advantages of masonary wall

Report
Guided by:Dr . Ravindra Nagar
(Prof.)
Department of Structural Engg.
MNIT Jaipur
Guided by:Dr . Sandeep Chaudhary
(Associate Prof.)
Department of Structural Engg.
MNIT Jaipur
Submitted byBHAWNESH
KULDEEP
(2010PST120)
M.Tech 3rd Sem.








MASONARY WALL
ADVANTAGES OF MASONARY WALL
TYPES OF MASONARY WALLS
FAILURE OF MASONARY WALLS
FINITE ELEMENT METHOD
ADVANTAGE
RESEARCH PAPER
REFERENCES

The masonry walls is built of individual blocks of
materials such as stone, brick, concrete, hollow
blocks, cellular concrete etc., usually in horizontal
courses cemented together with some form of
mortar.
REFERENCE FROM BINDRA &ARORA BOOK
ADVANTAGES OF MASONARY
WALL
•The
•The use
use of
of materials
materials such
such as
as brick
brick and
and stone
stone can
can
increase
increase the
the thermal
thermal mass
mass of
of aa building.
building.
•Brick
•Brick typically
typically will
will not
not require
require painting
painting and
and so
so can
can
provide
provide aa structure
structure with
with reduced
reduced life-cycle
life-cycle costs.
costs.
•Masonry
•Masonry is
is very
very heat
heat resistant
resistant &
& thus
thus provides
provides good
good
fire
fire protection.
protection.
•Masonry
•Masonry walls
walls are
are more
more resistant
resistant to
to projectiles.
projectiles.
•Masonry
•Masonry structures
structures built
built in
in compression
compression preferably
preferably
with
with lime
lime mortar
mortar can
can have
have aa useful
useful life
life of
of more
more than
than
500
500 years
years as
as compared
compared to
to 30
30 to
to 100
100 for
for structures
structures of
of
steel
steel or
or reinforced
reinforced concrete.
concrete.
TYPES
•Stone masonary
•Brick masonary
•Hollow block concrete masonary
•Reinforced masonary
•Composite masonary
REFERENCE FROM BINDRA &ARORA BOOK
http://www.staff.city.ac.uk/earthquakes/MasonryStone/images/StoneMasonryWallDetail.png
http://buildipedia.com/images/masterformat/div04/20/images/042113_brickmasonry/040000_
masonry-wall-07.jpg
http://content.answcdn.com/main/content/img/McGrawHill/atchitecture/f0184-03.png
http://www.world-housing.net/uploads/101068_074_18.jpg
http://www.maconline.org/50.gif

There are three ways in which a masonry building
wall may collapse. The wall may fall straight out in a
monolithic piece at a 90 degree angle, in a manner
similar to a falling tree; the wall may crumble
straight down in a so-called "curtain" fall collapse; or
the wall may collapse in an inward / outward
fashion, with the top falling inward and the bottom
outward.
90-Degree-Angle
This is the most common type of masonry wall
failure which occurs at fires. The wall falls straight
out and the top of the collapsing wall strikes the
ground, a distance equal to the height of the failing
section measured from the base of the wall. A fiftyfoot section of wall collapsing in a 90-degreeangle
fall will cover at least fifty feet of ground with brick.
Bricks and steel linters may bounce or roll out even
farther.
 The wall begins to lean outward at the top,
separating from the other enclosing walls, and falls
straight out at a 90-degree angle.

Curtain-Fall Collapse

In this type of collapse, the exterior masonry wall
drops like a falling curtain cut loose at the top. The
wall crumbles and falls straight down, with bricks
and mortar forming a pile on the ground near the
base of the wall. The collapse of the brick veneer,
brick cavity, or masonry-backed stonewall often
occurs in a curtain-fall manner
Inward/Outward Collapse

When a masonry wall becomes unstable and begins
to lean inward, it does not always mean that the
wall will fall inward. Firefighters operating ground
streams must still maintain a safe distance between
themselves and the unstable wall, for when a
section of the broken wall falls inward, the lower
portion of the wall may kick outward, or the upper
portion may initially fall inward but then slide down
and outward into the street, bottom first. Known as
an inward/outward collapse.
INTRODUCTION FEM: Method for numerical solution of field
problems. FEM cuts a structure into several
elements (pieces of the structure).
 Then reconnects elements at “nodes” as if nodes
were pins or drops of glue that hold elements
together.
 This process results in a set of simultaneous
algebraic equations.






Number of degrees-of-freedom (DOF)
Continuum: Infinite
FEM: Finite
(This is the origin of the name,
Finite Element Method)
WHY FEM ????
Non linear problems easily solved.
Easy formulations allow many different types of
problems to be solved.
 The most attractive feature of the FEM is its ability
to handle complicated geometries (and boundaries)
with relative ease
 There are reasons to consider the mathematical
foundation of the finite element approximation
more sound, for instance, because the quality of the
approximation between grid points is very good.


