Section 10 in Multi-Storeyed and Public Buildings Rules, 1973
10. Structural sufficiency. - (1) Foundations.
-(a)Every wall, column post and beam of building shall be supported adequately by foundations of concrete or reinforced concrete, piles, piers, caisson or other foundations of such thickness and projection as will be necessary to safely sustain and consult all the dead and superimposed load without exceeding the limitations of permissible stresses provided in these rules.(b)All foundations, apart from those resting on bedrock, shall be carried down below the level of possible damage by frost or seasonal changes on soils possessing shrinking and swelling, characteristics, such as clayey soils.(c)The structural design of the foundations shall be determined as per the recommendations in the National Building Code of India, 1970 to ensure sufficiency and safety of the structures and to keep the stresses of the foundation materials and supporting soils within permissible limits prescribed in these rules.(d)Piles, either friction piles or end bearing piles, may be used for the foundations of a building when soil condition are suitable and their design, use and spacing shall conform to the recommendations in Part VI - section 2 of the National Building Code.(e)All piles used to support any structure or part thereof shall be driven, jetted or otherwise embedded to such depth as is necessary to secure adequate soil or rock bearing capacity and in such a manner as not to impair their strength and shall be of sufficient strength to Withstand also all stresses resulting from the handling and driving.(2)Walls and Columns. - (a) The thickness of every load-bearing non-reinforced masonry wall shall be sufficient at all points to ensure that the stresses due to the worst conditions of loading for which the structure is designed are within the limits prescribed.(b)Maximum slenderness ratio:Walls. - For a wall, the slenderness ratio shall be the effective height divided by the effective thickness or the effective length divided by the effective thickness whichever is less.Column. - For a column, the slenderness ratio shall be the effective height divided by the corresponding lateral dimension (thickness or width),(i)In the case of load-bearing walls set in cement mortar (1: 6) or cement lime mortar (1:2:9), the slenderness ratio shall not exceed 18 and for those set in lime mortar it shall not exceed 12.(ii)In the case of non-load-bearing walls, the slenderness ratio shall not exceed 30 for panel walls and curtain walls and shall not exceed 24 for force standing walls and parapet walls.(iii)The slenderness ratio for load-bearing column shall not exceed 12.(c)Where a solid wall or masonry is load-bearing, its thickness shall not be less than that determined by the calculated masonry method through the monograms of the National Building Code of India, 1970 unless otherwise determined through the structural analysis of the building on accepted principles of mechanics to sustain the most adverse combination of loads to which the building shall be subject to during or after erection.(d)The design loads and other forces to be taken for the design of masonry structures shall conform to those laid down in Part VI -Section I of the National Building Code of India, 1970 briefly extracted in Appendix-L to these rules.(e)Where a wall is sub-divided into panels by adequate horizontal or vertical supports or both, the individual panels shall be designed for structural sufficiency.(f)Where reinforced concrete walls are intended to carry vertical loads, they should be designed generally in accordance with the design criteria for columns. The cross-sectional area of vertical reinforcement and the lateral reinforcement parallel to the wall face may be reduced to not less than 0.2 per cent.(g)The thickness of a reinforced concrete wall should not be less than 10 cm.(3)Concrete and steel structures. - The design and structural use of plain, reinforced and pre-stressed concrete for buildings and the component parts shall conform to the recommendations of the National Building Code of India in its Part VI - Section 5 and the use of structural steel in general building construction shall conform to the stipulations in Section 6 of Part VI of the said National Building Code.(4)Pre-fabricated building. - The modular planning, component sizes, joints, manufacture, storage, transport and erection of pre-fabricated elements for use in the building shall conform to the recommendations in Section 7, Part VI of the National Building Code of India, 1970.(5)Excavations. - (a) All excavations shall be protected and properly guarded in such a manner as to prevent danger to life or property; where necessary, excavations shall be sheet-piled to prevent the earth, soil or surface of any street or adjoining property from caving in or being damaged thereby.(b)No excavation for any purpose shall extend within 30 cm. of the angle of repose or natural slope of the soil under any footing or foundation unless such footing or foundation is properly under-pinned or protected against settlement.(c)Where an excavation is back filled, measures shall be taken to place the back fills as to -(i)maintain the lateral support of the soil exposed by the excavation;(ii)have a bearing capacity adequate to support the anticipated surcharge; and(iii)prevent detrimental settlement.
