Design of Reinforced Concrete Solid Slabs (Part 3) - Continuous One-Way Slab - Worked Example

[@mohdaishahruddin8357]

Thank you so much Dr. It is very helpful. My semester of study for concrete design was just explained in less than a weeks.

[@MrElgamal77]

Happy that it helped you

[@jeangc4283]

Great explanations throughout. Thank you!

[@amralshawafi1478]

Thank you Dr. For these videos, please do on ribbed slab and flat slab.

[@tasneemadamjee7782]

When calculating A s-min should we take value of h as 175 or 145? Timeframe 12:11

[@MrElgamal77]

175

[@dnyikango1]

Thank Dr. for this great work, kindly do vids on flat slab design.

[@iwumezieuche8321]

Doctor I loveeeeeee yooooouuuuu🌹🌹❤️❤️

[@abdullahiibrahim4879]

استمر ياا دكتور المحتوى مفيد جدا.

[@jkengineeringarchitecture.]

How do you get 189 mm2/m as Area of steel required for outer support when the moment equals zero. could you pleas explain.

[@princekadema6010]

hey, were you able to find out how 189 was found for the outer support

[@jkengineeringarchitecture.]

@princekadema6010 Yes. Thanks he mentioned how he got it, but somehow I didn't hear. But when I re-watch it, I heard he stated to use the minimum reinforcement which is 0.13%bh. Thanks very much for reaching out to me.

[@princekadema6010]

@@jkengineeringarchitecture.okay alright

[@adomarthiabah9048]

from the beginning of the question you stated that diameter of bar is 10 and used that to calculate of the width of the slab. but in the middle of the calculation for reinforcement, you used a diameter of 8 (10:11) any explanation?

[@MrElgamal77]

At the beginning, we assume 10 mm. Then we calculate the thickness and round it. After that, you can use any diameter provided that deflection and shear are fine. Changing from 10 to 8 or to 12 will have almost no effect.

[@SayedTaha]

Great lecture , I have a question for the example solid slab with thickness 200 mm , does not it need a top reinforcement mesh to resist shrinkage stress ?

[@mohamedabdullahi2397]

thank you DR SHARIF

[@martinmtotera282]

Great explanations prof. You always makes things simple. I have a question on curtailment iam a bit confused on how to use c=0.15l I always use the 0.3l and disregard the 50% of c=0.15l Correct me if I may be wrong because I do that in real structures

[@MrElgamal77]

What you are doing is correct and more safe.

[@nkatiachomba2148]

15:22 How did v =Vmax/(bd) give you 0.225??

[@MrElgamal77]

I do not remember. I prepared it a long time ago.

[@MrElgamal77]

I checked it. It = V/(bd)= 32.6*1000/(1000*145)=0.225

[@ahmedalgaale6368]

جزاك الله خير يادكتور نريد المزيد من المحاضرات وياحبذا اذا اشغلت مبني متعدد الطوابق

[@DEMIIEEE]

Please what happened to the negative moments? Because its like you ignored the negative and made them positive them when solving

[@dennythomasmulavana8694]

Thank you very much sir

[@Ryuzaki14YT]

10:46 really struggling with how this value of As minimum was agreed or found please help

[@blessingohai6942]

Please do you have a video on understanding bending moment and shear force calculation and diagram

[@OmarSophi10]

Dear Dr. Sharif I confused difference between actual span/d and allowable span/d . what is actual span/d and allowable span/d ?

[@ahmedalaamri5060]

Allowable is the maximum allowed by the code, and the actual is whatever is happening in the slab you are solving sue to the provided thickness and reinforcement. These are reflecting the maximum allowed deflection and the actual deflection. All the best

[@Atlas806]

When checking for deflection, what if the modification factor is greater than 2?

[@ahmedalaamri5060]

Reduce the thickness of the slab, the slab is thicker than required

[@ahmedaweysmohamed6378]

Take 2 as a modification factor

[@yaasirahmed1528]

at 6:38 it says total design ultimate load = 12.08 KN/m^2. then next slide the force = 12.08 * 4.5 = 54 KN , how shouldnt it be 54 kN/m

[@MrElgamal77]

Yes. It is correct. When you solve for 1 m strip, the 12.08 kN/m2 will be 12.08 kN/m. Then the resultant will be 12.08 × span (4.5)= about 54 kN

[@jenifferngugi7112]

Hi Dr. For the minimum steel, is the h not 175mm. You used 145mm

[@MrElgamal77]

Thank you. You are right. 145 was used by mistake.

