UmarMakhzumi

Manual calculations can be done by using one of the various moment coefficients methods, which are based on elastic thin plate theory. You can consult following references which gives moment coefficients for various end conditions of plate:
1) Moments and reactions for rectangular plates-Engineering Monograph 27. Here is the link:
https://www.usbr.gov/tsc/techreferences/hydraulics_lab/pubs/EM/EM27.pdf
2) Rectangular concrete tanks, 5th Edition by Javed Munshi
3) Reinforced Concrete Designers Handbook_11th Edition by Reynolds & Steedman
Needless to say that you can also use software.
 

How to design this type of flat slab? It does not fulfil the DDM criteria.
First image is UGWT top slab and second one is OHWT top slab

My name is Badar. You are addressing me with the wrong name.
It seems that you are not able to realize that the eccentric nature of connection between  cast-in-place beam and pre-cast hollow core slab will transfer torsion in addition to the UDL in the beam.
It is better, in this case, to design the beam for the torsion due to eccentric transfer to shear between slab-beam interface. Do not use 0.35 modifier for torsional constant.
The practice of using a modifier <1 for torsional constant is for monolithic construction involving combability torsion, which is due to the transfer of negative moment from slab end to  the supporting beam (you do not have these moments because of your connection detail).

This approach will give you the same behavior as membrane.
I am not sure about your intent. The UDL is not the only effect of connection that you intend to use.
Let me explain it this way: The beams supporting the ends of one-way ribs of hollow-core floor system will need to be loaded with the line load and torsion. See the attachment.
 

Yes, membrane assignment will do the job assuming that you are only concerned abut estimation of demands on the frame elements and not the hollow-core slab itself.
With your shear connection detail between beam and slab in the form of rebar-dowels, it would be wrong to model the slab with flexural stiffness (shell) , as it would lead to an underestimation of flexural demands on beams.

This structural element has shear, flexural and axial stiffness. It is not a membrane. Having said that, you can model it as membrane; You need  to decide about the modelling approach based on your design assumptions for supporting members and structural system as whole.

Assalam O Alykum 
Small question
The hollow core slabs are defined as a membrane or shell element ( In the direction of hollow core panels)
As a hollow core slabs are rests by bearing on the beams with grout and screed on the top with no composite action between beams and hollow core slab.
Thank you 

After analysis, while starting the design Etabs give this error only while performing concrete frame design. Any one who knows the solution reply to it..
I had this problem during my project. It had been a headache for me for 2 days. This problem arised due to modeling by using beam auto option or column auto option. When ever this problem comes firstly check the modeling. If you have modeled using auto option then replace those beams and columns by any user defined beams.
Thanks

Hi, Mr. Umar. Thanks for your reply to clear my doubt. May I know is there any quick way to locate the part causing the eigenvalue instability problem? 

Assalamo Alaikum!
Building Code of Pakistan 2021 edition has been printed. PDF version of the same is available at the following link.
https://drive.google.com/file/d/154K6RIJ0QZJCJ0Q4HsYl-KVqMuJZZF_o/view?fbclid=IwAR3mWSF1X5xBWywdz3-l1kKt7C4HSQi6D4RYZ5RMS0q-eRZ9GGIj8-vJEUk
Regards.

Leong,
Here is the description of this error:
Please check your model for instability although the above does say that it is a warning not an error but that is my suggestion.
Negative force in column means that you column is in tension. This is common condition. For lateral loads, one side columns are normally in tension and other side in compression.
Thanks.

Yes, looks good. The concept picture that you attached about rebar detailing is correct. I am attaching it below for clarity.

 
Depends on door height. If the door height is to the top of slab normally slabs are poured with beams and the beam and in that way the beams extend over the doors. Where doors are shorter, there is a sill beam placed. 
Thanks.
 
 

This is complicated framing.
Make a line model of every beam in some software, load it properly, provide reasonable restraints, make load combinations, run 2D analysis and take out variation of moment and shear for various load combinations. You will now the location of design shear, and moment from that. 
Consult a book on RC to help you decide rebar requirement from moment and shear. It is pretty basic.
I have attached a sketch of one of the beams which you can use as a reference to model. Correct estimation of point loads and UDL is key .

