UmarMakhzumi

either you do welding or make a bolted connection, your scheme of welds and bolts will gonna decide if your connection can takeup the moment or not

From the website, where you can download this as well fo free.
DOCUMENT DETAILS
Publication Year: 2015
Pages: 31
ISBN: 
Formats: PDF
TABLE OF CONTENTS
Design Aid J.1-1 Areas of Reinforcing Bars
 
Design Aid J.1-2 Approximate Bending Moments and Shear Forces for Continuous Beams and One-way Slabs
 
Design Aid J.1-3 Variation of φ with Net Tensile Strain in Extreme Tension Steel εt and c / dt – Grade 60 Reinforcement and Prestressing Steel
 
Design Aid J.1-4 Simplified Calculation of As Assuming Tension-Controlled Section and Grade 60 Reinforcement
 
Design Aid J.1-5 Minimum Number of Reinforcing Bars Required in a Single Layer
 
Design Aid J.1-6 Maximum Number of Reinforcing Bars Permitted in a Single Layer
 
Design Aid J.1-7 Minimum Thickness h for Beams and One-Way Slabs Unless Deflections are Calculated
 
Design Aid J.1-8 Reinforcement Ratio ρt for Tension-Controlled Sections Assuming Grade 60 Reinforcement
 
Design Aid J.1-9 Simplified Calculation of bw Assuming Grade 60 Reinforcement and ρ = 0.5 ρmax
 
Design Aid J.1-10 T-beam Construction
 
Design Aid J.1-11 Values of φVs = Vu - φVc (kips) as a Function of the Spacing, s
 
Design Aid J.1-12 Minimum Shear Reinforcement Av, min / s
 
Design Aid J.1-13 Torsional Section Properties
 
Design Aid J.1-14 Moment of Inertia of Cracked Section Transformed to Concrete, Icr
 
Design Aid J.1-15 Approximate Equation to Determine Immediate Deflection, Δi, for Members Subjected to Uniformly Distributed Loads
 
Design Aids J.2 Two-Way Slabs – Direct Design method, includes the following:
- Conditions for Analysis by the Direct Design Method
- Definitions of Column Strip and Middle Strip
- Definition of Clear Span, 
- Design Moment Coefficients used with the Direct Design Method
- Effective Beam and Slab Sections for Computation of Stiffness Ratio, αf
- Computation of Torsional Stiffness Factor, βt, for T- and L-Sections
- Moment Distribution Constants for Slab-Beam Members without Drop Panels
- Stiffness and Carry-Over Factors for Columns

if you want to model a beam as simply supported beam , then you will need to end realese , so the beding moment draw as for simply supported beam, other wise without relase , depending upon the stiffness , negative and positive both moments comes in beam

1. A beam is fixed, where no rotation of beam column joint occurs, or pinned, where the beam is free to rotate.
2. In most RC detailing the top bar runs through the column, for robustness, so you always get some fixity.
3. Get a detailing manual (ACI detailing manual maybe) and see how a "true pin" can be detailed with rebar/reinforcement. .... a sort of intersection of the 'X' pin-points the "pin" location, putting it simply. 

You cannot generalise, as eccentricities can vary and heavily loaded beams at greater eccentricity, can generate significant bending moment in the column, and the increase the reinforcement (bar size or number) in the column; The column would need to be deigned for both axial and bending. There is no hard fast rule for this, each beam/column location needs to be looked at and decision made.
A concrete frame can come in many configurations:
1. The floor plate say with 2-way spanning floor slab supported on beams in both direction; Here slab load (dead and imposed) is shared by all four beams; One beam being slightly eccentric would be less onerous;
2. The floor plate say with one-way spanning slab with beams in one direction only, would mean greater loading on the beams, greater reaction onto the column meaning, then eccentricity consideration is important;
3. Say you have 300mm thick 'flat-plate' or 'flat slab' then the slab load comes into the column, and eccentricities become less critical . In this situation assuming slab punching shear etc has been checked, eccentricity of slab loading becomes less critical.
Where torsion occurs, say a beam going pas and connected to one face of the column, then the torsional moment - and torsion reinforcement - would need to be designed for.
With the question being asked, I am assuming you are designing a simple structure, hence not too much to worry – but do talk to senior engineer in your office and take his/her view.
 
In highly seismic areas the reinforcement continuity is more critical, and detailing for load/stress reversal is critical. My advise would be:
(1)   to close up the spacing of the shear links/stirrups closer to the column joint, half the spacing to what you have in middle of beam. Say if you have shear links at 300mm centre at the middle of the beam, then make them 150mm centres closer to the beam/column joint - for a length of say 1/8 span length from face (in both beam and column either side of joint)
(2)  Provide sufficient tension lap lengths (say 40 times bar diameter, as a rule of thumb)
Talk to a senior engineer in your office for job specific consideration.

