Structural Failure Report

Building Surveying Studio 1

BUILDING SURVEYING STUDIO 1

RBS 201/5ACADEMIC SESSION 2010/2011

STRUCTURAL FAILURE REPORT

NAME : Mohd Ariff Bin Mohd Jafri

GROUP : A2

NO MATRIX : 103708

MAJOR : Building Surveying

LECTURER : Mohd Zaid bin Hj. Yusof (Ir. Dr.)

Mohd Ariff Bin Mohd Jafri 103708


INTRODUCTION

A structure usually refers to any large, man-made object permanently fixed to Earth's

surface or in its orbit, as a result of construction. These are divided into buildings and

nonbuilding structures, and make up the infrastructure of a human society. There are

also animal-built structures, such as anthills and beaver dams.

Structural failure refers to loss of the load-carrying capacity of a component or

member within a structure or of the structure itself. Structural failure is initiated when

the material is stressed to its strength limit, thus causing fracture or excessive

deformations. In a well-designed system, a localized failure should not cause

immediate or even progressive collapse of the entire structure. Ultimate failure

strength is one of the limit states that must be accounted for in structural engineering

and structural design.

Structural design is a systematic and iterative process that involve:

1. Identification of intended use and occupancy of a structure.

2. Development of architectural plan and layout.

3. Estimation of structural loads depending on use and occupancy

4. Structural failure refers to loss of the load-carrying capacity of a component or

member within a structure or of the structure itself. Structural failure is initiated

when the material is stressed to its strength limit, thus causing fracture or

excessive deformations. In a well-designed system, a localized failure should

not cause immediate or even progressive collapse of the entire structure.

Ultimate failure strength is one of the limit states that must be accounted for in

structural engineering and structural design.



OBJECTIVE

In our test at the lab structure, we can know how to structure is failure happen

depend on the strength structure to endure compulsion which given on the structure.

How many stress in ton to make the structure is crack.

Concrete cubes are tested for compressive strength on machines which must

comply for accuracy and repeatability with the requirements of BS 1610 “Method for

the Load Verification of Testing Machines”. BS 1881 set out other criteria regarding

the machine platens , spacer blocks and auxiliary platen which may be used.

1. To determine the proportions of concrete mix constituents of; cement, fine

aggregate (or normally sand), coarse aggregate, and water.

2. To produce concrete of the specified properties.

3. To produce a satisfactory of end product, such as beam, column or slab as

economically as possible.

4. To test the compressive strength on concrete cubes and concrete beam.

5. Understand how the structures workThe best place to begin an understanding of simple structural analysis isn’t in the building codes and the stipulated loads, but in knowing how simple structural elements work and fail.



METHODS

Apparatus using in this test are cube mould, RC beam, cement, sand, water, trowel

to mix concrete mixture, bucket, steel tamping rod, gallon bucket, reinforcement bar

and wires.

Procedure :

1. Cement, sand and water are weight according to the specification.

2. Cube and prism mould are cleaned and oiled.

3. The mould is fully tightened and attached firmly to its base plate.

4. ) Mortar sample are remix, fill the mould to 50 mm depth and compact thoroughly using at least 35 stamps of a 25mm square tamping bar at least 25 strokes for a 100mm cube.

5. When the mould is full, roughly trowel of the surface, leaving the concrete slightly proudly than the cube are leave for an hour before final smoothing whit a trowel. This permits the concrete time to settle well into the mould.

6. cubes are carefully removed from their moulds around 24 hours.

7. The cubes are submerged in a tank filled with water maintained at a temperature of 20 ºC ± 1 ºC and the keep them damp until the time of testing (after 5days, normally 7 or 14 days).


