Type of Loads Acting on a Structure/ Building

1. Building Construction & Materials 2
LECTURE # 1
Introduction to the Types of Structure, Types of Loads, Load Bearing Structure,
Materials used in Load Bearing Structure
Course Instructor: Ar. Madiha Waseem

2. Understanding of Structure
 Architectural Structures in particular enclose and define a
space in order to make it useful for a particular function. The
utilitarian element differs structure from a sculpture.
 An enclosed surface may be built to serve for different
purposes requiring different structures e.g. stadium, hospitals,
malls etc. but main purpose of structure is to resist loads.
 A Structure is actually shaping certain materials and to use
them in certain quantities that resist variety of loads acting on
it.
 Structure is an essential component of architecture that
allows a building to withstand against the pull of earth and
other loads acting on it.

3. Type of Loads Acting on a Structure/
Building
 Loading conditions on same structure varies from time to time or may
change rapidly with time.
 The most important loads carried by an architectural structure do not
change abruptly. These are called STATIC LOADS. They are not evaluated
case by case but are referred from codes, that code substitutes for an
equivalent load that is derived on statistical evidences on given types of
buildings so that under the worst circumstances floor will not fail.
 But it is not always sufficient to depend on these codes as responsibility for
strength of the structure is not taken by the code authorities but with the
architect.
 The types of loads acting on a buildings are Dead Load, Live Loads, Thermal
& Settlement Loads and Dynamic Loads

4. Dead Load (DL)
 The load of the structure itself is dead load; it includes the load of structural
system (walls , columns, beams, space frame) cladding material (interior &
exterior), Slabs, partition walls and weight of other permanent service
equipment HVAC or Plumbing).
 The dimension of a structural element
depends essentially on the loads acting on
It.
 The dead loads are easy to calculate,
Weight is evaluated by consulting tables of
Unit weights of structural material

5. Live Load (LL)
 All other loads acting on a structure other than
dead loads of the structure is called live load. They
include all the movable weights that include
human, furniture & fixtures and other non structural
elements such as rain, snow & ice. The wind
pressure, water pressure or push of earth are also
included in Live Load.
 Wind has become a very important load in recent
years due to the extensive use of lighter materials
and more efficient building techniques.
 The wind load on building are difficult to ascertain
to an accurate level; Average wind velocities are
known to certain degree of Certainty.
 The impact of a hurricane winds on skyscraper may
have to be found by means of aerodynamics tests
on a model in a wind tunnel.

6. Thermal & Settlement Loads
 All building materials expand or contract with temperature change.
 Long continuous buildings will expand, and it is necessary to consider the expansion
stresses.
 Expansion joints are provided at these points so that the structure is physically separated
and can expand without causing structural damage.
 Another condition, producing equivalent effects as
of high loads, stems from an un even settlement of
the foundation of the building. The poor soli
condition may reduce the support of the
foundation.
 N additional load is applied to the building but due
to uneven settlement, the supported portion of the
building carries more load.

7. Dynamic Loads
 Load that change rapidly or applied suddenly are called dynamic loads.
They are exceptionally dangerous if ignored.
 the magnitude of a load can be greatly increased by its dynamic effect.
 For e.g. driving a nail with hammer blow the more hard the blow is the
greater the effect.

8. Types of Structural Systems
Load Bearing Structures
Frame Structure (Skeleton Structure)
1. Post & Lintel Structure
2. Simple & Multiple Frame Structure
Compression & Tension Structure (Cables, Trusses,
Space Frames)
Membrane & thin Shell Structures

9. Load Bearing Construction
 The key idea with this construction is that every wall acts as a load carrying
element.
 Load bearing masonry construction was the most widely used form of
construction for large buildings from the 1700s to the mid-1900s.
 It is very rarely used today for large buildings, but smaller residential-scale
structures are being built.
 It essentially consists of thick, heavy masonry walls of brick or stone that support
the entire structure, including the horizontal floor slabs, which could be made
of reinforced concrete, wood, or steel members.

10. Limitation of Load Bearing Structure
 It does not perform very well in earthquakes. Most deaths in earthquakes around
the world have occurred in load bearing masonry buildings.
 It is extremely labor-intensive, as it is built mainly of masonry, which is made by hand.
This also makes for very slow construction speeds in comparison with modern
methods that are far more mechanized.
 It is extremely material-intensive. These buildings consume a lot of bricks, and are
very heavy. This means that they are not green.