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The Comparative Analysis Of The Strength Of Concrete Made From Various Aggregate
CHAPTER ONE -- [Total Page(s) 3]
Page 3 of 3
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FORCES ON A CANTILEVER RETAINING WALL
Due
to the difficulty in getting or calculating the wall frication, Rankin
active pressure is normally used (ie O=o) mainly for walls less than 6
to 7 matters in heights
It is more economical to use the coulombs
equation for walls over 7m in height. It should also be clear that it
is not the height it used for computation if max. Shear and bending
moment that is used for sliding computation to get the driving force. It
is left for the design to decide whether to use passive pressure from
the soil in front of the toe and whether the soil covering the top
portion will be available for existing over turning moment and sliding.
Sometimes this is not considered. Just for conservative purpose
The triangular pressure diagram on the stem,wil yield a shear diagram that is a third degree curve.
The use of the different equations for shear and moment seems to be easier.
This
enables the roped computation of the cut off points for there in
forcing steel since it is uneconomical to use a constant amount of
reinforcement for the entire wall height.
From the diagram shown
below. The with of the base slab is deduced from the gross. Soil
pressure diagram before computing the shear and moments diagrams. The
eccentricity of computed by equation (iii) and (iv) shown below.
Differential
equations can also be used to compute the shear and moments of the base
slab if the safe of the cane is desired and even when numerical values
are required.
Fig 1-4 shows these illustrations diagrammatically
Forces on cantilever wall (a) entire unit; free bodied for (ii) stem,(ii) toe, (iv) heel. Note that
M1+M2+M3 = Y0
Fig (1-5)
Cantilever retaining wall (a) stem shear and moment (b) to and heel shear and moments.
CONTERFORT RETAINING WALL
Counterfort
retaining wall, are similar to the cantilever retaining wall only that
this type has counterforts built behind to hold the wall (stem) and
base together and is used where the cantilever is long or for very high
pressure behind the wall this counterforts behinds the wall are
subjected to tensile forces.
The dimension indicated in the diagram
below, only act as a guide, some walls which are about 100mm to 150mm
thick have been built in area like united Kingdom. Any thickness which
satisfies stability of the wall can be used.
Relative costs of forms,
concrete, enforcement and labour will determine to use of counterfort
but it is doubtful if a counterfor wall will provide any relative
construction economy values it is over 7m is height.
The spacing in
the counterforts is based on the trail and error in other to huiumise
cost. The most economical method is placing them 1/3 to ½ H (height)
apart. by conventional beam theory bending moments in the face slab
cantilevered part of the wall as at the interior if the length of over
hang is made 0.411 and a spacing between counterforts of L.
CHAPTER ONE -- [Total Page(s) 3]
Page 3 of 3
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ABSRACT - [ Total Page(s): 1 ]The work has gone a long way in determining strength of concrete made of various aggregates such as granites stone, black gravel, washed gravel and surface gravel.Some factors such as porosity of the aggregate temperature coursing lose of water plate form for mixing of concrete mix affect the workability and eventually the strength of concrete.This project work consist of using hydraulic machine to carryout the compressive test of the strength of concrete made of the earlier mentioned aggregat ... Continue reading---
