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Everything posted by Rana


    You will not get same results in both software. In ETABS you are assuming cracking and applying certain modifiers, where as in SAFE cracking analysis is done internally based on required or provided reinforcement iterations.
  2. Ordinary shear wall design - ACI

    It's up to you to decide which type you intend to use (ductility) and then design accordingly.
  3. It will be okay for earthquake. Because all american codes share same philosophy. Load factors and combinations are same. Its not okay for wind design and as from ACI 318-11 wind is changed to strength level.
  4. My House Design Suggestions

    This is not the right place to discuss/seek consultancy advice/design of a complete structure, in fact it is dangerous. Please hire a professional structural engineer to properly check and design it.
  5. ETABS 9.7.4 Runtime Error Message

    Yes, but my post was, how to do this in ETABS 9.7 if some one doesnt have v13.
  6. 6-ft Mass Concrete

    You or someone else, need to design the form work for that load and make sure the slab sustains its self weight and construction live load.
  7. Corbel action on Column analysis

    Could you please provide a sketch to be more clear? You can do this by clicking on the button just above the 'Submit Reply', the button is 'Insert other media'.
  8. ground slab above mat foundation..

    If it is directly resting above mat foundation, then yes, all the loads (ground slab+backfill+dead+live) should be used to calculate bearing capacity.
  9. Ordinary shear wall design - ACI

    Ordinary shear walls are designed as normal shear walls according to chapter 14. Boundary elements are required for special structural walls, where compression load is high and the bars could buckle. For cast in place shear walls, yes the limit for vertical bars is 0.0025, where did you find 0.0015 limit? Please quote.
  10. ETABS 9.7.4 Runtime Error Message

    The first step towards obtaining the stiffness matrix, is to obtain the Jacobian, using an equation which you can find in any finite element analysis book. This equation has a shape function matrix which depends on the nodal displacements. Once Jacobian obtained, the strain displacement matrix is obtained and transposed and then finally stiffness matrix is obtained. Jacobian will be negative if there are distorted elements, local axis of connected elements is different etc. Check element 22836. If you cannot find this in ETABS 9.7, then do this to find coordinates. Display > Show Tables > Model Definitions > Area Assignments > Area Assignment Summary Then export to EXCEL, find area 22836, and then within the same row, look for centroidx and centroidy coordinates.
  11. job hunting

    I am planning for an executive mba. How did you experience go with engineering + mba?
  12. There is no question of stiffness in this case. Yes, stiffness will also be affected by the reinforcement but we ignore it. Only concrete dimensions are taken for stiffness. Second, what is the purpose of providing boundary elements? This should answer your question. They are not separate physical members, but just a concentration of reinforcement like columns. It has nothing to do with stiffness and modelling. Its a reinforcement detail for ductility.

    Why NOT? The ONLY limit on your thoughts is the one you put on yourself.

    F11 is axial force along local 1-1 axis. Negative is compression. Positive is tension. Gravity loads cause bending moment as you know it. Moment is nothing but a couple with opposite forces. These are F11. Multiply this with depth of beam (which is equal to distance between couple forces), you will get the moment at mid-span for example. You can verify by hand. Shear is not F11..Shear is F12. Remember the basic cube with directions marked on it in strength of material course?

    Not true. It depends on how you are designing. Also depends on the stiffness of column as well as the supporting slab. If the supporting slab has not much stiffness, the pickup columns act like hanging threads carrying no load at all.
  16. You dont need to separately model the columns for boundary elements. Read the wall design manual from ETABS help. It explains the design procedure.
  17. Reinforced Concrete Design of 3 hinged arch

    If you have calculated the forces already, then go for reinforcement design as Ayesha suggested..Its just the distribution of forces that are different in an arch, reinforcement design of a concrete section is same. Not to mention that you have to keep the resultant in the middle third of an arch but again thats part of the analysis which you already have calculated.
  18. mesh the slab for these dummy lines...otherwise..if it is in the middle of a slab..just simply convert it equivalent uniform load. if the slab modeled is membrane, you cannot simply apply line loads on it..so again..convert it to uniform load.
  19. mode shape displacements are not abs values. They are relative values compared to max value of 1.0. The max displacement is always 1.0 and then the others are compared to this e.g. 0.5 etc. You multiply this modal amplitude values. Solve one mode shape by hand of a 2 storey frame you will get it. Anyway for separation, see it on response spectrum case or combination. For more detail you can combine modes as described in CSi ETABS Wikki help pages online. The topic is about accidental amplification of torsion in response spectrum cases. Look for that.
  20. Reference Point in ETABS

    search the forum, i shared one excel sheet for that some time back.
  21. Mat footing

    Your question is not clear.
  22. why not? any good reason why it can't be used?
  23. Final Year Project

    Blast "proof", nothing is proof, i guess. Second, doing blast analysis in bachelors is in my opinion too much work/understanding. Question: What you want to pursue in future (atleast next 5 yrs)? hard core structural engineering design? if yes, then do something related to a bigger scope giving you an overall understanding instead of a specialized topic. if no, you could do anything then. Just my opinion.
  24. Thanks for sharing, will study more about this. The usual practice is to assume hinge for isolated foundations unless they are massive, and fixed for raft in analysis.
  25. Yes agree with @BAZ that foundation must be strong enough to allow forming hinge at base of column but my point is that this is the usual assumption in normal code based design along with many other assumptions. Yes, we can go a step ahead to non-linear design and soil structure interaction but usually thats not done. Please correct me if wrong, I think that all is done in weaker soils and high seismic zones, so I personally have not experienced this kind of analysis.

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