Leaderboard

Hi Aung! One method of calculating the Area Springs, is with reference to 'Soil subgrade modulus, k' value. For example, if the k value of a soil is 120 ksf/ft and the area spring is applicable to an area of 1 square foot (sf), value of area spring will be 120 ksf/ft*1 sf = 120 kip/ft or (120 /12 = ) 10 kip/in. since k value can be calculated from B.C. value, IMHO your friend is partially right. Using the method given in Chapter 9 of 'Foundation Analysis and Design' by Bowles 5ed, if the soil bearing capacity is in ksf, approximate value of k = 36* B.C (answer is in ksf/ft). This, in case of your example with B.C. = 2.24 ksf, should result in an area spring value of k = 36*2.24 =80.64 kip/ft (= 80.64/12 = 6.72 kip/in.) HTH Regards.

Assalam-o-alaikum! A little addition. As far as I know, the passwords for the above mentioned two files are the same for all. These are given below: 1. PCA Notes on ACI 318-11 (Password: '2013PCAEB712') 2. 'Simplified Design of Reinforced Concrete Buildings', based on ACI 318-11 and IBC 2009 by Kamara & Novak 2013 (Password: '2011PCAEB204') Regards.

1DL + 1LL is for short term linear elastic deflection. You should multiply this by a factor given in ACI chapter 9 for long term deflection. Or perform actual long term deflection in SAFE by using creep and shrinkage coefficients (time taking and boring..right? Okay! just a trick here, make ETABS combination of 1.0 Dead cases + 1.0 Live cases and apply cracked modifiers. Check this deflection, it should be nearly similar to long term deflection. Increase it by some percentage to be on safer side. Compare this by L/240 or L/480 and L should be in the direction of deflected shape contour.

Ofcourse, see ACI chapter 9 for calculating minimum thickness of two way slabs and one way slabs. It is Ln/36 etc. Where Ln is the span. Working load is the load, a structure can carry safely without failing. Service load corresponds to the serviceability limit state. The load at which a structure or a building or an equipment continues to function properly. For example for your home, ultimate load could be very high which your house could sustain, but some percentage of this load might cause one of the doors in your home to stop working. So the serviceability is disturbed. Load less than that was the serviceability limit state of that door. I did not get it. There are many things to relate Thickness of slab must be greater than s/2 where s is the main reinforcement spacing in two way slabs or s/3 in one way slabs you can also relate it to the beam stiffness Section modulus of beams and columns? Section modulus if a shape property. Check your question again

If beams fails in shear and torsion combined, you should increase the concrete section. Engr Uzair, ties will not help because the combined stresses are more than 8xf'c^0.5 (imperial units). You need to increase concrete section size. Will update later. This happen sometimes. Dependence of foundation on bearing capacity of soil? I did not get it. But in SAFE there is no bearing capacity. You have to put modulus of sub grade reaction (you can relate bearing capacity with k as k=120 times the bearing capacity in SI units). See Bowels book or use k from geotechincal report. Two way shear or punching shear can be checked in SAFE from the menu: Design>Punching check One way shear can be checked by showing contours of V13 and V23. V = SRSS of both these components. And phi Vc = 2xf'c^0.5x0.75 in Imperial units or 0.17xf'c^0.5x0.75 in SI units Mass is used in dynamic and seismic analysis. You should study about excitation of mass and lumped mass from any book on dynamics. Weight is the normal weight of materials acting as loads on the structure. For example dead, live etc. W=mg as Engr Uzair said. Excessive gravity load buckles the building or column sideways by delta. This delta creates additional moments M=P (gravity) x delta. Thats why this moment is called P-delta moments. If you have not designed for this additional moment, your structural gonna collapse. Ofcourse this happens in very slender columns or building or very heavily loaded columns. Weight or load is involved in calculations. In dynamic analysis (usually done for irregular buildings) you try to capture higher modes. This is done by lumping mass at story levels. There are SDOF (single degree of freedom) and MDOF systems. Read from any book on dynamic analysis. Mass is involved here. Strength of concrete depends on proper curing and mix ratio of ingredients. Punching ratio=1 means, Shear stress is exactly equal to the shear capacity of concrete section. Shear capacity of concrete for punching is calculated from 3 formulas given in code. The least value is used. Open any book on concrete and see punching shear topic. In ACI-318; There is no storey drift limitations. However, you can find these limits in ASCE/IBC. Its the same thing. Cracking limit in ACI can be found in chapter 9 (i think) or chapter 10. For water tight structures you need to refer to ACI 350. For detailed cracking limits you need to refer to ACI 224-06. Beaware that ACI 224-06 and 224-01 or 02 and ACI-95 differ in methods