UmarMakhzumi

Sohaib,
 
There are two standard ways to work with foundations: ASD and ULS. Please have a look at the two discussions below. The method you should adopt depends upon the codes you are following and recommendations in that code. 
 
http://www.sepakistan.com/topic/1519-deduction-of-overburden-from-bearing-capacity/
http://www.sepakistan.com/topic/1700-column-footing-size-for-high-snowfall-areas/
 
Thanks.

What Rana means is to play with the wall stiffness modifiers till you get 25% base shear resisted by columns. This is different from standard stiffness modifiers applied to each structure irrespective of their geometry as per Section 10 of ACI.
Thanks.

I was browsing through my archives are noticed a bunch of articles written by NICEE (National Information Centre of Earthquake Engineering (NICEE) was established in IIT Kanpur with the mandate to empower all stakeholders in the building industry in seismic safety towards ensuring an earthquake resistant built environment. NICEE maintains and disseminates information resources on Earthquake Engineering. It undertakes community outreach activities aimed at mitigation of earthquake disasters. NICEE’s target audience includes professionals, academics and all others with an interest in and concern for seismic safety).
The articles are free to publish as long as original content stays unchanged. These articles are good for fresh structural engineers and Civil/ Structural Engineering Students. The best thing about them is that they are only 2 pages and full of images. It literally takes less than 5 min to go through each.
 
EQTip19.pdf
EQTip20.pdf
How architectural features effect buildings.pdf
How buildings twist during earthquakes.pdf
How do Beam-Column Joints in RC Buildings Resist Earthquakes.pdf
How do Brick Masonry behave during Earthquake.pdf
How do Columns in RC Buildings Resist Earthquakes.pdf
How do Earthquake Affect Reinforced Concrete Buildings.pdf
How Flexibility of Buildings affect their earthquake response.pdf
How the ground shakes.pdf
How to make building ductile for Good Seismic Performace.pdf
How to make Stone Masonry Buildings Earthquake Resistant.pdf
How to Reduce Earthquake Effects on Buildings.pdf
What are magnitudes and intensity.pdf
What are seismic effects on structures.pdf
What causes earthquake.pdf
What is seismic design philosophy of Buildings.pdf
Why are Buildings with Shear Walls Preferred in Seismic Regions.pdf
Why are horizontal bands necessary in masonry buildings.pdf
Why are Open Ground Storey Buildings Vulnerable in Earthquakes.pdf
Why are Short Columns more Damaged During Earthquake.pdf
Why is vertical reinforcement required in masonry buildings.pdf
Why should Masonry Buildings have simple Structural Configuration.pdf

Hi @Rahulkld,
That is expected. Since your bottom and top chords have high axial load near support, the first 2 diagonals are always critical. You can use heavier sections for the first two diagonals and lighter elsewhere.
Thanks.
 

I think @Simple Structures has UK experience and would be able to help. Please reach out to him.
Thanks.

Hello!
in Etabs V19, they have removed UBC-97 optino. however, in ETABS V19, they have retained UBC-97
the question is, while using the Design in Pakistan following BCP-2021. in ETABS for Seismic type in load pattern option, should we select UBC-97 or ASCE 7-16 ?
If ASCE 7-16, how to use the values for Ss and S1?
Thanks

BCP 2021 is now available on PEC website. It has tables for Ss and S1 values. So check there. Remember you have to use ACI 318-14 now as a design code. So lots of changes there also. Here is the link https://drive.google.com/file/d/1lqD7QvQ7Auo3yDM3Vd05tmbRnoYD-icm/view

Hello members I hope this thread finds you well. 
My query today is related to compressive strength of concrete bored piles. The issue is that pilegroup with 24 no of piles have been casted almost two years ago but there were observations regarding quality control on couple of piles in the group which are not known. Now the higher-ups are recommending to resume the project again and unfortunately I'm the incumbent and have to propose a methodology. Now the question is that since the piles are already buried underground, which procedure shall be adopted to predict its compressive strength near to its actual. Your suggestions will highly be appreciated. Thanks. 