100


RESULTS

Mix Design

Table 1

ITEMS 1M3 +

CEMENT (KG) 380 11.02

SAND (KG) 380 11.02

TRAVEL (KG)(COURSE AGREGAT)

760 22.04

W/C 0.55 0.55

WATER (KG) 2.09 6.06

1200

100 100 100

150 + 100 100 100

100

CALCULATION

= [ 1.2 X 0.1 + (0.1 X 0.1 X 0.1) 3 ] 14

= 0.0294



(1:1:2)

CEMENT

0.029 mm3 = x

X = 0.029 x 380 /1mm3

= 11.02

Sand

X =0.029 x 380 / 1mm

= 11.02

Travel

X = 0.029 x 760 / 1mm

= 20.4

Water

W = 0.55 x 11.02

= 6.06

W/C = 0.55



RESULTS

FAILURE OF MATERIAL

TABLE 2

Before Test

SPECIMENT SIZE CASTINGDATE

TESTING DATE

FCU REMARKS

CUBE 10 X 10

=100mm

04/ 10 / 2010

(5 days)

08/ 10/ 2010

20mpa

Table 2

After Test

SPECIMENT TESTING DATE

fcu remarks

CUBE O8/ 10/ 2010

After 5days

20mpa

52000pound

FCU (COMPRESSIVE STRENGTH)



Pound newton (N/mm2)

x 4.447

1002

52000 pound x 4.447

1002

= 23.12 N/mm 2

Results


Cube 1


Failure of bending member

Table 3(before test)

Element Size

Casting date

Testing date

Failure ultimate

Remarks

fcu fail

RC BEAM

04/ 10/ 2010

(5 days)

08/ 10/ 2010

20mpa

Table (after test)

Elements Testing date

Failure ultimate remarks

Rc beam 08/10/2010

fcu fail

20mpa 1. 1.75 ton

(first crack)

2. 2.35 ton

(Failure)

Convert calculation

1 Ton = 9.806652



I. 1.75ton

= 1.75 x 9.806652

= 17.16Kn/mm

II. 2.35ton

=2.35 x 9.806652

= 23.04kN/mm

CONCLUSION

The result is as in the table above based on our test after 5days. Slump test that have been conducted in the experiment shows that our mortar mixing are quite good because the drop are about 5cm. Which means our mortar mix are good. When we conduct a pundit test on our mortar, our entire prism gives us more or less the same data because the all of it are using the same mixing ratio.

But, when we conduct a flexity test on the prism. They had gives us the different data. Prisms 1 has a greater weight and give us more flexity compare to prism 2.

The results are presented of the experimental investigation to study the effect of coarse aggregates with different characteristics on the compressive strength, flexural strength, and flexural strength/compressive strength ratio of normal- and high-strength concretes.

QUESTION 1:



IS DEFLECTION IMPORTANT IN STRUCTURAL DESIGN?

Deflection is important in structural design. Deflection is a term that is used to

describe the degree to which a structural element is displaced under a load. The

deflection of a member under a load is directly related to the slope of the deflected

shape of the member under that load and can be calculated by integrating the

function that mathematically describes the slope of the member under that load.

A important factor which has to be taken into account when calculating

deflection is the nature of the material. It is known that force cannot be applied to a

material without altering its dimensions.It therefore follows that, for identical

conditions, aluminium beams would have to be bigger than steel beams in order to

limit deflections. It shows that deflection is important in structural design.

Most of the building failures around the world is the mistakes of the structural

engineers who are responsible to design the structure. Failed to take consideration

of the deflection is one of the major mistake that cause the failure. Large deflections

of beams can lead to cracking of nonstructural elements such as plaster ceilings, tile

walls, or brittle pipes.

A beam may be strong enough to resist safely the bending moments and

shear forces and yet be unsuitable because its deflection under the calculated safe

load is excessive. Apart from being unsightly and giving an impression of insecurity,

excessive deflection can cause cracking of plaster ceilings and partitions.

QUESTION 3



BRIEFLY EXPLAIN THE TYPES OF FAILURE VIEW THE UNCONFINED COMPRESING REFER TO TEST DATE ON 08/10/2010?

There are 3 types of failure with the Unconfined Compressing Test. There are

Shear Failure, Longitudinal Splitting and Crushing Failure. The test on 08/10/2010

shows that the type of the failure is Crushing Failure.

The crushing mode is characterized by a symmetric distortion of the test specimen.

