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 component 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 by expansion joints.

Structures and their details are always subjected to influences by diverse forces that are the result of setting, temperature and humidity variations, static and dynamic loads. These forces cause tensions within components, which can cause the emergence of irreversible changes in the parts or cause the material to crack, or in the extreme cases, to fracture.
In order to reduce the possibility of permanent damage emerging or of damage spreading to other parts of the structure, individual building components are allowed to work independently with respect to their statics. This requirement is fulfilled by the designed structure joints - expansion joints.

Mutual movements and the width of the expansion joint are determined in the design phase. Of significant importance during the design phase is the designing entity that decides on the choice of appropriate expansion profile system. The contractor in turn should adhere to recommendations and instructions of the expansion joint profile system manufacturer
The choice of appropriate profiles for installation of the expansion joints is thus decisive for their proper operation.
Should the issue not be treated seriously enough, damage such as surface cracks, fractures on corners, structure humidity, flaws and profile structure damage will emerge.
In case of expansion joints in floors of industrial and warehouse structures, one should consider, beside the width of the slits, also the thickness of the floor surface and the movement values to be expected, loads from wheels of transport vehicles and their tyre types.
Information on tyre types is very important, because one assumes the use of vehicles with small wheels that have a small width, made i. e. of hard polyamide or vulkollan.
Point loads that are then transferred to the expansion joint protection component (profile) are very high, and even if the slits are comparably narrow, appropriately massive expansion profile structures need to be used.
How the pressure forces and pull forces act on the structure, is presented in the image below.

 

For floor profiles, static tests were conducted according to load data for forklift trucks per norm PN-EN 1991-1-1 and DIN 1072 - loads from vehicle traffic.

In case of proper profile choice, the following decisive criteria should be taken into account:
a) allowable horizontal shift ±
b) allowable vertical shift - surface setting (i. e. cave-in area, earthquake area or joints of new buildings with existing structures),
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),
h) place of use, i. e. structures with high hygiene and sanitary requirements (hospitals, schools, etc.),
i) aggressive media (chemical industry, milk manufacture plants, etc.),
j) providing the interior with a particular aesthetic design,
k) option of installation on the finished floor surfaces at a later construction phase or in unfinished surfaces.

The load table, according to which an initial choice of expansion profile may be made, is found below.

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

Considering structure reliability, usability as well as aesthetics and functionality of a site, one should make all effort to provide appropriate protection of expansion joints. Experience shows that increased expense borne in this respect and high professional quality of the contractor limit to a great extent expenditures for refurbishment and mitigate difficulties during site use. 
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.


In the following table are presented the most important properties of Deflex expansion profiles, facilitating the initial choice of the proper solution.

Expansion profile types Load type Expansion slit width [mm] Material Movement direction
Aluminium Others Levels Vertical Horizontal
DEFLEX 418
             

50-100
.

.

.
DEFLEX 423/ALR


30-100
.

. . .
DEFLEX 423/NALR


55-135
.

. . .
DEFLEX 424/NALR


35-100
.

.
.
DEFLEX 425/AL


35
.
rubber .
.
DEFLEX 426/ALR


40-100
.

. . .
DEFLEX 426/ALR-RS


40-100
.

. . .
DEFLEX 426/ALRV


35-100
.

. . .
DEFLEX 426/ALRV-RS


35-100
.

. . .
DEFLEX 426/NALR


70-100
.

. . .
DEFLEX 426/NALR-RS


70-100
.

. . .
DEFLEX 427/ALR


40-100
.

. . .
DEFLEX 427/ALR-RS


40-100
.

. . .
DEFLEX 427/ALRV


40-100
.
. . .
DEFLEX 427/ALRV-RS


40-100
.

. . .