In the cantilever method of lateral load analysis, which of the following assumptions are made?
(i) The axial force in the beam is zero.
(ii) The intensity of axial stress in each column of a storey is proportional to the horizontal distance of that column from the centre of gravity of all columns of the storey under consideration.
(iii) The total horizontal shear on each storey is divided between the columns of that storey so that each interior column catties twice as much shear as each exterior column.
The correct answer is

Explanation:

• The cantilever method is a simplified approximate method used to analyze lateral loads (wind, earthquake) in multi-storey buildings.

• The method assumes that the building behaves like a vertical cantilever beam, with the base fixed and the top free.

• The columns act like longitudinal fibers of the cantilever — resisting bending.

• The method assumes that the beams do not resist axial force — only flexure.

• The axial force in each column is assumed proportional to its horizontal distance from the centroid of all columns in the storey.

• This models the "fiber" action of the cantilever analogy.

Additional Information

• The Portal Method is an approximate, simplified analysis method used to analyze lateral forces (like wind or earthquake) in low to medium-rise framed buildings.

• It is typically used for rigid frames in portal-shaped structures or for frames with a series of columns and beams.

• The structure is assumed to behave like a series of interconnected portals.

• For preliminary analysis and design of multistorey buildings subjected to lateral loads.

• Suitable for buildings with 3 to 5 storeys.

• Common in situations where full structural analysis (moment distribution or matrix methods) is too time-consuming.