ABUTMENTS :-

           Ab abutment is a structure located at the end of a Bridge. The basic functions of an abutment are:

• Supporting the bridge Deck at the ends
• Retaining the approach road embackment
• Connecting the approach road to the bridge Deck

           There are different types of abutments. The selection of a perticular form of abutment depends on the geometry of the site and the size of the bridge. The simplest form of an abutment is a wall of considerable thickness provided with bridge seating arrangement at the top. A major difference b/w a conventional retaining wall and an abutment is that, an abutment is always associate with additional walls called WING WALLS. The major types of abutments currently  in use are explained below

Gravity Abutment :-

           A gravity Abutment resists horizontal earth pressure from the rear, with its own dead weight. To be stable, this leads to massive-sized abutment. These abutment may be of mass concrete or stone masonry. A gravity Abutment is composed of a back wall and splayed wing walls, which rest on foundation. The cross-section of this type of abutment is shown in below fig.....

U-Abutment :-

           When the wing walls of gravity Abutment are placed at the right angle to the back wall, the abutment is known as U-Abutment. The name U-Abutment is due to the Shape of this Abutment in plan. The wing walls are typically cast monolithically with the abutment back wall and cantilevered both vertically and horizontally. As shown in below fig...

Stub Abutment :-

           Stub Abutment are relatively short abutments, which are placed on top of the embackment or slope. Sufficient rocky terrain must prevail at the site, so that the stub Abutment can be support on piles which extend through the embackment. This is portrayed in Fig..

Counterfort Abutment :-

           A Counterfort Abutment is a very much similar to a Counterfort retaining wall. In Counterfort Abutment, a thin wall called counterfort connect the breast wall to the footing. These Counterfort are spaced at regular intervals so that the breast wall is designed as a supported slab rather than as a cantilever. Counterfort Abutment are used when high Abutments are required. This type of Abutment is shown in fig.....

Abutment

Tunnel

Tunnel

 Tunnel :-

           A tunnel can be defined as an underground passage for the transport of  passengers, goods, Water, sewage, oil, gas, Etc. The Construction of a Tunnel normally carried out without causing much disturbance to the ground surface.

Size and Shapes of the tunnel :-

           The Shapes of tunnel linings are usually determined by their purpose, ground conditions, construction method or lining materials.

Rectangular shape:-

            Rectangular shaped tunnel are usually adopted by the cut and cover method. It is particular suitable for pedestrian and highway tunnels. On the other hand, multi-lines submerged highway tunnels are often in rectangular shape.

Elliptical shape / Egg Shape:-

               Elliptical shape tunnels are have the advantages for the transportation of sewer. The smaller cross section at the bottom maintains the flow at the required self cleaning velocity. However , due to the difficulty in construction, circular shape once are more common. 

Circular shape :-

              A circular shape tunnel has the greatest cross-section area to perimeter ratio. They are often associated with TBM or the shield tunnelling methods. 

Horseshoe / segmental shape :-

           They are commonly used for rock tunnelling. It has the advantages of utilising the compressive strength of concrete in resisting the loading by means of arch action and the base is wide enough for traffic.

Rails

 Rail :-

            The Rails on the track can be considered as steel Girder For the purpose of Carrying axle Loads. They Are made of High Carbon Steel to withstand Wear & Tear. Normally Flat Footed Rails  (FF) are mostly Used in Railway track specially In Indian Railways.

             Standard Rails Used By Indian Railway As shown in below picture.

Functions of  Rails :- 

• Rails provide a hard ,smooth & unchanging surface for passage of heavy  moving loads with a minimum friction between the steel rails and steel wheels.
• Rails bear the stresses developed due to heavy vertical loads, lateral and braking forces and thermal stresses.
• Rails transmit the loads to sleepers and consequently reduce pressure on ballast and  formation below.     

Types of  Rails :-

• Double Headed Rails (DH)
• Bull Headed Rails (BH)
• Flat Footed Rails (FF)

 Double Headed Rail :-

              Uppar head and the lower head of the Rails have Same  dimensions or upper table and lower table have same width is known as Double Headed Rails (DH).

              

Generally  we use ;

• Total depth/height of the Rail = 152.5mm
• Width of both heads = 70mm
• Depth/height Of the both heads =44.5mm
• Depth/height of the web = 63.5mm
• Width of the web = 19mm

Bull Headed Rails :-

          It name as indicates its lookes like bull head in one side. Because of the one head of rail is larger than another head.

