensity), varying temperatures and the influence of aggressive substances and water. The floor covering durability during use may be guaranteed by an appropriate expansion profile system.

Expansion slits are, regrettably, spots that are under the greatest threat of damage, and that is why they must be appropriately protected. Even during the design phase, the expansion profiles should be selected, taking into account the conditions of its later operation. This allows the floor covering to work without flaws for long years to come.

Double-layer floors
Concrete floors are constructed up in most cases of two layers, the load bearing structure (construction layer) with a thickness of 10 cm - 20 cm, depending on the load volumes and types, and a top (wearing) layer with a thickness of 3-6 cm. The most appropriate solution is for the expansion slit to pass through both of these layers.

Single-layer floors
Single-layer floors are made on a thoroughly packed sand subsurface laid out on soil.
The thickness of the concrete subsurface (structural load bearing layer) on a sand layer, depending on the load volume and type, amounts to 10-40 cm. The finishing layer of a traditional mineral floor does not exceed 3-5 cm, and in case of use of special low-wear composite materials - several millimetres.

During the design of such a floor, one needs to remember that under the load of forces, particularly focused forces, the floor works as a support component close to the expansion slit. In order to avoid excessive deflection, under the expansion slit one must execute, along its entire length, a so-called expansion slit foundation.

 

Depending on the location of the floor within the building, its structure may be composed of several layers: the floor proper, the subsurface, the insulation (be it thermal or noise insulation) and humidity (or water) insulation.
The method of construction of the joint between the floor structure layer and the substructure allows differentiation between:
- floors bound with the subsurface,
- floating floors, laid out on a slip layer.

An appropriate expansion profile choice should consider:
a) horizontal shift (±),
b) vertical shift - surface setting (i. e. cave-in area, earthquake area or joints of new buildings,
c) expansion joint width,
d) height of profile installation into structure,
e) visible profile part,
f)  other materials, with which the profile will come into contact (i. e. screed, asphalt),
g) normal loads (standards per PN-EN and DIN 1072), profiles transferring higher loads - upon request,
h) aggressive media (chemical industry, milk plants, etc.).

In case of queries concerning profile selection with respect to day joints (Omega profile), one needs to provide:
a) steel grade, of which the profile is to be made,
b) sheet steel thickness,
c) profile height,
d) diameter, length and spacing of the bolts.

Considering a structure's durability and its operational usability, the interior aesthetics and the structure's operational abilities, one should make every effort to ensure appropriate protection of the expansion joints. Experience shows that increased expenses used for the protection of expansion joints as well as high quality and professionalism of the contractor greatly limit refurbishment costs and reduce hindrances over the structure's lifetime. 

This catalogue should be helpful material for the purpose of design of expansion slit execution and for the choice of appropriate profiles.
In case of any doubts, please contact our technical advisors. We are convinced that we able to provide optimum solutions even for the most uncommon situations.

In case of queries concerning the choice of expansion profile, please indicate:
- expansion slit width,
- expansion slit movement compensation,
- structure profile installation height,
- load amount,
- point of installation.

The table below presents the most important properties of the individual Deflex expansion profiles simplifying the initial choice of the best solution.

Expansion profile types

Load type

Expansion slit width [mm]
Material
Movement direction

Steel
Aluminium
Levels Vertical Horizontal
DEFLEX 420/SP
       

250

. . . .
DEFLEX 420/SPN


50-100

. . . .
DEFLEX STF 60


0-100
.

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  Day joint profiles
OMEGA

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