Types of Stairs


  • Stairs are an important component of a building and often the only means of providing access between the various floors of a building. 
  • The staircase essentially consists of landings and flights. Often, the flight is an inclined slab consisting of risers and treads (collectively called the going of a staircase), whereas the landing is a horizontal slab.
  • From a structural point of view, a staircase consists of slab or beam elements.

Definition of Terms:


Components of a staircase (a) Plan of staircase (b) Terminology used (c) Part section

Tread or going of step: Tread is the horizontal upper portion of a step where the foot rests. Going to step is the horizontal distance of the tread minus the nosing.

Nosing: Sometimes, the tread is projected outwards for aesthetics or to provide more space; this projection is called the nosing. Many times, the nosing is provided by the finishing over the concrete tread.

Riser and rise: Rise is the vertical distance between two consecutive treads and riser is the vertical portion of the step.

Flight or going of stair: Flight is a series of steps provided between two landings. Going of a stair is the horizontal projection of the flight.

Landing: Landing is the horizontal slab provided between two flights. It is provided every 10–14 steps for comfort in climbing. Landing is also  provided when there is a change in the direction of the stairs.

Overlap: The amount by which the nosing of a tread (or landing) over sails the next lower tread (or landing) is called the overlap.

Waist: It is the least thickness of a stair slab.

Winder: The radiating or angular tapering step is called winder.

Soffit: It is the bottom surface of a stair slab.

Headroom: The vertical distance of a line connecting the nosings of all treads and the soffit is referred to as the headroom.
Steps may be of three types as follows:
(a)Brick or concrete steps on inclined slab
(b)Tread-riser steps
(c)Isolated steps

Type of steps (a) Steps on waist slab (b) Slab-less tread-riser (c) Isolated steps


Types of Stairs

There may be following types of stairs:

1. Straight flight stairs with or without intermediate landing.

2. Quarter-turn stairs

3. Half-turn stairs also referred to as dog-legged or scissor-type stairs

4. Branching stairs

5. Open-well stairs (half-turn) and quarter-turn landing

6. Spiral stairs

7. Helicoidal stairs


Some of the most common geometrical configurations are shown in Fig, which includes the following:



Plan views of various types of stairs (a) and (b) Straight flight stairs (c) Quarter-turn stairs
(d) Half-turn stairs (e) Branching stairs (f) Open-well (half-turn) stairs (g) Open-well stairs with
quarter-turn landing (h) Part-circular stairs (i) Spiral stairs (j) Helicoidal stairs

Spiral, helical, circular, and elliptical stairs are classified under Geometrical stairs


Structural Classification of Stairs:


For design purposes, stairs are classified into the following two types, depending on the predominant direction in which the slab of the stair deflects in flexure.

1.Transversely supported (transverse to the direction of movement in the stair)

2. Longitudinally supported (in the direction of movement)

Selection of Stairs

The type of stairs and its location are selected based on architectural considerations, such as accessibility, function, comfort, lighting, ventilation, and aesthetics, as well as structural and economic considerations.


Principles to be observed while Planning and Designing a Stair

Width of the stair should not be less than 1.00 m.
Length of flight: The number of steps in a single fight should not be more than 12.
Pitch of the Stair should be 25 to 40
Width of landing should be 150 mm more than width of stair.
Hand rails should be 750 to 850 mm. in height from the top of respective step.

Classification of Columns

  • A Column or strut is defined as a compression member whose effective length exceeds three times the least lateral dimension.

Read in details: What are Columns?

  • A structural element that is predominantly subjected to axial compressive forces is termed a compression member.

  • When a compression member is vertical, it is called a column, and when it is horizontal or inclined, it is called a strut.

Classification of Columns

The Classification of columns can be done on following Basis:

Classification of Columns based on Cross Section




1.Rectangular Columns
2.Square Columns
3.Circular Columns
4.Hexagonal Columns
5.T, L, or + shapes Columns


Classification of Columns based on Type of Reinforcement



1.Tied columns
    Columns reinforced with longitudinal reinforcement and lateral (transverse) ties. Tied columns are applicable to all cross-sectional Shapes.

2.Spiral columns:
    Columns with longitudinal reinforcement tied by continuous spiral reinforcement. Spiral reinforcement is used mainly in columns Of circular cross-section, though they can have hexagonal, octagonal, or even square shapes.

3.Composite columns
     Columns reinforced longitudinally with structural steel sections, such as hollow tubes and I-sections, with or without additional longitudinal reinforcement or transverse reinforcement.




Classification of Columns based on Types of Loading




Classification of columns
Cross section of column with different types of loading (a) Concentric axial loading (b) Loading with one axis eccentricity (c) Loading with biaxial eccentricities


1.Columns with concentrically applied loads: 
   Such columns with zero bending moments are rare. In multi-storey frames, interior columns will be subjected to axial compression and shear, under gravity loads.

