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 by expansion joints.

Structures and their individual details are without exception always subjected to influence by diverse forces that are the result of the building setting, temperature variations, changing humidity as well as static and dynamic loads. These forces cause changes in the tensions of the individual components, which may contribute to irreversible changes within the components or to cracks in the material, or, in extreme cases, to the material breaking.
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.

Vibrations caused by mining are a phenomenon caused by rapid movement, cracking or breaking of the rock material layers, where the mining work is being carried out. Shakes of the rock mass cause the release of seismic energy and is a source of vibrations - the seismic wave. Influence of underground mining work greatly impede the use of surface areas, and limit and interrupt investment processes. In Poland, such areas are seen primarily in the Silesian, Lower Silesian and Lublin Voivodeships.
Structures on areas with present and past heavy mining should be designed according to the Ordinance of the Polish Minister of Infrastructure of April 12th, 2001., on the technical conditions to be fulfilled by buildings and their location (Journal of Laws of 2002, no. 75, item 690). In that respect one should consider the influence of mining activities - forced deformations, vibrations as well as a change in the hydrological characteristics. A decision on whether a particular area is fit for investment is taken on the basis of the foreseen properties and intensity of the mining damage and the current hydrological and geologic conditions.
One needs to remember that it is the designer that is responsible for a site's safety and the durability of the structure across its entire lifetime. The design documentation should include a detailed description of the geologic and mining situation with a description of potential hazards, values of deformation indicators, safety indicators and acceleration values for soil vibrations. The designer should describe in detail the site safety measures protecting it against mining-related damage, values of expected deformations and movements of the structure components.
During the design process, one should consider all disadvantageous soil conditions. This may possibly prevent possible damage, and thus, increase the comfort and safety of the structure's future users.
The constructional arrangement of buildings erected at locations characterised by the possibility of emergence of seismic waves should be characterised by symmetry and regularity. It is not recommended for the horizontal view of the building to contain concave external angles around its circumference. Stairwells and elevator shafts should be designed, as long as this is possible, halfway through segment length. the basic issue, in order to reduce the possibility of permanent damage to the structure, is conscious targeted separation of a structure part. The required width of expansion joints should be a direct result of the geometric characteristics and the values for inclinations caused by soil loosening. The separated structural components may not come into contact during the assumed movements. In case segment heights vary, it is recommended to select expansion joint widths just like for upper segments.
In practice, if happens quite often that mistakes emerge related to:

  • improperly executed expansion joints, i. e. not cleaning the joint of excess material during structure erection or not protecting it against intrusion by foreign matter that may impede structure operation,
  • wrongly designed expansion joints, i. e. too narrow joints,
  • damage caused by a change in the mining method, causing terrain deformation increases.

The maximum length of components separated by expansion joints is determined according to the following rules:

  • in rigid structures, the segment length may not exceed 30-35 m,
  • in deformable structures, the segment length should be limited to approx. 48 m, in halls equipped with tracked cranes, to approx. 36 m.

In addition, irrespective of segment length, expansion joints should be designed in structures with irregular horizontal circumference designs (shaping the segments as cuboids) and in locations, where:

  • the structure foundation depth changes,
  • the structure height changes,
  • the physical and mechanical soil properties change.

An expansion joint should be constructed in such a way so that it passes through the entire width and height of a structure, from the foundation to the roof.
In the underground section, the expansion joint requires protection against overfilling in a manner allowing unhindered movement of the segments. In the overground area, expansion slits should have covers or hoods in the form of expansion profiles. Deflex expansion profiles at the same time ensure complete separation of structural components, allow the transfer of required motions, and at the same time protect the slit against contamination.
The choice of the proper profile should be closely related to the slit width, the height of installation of the profile into the structure, the type and standard of finishing of the area requiring the expansion slot, the size of burdens expected (i. e. foot traffic, vehicle traffic) as well as cleanliness requirements and chemical resistance.

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 durability, functional usability as well as aesthetics and scope of use of the structure, one must do all that is possible to provide appropriate protection of expansion slits. Experience shows that increased expenses spent in this area as well as high quality and professionalism of the providing contractor limit, to a great extent, the expenses required for refurbishment and mitigate hindrances in the period of use of the structure.
The present catalogue should be helpful during the design of execution of expansion slits and in the choice of appropriate profiles. In case of any doubts, please contact our technical advisors. We are confident that we are able to provide optimum solutions even for the most difficult of cases and conditions.
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

Elastomer
Aluminium
Others Levels Vertical Horizontal
DEFLEX 800
       

120-320
.
.
. . .
DEFLEX 810


135-340

.
. . .
DEFLEX 810/ RS


135-340

.
. . .
DEFLEX 820


135-340

.
. . .
DEFLEX 820/ RS


135-340

.
. . .
DEFLEX 830


120-300
. .
.
.
DEFLEX 840


110-380
. .
.
.
DEFLEX 850


100-200
. .


.