Most software nowadays inputs physical member sizes, i.e. column size and beam size, including centre lines. The analysis programme is therefore able to calculate any additional moment due to eccentricity. 
Also, in concrete frame buildings there is the slab, which is built into both beams and columns, and helps mitigate eccentricity. 
You can also cross check with a hand calculation knowing the eccentricity of loading - this hand calc check should assure you.
Remember the beam width does not always match the column plan size - especially around the perimeter, where the edge beams may be set to align with the outer edge of column.
Keep things simple. Remember In the old days there were no computers and all calculations were by hand! 

we usually design stair only for gravity loading because it is designed by using hand calculation that give only gravity resistant detailing. So during earthquake,it may be structural fuse and can't resist lateral load. But,if we draw stair on model,it is shell and can resist lateral load.Not align with reality.
How to solve this problem. In actual condition, Stair can resisit lateral load partially. Plz suggest me how to do and share your experience.
Is it ok if we design stair ramp as crack section analysis?

1. Design for gravity initially, then for axial loading (+/-) a part of a braced system.
2. Make slab / landing connection enough to allow for excessive deflection and reversal of loading, with some torsion.
3. Always put staircase inside core walls – i.e. rectangular concrete box - if you can. This allows better detailing and transfer loads via wall.
4. Most stairs in South Asia span between columns (i.e. corner connections), thin slabs with brick on top to make steps; Poor stair / column connection leads to failure in many cases. Also, quality of concrete is often poor.
5. Design stair as diagonal bracing subject to push-pull loads, with the vertical support member / column connection given greater attention; Hence best to have them spanning onto walls between column.... this then leads to "captive column" scenario. Design with full tension laps, with torsional provision in built. 
6. Modelling of staircase in computer model will help give idea of behaviour, then you use your engineering judgement to improve the robustness of the staircase slab and its end connections.
7. Remember staircases are used for emergency evacuation following an earthquake, so should be designed a s "key element".
Conclusion - a combination of modelling and engineering judgement helps - give the staircase slabs maximum attention - rest is often luck.
 

The Question is a little vague, and also difficult one at the same time.
I am not an expert on finite element modelling but here are general thoughts to move the discussion along, based on my basic understanding.
Firstly, here is my interpretation of question you have asked - You are referring to modelling the diaphragm (floor) and frame (columns and walls) for your computer analysis program input?  
1. In a concrete frame building, one uses the floor slabs to act as diaphragms (deep beam analogy approach, where beam-depth is assumed width of slab, we then have tension and compression flanges/ chords etc) to transfer horizontal wind or notional force or earthquake loading to the core walls or shear walls, which in turn take it not the foundation and the ground. In this case, we detail the edges of slab with additional 'deep beam' reinforcement, and also design the connection between the slab and vertical elements (walls and columns) to transfer the load. Openings in the slab, floor plate shape all play a part in the way diaphragm will act. Also, a slab diaphragm can be designed by hand calculations using 'deep beam theory' approach!
2. Under horizontal wind or seismic loading, there will be a vertical element (column, wall) drift or sideways movement, and also side-way deflection of the slab, at mid span of slab 'length'' (along edge of slab).
3. Refer to the User Manual or commentary of the software you are using, look at its definition and input requirement of the two types of diaphragm discussed in your question. Some seismic codes also define - shell, rigid, flexible diaphragms etc. Rules and definition for each are given in the relevant codes. Span-to-depth ratios in the horizontal plane come into play here.
4. In an analysis I can make the diaphragm rigid (ignoring deformation) or model the in-plane stiffness as a shell diaphragm. In this case one will get slightly different results from the computer output, based on what assumptions we made in modelling stiffness. If no stiffness is inputted, then no output of force will be possible.
5. Therefore, putting it simply, the slab (diaphragm) is inputted in many analysis software as shell elements with defined nodes, and with defined parameters. Then where the frame (columns and walls) meet the slab elements, joint nodes are created, and these are checked and input with the relevant degrees of freedom and/or joint releases. Forces and moments can then be taken at these shell and joint nodes. 
6. During modelling the diaphragm and walls are attached to the same mesh nodes, whilst diaphragm and column are attached to the same joint.
7. Finally, look at the Design Codes definition of the same & also your software User Manual, as a starting point to getting an answer to your query.
I am not sure if I have answered the question asked by you, but hope I have at least moved the topic along, for other engineers to contribute further?
 