There are different way depending upon the risk category of the structure. 
Pile capacity of concrete is one things and geotechnical capacity is another. The best way would be to do a pile load test on this pile group. Geotechnical consultants normally do such test and it helps verify capacity of existing piles both structurally and geotechnically.
For concrete strength, like you said core testing is one way. I am not familiar with GPR for strength testing of concrete piles. I have seen a lot of results of GPR surverys to find buried lines but nothing to determine strength.
Hope this helps.

I have worked with some engineers that like to assign high stiffness modifiers to rafts to get conservative flexural and shear design of foundation. Assigning modifiers would increase amount of rebar in your raft.  I personally think that this is good practice as nothing is perfectly rigid and cracking in inevitable, which would result in loss of inertia and high flexural stresses.
The general procedure is to create two models. One with no stiffness modifiers and one with modifiers for foundation/ raft. You should use the first model to calculate piles reactions and the second to do flexural and shear design. 
Thanks.

Hello,  I have tested a frame in etabs with multiple variations. The portal frame is the exact same dimensions in all cases, with the only difference being that the wall mesh is getting smaller/finer each time. The Shell dimensions are 250x1000mm in all cases and the beam size is 250x500mm. Can someone explain to me how the mesh of the shell element affect the beam? I did not assign any releases to the beam but as the mesh gets smaller it looks like the beam is simply supported.
ETABS.pdf

The allowable settlement criteria is based on utility of structure. For examples, in Process and Oil & Gas industry, piles supporting structures that have pipes are normally limited to 6mm vertical deflection. This value of 6mm is also considered by Pipe Stress engineering when they are doing their pipe design and in this way the design comes to full circle. Differential settlement is also considered. 
If you are asking for a building, the it depends on what values your building columns can tolerate considering differential settlement and not fail. Piles undergo short term and long term settlement in clay soils. You should evaluate both based on the recommendations of geotechnical engineer and see how the values affect your superstructure.
Thanks.
 

By ACI, I reckon you are referring to the ACI 318 document.
That document primarily lays out guidelines for safe construction and design of some of the reinforced concrete structures. That document does not give guidelines to calculate wind, seismic, or other kind of forces.
For these guidelines, you need to consult IBC, UBC, or ASCE7 documents.
The inclusion of live load in seismic weight is laid out differently in US-based codes.
Following are the statements from UBC 97 (Section 1630.1.1):
Seismic dead load, W, is the total dead load and applicable portions of other loads listed below.
1. In storage and warehouse occupancies, a minimum of 25 percent of the floor live load shall be applicable.
2. Where a partition load is used in the floor design, a load of not less than 10 psf (0.48 kN/m2) shall be included.
3. Design snow loads of 30 psf (1.44 kN/m2) or less need not be included. Where design snow loads exceed 30 psf (1.44 kN/m2), the design snow load shall be included, but may be reduced up to 75 percent where consideration of siting, configuration and load duration warrant when approved by the building official.
4. Total weight of permanent equipment shall be included.
Following are the statements from ASCE7-22 ( Section 12.7.2):
1. In areas used for storage, a minimum of 25% of the floor live load shall be included.
2. Where provision for partitions is made or where required by Section 4.3.2 in the floor load design, the actual partition weight or a minimum weight of 10 lb/ft2 (0.48 kN/m2) of floor area, whichever is greater.
3. Total operating weight of permanent equipment.
4. Where the flat roof snow load, Pf , exceeds 45 lb/ft2 (2.16 kN/m2), 15% of the uniform design snow load, regardless of actual roof slope.
5. Weight of landscaping and other materials at roof gardens and similar areas, as defined in Section 3.1.4.
6. Weight of fluids and bulk material expected to be present during normal use.

You need to look at the results again. They do show the governing load combinations. See the attached snapshots; look for combo ID.