The distortion may either be a uniform bulging of the entire specimen or a localized

bulging. The bulged area of the specimen is highly deformed and usually contains a

uniform distribution of microcracks. If localized bulging occurs there is seldom

significant deformation or micro cracking outside of the bulged area.

Speciment failing in the crushing mode rarely rupture completely. Ir rupture does

occur it is usually as a result of the development of a shear plane. This is due largely

to the constrain imposed on the material by the endcaps. The endcaps prevent

lateral expansion of the ends of the specimen creating shear stresses in the ends.

These shear stresses will ultimately cause failure of the test specimen even though a

major portion of the material has undergone a relatively homogeneous compressive

deformation.

QUESTION 4



BRIEFLY EXPLAIN THE CAUSE OF SLOPE FAILURE?

There are 4 types of slop failure which are Falls, Topples, Slides, Spreads, and

Flows.

Falls is a slope failures consisting of soil or rock fragments that drop rapidly down a

slope. Falls is most often occur in steep rock slopes. It is usually triggered by water

pressure or seismic activity. Topples is similar to Falls, except that it begins with a

mass of rock of stiff clay rotating away from a vertical joint. Slides is a slope failure

that involve in or more blocks of earth that move down slope by shearing along well

defined surfaces or thin shear zones. Spreads is similar to Slides except that the

blocks separate and move apart as they also move outward.It can be very

destructive. Flows is a down slope movement of earth where the earth resembles a

viscous fluid. Mudflow can start with a snow, or be in conjunction with flooding.

There are 5 causes of slope failures.

Gravity is the main force responsible for mass wasting. Gravity is the force that acts

everywhere on the earth’s surfaces, pulling everything in a direction toward the centre

of the earth. On a flat surface the force gravity acts downward. So long as the material

remains on the flat surface it will not move under the force of gravity.

Gravity. Gravity is

The Role of Water. Addition of water from rainfall or snow melt adds weight to the

slope. Water can seep into the soil or rock and replace the air in the pore space or

fractures. Since water is heavier than air, this increases the weight of the soil. Weight

is force, and force is stress divided by area, so the stress increases and this can lead

to slope instability.Water has the ability to change the angle of repose (the slope angle

which is the stable angle for the slope).Think about building a sand castle on the

beach. If the sand is totally dry, it is impossible to build a pile of sand with a steep face

like a castle wall. If the sand is somewhat wet, however, one can build a vertical wall. If

the sand is too wet, then it flows like a fluid and cannot remain in position as a wall.



Troublesome Earth Materials.Expansive and Hydrocompacting Soils - These are

soils that contain a high proportion of a type of clay mineral called smectites or

montmorillinites. Such clay minerals expand when they become wet as water enters

the crystal structure and increases the volume of the mineral. When such clays dry

out, the loss of water causes the volume to decrease and the clays to shrink or

compact (This process is referred to as hydrocompaction).

Weak Materials and Structures.Bedding Planes - These are basically planar layers of

rocks upon which original deposition occurred. Since they are planar and since they

may have a dip down-slope, they can form surfaces upon which sliding occurs,

particularly if water can enter along the bedding plane to reduce cohesion. In the

diagram below, note how the slope above the road on the left is inherently less stable

than the slope above the road on the right.

Triggering Events

A mass-wasting event can occur any time a slope becomes unstable. Sometimes, as in

the case of creep or solifluction, the slope is unstable all of the time and the process is

continuous. But other times, triggering events can occur that cause a sudden instability

to occur. Here we discuss major triggering events, but it should be noted that it if a

slope is very close to instability, only a minor event may be necessary to cause a

failure and disaster. This may be something as simple as an ant removing the single

grain of sand that holds the slope in place.

Reference



1. Basic theory of structure by J.S.C BROWNE,B.sc(eng)

2. STRUCTURES by JE GORDON

3. http://en.wikipedia.org/wiki/Failure_theory_(material)

4. Theoretical Foundation Engineering by BRAJA M. DAS.


Structural Failure Report

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