Various types of Gravitational and Lateral Loads (I.S. 875) such as Dead, Live, Wind, Earthquake etc. Theory of Structures

1. THEORY OF
STRUCTURES
By – Prof. Manvinder Kingra ( Assistant Prof.)

2. Content to Study
 Various types of Gravitational and Lateral Loads (I.S. 875) such as Dead, Live, Wind,
Earthquake etc.
 Type of Forces, Cause- Effect, Concurrent Forces, Coplanar Forces and Parallel
Forces. Triangle Law of Forces, Parallelogram Law of Forces, Equilibrium of Forces,
Concept of Resultant, Conditions of Equilibrium

3. Introduction
What is
Structure
actually means
to you??
Within the context of the built environment, the term ‘structure’ refers to anything that
is constructed or built from different interrelated parts with a fixed location on the ground.
This includes buildings, but the term structure can also be used to refer to any body of connected parts that is
designed to bear loads, even if it is not intended to be occupied by people. Engineers sometimes refer to these
as 'non-building' structures.

4. Structure for a Civil Engineer
A structure refers to a system of connected parts used to support a load.
Important examples related to civil engineering include
 buildings,
 bridges and
 towers;
and in other branches of engineering,
 ship and aircraft frames,
 tanks, pressure vessels,
 mechanical systems, and
 electrical supporting structures
 Such structures are composed of one or more solid elements arranged so
that the whole structures as well as their components are capable of
holding themselves without appreciable geometric change during
loading and unloading.

5. The design of a structure involves many considerations, among which are four major
objectives that must be satisfied:
The structure must meet the performance requirement (utility).
The structure must carry loads safely (safety).
The structure should be economical in material, construction, and cost (economy).
The structure should have a good appearance (aesthetics).

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Sky city and bicycle skyway: Sustainable city planning

7. Types of Loads on Structures and Buildings
Economy
Safety
Major
Concern
Deformations
Stresses,
Displacements.
Major
Actions
Compression
Tension
Shear
Load
Apply
Vertical load
Horizontal
load
Longitudinal
load
Load
Type

8. What is Structural LOAD?
 Structural loads in buildings produce various types of action such as deformations, stresses,
or displacements. Structural loads are an important factor in the design of buildings. There
are different types of load that act on a structure such as vertical load (dead load, Live
load), horizontal load (earthquake load, wind load) and longitudinal load, etc.
 The main reason behind the failure of any structure is load-carrying capacity is low
as compared to the actual load applying to the structure. The structural load may
be Compression, Tension, and Shear in nature.
Determining the total load acting on a structure is
very important and complex.

9. Types of Loads on Structures and Buildings

10. Dead Loads: Structural Gravity Load
 Dead load is a stationary or permanent load. This dead load transferred the load to
the structure throughout the life span of the structure. Dead load is acting due to the self–
weight of structural members, fixed permanent equipment or Furniture, permanent unit.
(Note: IS CODE 875– 1987 (PART 1) code covers unit weight or mass of
the various types of materials and various components in a building and
that apply to the determination of dead loads in
the design of buildings or Structures.
Dead loads are permanent gravity loads acting on the
structure.
Dead loads can be either (1) self-weight, or (2) superimposed. To
clarify, let’s define what a structure is, an assembly of parts designed
to bear loads. For instance, different parts such as footings, beams,
and columns, make a building.

11. Assessment of Dead Load
The following factors affect the calculation of dead load on
the structure,
•Self–weight of the member or structure.
•Weight of various materials in the construction.
•Weight of permanent Member or Structure.
•Weight of fixed service equipment and furniture.
•Net effect of pre–stressing.
For suppose The column is made of Reinforced cement concrete
and having a length, breadth and depth as shown, then the dead
load of the column is
The total volume of concrete = 3 x 0.4 x 0.4 = 0.48m3
The dead load of the column = 0.48m3 x 25KN/m3 = 12KN

12. LIVE LOADS: STRUCTURAL GRAVITY
LOAD

13. Imposed loads-Live Loads: Structural Gravity Load
 Live loads are temporary gravity loads which can vary both in magnitude and
location. In other words, anything that occupies the structure and moves is a
live load. For instance, crowds of people, furniture, and vehicles vary in
weight and positioning; hence, they’re considered live loads. Together
with dead loads, it is a common form of load for designing structures.
Note: IS CODE 875– 1987 (PART 2) code covers imposed loads or live loads to be assumed in the design of buildings. Generally imposed
loads are minimum loads that should be taken into consideration for the purpose of structural safety of buildings.
Live loads vary depending on the use of the building. As an example,
since there is a higher occupancy for commercial buildings and
institutions such as hospitals, schools, and offices, the live load is
heavier compared to a residence.
But it does not including the earthquake
load, seismic load, wind load, snow load, and other loads due to change
in temperature, differential settlement, shrinkage, etc.

