Type of Loads Acting on a Structure/ Building

1. LOAD BEARING CONSTRUCTION &
MATERIALS

2. Load Bearing Construction
 Load bearing masonry is among the oldest and most widespread building
techniques in the world.
 The earliest load bearing masonry consisted to stones stacked one over the other.
Over the passage of time, the stones were chiseled and dressed to make more
stable masonry walls.
 The firing of earth blocks gave rise to the earliest form of brick masonry.
 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.

3. 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.

4. Evolution; Load Bearing Masonry through History
 To start with, masonry structures were large and
solid, like the pyramids.
 With the development of the arch, openings were
created in these structures, and large structures like
the colosseum in Rome were built.
 In India, builders started using horizontal slabs of
stone to construct floor plates. This is
called trabeate construction. The Taj is built of red
standstone masonry walls faced with white marble.
Its walls are 6ft (1.8m) thick in some places.
Europeans built fine stone walled buildings with floor
slabs made of wood beams and planks. The
buildings had elaborate arched openings and very
finely crafted domes. These buildings have lasted
hundreds of years, with limited repair.
 the Mondadnock Tower, a 16-storey office building
built in 1893 in Chicago. It was made of brick walls 6
feet thick at the base and about 18" thick at the
top. It still exists

5. Foundation Suitable for Load Bearing
Construction
 Probably the most common form of
modern foundation, this is created
by digging a trench to the pattern of
the load-bearing walls of the
building and then pouring concrete
into the bottom of the trench.
Frequently, the concrete is
reinforced by laying steel bars or
mesh into the wet concrete. Once
the concrete has dried the walls are
then constructed, using the
foundation as a base.

6. Materials Used for Load Bearing Masonry
 Over the centuries, masonry has evolved into a precise science with a myriad of
options in materials and styles.
 Some of the more common load bearing masonry used today is brick, stone and
concrete masonry units (CMU) or concrete blocks.
 Among these there are several varieties depending on the materials and system of
laying the masonry units. Some of the more recent advancements are aerated
concrete blocks, hollow concrete blocks, etc

7. Stone & Types of Stone
 The term Stone refers to the natural Rocks after their removal from the earth’s crust.
 Stone When Derived from rocks are very irregular in shape size; they are dressed for
proper bedding, thin joints & speedy construction.
 It has been widely used through out the history, evidences can be seen in Egyptian
civilization, Incas of Peru etc.
 Geologically we have three categories of rocks. Igneous, metamorphic &
Sedimentary.
 IGNEOUS ROCKS are the oldest & formed by the solidification of molten magma.
Granite & Basalt are the are quarried from igneous rocks.
 SEDIMENTARY ROCKS are formed by the erosion of older rocks, that were originally
igneous. Sandstone & Limestone are quarried from Sedimentary Rocks.
 METAMORPHIC ROCKS are from by recrystallization of older locks under intense
pressure & heat. Slate, Marble, Quartzite & alabaster is quarried through the
metamorphic rocks.

8. Stone Masonry & Types of Stone Masonry
 Stone Masonry is the art of building structures
with stone, Stone is not cheaply available in all
country. They are difficult to handle due to their
heavy weight & they are costly in construction
due to transportation and high dressing
charges.
 Stone Masonry is broadly classified in to two
categories; i-Rubble Masonry ii Ashlar Masonry.
 Rubble Masonry: The masonry in which
undressed stone or roughly dressed stone is laid
in a suitable mortar, in this masonry the joints of
mortar are wider and not uniform.
 Ashlar Masonry: The stone Masonry having
finely dressed stones laid in cement and lime
mortar is known as ashlar Masonry.

9.  TYPES OF RUBBLE MASONRY: Rubble masonry
is further divided into four categories
1. Un-coursed Rubble Masonry: The stone
Masonry in which stones are laid without
forming course. Suitable for constructing low
walls
2. Random Rubble Masonry: The rubble
masonry in which stones are laid to some
what level coursed with non uniform joints.
Suitable for constructing residential buildings,
godowns, boundary walls.
3. Coursed Rubble Masonry: The stone
Masonry in which face stones are squared
on all joints and bedded by chisel or
hammer dressing before laying. Suitable for
Residential and Public buildings
4. Dry Rubble Masonry: the stone Masonry in
which stones are laid with mortar.it is used for
compound walls, retaining walls; height should not
exceed 6ms.

