Hi (Assalamu alaikum) peace to you in this video we will learn how to analyze and
design the ,,,,,,,,,,,,,,,,,, the combined footing in SAFE 2016, first of all we will go
from the zero level I am going in the file new model and here is the design
code ACI 318-14 and I will choose the metric system SI
system but you can use you as default whatsoever you like so I am hitting ok
and now from here I will select the combined footing so there is also all
other types of fittings like base mat have single footing and here as I am
clicking combined footing and they combined footing is showing the plan
dimensions like left edge distance is 2 meter and white as distance is e 2 meter
means left edge and right edge and top distance and the bottom from top and
bottom, both are 2 meters and Load spacing in this spacing between two
foundations is 8 meter so whatsoever you like you can adjust according to your or
desired loads and desired loading and geometric conditions and here is the
loading condition here is P dead and live loss 1000 and 500 kilo Newton so I
am here also applying little bit moment like 60 kilonewton meter Mx and also
in the load-2 type in 60 in here so whatever the moments are you are having
you can put according to your desire to total sign the combined footing so I am
here putting the footing Technol 600 millimeter but after in the main window
you can change according to your needs so here I am putting the subgrade model
subgrade modulus basically - to model the foundations to make the real
condition like in in the real conditions we are
having the bearing capacity allowable bearing capacity and the allowable
settlement so I am here going to show you how to calculate the soil subgrade
modulus in the soil subgrade modulus is equal to the pressure of a deformation
pressure is basically allowable bearing capacity which we get after from this
field testing or from the laboratory testing and the deformation is allowable
settlement in the foundation so whichever type of foundation you are
designing so according to that the allowable settlement you can choose for
example in isolated footings you can use 25 millimeter and for the
mat or raft foundation you can use 50 millimeter as allowable settlement and
now here I am showing the calculation for the subgrade modulus and allowable
bearing pressure is the 200 kPa and allowable settlement is 25 millimeter
the soil subgrade modulus will be K is equal to 200 divided by defamation is 25
divided by 1000 to convert into meter so here I am getting 8 thousand kilo Newton
per meter cube so I will put in case of in this space of modulus of soil
subgrade modulus 8,000 kilo Newton per meter cube okay so after hitting ok you
can see the the footing and as you have as you want to model in the sea as I
safe 2016 software so before going further I will first draw the design
strips add design strips so here you can do by automatic or you can also draw by
manually like Here I am drawing the draw thin strips here draw design strips
strip layer is a and from here to here and in the other direction I am naming
it B from here to here
why I am doing this assigning the design strips basically the software designed
the foundations in two ways one is FEM finite element method and second is the
strip design method for the strip design method we have to assign the strip's
like I have I did now in this foundation and now I am going to save this model
with the name combine Footing design
after saving the model we have basically applied the loading successfully and the
boundary conditions like we have defined the soil subgrade modulus we can also
check again define in soil subgrade modulus and here the soil subgrade
modulus which we have defined soil one here is two but here which you have we
defined soil is 8,000 okay now we can check we have defined the soil property
okay before running the analysis and design I am going to define the load
combinations there are two load combinations i have define so I will
just delete them and I will assign the all design combinations
according to service normal conditions okay and you can check the load
combinations one dead one life and one day so in the design combinations design
preferences you can see the covers as for example these are slabs so prefer
bar size whatever you want okay
in design combinations we will state service we are design according to
service normal okay so now I am running the analysis and design so after running
the analysis and design you can see display show deformed shape against load
combinations lie there is a maximum is 8 millimeter which is less than 25
millimeter so it's okay again the thing again second combination again again the
settlement in the foundations at all the point is less than 25 millimeter which
is okay so now I am checking the bidding pressure show reactions soil pressure
against COMO1 is at mini maximum minimum are less than 200 kPa
so it's okay Oh second combination that's also okay so now I am going to
check the punching shear design check so the punching shear design checks are
less than once there's are okay so here are basically
three checks pressure and reporting less than 200 okay deformation under a
floating less the 25 millimeter okay and punch shear is less than one is also
kept preferable should be less than 0.9 if you are filling in any chair go
towards the inputs like geometric ,,, it means you have to change the length
of the Footing width of the footing and thickness of the footing and you can
also change the material property like concrete compressive strength etc so
here now I am going towards the design so all checks are okay show slab
design then you show slab line there are two methods of design basis one is FEM
second is STRIP Method,,, in the FEM you can for example you want to see the
top reinforcement how much is required so here you can see here the top reinforcement
of top reinforcement so like in the bottom here under the
bottom reinforcement required in the middle no same way in the second so I
will prefer in the Strip method in strippers for example in the layer a and
layer B apply in the expression layer a here is important area required under
1500 6 1 millimeter scale per meter so in the y-direction is the B strips here
you can see get to open border reinforcement requirements in the
y-direction so I will just apply here is the
required reinforcement in the top and bottom direction of the combined footing
so I will just provide by example number 12 @ 250 millimeter spacing but
this provide reinforcement is still less than the required so I will just crease
by example 20, apply so still in the reinforcement but reinforcement top so I
am just decreasing this spacing it to 150 line so now it means if we provide
this reinforcement I am destroying the demonstration video so you can change
according to the desired or optimization base so here you can see and also there
is a one beautiful function of the detailing so in detailing you can see the
drawings okay the drawing sheets cover sheet showing in the note, layout
plan floating table here it is showing for example these are Bar A, Bar B and
total thickness is 600 millimeter so that is 0.6 meter ly,,and,,, Lx by geometry
dimensions and footing for example F1 so it's 20 to
number of 16 bars and 18 number 16 bars in the A and in the B direction
so that's all, Have a nice day
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