2.Columns with uniaxial eccentricity—ex = 0, ey ≠ 0 or ex ≠ 0, ey = 0: 
    Edge columns such as B and D in Fig. 13.3 are subjected to uniaxial bending moments.

3.Columns with biaxial eccentricity—ex ≠ 0 and ey ≠ 0: Corner columns like C in multi-storey buildings are subjected to biaxial bending moments in addition to the compressive force. When subjected to lateral loads, most of the columns will be subjected to uniaxial or biaxial bending moments.




Classification of Columns based on Slenderness Ratio


What is Slenderness Ratio?
The Slenderness ratio of a member is defined as the ratio of the effective length and the radius of gyration of the section.

Columns, struts, beams, and ties are often slender members. 

Based on the slenderness factor, columns can be classified as follows:

1.Short columns: These types of columns generally fail after reaching the ultimate load carrying capacity of columns.

2.Slender columns: These types of columns generally fail suddenly at relatively low compressive loads due to buckling.

Read also: What are Columns?




10 Reasons to Date a Civil Engineer

I had a friend who was a Civil Engineer by profession. Whenever I used to call him, all I could hear is the noisy sound of massive cranes and heavy machines at the site and the construction workers murmuring in the background.




Sometimes he used to cough heavily due to dust and all and asking me to talk loudly and I was like,
"Helloooooooooooo, Hellllooooooooo, Can you hear me?"

When I asked him out. I got an answer that he can't as
 "The Project is in the critical phase and to be completed before deadlines."

This is the life of a civil engineer.




Civil Engineers are the great guy. Here are top 10 reasons why you should date a Civil Engineer:




#1.
Civil Engineers are more detail oriented which makes them good listeners. Don't be surprised if a civil engineer suddenly shows up growing a beard, it might be because you mentioned that you like beards in a group chat on 26 November, 11:54 pm.


#2.
Civil Engineers have the patience of the world, be it on-site work, our boss brooding over some unfinished work or be it in the personal life. They can handle things real calmly.

#3.
Civil Engineers are keen observers: It is a skill they acquire with the long hours of working with disdainful and irresponsible workers. They tend to keep a silent watch on every step taken because, at the end, it all turns up in the bill. So, they can give you surprises a lot many times that you expect.

#4.
Civil Engineers are excellent in maths: They have the ability to process large amounts of data and analyze solution both in professional and the personal life.

#5.
Civil Engineers always have a B-Plan: Their profession has made them so cautious that they always have a 'Plan-B', just in case 'A' didn't work, sometimes he is ready with plan 'C' 'D' & 'E' as well. You will never be bored without plans.

#6.
Civil Engineers do not show-off: They usually have that straight, non-expressive face all day dealing with the contractors and laborers. So when they smile at you, you can be sure that it is genuine.

#7.
Civil Engineers have the ability to guess the exact location of toilets, stairs or parking even in any new building.

#8.
Civil Engineers know the importance of safety: As the civil guy very well knows the importance of helmets & safety belts you save yourself the worries when they go for that long road trip with friends. 

#9.
Civil engineers are too busy to have an affair and even if they do, they are too dumb to lie to you about that.

#10.
Civil Engineers have the ability to explain complex things in easy laymen's terms.
So What have you thought, Keep calm and date a civil engineer :)

One Way and Two Way Slabs

                                     

                                        One-way Slab

  • One-way slabs, supported by parallel walls or beams, bend in only one direction and transfer their loads to the two opposite support walls or beams.

  • Even when a rectangular slab is supported on all the four edges, the slab may be considered as a one-way slab if the length-to-breadth (L/B) ratio of the slab is equal to or greater than two.

  • A one-way slab is designed for the spanning direction alone; the main tension reinforcing bars of such slabs run parallel to the span. For the transverse direction, a minimum amount of shrinkage reinforcement is provided.

  • One-way slab action is assumed in a ribbed floor (slab with joist beams) made of precast double-tee sections, in a ribbed floor with integral beams, and also in hollow-block or -cored slabs.


Plan view of one-way slab (a) Supported on two opposite edges
(b) Supported on all edges (L/B > 2)



Two-way Slab

  • When the ratio of long side to short side of a slab is less than two, it is called two-way slab.

  • The panel will deflect in a dish- or saucer-like form under the action of external load and its corners will lift if the slab is not monolithically cast with the supports.

  • Two-way slabs are designed to transfer their loads to all the four support walls. A slab supported on three edges or two adjacent edges may also be considered as a two-way slab. The load gets divided in the two directions, depending on the ratio of the sides.