Baz replies are very detailed, and here is one item I can re-elaborate on since you have asked it again.
Because the way your slabs are being connected to your beam (The slab is connected to the face of the beam), you will always have torsion and you need to deign for that torsion as that is the only load path from slab to beam with the provided connection concept. 
If you want to reduce or avoid torsion, your slab to beam connection philosophy needs to be revised. For example, if this hollow slab was "casted above the beam" you will not have this issue (torsion will reduce at the center beams but will still have torsion at corner beams), but you will need to connect your slab and beam through some system and in that way your beam depth will be much smaller. 
Thanks.

Baz replies are very detailed, and here is one item I can re-elaborate on since you have asked it again.
Because the way your slabs are being connected to your beam (The slab is connected to the face of the beam), you will always have torsion and you need to deign for that torsion as that is the only load path from slab to beam with the provided connection concept. 
If you want to reduce or avoid torsion, your slab to beam connection philosophy needs to be revised. For example, if this hollow slab was "casted above the beam" you will not have this issue (torsion will reduce at the center beams but will still have torsion at corner beams), but you will need to connect your slab and beam through some system and in that way your beam depth will be much smaller. 
Thanks.

Straying away from your questions, I am curious how will the construction of floor-system with these connection details take place?
Will they cast the frame with rectangular X-sections of beams first, and then install the panels?
Will they drill the dowels afterwards? Will the dowels be left in place during pouring of concrete for RC beams.
How will they adjust the dowels at their right position in precast hollow-core panels?
For these kind of construction, I have seen following construction methodologies:
1- Hollow-core panels supported on ledges of RC/Pre-case beams.
2- Hollow-core panels supported on horizontal joint of RC beams. In this case, they do not pour concrete on the full depth of beam, leaving room equal to the thickness of floor on top of horizontal joint with-in beam's depth.

Rigid diaphragm is reasonable assumption for this kind of arrangement for vertical members of lateral-structural system. 
I already answered the issue of torsion constant. In the first run, analyze the section with out using any reduction in constant for torsion (use 1).
Make changes if you are redistricted in the choice of section size for beam. In this case, how will you know if the additional flexural demands in hollow-core panels, due to torsion-related cracking in RC beam, will be taken into account?

Do you understand that the supporting beam is subjected to torsion, in addition to shear and bending moment, due to connection detail chosen for transferring forces from the precast hollow-core slab to RC beam?
Can you imagine what will happen if beam has not been designed for the interaction of torsion and shear?
Can you imagine that the beam will tend to twist or rotate about its longitudinal axis if the adequate amount of torsional reinforcement is not present?
What will be the result of that rotation?
In this case, can it lead to an increase in connection forces that may not have been accounted for?

I do not have enough information about your framing to comment on that.
 Generally speaking, this assignment, in most cases, has a limited effect on  elements of Vertical Lateral load resisting system.
When Structural Engineers  intend to check forces in chord members of diaphragm, for the purpose of estimating its suitability to transfer lateral forces to vertical elements, they use this semi-rigid option. The rigid-option does not let you check these  diaphragm forces.
The assignment also depends on your structural system. CSi has a simple video on it. 
 
 
You cannot assign membrane behavior to column.
You can assign membrane behavior to shear walls. It is reasonable simplification for a majority of design scenarios. 

Excellent answer by @Badar (BAZ) like always.
I will add to the last item posted that you can do quick plate analysis and get max moments. If you choose to proceed this way, after get your analysis results, please add you Mx and Mxy together and design the slab for this total moment. 
Thanks.

Excellent answer by @Badar (BAZ) like always.
I will add to the last item posted that you can do quick plate analysis and get max moments. If you choose to proceed this way, after get your analysis results, please add you Mx and Mxy together and design the slab for this total moment. 
Thanks.

Seminar on "Designing of Post-Tensioning & Field Quality Control"
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You can use default design combinations in ETABS, but make sure you design preferences are accurate before using default design combos.
For Loads on structures kindly watch this:
https://www.linkedin.com/posts/mqasimnawaz_structural-concrete-design-activity-6905953661353357312-8R9q

Salam,
You can make an envelope for load combinations, and check the forces corresponding to the enveloped combination. in this way you will be able to check against the governing load combination.
hope it helps!