Look at page 20 of this document.

Hollow concrete blocks if made following standard procedure are usually very durable and have substantial strength. As far as i know, these blocks have low water absorption than conventional bricks. I think if they are properly placed with high quality mortar, you shouldn't have a problem.
You should take my advice with agrain of salt since this type of construction is not very common in pakistan.

You can use section 8.5.4.2 of ACI 318-19 as a reference for acceptable location of openings.
 
 
 

It appears that you have misunderstood the point about available length of residual bar  that can serve the demand of negative moment. You do not have 990mm.
 
 

I have already addressed that: You can provide extra rebars as per details shown by Ayesha.
 
It is what it is!
 
You cannot avoid them. What you can do is to limit their width so that the structure can have an longer service  life, and the rebars remain corrosion free.
I hope you understand that main/non-main depends on whether there is one-way or two-way action.

Negative rebars are the ones near the top of slab. With respect to my figure, it is the wall-rebar bent into the slab near its top face. It is a widely accepted practice to extend the top (negative) rebars to a distance of about span/4 from the face of support. For a 4m span, this would mean that you require 1m. But, as per your drawings, you do not have 1m; the available length of residual bars from the face of wall is about 1200 -150-300= 750. So you need extra rebars as per the detail shown in the comments of Ayesha for those spans. PS: In RCC structures there is no one-fits-all solutions. There are multiple loads paths. Even if you do not provide the lengths mentioned above, the slab can still have the required strength if you have provided extra reinforcement in the mid-span (i.e bottom bars).
The difference will be that you might get wider cracks (on top near slab to wall connection) if you do not follow the detail suggested in my comments.
But, you may not get to see them ever as flooring on the slab will make them invisible. This is the reason many engineers and contractors will say to you that do not worry about top rebars.

Pls explain auto mesh option and divide shell option.
when I select auto mesh option etabs show mesh 1x1 but the slab is not divided by 1x1 in actual, but when I divide shell by 1x1 it actually shows that slab is split into an area of 1x1. which type of meshing is correct in every situation. what type of meshing we should do. pls explain. I got really confused.

Consult PCA notes on ACI 318; chapter 10 of PAC Notes on ACI 318-08.
It is better to check them in software by considering the creep and shrinkage as well as excluding the deflections occurring before the installation of partitions.

Divide option is not meant for meshing in ETABS. It is to "divide" an already drawn panel after one has changed his/her mind regarding the assignments of that element.
Having said that, you can use it for meshing as well. But, it will become very cumbersome and lengthy when you want to change some assignments in divided slab elements, as you will then have to select those small panels by zooming on screen.
Use meshing option to mesh the area elements. Meshing can be viewed by activating the "Shell Analysis Mesh" option from "Set View Options" tab.

It has been shifted here as attached.
Path to get to that is: Define > Load cases > Add New Case

 

Hashmi,
For steel piles that are hammered/ driven in the ground: 2.5 * Outer Diameter of the pile is the minimum distance that is kept in Canada (I think this comes from Canadian Foundation Engineering Manual but can't recall the reference). This is out general accepted practice but normally we want to keep the minimum distance as 3.0* Outer dia of pile. If that can't be achieved then we go for 2.5*D but never lower than that. Sometimes, the piles will heave a little out of ground when adjacent piles are being driven (even with keeping 2.5-3 *D) distance. Such piles should be re-tapped.
Thank you.
 
 

Hi Ayesha,
Actually i have carried out ambient vibration measurements on a building and i need to compare dynamic results with 3D model. That’s why i need a shear beam model assumption. I have couple mode shapes (translation + torsion). 

Waslaam,
Lap splices are prohibited within the region expected to develop a flexural hinge ( the region is approximately: 2 x member depth from the face of column for  Bernoulli-Euler beams) to improve the post-yield deformation capacity in SMRF. This provision is there in the first code that I read (ACI 318-02); it still exists, as it should.