DISCUSSION NO. : 1
Mohammed S. Mohammed(2010) carried out Finite
Element Analysis of Unreinforced Masonry Walls
 TYPE OF WALL-Unreinforced masonary wall
 AIM-to provide efficient tools for better
understanding of their complex behaviour

APPROACHES
There were two main approaches that developed
for the constitutive description of masonry,are
following:
 macro-modeling
 micro-modeling

MACRO-MODELING MASONRY

In macro-modeling masonry, no distinction
between the individual units and joints is made, and
masonry is considered as a homogeneous, isotropic,
or anisotropic continum. As macro-modeling of
masonry is advantageous when the global behavior
of the structure is important. The influence of the
mortar joints acting as planes of weakness cannot
be addressed
MICRO-MODELING APPROACH

The
alternative
micro-modeling
approach,
expanded units are modeled with continuum
elements, while the behavior of the mortar joints
and unit-mortar interface is lumped as
discontinuous line interface elements . In this
research micro-modeling has been adopted in
preference to the macro-model.
FINITE ELEMENT MODEL
APPROACH

In the finite element analysis, masonry is treated
with micro-model, in which the units of brick and
joints are modeled individually with different type
of elements. The masonry units are modeled with
smeared crack elements, which account for both
tensile and compressive fracture of the units, while
the mortar joints are modeled with interface
element to account for the inherent planes of
weakness to include all the basic types of failure
mechanisms that characterize masonry.
FAILURE MECHANISM
CONCLUSION

This study presents an efficient finite element analysis
technique which shows a great versatility in analysis
complex discontinuities in the analysis of masonry walls
structures by use of interface elements with a
constitutive model entirely established on the basis of
the incremental theory of plasticity to simulate the actual
behavior at the interface between contacting materials.
It was shown that the finite element method model was
able to predict effectively the behavior of masonry
structures, with both confined and unconfined masonry
wall, as well as sufficiently accurate collapse load values.
DISCUSSION NO.:2

Jahangir Bakhteri et al (2004) carried out finite
element modelling of structural clay brick masonry
subjected to axial compression
To prove that for a normal case, where elastic
modulus of mortar, Ej, is less than elastic modulus of
brick, Eb,
 Increase in mortar thickness results in reduction of
elastic modulus of the masonry,
 And increase of elastic modulus of mortar, which
leads to an increase in the elastic modulus of
masonry


The models were assumed to be constructed from
five local clay bricks having dimensions of 212 mm ×
92 mm × 66 mm (length × width × height), and each
model with unique mortar joint thickness. There
were five sets of models having different mortar
joint thicknesses, which were 7.5, 10, 12.5, 15, and
20.0 mm.
TYPICAL MODEL SHOWING THE APPLIED
LOAD AND BOUNDARY CONDITIONS
DEFORMED SHAPE OF THE MODEL WITH
7.5 MM MORTAR JOINT THICKNESS
Stress-strain curve for model with 7.5 mm mortar joint
thickness
By increasing the mortar joint thickness, the
strength of the masonry will decrease
 The maximum compressive strength of models was
obtained when the thickness of the mortar joint was
7.5 mm.

Kirk Martini carried out finite element studies in the
two-way out-of-plane failure of unreinforced
masonry
 Type of wall:- unreinforced masonry wall
 Dimensions:-length = 12.2 m (40 ft); height = 6.1 m
(20 ft) thickness = 0.51 m (20 in); E = 0.62 GPa (90
ksi); weight density = 15.7kN/m3 (100 pcf).

Organization of the finite element mesh for the block-interface model

The panel was tested with a variety of mesh
configurations to assess the fineness of the mesh
required to achieve satisfactory results. loaddisplacement curves for three different mesh
configurations; each mesh uses 10 courses
composed of either 10 full blocks or 9 full blocks and
two half blocks at the ends, each with four
laminations.
Load-displacement curves for three different mesh configurations of the study panel
Comparing the finite element results with the yield
line analysis reveals important aspects of both.
First, the yield line method predicts a failure load of
1.5 kPa, somewhat lower than the finite element
analyses which predict in the range of 1.6 to 1.7 kPa
 This knowledge will help in interpreting patterns of
damage in ancient and modern masonry structures,
and in developing renovation strategies that
account for the strengthening effect of two-way
spanning action.


Mohammed S. Mohammed(2010) ,Finite Element
Analysis of Unreinforced Masonry Walls

Jahangir Bakhteri et al (2004) finite element
modelling of structural clay brick masonry subjected
to axial compression

Kirk Martini finite element studies in the two-way
out-of-plane failure of unreinforced masonry

Bindra and arora book

Wikipedia and google images
THANK YOU…

similar documents