Beam Settle
Content
Differential Settlement : It is the maximum difference between two points in
a building element.
Differential Settlement = Smax - Smin
Angular Distortion : It is another method of expressing differential
settlement.
Angular Distortion = Differential Settlement/Length of element
= (Smax - Smin)/L
Fig. 8.2 represents soil movement under different circumstances at the
ground level. The fluctuation in the elevation of ground level depends on
seasonal changes in expansive (Indian Black Cotton) soils and
Fig.8.2 : Soil movement in different situations
Table 8.1 presents the different types of movements experienced by various
soils. It can be noticed that only few soils such as clay can experience swell.
Further, consolidation settlement and creep settlement are more pronounced
in clay. Immediate or elastic settlement is observed in each and every soil.
First three, namely Immediate, Consolidation and Creep settlement cause
downward movement of ground while swell causes upward movement of
ground.
Table 8.1: Types of Movement in different soils
Principal
Soil
Type
Type of Movement
Immediate Consolidation Creep Swell
Rock Yes No No Some
Gravel Yes No No No
Sand Yes No No No
Silt Yes Minor No Yes
Clay Yes Yes Yes Yes
Organic Yes Minor Yes Yes
8.2 Extract from IS 1904 -1986 : General Requirements for Design &
Construction of Foundation
IS 1904-1986 presents Table 1 which gives details about the permissible
settlement in steel structures, reinforced concrete structures, multi-storeyed
buildings and water towers and silos in two different types of soils, namely
(1) Sand and hard clay and (2) Plastic clay. The settlements considered are
maximum settlement, differential settlement and angular distortion or tilt.
The details in this table can be followed in the absence of more precise
settlement suggested by the user. In case of multi storeyed buildings both
RC frames and load bearing wall structures are considered. Load bearing
structures with L/H 2 and 7 are dealt with. Two types of foundations
considered are isolated footing and raft foundation. Table 8.2 gives the
extract of IS code and Table 8.3 presents the same table in different form for
steel and RC structures. A maximum settlement of 75 mm, differential
settlement of 0.0015L
a building element.
Differential Settlement = Smax - Smin
Angular Distortion : It is another method of expressing differential
settlement.
Angular Distortion = Differential Settlement/Length of element
= (Smax - Smin)/L
Fig. 8.2 represents soil movement under different circumstances at the
ground level. The fluctuation in the elevation of ground level depends on
seasonal changes in expansive (Indian Black Cotton) soils and
Fig.8.2 : Soil movement in different situations
Table 8.1 presents the different types of movements experienced by various
soils. It can be noticed that only few soils such as clay can experience swell.
Further, consolidation settlement and creep settlement are more pronounced
in clay. Immediate or elastic settlement is observed in each and every soil.
First three, namely Immediate, Consolidation and Creep settlement cause
downward movement of ground while swell causes upward movement of
ground.
Table 8.1: Types of Movement in different soils
Principal
Soil
Type
Type of Movement
Immediate Consolidation Creep Swell
Rock Yes No No Some
Gravel Yes No No No
Sand Yes No No No
Silt Yes Minor No Yes
Clay Yes Yes Yes Yes
Organic Yes Minor Yes Yes
8.2 Extract from IS 1904 -1986 : General Requirements for Design &
Construction of Foundation
IS 1904-1986 presents Table 1 which gives details about the permissible
settlement in steel structures, reinforced concrete structures, multi-storeyed
buildings and water towers and silos in two different types of soils, namely
(1) Sand and hard clay and (2) Plastic clay. The settlements considered are
maximum settlement, differential settlement and angular distortion or tilt.
The details in this table can be followed in the absence of more precise
settlement suggested by the user. In case of multi storeyed buildings both
RC frames and load bearing wall structures are considered. Load bearing
structures with L/H 2 and 7 are dealt with. Two types of foundations
considered are isolated footing and raft foundation. Table 8.2 gives the
extract of IS code and Table 8.3 presents the same table in different form for
steel and RC structures. A maximum settlement of 75 mm, differential
settlement of 0.0015L