10. TYPES OF ASHLAR MASONRY:
 Course Ashlar Masonry: Stone block of same height is used. Every stone is fine tooled
on all sides. Thickness of mortar joint is uniform.
 Random Course Ashlar Masonry: This type of Ashlar Masonry consist of course of
varying thickness.
 Rough Tooled Ashlar Masonry: Sides of stones are rough in each course but mortar
joints are uniform.
 Block-in-course Masonry: its an intermediate between rubble and ashlar Masonry. All
stones are properly dressed and squared but edges of the stones are rough and of
varying length.
 Above all are suitable for Retaining walls, sea walls. But it is also used for Large Public
Buildings.
 Ashlar Facing: It is the best type of Ashlar Masonry. Since this type of Masonry is very
expensive. It is not used through out the wall except in work of great importance. In
this wall is made of rubble masonry back with Ashlar Facing.

11. GENERAL CONSTRUCTION ASPECTS FOR
LOAD BEARING CONSTRUCTION
 The height of the construction may be
restricted to four story of category, Where
light sheeted roof is used, an attic floor may
also be used.
 The height of a story may be kept as low as
2.5 m but not more than 3.5m.
 The wall thickness should be used as small as
feasible, say 300 to 450mm.
 Openings should be as small and as
centrally located as practicable

12. Stone Masonry in Abbottabad (A Case Study)
 Non-engineered construction is very common in many parts of Pakistan. Most such
buildings are unreinforced masonry (URM) structures with walls constructed from
either stone, brick or concrete block masonry, depending on which material is
locally available. These masonry walls are brittle and often cannot resist the lateral
forces which are generated during a seismic activity. In the Kashmir 2005
earthquake, an estimated 19,000 children died due to the collapse of masonry
school structures.
 The case-study school is situated in the seismically active Abbottabad region. The
school has been built using a design template which is the same for most of the
schools in the area.
 The school consists of four classrooms which have been divided into 3 blocks.
 The structural system of the building consists of load bearing walls which have been
constructed using random rubble stone masonry with a cavity in the middle. The
roof is constructed of timber trusses topped with metal sheets.

14. RETROFITTED SOLUTIONS
 Lateral load resistance of individual masonry
walls have been increased by providing both
horizontal as well as vertical metal strips (50 x 6
mm). These strips have been provided on both
the internal and external faces of the walls and
well connected with each other.
 All the four walls have also been connected
together at their junctions using steel angles (75
x 75 x 3 mm) from inside as well as outside to
enable closed box action and provide a
stronger lateral load resisting system.
 Weak areas within the walls such as openings
for doors and windows were additionally
strengthened using metal strips around the
openings from both inside and outside.
 Individual and isolated members, such as stone
masonry columns, were tied together by tie
beams both at plinth and lintel levels

15. Application of Stone
 Due to the Advancement in construction techniques and structure evolution. And
due to its availability , high transportation and dressing charges Application of stone
as main building material for construction is suitable to heavy and monumental
works. Although its application as cladding material for floor and walls is widely used.
I. GRANITES are hard and dense and are very stable and durable material. Its virtually
impermeable to water. It is available in variety of color and texture. But the highly
polish granite is effective at displaying colors and crystalline texture. But because its
high cost of quarrying and finishing . It is used as cladding material for floors for hard
landscape and also in countertop material in kitchen.
II. CAST BASALT is a fine grained stone nearly as hard as granite. It is used in tile units or
as worktops.
III. SANDSTONE may be fine or coursed in texture depending on the nature of the
original sand deposit. It ranges in Color from white, grey, brown and shades of red. It
can be used as main building material but is normally used for wall cladding
(thickness is 75 to 100mm)

16.  SLATE is typically used as cladding material for roof it can also be used at walls. Its
available in variety of colors blue, grey, green, silver grey. Slate is strong acid and
frost resistant and lasting up to 400 years as a roofing material.
 MARBLE is metamorphosed limestone and its appearance of marble is associated
with the impurities in lime stone. Its extensively used as cladding material. For
external cladding above 1st floor its thickness should be 40mm while for internal and
lower level it could be 20 mm in thickness