Expansion joints

This blog is created with reference data available in Google.com:

BS 6920, ASTM C 920, BS 4254, BS 6093, BS 5212, BS 5215, BS 4254, BS 5889, BS 476 (not elaborated as this is for testing for fire regarding tests), BS EN 15651, BS 3712, ACI 504R, IS 11600 and ACI 224.3R-95. Building Movement AAMA 501.4 Static, AAMA 501.6 Dynamic

In most buildings, there is some form of restraint that limits how much they can expand or contract. The amount of stress caused by temperature changes depends on how much the temperature changes. Large temperature shifts can cause significant stresses that need to be accounted for during design, while small temperature changes usually have little effect. These stresses happen because a structure changes in size when its temperature changes, especially between points where it is fixed or restrained. To estimate how much a building will expand when temperatures rise, you can multiply the coefficient of concrete expansion (about 12 x 10-6 /℃) by the building's length and the temperature change.

For example, a 200-foot-long building that heats up by 25 degrees Fahrenheit (14 degrees Celsius) will expand by around 3/8 inch (9.5 millimeters). To prevent damage from this expansion, expansion joints are used to allow the structure to grow or shrink without creating too much pressure.

There are many reasons expansion joints are required such as:

1. Structure Size / Length
2. Structure Shape or Irregularities
3. Isolation of Dissimilar Building Classifications
4. Fire Separation
5. Thermal Movement

Expansion joints may be provided at:

1. Floor-to-floor
2. Floor-to-wall
3. Wall-to-wall
4. Ceiling-to-ceiling
5. Ceiling-to-wall
6. Roof-to-roof
7. Roof-to-wall

Guidance from the American Concrete Institute (ACI PRC-224.3-95: Joints in Concrete Construction) says that “the expansion of concrete slabs on grade is generally less than the initial shrinkage, and provision for expansion is seldom required.” Regarding the regular use of expansion joints, the guide also states “expansion joints in pavements are needed only in very unusual conditions of construction or with unusual materials.”

The design temperature change is calculated based on the difference between the extreme values of the daily maximum and minimum temperatures. In addition to general guidelines, various methods have been developed to calculate the appropriate spacing for expansion joints.

Indian Standards Institution (1964): 45 m (≈ 148 ft) maximum building length between joints
PCA (1982): 200 ft (60 m) maximum building length without joints
ACI 350R-83: 120 ft (36 m) in sanitary structures partially filled with liquid (closer spacings required when no liquid present).

As mentioned in ACI 224.3R-95 - Reported by ACI Committee 224 

Formula for the expansion joints:

Bridge expansion joints, there are various types, which can accommodate movement from 30 to 1,000 millimetres (1.2 to 39.4 in), including joints for small movement (EMSEAL BEJS, XJS, JEP, WR, WOSd, and Granor AC-AR), medium movement (ETIC EJ, Wd), and large movement (WP, ETIC EJF/Granor SFEJ).

Control joints: must have adequate depth and not exceed maximum spacing for them to be effective. Typical specifications for a four-inch-thick slab are:

a. 25% depth of material

b. Spacing at 24 × to 36 × of slab depth (some specification call for a maximum of 30 ×) 

c. Special care for inside corners

IS 12118-1 similar

How shall be the sealant material... As per BS EN 15651: Sealants for non-structural use in joints in buildings and pedestrian walkways, as follows: 

Part 1: Sealants for facade elements, 

Part 2: Sealants for glazing (this document), 

Part 3: Sealants for sanitary joints, 

Part 4: Sealants for pedestrian walkways, 

Part 5: Evaluation of conformity and marking. 

As per IS 6494 - expansion joints shall be not be provided in concrete swimming pools, small and medium capacity reservoir....Page No 5.

Building Movement AAMA 501.4 Static, AAMA 501.6 Dynamic:

AAMA 501.4 Static AAMA 501.6 Dynamic The seismic behaviors of façade systems are tested with three-dimensional pneumatical seismic test units in accordance to AAMA 501.4 and AAMA 501.6. In our facilities, samples as small as 1000 mm x 1000 mm and as large as 3500 mm x 4800 mm can be tested as part of the seismic test. Displacements up to 150 mm can be reached, and in dynamic tests, frequencies of 0.4 and 0.8 Hertz can be applied onto the samples. As a result, any risks of falling glass and permanent deformations are looked for, and if found, recorded to the report.

Let see the testing video: