Friday, 17 June 2016

Slope deflection method sway portal frame numerical probleam

Analysis the portal frame shown in following fig. by Slope deflection method and draw bending moment diagram.


Answer:-

Slope deflection method is help to determine the bending moment of sway portal frame.

Step 1:-  At fixed support the angle is zero i,e it and the deflection in beam as a delta is shown in fig. All loads are applied on it.





Step 2:- Very 1st the calculation of fixed end moment is determine by using simple fixed end formulas. And the sign convension are placed -ve & +ve respectively.

Wednesday, 15 June 2016

Types of Stairs


The stairs may be built with wood, concrete masonry or with cast iron. Wooden stairs are not safe, because of the danger of fire. However they are used in buildings to access to small areas in the upper floors.

 Cast iron or steel stairs in the spiral forms were used commonly to reduce stair case area. In many residential buildings masonry stairs are also used. Reinforced concrete stairs are very commonly used in all types of buildings.

PLASTERING


Applying mortar on the surfaces of walls, columns, ceiling etc. to get smooth finish is termed as plastering.

Mortar used for plastering may be lime mortar, cement mortar or lime-cement mortar.

Lime mortar used lime to sand ratio of 1 : 3 or 1 : 4.

Cement mortar of 1 : 4 or 1 : 6 mix is very commonly used for plastering, richer mix being used for outer walls.

CELLULAR CONCRETE


It is a light weight concrete produced by introducing large voids in the concrete or mortar. Its density varies from 3 kN/m3 to 8 kN/m3. It is also known as aerated, foamed concrete.

Properties of cellular concrete
1. It has low weight.

2. It has good fire resistance.

Compaction factor test.


This is another test to  identify the workability of concrete. This test is conducted in the laboratory.

The test equipment consists of two hoppers and a cylinder fixed to a stand, the dimensions and the distances between the three vessels being standardized. Vessel A and B are having hinged bottoms whereas cylinder C is having fixed bottom.

What is uses of timber?


1. For heavy construction works like columns, trusses, piles.

2. For light construction works like doors, windows, flooring and roofing.

3. For other permanent works like for railway sleepers, fencing poles, electric poles and gates.

4. For temporary works in construction like scaffolding, centering, shoring and strutting, packing of materials.

What is CEMENT & its Chemical properties


Cement is a commonly used binding material in the construction. The cement is obtained by burning a mixture of calcarious and argillaceous material at a very high temperature and then grinding the clinker so produced to a fine powder.

It was first produced by a mason Joseph  Aspdin in England in 1924. He named it as portland cement.

#Chemical properties of ordinary portland cement.

What are the common building stones?


(i) Basalt and trap

(ii) Granite

(iii) Sand stone

(iv) Slate

(v) Quartzite.

(vi) Marble

Uses of Stones.


(i) Stone masonry is used for the construction of foundations, walls, columns and arches.

(ii) Stones are used for flooring.

(iii) Stone slabs are used as damp proof courses, lintels and even as roofing materials.

What are the Properties of Stones?


(i) Structure

(ii) Texture

(iii) Density

(iv) Appearance

What is stone ?


Stone is a ‘naturally available building material’ which has been used from the early age of civilization. It is available in the form of rocks, which is cut to required size and shape and used as building block. It has been used to construct small residential buildings to large palaces and temples all over the world.

A. Type of Stones

• Geological   • Physical    • Chemical

Tuesday, 7 June 2016

DETERMINATION OF MOISTURE CONTENT


OBJECTIVE 

Determine the natural content of the given soil sample.  

NEED AND SCOPE OF THE EXPERIMENT

In almost all soil tests natural moisture content of the soil is to be determined. The knowledge of the natural moisture content is essential in all studies of soil mechanics. To sight a few, natural moisture content is used in determining the bearing capacity and settlement. The natural moisture content will give an idea of the state of soil in the field. 

DEFINITION

The natural water content also called the natural moisture content is the ratio of the weight of water to the weight of the solids in a given mass of soil. This ratio is usually expressed as percentage.

APPARATUS REQUIRED

    1. Non-corrodible air-tight container.       2. Electric oven, maintain the temperature between 1050 C to 1100 C.      3. Desiccator.      4. Balance of sufficient sensitivity. 

PROCEDURE

1. Clean the container with lid dry it and weigh it (W1).  2. Take a specimen of the sample in the container and weigh with lid (W2).  3. Keep the container in the oven with lid removed. Dry the specimen to constant weight maintaining the temperature between 1050 C to 1100 C for a period varying with the type of soil but usually 16 to 24 hours.  4. Record the final constant weight (W3) of the container with dried soil sample. Peat and other organic soils are to be dried at lower temperature (say 600 ) possibly for a longer period. 

  Certain soils contain gypsum which on heating loses its water if crystallization. If itb is suspected that gypsum is present in the soil sample used for moisture content determination it shall be dried at not more than 800 C and possibly for a longer time.

OBSERVATIONS AND RECORDING

Data and observation sheet for water content determination  

S.No. Sample No. 1 2 3

1 Weight of container with lid W1 gm

     

2 Weight of container with lid +wet soil W2 gm

     

3 Weight of container with lid +dry soil W3 gm

     

4 Water/Moisture content

W = [(W2−W3)/(W3−W1)]100

     

   

  RESULT

The natural moisture content of the soil sample is ________ 

 REMARKS

1. A container with out lid can be used, when moist sample is weighed immediately after placing the container and oven dried sample is weighed immediately after cooling in desiccator.

2. As dry soil absorbs moisture from wet soil, dried samples should be removed before placing wet samples in the oven.

Monday, 6 June 2016

Self compacting concrete.


