Quantity Surveying -II Lecture notes -2

 

Characteristics of a Good Staircase

A good staircase should have the following characteristics.

·        It should have sufficient size. It should not be too large or too small.

·        The step of the stair should be sufficiently wide.

·        The stairs should be solid and durable.

·        The riser should not be higher than 20cm.

·        The inclination should not be less than 25^o and not exceed 45^o.

·        A flight of stairs should have a minimum of 3 steps not exceeding 15 steps.

·        It should have a sufficient landing area.

·        It must have handrails.                   

·        It should be easily accessible from all rooms of the building. It should be centrally located in residential buildings and at the entrance of public buildings.

Types of Staircases

Staircases are classified into different types depending on the type of tread and landings provided. The landing style and the type of tread to be used depend on the vertical distance between the two floors and the space available for the staircase.

1.     Straight staircase

Stair may have one flight or two flights with a landing. These are normally open-type stairs with one side open and are space constraints. This type of staircase is preferred for small or domestic buildings. Straight stairs can be made of concrete, stone, wood, steel, or a combination of any of these. Fig 2 below shows a straight staircase.

2.     Dog legged Staircase

A Staircase to which newel posts are provided at the beginning and end of each flight is known as a Dog legged staircase. There is no space between two flights. A half-spaced landing is provided generally that affects the change in direction. Fig. 1 shows a doglegged staircase.

1.     Quarter turn Staircase

A stair turning through one right angle i.e., 90^o is known as quarter turn stairs. These are also known as Newel Quarter turn staircase. The change in direction can be affected by either introducing a landing or by providing winders. The stairs rise to a landing between two floors, turn through 90, then rise to the floor above. This type of staircase is often used in two-floor semi-detached houses.

2.     Open Newel Stair

This type of staircase has a well or opening between the flights in a plan. The well may be rectangular or of any geometrical shape and can be used for fixing lift. Fig.4 shows an illustrated example of an open newel staircase.

3.     Three quarter turn stairs

The staircase where the direction of the flight is changed by 3 times in 90^o or quarters is known as three quarter turn stairs. This type of stair is preferred when the length and breadth of the stair room are limited and the vertical distance between two floors is quite large. Fig.5 represents the plan of three-quarter turn stairs.

4.     Bifurcated Staircase

If a quarter-turn stair is branched into two flights at a landing, such a staircase is known as a Bifurcated staircase. This type of stair is commonly used in public buildings near the entrance hall. The stair has a wider flight at the bottom which bifurcates into two narrower flights at the landing. One turns into the left and the other to the right. These staircases may or may not have equal flights. Fig.6 represents the plan of a bifurcated staircase.

1.     Geometrical staircase

This type of stairs has a geometrical shape and does not require a newel post. This type of stair is similar to open newel stair except the well-formed between forward and backward flight is curved. Change of direction in such stairs is achieved by winders and not by landings. Figure 7. a shows the elevation and fig 7. b shows the plan of a geometrical staircase.

2.     Circular staircase

These are also known as spine wall stairs. They consist of a central vertical wall from which the flights and half-space landings are cantilevered. All the steps in the circular staircase are winders. This type of stair is provided where space is limited and traffic is casual. These are mostly located at the rear of the building. Figure 8 represents a circular staircase.

Quantity Surveying -II Lecture notes -1

 

Unit – 1 DETAILED ESTIMATE OF R.C.C ELEMENTS

Staircase

• Staircase is an important component of a building providing access to different floors and roofs of the building. It consists of a flight of steps and one or more intermediate landing slabs between the floor levels. Staircase divides a large vertical distance into smaller distances in the form of steps.
• Stairs can be defined as a series of steps suitably arranged to connect different floors of a building. It may also be defined as an arrangement of treads, risers, stringers, newel post, handrails, and baluster, so designed and constructed to provide easy and quick access to the different floors.
• A connected series of steps without any break between landing and floor is called a flight of stairs or Stairway.
• Stairs can be made of concrete, stone, wood, steel, or a combination of any of these.

 

Primary Functions

• Provide access from one floor to another.
• Provide a safe means of travel between floors.
• Provide a degree of insulation, where part of a separating element between compartments in a building.
• Provide a suitable means of escape in case of fire.
• Provide a means of conveying fittings and furniture between floor levels.