 
 
 

I will recommend you to go through these two documents to understand the difference between hysteresis and simple stress strain curve (monotonic curve)
http://web.mit.edu/course/3/3.11/www/modules/ss.pdf
https://etda.libraries.psu.edu/files/final_submissions/4432
For nonlinear analysis(cyclic loading), hysteresis rules are required. In SAP2000, there are two models Pivot Hysteresis and Takeda Hysteresis. I dont know that whether SAP2000 has option for user defined hysteresis model or not. The hysteresis model will affect the force-deformation graph that is produced on links or hinges.
 

There's an introductory chapter in every code which specifies the use and limitations of that perticular code.
I didn't have the above mentioned code. So I downloaded it and as far as i can see it seems like a detailed version (or the application) of ACI 318 and ASCE, combine together, for low rise buildings.

Dear Yannick,
Both the beams behave similarly. However, while detailing, you detail the inverted beam as an upside down normal T beam. That means, now your bottom tension rebar(in span) can be distributed within the whole flange width. At supports, the flange part of beam will be in compression. Hope this helps.

1.     The geotechnical engineer - the soil specialist - should provide you the modulus of subgrade / elastic spring stiffness in his SI Report. Get in contact with him - this is the best and safest option. He is best placed to offer advice.
 2.     I have found that the geotechnical engineers often provide subgrade modulus to structural engineers by undertaking a CBR test, and then correlate the subgrade modulus to CBR value.  They use a (0.6m x 0.6m, or) 1m x 1m plate for the test. The reason they don't do it that they would need to bring in heavy weights to do the test, hence they don't bother! I am sceptical of the CBR test as it only gives the strength of the soil in the near surface - In my view it does not give much of an information at depth.
 3.     In the absence of any information consult Bowles book on Foundation Analysis and Design  I know has a table - which gives the different ranges of subgrade modulus based on various soil types. I don't have the book handy but recall it from distant past. If someone has the Bowles book handy, then they can help.
 

@Muhammad Umair Anwar , its very hard to predict whats wrong with your model without checking it. However you can check your model through Tools drop down list . For perfect modelling of plates please check the attached pics. If you still couldn't solve the issue please post your model.

Normally what I have seen is that almost all Client Specifications require buoyancy checks to be done assuming GWT is at grade irrespective of where it is  (to account for seasonal fluctuations and also because the approach is conservative). You only need to consider buoyancy for the volume of concrete that is displacing the water (assuming water table is at grade). For soil, you will have submerged unit weight that accounts the buoyancy affects.
Thanks.
 
 

Salman Ch,
Thanks for your comment. Pile cap would only behave as a deep beam if distance between ratio of slab thickness to distance between piles is more than whatever is required by code for deep beam action. I live in Canada and here if the shear span to depth ratio is less than 2.5, deep beam action can be considered. If not, it is a normal slab. ACI has a different limit. So yes, it may be a deep beam or not, but same would be applicable to a slab if your columns are too close. Anyway, thanks for highlighting that as now the clarification may be useful for someone who isn't aware of this
This is standard practice and there can be different reasons for not considering soil springs. For example, in North America, heave is a big problem and generally pile caps have a layer of void form below them. Void forms are compressible and analysis should never consider soil springs for that reason as there would never be a hybrid action in that scenario. Also in typical cases stiffness of pile group is >> than soil so it doesn't make sense to put soil springs.
Thanks.
 

Water pressure uplift - further thoughts
@UmarMakhzumi approach is safe so go with it.
Such technical deliberations, are also a matter of qualitative assessment by the Engineer.
Engineers everywhere take a different approach to ground water level. Here we assume the water table (i.e. a possible perched water table) at 1m (3.3’) below ground level - for a conservative approach to basements uplift calculations, unless we have definitive information otherwise.
If the structure is in water, or underwater, then the water level is taken as top tide level, or floor plain level.
Do remember water density is 1000kg/cum (62.4 p/cuf) whilst concrete is 2500kg/cum (156 p/cuf) ... therefore 400mm thick concrete slab equals to buoyancy force from 1m (3.3') on water uplift - then add the factor of safety. Then there is also the 'permanent' dead weight of the structure above too.
For shallow basements or structure,  2ft as you say, it may not be an issue provided there is sufficient dead concrete/structure weight?
For un-factored loading - Factor of Safety against uplift, I use is 1.2 - some codes use 1.25.
Most of the time dead wight of structure is well above uplift forces on shallow basements - there may be a need to control ground water pressures during construction of say basement slabs. Often water lowering (say pumping) methods are used during construction; Or you can use tension piles to hold the basement slab down against uplift for very deep basements.
 

Backstay Effect. See attached and:
Thanks.
 