A concrete which is capable to compact itself by its own self-weight under gravity without any external efforts like vibration is called as self compacting concrete. the mix is required to have ability of passing, filling and being stable.

Following ingredient are used to prepare self compacting concrete.

1. cement :- OPC 43 or 53 grade.

2. Aggregates:- well grade rounded or cubical aggregate of size 10 to 20mm uniformly graded fine aggregates.

3. Good quality of mixing water.

4. Super plasticizer like poly-carboxylated ether to improve the workability and viscosity modifying agent.

5. Mineral admixture like fly ash, ground granulated blast furnace slag, silica flume, fiber, finely crushed lime stone, dolomite or granite

6. Under self weight , scc should level and deform itself without any compaction and external vibration. There should be not be any entrapped air in concrete.

7. SCC should be fully flowable but without segregation and bleeding. This is achieved by keeping higher viscosity of cement and mortar to ensure flowability while maintaning no sedimentation of bigger aggregates.

What do you mean by Maturity of concrete ?


It is not only the time but also the temperature during the early period of hydration that influence the rate of gain of strength of concrete. since the strength development of concrete depends on both time and temperature it can be said that strength is a function of summation of product of time and temperature.

This summation is called maturity of concrete.

Maturity = ∑ (time X temperature)

What is membrane curing?


Sometimes, concrete works are carried out in places where there is acute shorting of water. the lavish application of water for water curing is not possible for reason of economy.

It has been pointed out earlier that curing does not mean only application of water, it means also creation of condition for promotion of uninterrupted and progressive hydration.

Membrane curing is a good method of maintaining a satisfactory state of wetness in the body of concrete to promote satisfactory state of wetness in the body of concrete to promote condition hydration when original water/cement ratio used is not less that 0.5. to achieve best result, membrane is applied after one or two days of actual wet curing.

Since no replenishing of water is done after the membrane has been applied it should be ensure that the membrane is of good quality and it is applied effectively. two or three coats may be requires for effective sealing of the surface to prevent the evaporation of the water.

when water proofing paper or polyethylene paper are used care must be taken to see that these are not punctured anywhere and also whether adequate lapping is given at the junction and this is effectively sealed.

Water curing


This is by far the best method of curing as it satisfies all the requirements of curing, namely, promotion of hydration, elimination of shrinkage and absorption of the heat of hydration. it is desirable that a certain extent of water curing is done before the concrete is covered with membranes. water curing can be done in following ways:-

1. Immersion

2. Ponding

3. Spraying

4. Wet covering

the precast concrete items are normally immersed in curing tanks for a certain duration. pavement slabs, roof slabs etc. are covered under water by making small  ponds. vertical retaining wall or plastered surfaces or concrete column etc. are cured by spraying water. In some cases, wet covering such as wet gunny bags, hessian cloth, jute matting, straw etc. are wrapped to vertical surface for keeping the concrete wet. for horizontal surfaces saw dust, earth or sand are used as wet covering to keep the concrete in wet condition for longer time so that the concrete is not unduly dried to prevent hydration.

Curing


The process of maintaining a satisfactory moisture content and a favorable temperature in concrete during the period immediately following placement so that hydration of cement may continue until the desired properties are developed to a sufficient degree to meet the requirement of service is called curing of concrete.

curing methods may be divided broadly into four categories:-

1. water curing

2. membrane curing

3. Application of heat

4. Miscellaneous

 

Slump Test


Slump test is the most commonly used method of measuring workability of concrete. the apparatus for conducting the slump test essentially consists of a metallic mould in the form of a frustum of a cone having the internal dimensions as follows:-

Bottom diameter   20cms

Top diameter          10cms

Height                      30cms

The mould is the place on a smooth, horizontal, rigid and non absorbent surface. the mould is then filled in four layer each approximately 1\4 of the mould. each layer is tamped 25 times by the tamping rod taking care to distribute the stroke evenly over the cross sections. After the top layer has been rodded, top is struck off level with a trowel and tamping rod. the mould is removed from the concrete immediately by raising it slowly and carefully in a vertical direction. this allows the concrete to subsidence. this subsidence is referred as slump of concrete. the difference in level between the height of the mould and that of the height point of the subsided concrete is measured. this difference in height in mm is taken as slump of concrete.

slump requirement for beams and slabs 50mm to 100mm

for walls and columns 75mm to 100mm

Vibrated concrete 15mm to 25mm  

what are the partial properties of workability ?


Mixability, Transportability, Mouldability and Compactibility are the partial properties of workability.

a)  Mixability:-

It is the ability of the mix to produce a homogeneous green concrete from the constituent materials of the batch, under the action of the mixing forces

b) Transportability:-

Transportability is the capacity of the concrete mix to keep the homogeneous concrete mix to keep the homogeneous concrete mix from segregating during a limited time period of transportation of concrete.

c) Mouldability:-

It is the ability of the fresh concrete mix to fill completely the forms or moulds without losing continuity or homogeneity under the available techniques of placing the concrete at a site.

d) Compactibility:-

Compactibility is the ability of concrete mix to be compacted into a dense, compact concrete, with minimum voids, under the existing means of compaction at the site.

What is Workability of concrete ?


The ease with which the concrete can be mixed up with minimum quantity of water, transported, placed and compacted without segregation and bleeding is called workability.

Workability is defined as the property of concrete which determines the amount of useful internal work necessary to produce full compaction. workability concrete is one which exhibits very little internal friction between particle and particle.

The factor helping concrete to have more lubricating effect to reduce internal friction are as follows:-

a. water content

b. mix proportion

c. size of aggregate

d. surface texture

d. shape of aggregate

f. grading of aggregate

g. use of admixture.