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BUILDING (CONSTRUCTION) REGULATIONS, 1956
(4) (4) Every roof shall be constructed so as to be capable of resisting safely without exceeding the appropriate limitations of permissible stresses, the simultaneous effects of pressure and suction due to wind, considered as ncting normal to the surface of the roof, as specified in Table VII, in terms of the basic pressure (P) of Table VI appropriate to the height and exposure of that roof,
TABLE VII.
Wind pressure and auction on roofs. (Wind normal to zaver)
Angle of windward
surface of roof with horizontal
0* 10*
20*
Wind pressure
Windward slope (or half of flat roof)
Leeward slope (or half of flat roof)
1.00 P
0.70 P
0.75 P 0.50 P
0.40 P
0.45 P
0.30 P
0.46 P
a
+ 0.10 P
0.45 P
† 0.30 P
0.46 P
60
† 0.40 P
0.45 P
TO"
0.50 P
0.45 P
+ 0.30 P
0.45 P
7 0.30 P
0,50 P
40
50"
80"
In this table-
(i) the sign† indicates pressure and the sign-indicates suction; (ii) the pressure and suction for roofs having intermediate inclinations
shall be determined by interpolation;
(ii) the sign P means the basic pressure in Table VI appropriate to
the height and exposure of the roof under consideration.
(b) The wind pressure on a curved roof due to wind blowing at right angles to the axis of the roof shall be calculated on the assumption that the curved portion is divided into not less than four equal segments, and the pressure on each segment determined by the pressures and suctions specified in Table V11 appropriate to the slope of the chord of each segment.
(5) Where the building is adequately stiffened by the walls and floors the provisions of sub-regulations (a) and (3) shall not apply.
BUILDING (CONSTRUCTION) REGULATIONS, 1956
(a) where the height of such building does not exceed twice The width of the base upon which it depends for its resistance to the overturning action of the wind pressure,
nor
(b) to any part of a building which projects vertically or horizontally from the remainder of the building to an extent less than twice the width of that projection,
(6) Every individual part of the outside surface of a building shall be capable of resisting safely, without exceeding the appro- priate limitation of permissible stresses, a pressure, acting inwards or outwards of-
(a) in the case of wall panels, wall sheeting, and windows.
0.8 P:
(b) in the case of roofs, the appropriate pressures or suctions
of Table VII increased numerically by 0.3 P:
Provided that within a distance of 1/6th of the length of the building from the gables in the case of both walls and roof, and of 1/6th of the span from the eaves in the case of roofs, the pres- sures shall be taken at 1.5 P in the case of walls, and 2.0 P in the case of roofs.
(7) In this regulation the symbol P shall be the basic wind pressure specified in Table VI appropriate to the height and exposure of the part of the building under consideration.
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23. All parapets, handrails and balustrades shall be capable Horizontal of resisting safely a horizontal pressure, acting at handrail or Joad. coping level of-
(a) in the case of stairways, landings and balconies for
domestic buildings-25 lbs. per foot run.
(b) in the case of all other stairways, landings, and bal- conies, and all parapets and handrails to roofs-50 lbs. per foot run:
Provided that in the case of balustrades and barriers in places of assembly, a pressure of 150 lbs, per foot run shall be taken.
24. (1) The test load for any structure shall not exceed 1} Test load. times the imposed load for which the structure has or should have been designed.