  • Two-way slab behaviour is assumed in a waffle floor and in a waffle floor with integral beams. In waffle slabs, also called two-way ribbed slabs, ribs are provided in both directions of the span. The hollow block floor is constructed with blocks made of clay tile or lightweight concrete blocks.
Two-way slabs bend and deflect in double curvature





Achievements of E. Shreedharan

E. Shreedharan


E Sreedharan; popularly known as the "Metro Man" is a retired Indian Engineering Service (IES) officer . He is acknowledged for changing the face of public transportation in India for building the Konkan Railway route and the Delhi Metro.
  • Full name: Dr. Elattuvalapil Sreedharan
  • Born: 12 June 1932, Palakkad district, Kerala, India.
  • Studied Civil engineering at Government Engineering College, Andhra Pradesh.


  • Worked as a lecturer in Civil engineering at Government Polytechnic, Kozhikode for a short tenure.
  • Later,  Shreedharan joined the Indian Railway Service of Engineers (IRSE), after clearing Engineering Service Examination in 1953.
  • Awards: Padma Shri (2001),  Padma Vibhushan (2008)
  • Named one of Asia's Heroes by TIME magazine in 2003
E. Shreedharan



Mind blowing Achievements of Dr. E. Shreedharan



1. The Pamban Bridge

Date: 22nd of December in 1964
Location: Rameshwaram town
the coastal town of Rameshwaram was hit by a deadly cyclone on 22nd December 1964. 
As a sideshow, the cyclone destroyed the only bridge connecting Rameshwaram to mainland India: the Pamban Bridge. Now Rameshwaram was completely isolated. 
At that time, Dr. Sreedharan was a Deputy Engineer in the Southern Railway. And this damage was in his territory. Indian Railways gave E. Sreedharan 6 months to re-establish connectivity to Rameshwaram.
And
Dr. Sreedharan finished the project in just 46 days.
The Pamban Bridge

Dr. Shreedharan took one month and 15 days to reconstruct the Pamban bridge back to full operation. It was India’s longest sea bridge for 96 years, till the Bandra-Worli Sea Link was inaugurated in 2008.




  • According to the government rules, Dr. Sreedharan had to retire in 1990 when he completed 60 years of age.

But, when you are Dr. Sreedharan, you don’t have the privilege of retirement.

                                  2. Konkan Railway:
Dr. E. Shreedharan was asked to go to Mumbai to take charge of what was then deemed to be India’s toughest project since independence. This region was the Western Ghats of Maharashtra, affectionately called, the Konkan.

This is what Dr. E Sreedharan had to do,
Lay 760 Kms of railway track, through a terrain that had mountainous terrain with rivers and this infested with snakes and other dangerous snacks and perennially at the risk of land sliding and slope failures

And to do that, E. Sreedharan had to-
1. Acquire 5000 hectares of land from 42,000 assorted land owners.
2. Build 2000 Bridges, both major and minor, across Marshes, swamps, rivers and backwaters.
3. Blast 92 tunnels, totaling 83 kilometers in length through Basalt, nature’s adamantium and soft soil, nature’s china clay. You need nuclear weapons and Arnold to bore through the former while the latter generally collapsed on itself if someone as much as farted.
And to complete all of the above tasks, Dr. Sreedharan, was given 8 years.
Dr. Sreedharan, supposedly retired and who qualified for Indian Railway’s senior citizen quota, finished the job in 7 years.
Konkan railway

Dr. E. Shreedharan completed the railway's project that even the Britishers thought it was impossible.

Impacts of this project:

1. Three largest ports on the Indian coast: Mumbai, Karwar and Mangalore was connected directly for the first time.
2. The train travel time from the southern states to the north was reduced by up to 40 %.
  • Nethravathi Express used to take 38 hours to travel from Trivandrum to Mumbai. Now the same train takes 22 Hours. A 16-hour reduction in travel time. 




3. VIADUCT OVER THE PANVEL NADI:

Viaduct

The viaduct over the Panval river which basically is a Marsh between two Hills and to traverse it, the train has to travel at a height, which is as tall as Qutub Minar

In other words,
Dr. Sreedharan and his team, built a goddamn Qutub Minar, over a marsh, between two hills, just so that, a train could chug over it.


 4. Delhi Metro



In December 1997, one year before the Konkan Railway was opened to traffic, he was moved to New Delhi to head a new organization. It was created to find a viable solution to the traffic woes of the national capital.

This organization was Delhi Metro Railway Corporation (DMRC).

Delhi Metro


Since Delhi Metro was not India’s first metro. Kolkata has that honor. But Kolkata’s metro construction story was a sorry tale.
For Example:
1. It took 22 years to build the Kolkata Metro.

2. The Calcutta metro suffered from shortages in almost everything. Shortages of funds, shortages in labor and shortages in everything else. The only they had in plenty was those damn shortages.

But this was Dr. E Sreedharan.
Phase 1 of the 5 billion $ Delhi metro was completed three years before schedule, entirely within the initially stipulated budget without a single shard of corruption. In India, that is the closest we can get to walking on water.

The successful execution of the Delhi Metro made Dr. Sreedharan the torch bearer of the Metro Rail system in India. Every Indian city now wanted its own metro and Dr. E. Sreedharan as its consultant.