EARTHQUAKE RESISTANT MASONRY BUILDINGS

During Earthquake small residential houses made of conventional brickwall systems are seen to have major effect due to torsional and shear forces caused in various portions of the wall. Due to this various precautions to be taken during construction have been given by various technical institutes and government agencies from time to time. In general these should be consulted from structural consultants/ Architects but for places where a consultant is not available a few of the precautions in general are given below:

Walls having widths of 8" (200mm) to 9" (230mm) should not be more than 11'9" high and should have vertical as well as horizontal reinforced components.

VERTICAL REINFORCEMENT IN BRICK WALLS : - During construction provide vertical reinforcement at corners and T- junctions having dia of 20, 16, 12, 12mm high strength bar ( tor steel bar) respectively starting with 20 dia at G.Floor and reducing respectively at upper floors for a four storeyed building.

The bars should be provided at Corners and at T- Junctions as shown in Figures 1, 2, 3 and 4 above which also show the laying pattern of brickwork at corners and T- Junctions in consecutive layers. The bars should start from the foundation and should pass through all beams and slabs till the last floor,providing proper overlapping of bars. The bars should be encased in reinforced cement concrete of mix M- 15 ie. 1:2:4. Similarly Vertical reinforcement should also be provided around door and window jambs and these should start from plinth beams or roof beams and should continue upto lintel level beam. R.C.C plinth lintel and roof bands should also be provided as given below.

R.C.C PLINTH, LINTEL AND ROOF BANDS:

PLINTH BAND : As the names indicates this is a R.C.C beam provided at Plinth level ie. below D.P.C level, normally of 75 mm depth when two bars are provided in it and of 150 mm depth when four bars are provided in it. Generally its said that its top should be taken as D.P.C (damp proof course) top but we would prefer if a damp proof course is provided on this, since it shall then help in flooring level at doors where damp proof course is discontinued to maintain same flooring level as inside.The reinforcement details as per span of walls are given in Chart - 1 below.

LINTEL BAND : Lintel beam is provided at the top of doors and windows. Its preferable that the top of all doors and windows should be at the same level so that a continuous lintel beam can be provided on all walls. The reinforcement details as per span of walls are given in Chart - 1 below.

ROOF BAND : Beam is to be provided below roof on brick walls generally provided where instead of R.C.C or Brick Work slab other rofs such as pitched or wooden roofs are provided. The reinforcement details as per span of walls are given in Chart - 1 below.

CHART - 1
WALL SPAN IN (M)
H.S.D BAR NO'S
H.S.D BAR DIA.
Upto 5
2
10
6
2
12
7
4
10
8
4
12