In this ppt we can get clear knowledge about the substitute frames, gravity loads, shear wall concepts, lateral load methods.

3.  A multi-storey building is a buildings that has
multiple storey's, and typically contains vertical
circulation in the form of ramps, stairs and lifts.
 Using pre-fabricated frame components offers
significant benefits for construction site speed and
management. In typical multi-storey buildings, use
composite columns and welded WQ and UWQ beams.
 The system enables efficient space usage and flexible
functional arrangements for the property, through long
life spans and flat intermediate floors.

4. Fig 1: multi storey frame

5.  analysis of multi-storey building frames
involves lot of complications and tedious
calculations by using conventional methods.
To carry out exact analysis is a time
consuming task.
 Substitute frame method for analysis
of multistory frame can be handy in
approximate and quick analysis. This method
has been applied only for vertical loading
conditions.

6.  The process involves the division of multi-
storied structure into smaller frames. These sub
frames are known as equivalent frames
or substitute frames.
 The substitute frames are formed by the beams
at the floor level under consideration, together
with the columns above and below with their
far ends fixed.

8.  Stiffnesses K and stiffness factors k of the
columns composing the one-storey frames of
the previous paragraphs, reflect the actual
ones, as depending only on the geometry and
not on the magnitude of the forces or their
distribution along the height of the
building, since the structures were only single
storey.
 These stiffnesses were the absolute ones, but at
the same time they were also the relative ones
as there was only one storey.

9. FIG 3: Four-storey frame type structure comprising three
columns

10.  In multistory buildings, considered in this
paragraph, the seismic forces are applied along the
structure height and therefore another factor is
involved, namely the distribution of horizontal
seismic forces (orthogonal, triangular and
random).
 Consequently, stiffness's are independent of the
force magnitude, but dependent on the horizontal
seismic force distribution. Eventually, both
stiffness's K and stiffness factors k derived will be
the apparent values.
 Assuming that the horizontal forces act
simultaneously at the floors, the apparent floor
stiffness is meant to be relative with respect to its
lower one.

11. Substitute Frame - I:Frames
In the second degree of approximate, the
complete vertical frame which is subdivided in
several two storey frames within each floor.
The floor frame or substitute frame - I at any
floor consists of beams at the floor under
consideration together with all connected
columns in adjacent storeys, assumed to be
fixed at their far ends.

12. Substitute Frame – ii Bay Frames
Substitute Bay approximation at the level of third
degree, instead of taking entire columns and
entire beam segments, in adjacent two storeys,
this frame is further subdivided into separate
bay frames each one consisting of interested
beam along the connected columns and
adjacent spans beams only, fixed on their
distant ends

13.  Dead loads due to the weight of every element
with in structure and live loads that are acting
on the structure when in service constitute
gravity loads .
 The calculation of dead loads of each structure
are calculated by the volume of each section
and multiplied with the unit weigh

15.  Wind load is important factor that determines
the design of tall buildings over 10 storey's
where storey's heights approximately lies
between 2.7 to 3.0 m
 Buildings of up to 10 storey's ,designed for
gravity loading can accommodate wind
loading without any additional steel for lateral
systems

16.  Seismic motion consist of horizontal and
vertical ground motions , with vertical motions
usually having a much smaller magnitude .
 Mass of buildings resist this motion by setting
up inertia forces throughout the structure

18.  Frame structures are the structures having the combination of
beam, column and slab to resist the lateral and gravity loads.
 These structures are usually used to overcome the large moments
developing due to the applied loading.
 Types of frame structures
1. Rigid frame structure
Which are further subdivided into:
Pin ended
Fixed ended
2. Braced frame structure
Which is further subdivided into:
Gabled frames
Portal frames

19. Rigid Structural Frame
the word rigid means ability to resist the
deformation. Rigid frame structures can be defined
as the structures in which beams & columns are
made monolithically and act collectively to resist
the moments which are generating due to applied
load.
Braced Structural Frames
In this frame system, bracing are usually provided
between beams and columns to increase their
resistance against the lateral forces and side ways
forces due to applied load. Bracing is usually done
by placing the diagonal members between the
beams and columns.

20. K – Type Joints:
 K – Type joints in steel structures are formed
when the centroidal axis of horizontal member
and two lateral bracings meet with the central
axis of top chord

21. Knee – Type Joint:
 To increase the stability of connection between
vertical and horizontal members of structure,
knee-type joint is used.
 In welded knee-joint, the top chord is directly
welded to the main column and then a suitably
cut haunch is welded to the vertical and as well
as to the chord member for better stiffening

22. N – Type Joint
 N-type joint is formed as per the adopted
configuration, for connecting web members
to top and bottom chords. In this joint, first
the vertical member is put in place and
directly welded to top and bottom chords.
 Afterwards, the other inclined diagonal
member, with suitable double cuts at the
ends, is directly welded to top and bottom
chords and also to the vertical
.

23. Overlap Joint:
This type of joint is used in elevation for
connecting three smaller size members so that
two members are in close touch with each other
and also the intersection of their centroidal axes
lies on the axis of third member.

25.  Shear wall is a structural member in a
reinforced concrete framed structure to resist
lateral forces such as wind forces.
 Shear walls are generally used in high-rise
buildings subject to lateral wind and seismic
forces.
 In reinforced concrete framed structures the
effects of wind forces increase in significance as
the structure increases in height
 Codes of practice impose limits on horizontal
movement or sway.

26.  Limitations on the use of building,
 Adverse effects on the behavior of non-load
bearing elements,
 Degradation in the appearance of the building,
 Discomfort for the occupants

27. Method of lateral load

28.  The behavior of a structure subjected to horizontal
forces depends on its height to width ratio.
 The deformation in low-rise structures, where the
height is smaller than its width, is characterized
predominantly by shear deformations.
 In high rise building, where height is several times
greater than its lateral dimensions, is dominated
by bending action.
 They are two types portal and cantilever method

29.  The portal method is an approximate analysis
used for analysing building frames subjected to
lateral loads such as
Wind loads/ seismic forces.
 Each bay of a structure is treated as a portal
frame, and horizontal force is distributed
equally among them.

31.  Points of inflection occur at mid span of
beams.
 The points of inflection are located at the mid-
height of each column above the first floor. If
the base of the column is fixed, the point of
inflection is assumed at mid height of the
ground floor columns as well; otherwise it is
assumed at the hinged column base.

32.  This method is applicable to high rise
structures. This is based on the simplifying
assumptions regarding the Axial Force in
columns.

33.  Points of inflection occur at mid span of
beams.
 the points of inflection are located at the mid-
height of each column above the first floor. If
the base of the column is fixed, the point of
inflection is assumed at mid height of the
ground floor columns as well; otherwise it is
assumed at the hinged column base.