          Generally we use:-

• Width of head =68.7mm
• Depth/height head  =46mm
• Width of Foot =63.5mm
• Depth/height of foot=33mm
• Total depth/height of rail =144.9mm
• Depth /height of web = 65.9mm
• Width of the web = 16.7mm

Flat Footed Rails (FF) :-

              This type of Rails generally used in modern Rail way tracks, it is very Economical.

               This type of Rails have flat in below side and  traffic moving on upper side , or Have Flat type of Footing As shown in below picture.

Generally we use ;

• Upper side width =66.7mm
• Depth/height of the upper side =43.7mm
• Total depth/height of the Rail = 142.9mm
• Hight/depth of web =78.6mm
• Width of the web =13.89mm
• Width of flat foot =136.5mm
• Depth/height of the flat foot =20mm

 Normally in India the flat Footed Rails generally used.....

Contract in Civil engineering and Standards Construction Contract

 CONTRACT :- 

            When two or more persons have common intention communicated to each other to creat some obligation between them there is said to be an agreement. 

An agreement which is enfoerceable by law is a "Contract".  

            In civil engineering construction contract is an undertaking by a person or firm to do any work under certain terms and codicondit. The work may be for the construction or maintenance and repair, for supply of materials or labour, etc.

Contractor :- 

           The contractor means a person or firm to do any type of contract.

Types of Contract :-

•        Piece work contract
•       Item rate or unit price contract
•       Lump sum contract
•       Cost plus percentage contract
•       Combination of lump sum and        schedule of rates contract
•        Labour contract

  Piece work contract :-

            It is an agreement by which the worker agrees to execute the different items of work on mutually agreed rates. The agreement contains different items of work to be carried out with proper description and rates for unit quantity of work.

 Lump sum contract :- 

            In this contract the contractor agrees to execute within a specified time. The plan, drawings and specifications of all items of the work are provided to the contractor but the details of quantities and schedule of items will not be given and contractor will have to complete the work as per plan and specification within the contract period.

  Item rate or unit price contract:- 

             In this contract the contractor under takes the execution of work at the unit rates agreed at the time of tender. The payment is made to the contractor by detail measurements of the work actually executed by the contractor. This method of contact is used in most of the work in projects, maintenance of buildings, irrigation projects, etc.

 Cost plus percentage contract :-

               In this contract the contractor is paid the actual cost of the building plus a fixed percentage for his overhead expenses, services and profit. The contractor procure the materials and arranges the labours at his own cost keeping the proper account and he is paid by the department or owner the whole cost together with certain percentage, normally 10% as his profit.

  Labour contract :-

                   In this contract the contractor under takes only the labour portion of the work. All the necessarily materials are supplied to the site by the department or owner and contractor arranges his own labours and get the work done as per the specifications.

                    The contractor is paid for the labours only on the actual quantities of the work done measured under the item rate basis.

.civil Engineering

Types Of Loads On R.C.C Structures

Types Of Loads On R.C.C Structures :-   

      

           Structures are designed to withstand various type of loads. The various type of loads expected on a structure are as follows:

• Dead Load :- 

          

Dead, live and wind loads

             The unit weights of commonly used building materials are given in the code IS 875 (part-1)-1987

• Live Loads :- 

               Live loads on floors and roofs consists of all the loads which are temporarily placed on the structure, for example, loads of people, furniture, machines, etc. These loads keep on changing from time to time. They are also called as imposed loads. Various types of imposed loads coming on the structure are given in IS 875 (Part-2): 1987. The imposed loads depend upon the use of building.

• Wind Loads :-

            The force exerted by the horizontal components of wind is to be considered in the design of building. It depends upon the velocity of wind, shape and size of the building. The method of calculating wind load on structure is given in IS : 875 (Part-3) 1987. It is also called as Lateral Loads.

• Snow Loads :-

             The building which are located in  the regions where snowfall is very common, are to be designed for snow load. The code IS : 875 (part-4) 1987 deals with snow load on roofs of the building.

• Earthquake Loads :- 

           Earthquake loads depend upon the place where the building is located. As per IS : 1893-2002 (Part-1), India is divided into four seismic zones. The code gives recommendations for design of structures. It is also called as Lateral Loads.