Parts of Staircase

• Step: It is a portion of stairs that permits ascent & descent.
• Tread: It is the upper horizontal portion of the step upon which the feet are placed.
• Riser: The vertical portion between each tread on the stair.
• Handrail: A handrail is a rail that is designed to be grasped by the hand to provide stability or support.
• Baluster: It is a vertical member of wood or metal supporting the handrail.
• Newel Post: This is the vertical member which is placed at the ends of flights to connect the handrail.
• Run: It is the total length of stairs in a horizontal plane, including landings.
• Nosing: It is the projecting part of the tread beyond the face of the riser. It is rounded to give a good architectural effect.
• String or Stingers: These are the sloping wooden members which support the steps in a stair. They run along the slope of the stair.
• Winder: Winder Treads for stairs are intended for use on staircases that include winder steps. These are the triangular steps that are narrower on one side than the other. They change the direction of the staircase and are an alternative to a landing.
• Landing:  A landing is an area of a floor near the top or bottom step of a staircase. An intermediate landing is a small platform that is built as part of the stair between main floor levels and is typically used to allow stairs to change directions, or to allow the user a rest.

Quqntity Surveying -I Lecture Notes -1

 

UNIT-1         Basic concepts of Quantity surveying, units, and specifications

1.1 Definition  

Quantity Surveying

Quantity surveying is an estimation of materials and labor necessary for a construction job. A person who calculates the amount of material and labor required for construction or building work is known as a Quantity Surveyor.

Estimate

An estimate is a calculation of the quantities of various items of work, and the expenses likely to be incurred thereon. The total of these probable expenses to be incurred on the work is known as the estimated cost of the work.

1.2 Need for estimation

1. It helps to work out the approximate cost of the project to decide the feasibility of the project concerning the cost and to ensure the financial resources. It decides if a proposal can be approved or not.

 2. Requirements of controlled materials, such as cement and steel can be estimated for making applications to the controlling authorities.

3. It is used to frame the tenders for the works and check the contractor's work during and after execution to make payments to the contractor.

4. From quantities of different items of work, the estimate is calculated in detail. Resources are allocated to different activities of the project and ultimately their durations and whole planning and scheduling of the project is carried out.

1.3 Different types of estimates

1. approximate estimate

It is also called a preliminary estimate. This is prepared at the initial stage of a project to give a clear idea to the owner or client about the cost required for the project or construction, to get approval from necessary sanctioning bodies such as banks to get loans. This type of estimate is calculated with relevance to the previous experience.

Documents required: project drawing plans, details about the land like electricity and water supply

E.g.:  To calculate the estimate for a house, a previously (& also recently) completed similar house is considered. Here the estimator already knows the rate for a 1m² area & with that he/she calculates the cost estimate for the newly proposed area of a similar house.

Remaining topics will be continued in next post

compass surveying lecture notes-2

 

1.2  Procedure of taking observations with Prismatic Compass

1.      The prismatic compass is mounted on the tripod such that it is exactly over the ground station.

2.      A small stone is dropped from the bottom centre of the compass. If it falls on the peg driven on the ground, the centre point is correct.

3.      The surveyor has to judge whether the compass is in Level or not by sighting only. If not, it is levelled by ball and socket arrangement.

4.      Turn up the prism and the sighting vane vertically. Raise or lower the prism until the gradations on the ring are visible.

5.      Then turn the compass box until the ranging rod at the station is bisected by the hair when sighted through the slit above the prism.

6.      When the needle comes to rest look through the prism and note the reading at which the hairline produced appears to cut image of the graduated ring. Thus, the required bearing of the line is found.

1.3  Surveyor’s compass

1.      In the surveyor’s compass the gradation on the horizontal circle is in the quadrantal system. The value of the bearings thus varies from 0^o to 90^o.

2.      The north and south are marked 0^o. east and west are marked 90^o.

3.      Prism is not provided in this compass.

4.      The surveyor’s compass has now become obsolete.

 

1.4  Designation of bearings

1.4.1        Whole Circle Bearing System (W.C.B system)

In this system, the bearing of a line is always measured clockwise from magnetic north. The angle thus measured is the Whole circle Bearing of the line. Its value ranges from 0^o to 360^o.

 

1.4.2        Quadrantal Bearing System (Q.B system)

In this system, the bearings of lines are measured clockwise or anticlockwise from north or south, whichever is nearer to the line.

  

 

 

 

1.4.3        Reduced bearing (R.B)

When the W.C.B of a line exceeds 90^o, it must be reduced to the corresponding angle less than 90^o and the value recorded along with the quadrant in which its value falls. This angle is known as the reduced bearing.

