What is spacing, effective cover,stirrups and development length

What is spacing. 

  The distance between individual members which is used to separate from each other contact is called spacing. 

Example:

What is effective cover.

         The effective cover is the distance between the centre of steel bar to the concrete bed. The differ in value equal to half the diameter of steel bar.

      

What is stirrup. 

       A stirrup is a loop which is embedded in any concrete structure to hold the main rebars together. Or the stirrups used are generally made out of of a rectangular steel piece which is wrapped around top and bottom bars of the beam.

What is development length. 

        Development length defined as the amount of reinforcement (bar) length needed to be embedded or project into the column to establish the desired bond strength between the concrete and steel. 

RCC column reinforcement details

Estimation of column reinforcement details. With example
Example:
   

                  

More information about the RCC column reinforcement details please watch video link below. 

https://youtu.be/OsvZGt5TZtk

RCC column footing reinforcement details

Example:
             
                      

For more information about the example or full details about footing reinforcement details watch video link below. 

https://youtu.be/hCre-Ma20dE

How to check soil bearing capacity in construction site

Procedure: 

       (i) excavate a pit of required depth.

      (ii) take a iron cube or ball (whose                        dimension and weight are known)

     (iii) drop the cube or ball several times,                from known height on the excavate                pit.

     (iv) calculate the average value of the                    depth.


        R = (w×h)/d

Where
           R - ultimate resistance of soil in kg.

           d - average depth of impression in                         (cm).

          w - weight of solid ball or square cube                   in kg.
     
           h - height of fall ball of cube.


Example:
           Cube weight = 5 kg

          Height of fall = 150 mm

          Depth of impression - 9 cm,8.5 cm,6                                              cm,5 cm and 4 cm


Solution:- 

                  Average depth of impression
         d   = (9+8.5+6+5+4)/5 cm
              = 6.5 cm

         R  = (w×h)/d
              = (5×150)/6.5
              = 115.38 kg

Then, resistance of soil per unite area

               = R/A   kg/cm×cm

               = 115.38/(15×15)   kg/cm×cm
               = 0.51 kg/cm×cm


Safe bearing capacity of soil = R/(A×fos)

fos - resistance of soil per unite area reduce           2 to 3 times

 Safe bearing capacity of soil                                                    = 115.38/(15×15×2) kg/ cm×cm
                        = 0.256 kg/ cm×cm ans.
       

For  more  information  about this topic watch video link below.

https://youtu.be/sRspDdTRbVI

Facebook link.
https://www.facebook.com/sehbud.alam.52

Twitter link.
https://twitter.com/Sehbudalam7?s=09

Telegram link.
https://t.me/officialtkalam

Thnk you for visit.

How to find size of footing

Procedure: requirement

          . Load on it

          . Bearing capacity of soil



Formula = (load + safety factor (10% of                           load))/( bearing capacity of                             soil)


Example: 
                Load = 1500 kN

        Bearing capacity of soil = 200kN/m                                                                square 


Solution: 
                  Given
            Load = 1500 kN

Bearing capacity of soil = 300 kN/m square

      Safety factor = 10% of load
                              = (10/100)×1500
                              = 150 kN

Safe soil bearing = soil bearing                                    capacity       capacity/2
                               = 300/2 kN/ m square
                               = 150 kN / m square


Area of footing =( load + safety factor)/                                         safe soil bearing capacity
                            = (1500+150)/150 m×m
                            = 1650/150 m×m
                            = 11 m×m

Footing size square 
                     a×a = 11 m×m

                         a = 3.316 m ans.
             
                     

How to find size of column

According to IS-456 2000 find out the size of column need.

       . Load

       . Grade of concrete
   
       . Characteristic strength of the                           compression reinforcement

Formula:
                 Pu = (0.4fck×Ac)+(0.67×Fy×Asc)

   Where  Pu = ultimate load
                Fck = characteristic compressive                                strength of the concrete         
                  Ac = Area  of concrete
                  Fy = characteristic strength of the                             compression reinforcement

                 Asc = area of longitudinal                                             reinforcement for concrete 

             

Example: imposed load 2000 kn act on                the column size M20 grade Fe 415                grade steel. Find out the size of                    column.

                         

Solution: 

         

               Given 

                            Pu = 2000 kn

      

                           Fck = 20 N/mm square 

                           Fy   = 415 N/mm square 

Safety factor = 10% of load 

                        = (10/100)×2000 kn 

                        = 200 kn 

     Total load = 2000+200

                        = 2200 kn

   Grosss area= 100%
                Asc  = 1% Ag
                  Ac  = 99% Ag

                   Pu = (0.4×fck×Ac)+(0.67×fy×Asc)

 2200×1000    = (0.4×20×0.99Ag)+                                                  (0.67×415×0.01Ag)
           
  2200×1000   = 7.92Ag+2.7805Ag

  22000×1000 = 10.7005Ag

                   Ag = (2200×1000)/10.7005

                   Ag = 205597.869 mm square

Square size of column

                a×a = 205597.869 mm square
             
                    a = 453.42 mm ans.                     
                     

More information about size of column watch video link below. 

https://youtu.be/kQdKN8-vA_c

What is aggregate

What  is aggregate  

   Aggregate is a granular materials that act as skeleton and filling components in concrete and mortar, such as manufactured sand,natural sand,gravel,crushed stone and recycled concrete. Aggregate has a wide range of application in construction and other industries. 

                           

Types of aggregate 

    (i) coarse aggregate 

    (ii) fine aggregate 

What is coarse aggregate 

         Coarse aggregate will not pass through a sieve with 4.75 mm opening no 4 is portion of the concrete which is made up of the larger stones embedded in the mix concrete contains there ingredients, aggregate size larger than 4.75 mm is called coarse aggregate. 

               

What is fine aggregate 

         If the aggregate size is less than 4.75mm then it is called as fine aggregate. The minimum size of fine aggregate is 0.075mm is using for concreting work.

                   

  

Difference  between coarse aggregate and fine aggregate.