What is the Importance of the Span /depth ratio ?

Dear friends, 

You have so far seen many beams in your life. Right? 

Why a Beam is not cast with its larger side as horizontal? 

Why the larger dimension of the beam is always kept vertical? 

You must have asked this question many times. 

Read this post. 

It shall tell you the exact reasons for doing so. 

When selecting a rolled steel I-section for a simply supported beam, along with minimum section… by Santosh Kulkarni https://www.quora.com/When-selecting-a-rolled-steel-I-section-for-a-simply-supported-beam-along-with-minimum-sectional-modulus-a-minimum-value-of-span-to-depth-ratio-is-ensured-why/answer/Santosh-Kulkarni-37?share=4e7688b2&srid=zM5g

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Bar Bending Schedule for a RCC Beam

Hello Friends ,

Can you calculate the no of stirrups in this beam ?

Here is the actual example for you !

What is your answer ?

How many rings you have calculated in the entire beam ?

Oh.

You need a solution ?

Fine. Here is the solution :

Blog Stats for future reference :

Thank you so much

BEAM REBARS ? ..WHY WORRY ?

Good evening friends ,

 

 

 

 

RCC BEAM FULLY ANALYZED

Dear Friends ,

we are meeting after a long time.

Today , let us analyze a  RCC beam completely as per the drawing.

First , have a look at the RCC drawing for the ground beam.

Now look at the schedule of Beams.

We have randomly selected beam no P7 for the study today.

The beam looks like this :

For finding the cutting lengths of the various bars , we need to know the SPANS.

Look at this sketch.

With this sketch now , we shall calculate the cutting lengths as follows :

 

Form work for Curved beams

Curved beams :

Prologue :

The centering and shuttering of the curved beams does provide a different challenge as compared to the normal beams. This article attempts to identify the key steps in undertaking the curved beam form work with prefection.

Types of curved beams :
There could be two types of curved beams :
1. Curved in plan :
This could be either a circular beam or a arc beam either for the water tank or for the roof of a building.
2.Curved in elevation:
Mostly for the ornamental window lintels which are arch shaped beams.
3.Composite ( curved in Plan and elevation both ): Very typical folded structure which is circular in plan and also undulating in level on the circumference.

RCC beam reinforcement

EXERCISE :

FIND OUT THE TOTAL WEIGHT OF THE REINFORCEMENT FOR THE RCC BEAM.

• BEAM SIZE  300 X 600
• CLEAR SPAN : 4000MM (CLEAR SPAN : INTERNAL DISTANCE BETWEEN COLUMN TO COLUMN)
• TOP BARS : 2 X 12 T
• BOTTOM BARS : 4 X 25 T
• STIRRUPS : 10 T @ 200 C/C
• COLUMN SIZE : 300 X 300

FOR THIS FIRST WE NEED TO CALCULATE THE CUTTING LENGTHS OF EACH TYPE  OF BAR & STIRRUP.

• MAIN STEEL : STRAIGHT BARS
• BEAM SPAN O/O = ( 4000 + 2 X 300 ) = 4600
• CUTTING LENGTH OF STRAIGHT BARS = 4600 – 2X 25 = 4600 -50 = 4550 MM = 4.55M
• CUTTING LENGTH OF ANCHOR BARS = SAME AS MAIN BARS = 4.55 M

CUTTING LENGTH FOR THE STIRRUPS :

• STIRRUP WIDTH =  300 – 2 X 25 = 250 MM
• STIRRUP  DEPTH = 600  – 2 X 25 = 550 MM
• STIRRUP PERIPHERY = 2 X 250 + 2X 550 =1600 MM
• CUTTING LENGTH OF STIRRUP = 1600 + 120 =1720 = 1. 72 M
• NO OF STIRRUPS = 4000 /200 +1 = 21 NOS

• REINF.WEIGHT
• = NOS X CUTTING LENGTH X UNIT WEIGHT OF THAT BAR
• 1.MAIN BARS ( 25T ) =  4 X 4.55 X 3.86 = 70.252 KG
• 2.ANCHOR BARS ( 12 T ) =2 X 4.55 X 0.89 =8.10 KG
• 3.STIRRUPS ( 10 T )          =21 X 1.72 X 0.62 = 22.4 KG
•  TOTAL WEIGHT = 100.752 KG

• WT OF REINF. = 100.752 KG
• BEAM VOLUME =  4.6 X 0.3 X 0.6 = 0.828 CUM
• WEIGHT OF REINF PER CUM =  100.752 / 0.828 = 121 . 68 KG/ CUM

RCC Curved beam

One of my students has asked me this question today :

Sir , how to find out the reinforcement for the curved beam ?

So , dear readers , let us solve this question today.

For the sake of understanding , I have assumed the following data for the curved beam.

Curved length of the RCC beam : 8560 MM.

Note :

In case , it is not possible , to measure it from the drawing , due to lack of clarity on the beam curvature , I suggest that first let the beam bottom be fixed at the position and then actually measure the beam curved length at the position. This shall give the most correct beam length at site.

Beam size :

Width :250 MM.

Depth : 650 MM.

Beam top bars : 2 Nos x 12 mm dia.HYSD bars [ Straight ]

Beam Main bars : 4 x 25 mm dia HYSD bars [ Straight ]

Bent up bars : 2 x 25 mm dia HYSD bars 

Stirrups : 8 mm dia HYSD bars @ 200 c/c.

We also know that :

Beam cover : 25 MM.

Stirrup hook length : 2 x ( 10 X dia of stirrup bar )

Development length for the top bars : 450 mm.

Development length for the bottom bars : 450 mm.

Now with the above information , let us calculate the beam reinforcement as follows :

1. Top bars : [ 8560- (25-25)+ (450+450) ] = [ 8560 – 50 = 900 ] = 9410 mm = 9.41 M.
2. Bottom straight bars : 9.41M.
3. Bent up bars : ( 8560-50 )+ 2 {0.41( 650-50)} + (450+450) ] = ( 8510 + 2 x 0.41 x 600 )+900  = ( 8510 +492+900 ) = 7902 mm = 7.902 M.
4. Stirrups : Cutting length : 2 { ( 250 -50 ) +( 650 -50 )} + 2 X 10 x8 = 1600 + 160 = 1660 mm =1.660 M                                           No of stirrups : ( 8560/200 ) + 1 = 43.8 say 44 Nos.

Abstract for the weight :

1. Top bars : 2 x 9.41 M x 0.89 Kg/M = 16.75 Kg.
2. Bottom straight bars : 4 x 9.41 M .x 3.86 Kg/M = 145 Kg.
3. Bent up bars : 2 x 7.902 M x 3.86 Kg/M = 61 Kg.
4. Stirrups : Cutting length : 44 x 1.660 M x 0.39 Kg/M =   28.5 Kg.                                                                                                                                                                                                                                                                                                                                                  Total weight :  252 Kg.