[@SteveWrightNZ]

Is there a transcript from this video? many thanks.

[@onlygidee]

Good day sir, since this is a continuous structure why did you make use of simply supported moment formulas for the continuous beam

[@MrElgamal77]

I used the simply only at the end beam. This will be more safe as it gives higher +ve moment. At the connection of the slab with the end beam, we use minimum top reinforcement to consider for continuity.

[@onaziagbese7779]

Thanks Prof. You have made everything become so easy. I have a question please. This example you have solved, shows a one way continuous slab and its analyzed such as you have done, with the continuity in the shorter span. How about if the continuous spanning were to have been in the longer span of this same example?

[@ahmedalaamri5060]

The dominant side is always the short side and being moment is major towards that span and not the long span. All the best

[@ahmedalaamri5060]

The dominant side is always the short side and being moment is major towards that span and not the long span. All the best

[@MrElgamal77]

In one-way slabs, we do not design in the long direction. For longer span, we take only the minimum.

[@agostinhoinocencio7013]

Sr how did you get Area minimum= 188,5. 'cause i followed all your instructions but i got 227,5 can you pls make me understand

[@engrxiddig]

There is a mistake

[@paulmwangi5061]

Thanks doctor,could you please help on how to design ribbed and flat slab.

[@MrElgamal77]

I have first to prepare a video about footings.

[@themelvinawabil]

Why didn’t you use the values of the “continuous slab” instead of the simply supported

[@MrElgamal77]

Because the last support is assumed simply supported. This is a conservative design and will give more positive momentum in the first span

[@rachaelgichuke1905]

Hi Dr.. Thank you for the much informative and valuable tutorials, one question though, from the structural analysis section, why are we using values for moments and shear, in table 3.12 from the simply supported section and not the continuous section? I thought the slab was continuous.

[@ahmedalaamri5060]

Continuous in the BS code refers to the continuity of slabs in that particular joint and not the reinforcement. To counteract the top moment and the partial fixity between the beam and the slab, BS8110 recommends certain top reinforcement at the simple end. All the best

[@trivagravia4837]

Under "As required", "As provided" you could have explained how we arrive at those values...l got lost there..

[@blossomtaye7977]

Hi Dr. i have noted that in the calculation of reinforcement, at outer support, where the moment is 0, you have indicated that the Asmin = 189. in your previous lectures, you had indicated that the Asmin is derived from table 3.25, and in this case where fy =460N/mm2 and the section is rectangular, the minimum dimension of reinforcement is 0.13%. Upon calculation, i.e. 0.13% x 1000 x 175mm (b=1000mm, h= 175mm) you get Asmin as 227.5 mm , not 189 mm. Kindly comment. Regards,

[@MrElgamal77]

Hi Ezra. You are right. I think it was multiblied by d instead of h by mistake. Thanks.

[@masmhmd2488]

Great work I have one question, how can I design the cantilever of one way slab?

[@ahmedalaamri5060]

You may take it as Wl2/2 or if you want to be more precise, redistribute the moment taking into account the top moment of the continuous part of the neighbour slab

[@odohvictor9945]

Please what if the spans are not equal, can table 3.12 still be used?

[@yaasirahmed1528]

yes , find average moments using adjacent length at interior supports

[@sarahkimitu1096]

You are using BS8110 of which year ?

[@briankarani3551]

please check the F at 9.32.You dont need to multiply the F by the length again when finding the moments since its already done at the top

[@MrElgamal77]

No. You need to multiply it again by the length to get the moment. For shear, you do not.

[@ezatullaharif2855]

Salamu Alikum, would you please make some excel lecture on concrete design. thank you

[@wajidkhan-cc2ty]

any one plz how to find this As,req and spacing

[@mohamedhissali339]

Very fast calculations not explained clearly

[@agostinhoinocencio7013]

0.0013x1000x175=227.5

[@MrElgamal77]

You are correct. The 188.5 was a mistake.

[@agostinhoinocencio7013]

@@MrElgamal77 thanks so much Sr i appreciate that

[@girbertndayiringiye4468]

😚

[@amralshawafi1478]

Thank you Dr. For these videos, please do on ribbed slab and flat slab.