14. Live Loads: Moving
For certain structures like bridges, moving loads such as
vehicles and railcars are the primary design loads for
these structures. An example is the design truck which
varies depending on the code.

15. Imposed Floor Load For Different Occupancies
Floors shall be investigated for both the concentrated load and uniformly distributed load
Sr.No
.
Occupancy
Classification
Uniformly
Distributed
Load
Concentrate
d
Load / Point
Load
1. Residential Building
All Room and
Kitchen
2 KN/m3 1.8 kN
Toilet and Bathroom 2KN/m3 –
Passage, Staircase,
and Store Room
3 KN/m3 4.5 KN
Balconies 3 KN/m3
1.5 / m PL
at the outer
edge
Living Room, Bed
Room
2 KN/m3 1.8 KN
2.
Educational
Building
Offices and Staff
Room
2.5KN/m
3 2.7KN
Projection Room 5 KN/m3 –
Kitchen 3KN/m3 4.5KN
Toilet and Bath
Room
2KN/m3 –
Store Room 5 KN/m3 4.5KN
Reading Room 3KN/m3 4.5 KN
Point Load or Concentrated Load acting on the Roof
All roof covering materials other than glass or transparent made of fiberglass shall be capable of carrying a load of 0.90
kN concentrated on an area of 12.5 cm2.

16. WIND LOADS
Horizontal Loads : because of the movement of air relative to the earth
(Note: IS CODE 875 – 1987 (Part -3) code gives wind
forces and their effects in nature of static and dynamic that
used designing the buildings, structures, and components
of their Buildings.)

17. Wind Loads
In wind load, the main
consideration is the comfort of
people inside and outside of
the buildings.
Wind load is required to be considered in
design especially when the building exceeds
two times the transverse dimensions to the
exposed wind surface.
Wind can affect structures, especially forhigh-rise types.It can be a gentle breeze or something dangerous like gusts and storms.
The most dangerous winds are those coming from a tropical
cyclone. Recently, there have been reports of tropical cyclones
getting more intense; Hence, engineers have to design structures to
withstand these loads taking into consideration a lot of factors.
This types of loads are
considered in design if the
height of the building is more
than 15m.

19. EARTHQUAKE LOAD (SEISMIC LOAD)
IS CODE 1893-2002 ( PART-1 ) General provision for building

20. Earthquake load
depends on the
following factors,
1) Seismic hazard,
2) Parameter of the
structure and 3)
Gravity load.
Earthquake load acts over the surface of a structure placed on ground or with adjacent
building.

21. These type of loads causes movement to the foundation of structures. Earthquake forces are
internal forces that developed on the structure because of ground movements.
Three mutually perpendicular forces act on the structure during an earthquake, two horizontal
forces which acts in opposite direction and one vertical force due to the weight of the structure.
As vertical force doesn’t affect much during earthquake whereas two opposite horizontal forces
results in movement of the building during an earthquake. These two horizontal direction forces
are considered in the design.

23. Earthquakes are another big
environmental threat. They mostly occur
near tectonic plate boundaries and is
theoretically caused by the interaction
between two plates. A notable area
where earthquakes occur is the Pacific
Ring of Fire.
Earthquakes are unpredictable - have to rely on
a lot of historical data and their previous
experiences to design structures that are
capable of withstanding ground shake.

25. The amount of snow load on a roof
structure is dependent on various factors
Geometry of roof
Shape and size of the structure
Insulation of the structure
Frequency of wind
Duration of snow
Geographical location of the structure.

26. Snow loads are environmental
loads only applicable for
structures expected to receive
snowfall. Tropical countries do
not have to worry about snow
except for high-elevated areas
where it can snow.

27. Snow loads are calculated by the projections
made by snow at different parts of the structure,
The amount of snow load depends on the height
of building, size & shape of the roof, the
location of building whether it’s on the slope or
not, the frequency of snow etc. The more details
about snow loads are clearly mentioned IS 875
(part 4) – 1987.

28. FOR Queries
Email:
kingra.manvinder@gmail.com