Case	WCB between	RB	Quadrant
1	0o-90o	W.C. B	NE
2	90O-180O	180o-W.C.B	SE
3	180O-270O	W.C.B-180o	SW
4	270O-360O	360o-W.C.B	NW
The above table shows conversion of bearings from W.C.B system to Q.B system

 

The below table shows conversion of bearings from Q.B system to W.C.B system
Case	Q.B system	W.C.B system
1	NE	Q.B
2	SE	180-SE
3	SW	180+SW
4	NW	360-NW

 

1.5  Fore bearing and Back bearing

1.5.1        Fore bearing (F.B)

The bearing of a line in the direction of progress of the survey is called the Fore Bearing.

1.5.2        Back bearing (B.B)

The bearing of a line in the opposite direction of progress of the survey is known as Back bearing.

compass surveying

 lecture notes -1

3.1 Purpose and Principle of Compass Surveying

Compass Surveying

The location of a point concerning two predefined points can be expressed in other terms other than distance alone. In such cases, the direction of the point is used for locating a point by any of the following methods:

1.      By measuring its distance from one of the given points and its direction from the other point.

2.      By measuring its distance and direction from any of the two known points.

3.      By measuring its direction from each of the two known points.

The direction of the survey lines is measured with the help of an instrument known as Compass. The purpose of compass surveying is to determine the relative position of a point using direction.

 

Principle of Compass Surveying

The principle of compass surveying is Traversing. Traversing consists of several connected lines whose lengths are measured by chain or tape and angle is measured using Compass.

There are two types of traversing. Open traversing and closed traversing. If the starting and endpoint of the framework coincide then it is said to be Closed Traversing. If the starting and ending points of the framework do not coincide it is said to be Open Traversing.

 

3.2            Prismatic Compass

The prismatic compass reads the line of an object in the whole circle bearing system directly. The parts of a prismatic compass are as follows.

1.      non-metallic box

2.      Graduated ring

3.      Pivot

4.      Magnetic needle

5.      Glass cover

6.      Eye vane

7.      Eye hole

8.                Sunglasses

9.                Prism

10.             Prism cap

11.             Object vane

12.             Horsehair

13.             Adjustable mirror

14.             Lifting pin

15.             Lifting lever

 

1.      Metal box:  The cylindrical box with a size of 8 to 12 cm covers the compass and then the whole casting or body of the compass.

2.      Graduated ring: It is an aluminium ring labelled 0^o to 360^o to calculate all potential line bearings and connected with a magnetic needle.

3.      Magnetic needle: The magnetic needle points the magnetic north.

4.      Pivot: The graduated ring and the magnetic needle rests on the pivot.

5.      Glass cover: It covers the top of the metal box so that the needle and the graduated ring can be observed from the top.

6.      Eye vane: All observations are noted from the eye vane.

7.       Eye hole: readings are noted from prism through the eye hole.

8.      Prism: Prism is used to read graduation on the ring and to take an exact reading by compass. It is placed exactly opposite to object vane. The prism hole is protected by a prism cap to protect it from dust and moisture.

9.      Object vane: The object vane carries a vertical hair of fine silk or horse hair attached to a suitable frame.

10.   Sliding mirror: The object vane is provided with a hinged mirror that can be raised upwards or lowered downwards and can slide thus changing its position if required. This is used to sight objects that are too high or too low.

11.   Sunglasses: Sunglasses are provided on the prism to sight luminous objects.

12.   Braking pin: it is provided at the base of the object vane to dampen the oscillations of the needle to facilitate the reading.

3.3  Procedure of taking observations with Prismatic Compass

1.      The prismatic compass is mounted on the tripod such that it is exactly over the ground station.

2.      A small stone is dropped from the bottom centre of the compass. If it falls on the peg driven on the ground, the centre point is correct.

3.      The surveyor has to judge whether the compass is in Level or not by sighting only. If not, it is levelled by ball and socket arrangement.

4.      Turn up the prism and the sighting vane vertically. Raise or lower the prism until the gradations on the ring are clearly visible.

5.      Then turn the compass box until the ranging rod at the station is bisected by the hair when sighted through the slit above the prism.

6.      When the needle comes to rest look through the prism and note the reading at which the hairline produced appears to cut image of the graduated ring. Thus, the required bearing of the line is found.