Backstay Effect.pdf

Uplift on a Raft:
Groundwater table fluctuates;
However, site investigation companies can monitor GWL (piezometers are used for this purpose) over time and get a fair assessment of the water table. If you are founding on impermeable clay, then you can get a perched ground water table and pressure.
In some countries with a lot of rain they assume GWL at 1m below ground level .... unlikely in majority of Pakistan where ground water levels/table are sinking (a major worry for future PK generations that we are not now addressing in our ignorance).
Uplift Calc: Working to metric units:
2' above GWL = 0.6m;
Uplift = 10x0.6= 6kN/sqm (can be resisted by 0.25m (equivalent to 10" thickness of concrete!) - hence uplift should not an issue! RAFT and building DEAD WEIGHT would be much greater!
Say FoS= 1.1 against uplift and take Dead weight load factor as 0.9, for conservative design check.
As @Ayesha said check fluctuation of Ground Water Table with the geotechnical engineer - geotechnical Engineers and their investigation report worth needs to be appreciated!
There may be other practical construction related issues with constructing a raft under water - hence ground water level would need to be temporarily lowered - should not be an issue of the experienced builder who knows what he is doing. 
 
 
 

Water table can seasonally fluctuate and you can have a condition where the soil below raft is submerged in water. In that case, bearing capacity of the soil would be reduced to some degree. Speak with your geotechnical consultant to get the exact number.
You can do a separate buoyancy check if you want but I don't suggest providing an uplift pressure and you might not end with a lower bound solution.

So looks like today, I came across the same problem that is being discussed here. I had to provide a design criteria for a buried concrete pit. I will summarize my findings below for the benefit of everyone. This applies to structural members that are subjected to environmental exposure conditions or that are required to be liquid tight. 
1) The first step is to calculate flexural demand in the walls of concrete pit/ water tank based on all possible conditions. For the case of buried concrete pit, it included, empty condition (no fluid in the pit) , operating condition (full of liquid), test condition (no backfill  around the pit and it is full of liquid) etc. Buoyancy checks should also be performed.
2) Compare required flexural reinforcement against minimum reinforcement ratio = 0.006 per ACI 350, Table 7.12.2.1 & ACI 224 , Section 3.5 and provide whichever is the maximum. The ratios provided are basically temperature and shrinkage reinforcement ratios based on gross section so provide half of the reinforcement at each face.
3) Satisfy maximum crack width of water-retaining structure = 0.10 mm, ACI 224R-01 Table 4.1 based on the reinforcement already provided. If the reinforcement is inadequate, increase the reinforcement till this requirement is met. To meet this requirement, smaller bars should be used with close spacing.
Now a few comments on the the excellent discussion above.
@Khawaja Talha post above is applicable for all normal cases where there is a restraint to shrinkage and temperature movements only. If you have a condition like that, you need to provide 0.45% reinforcement ratio in your slabs. Example of a situation where this would be applicable will be a structure where movement or expansion joints haven't been provided at industry standard spacing. But if you want to meet liquid tight start with 0.6% as a minimum and work your way as suggested above.
Other posts above explain the same things in a slightly different manner but all good.
Thank you
 

Bridge that collapsed six hours after opening was built without geotech investigation of riverbed: Reeve
Read more:
https://www.cbc.ca/news/canada/saskatchewan/bridge-that-collapsed-six-hours-after-opening-was-built-without-geotech-investigation-of-riverbed-reeve-1.4829890
 

AA. 
    Depending upon whether you want to follow American or European codes, following references might be helpful in learning the design of bridges:
1. Based on American codes
    a. Design of Highway Bridges_An LRFD Approach by Barker and Puckett
    b. AASHTO LRFD Bridge Design Specifications
    c. AASHTO Guide Specifications for LRFD Seismic Bridge Design
    d. Design of Modern Steel Railway Bridges by Unsworth
    e. AREMA Manual for Railway Engineering (MRE)
2. Based on European codes (Eurocode)
    a. Designers Guide to Eurocode 1_Actions on Bridges
    b. Designer's Guide to EN 1992 Eurocode 2 Design of Concrete Structures Part-2 Concrete Bridges
    c. Designers' Guide to Eurocode 8 - Design of Bridges for Earthquake Resistance EN 1998-2
    d. Bridge Design to Eurocodes Worked examples (European Commission Joint Research Centre)
Regards.

There is a large difference between section properties of the required and the available steel girders. Required major section modulus Sx is 3.63 times that of the available girder. It means that capacity of the available girder has to be increased to about 4-times its present capacity. It might not be an easy or even cost effective task.

Check out the following books:-
1. Ground Improvement by Kirsch and Bell (CRC Press)
2. Principles and Practices of Ground Improvement by Jie Han (Wiley)
3. Soil Improvement and Ground Modification Methods by Nicholson (Elsevier)
4. Ground control and improvement by Xanthakos et al. (John Wiley and Sons)
5. Ground Improvement Techniques by Purushothama Raj
Regards.