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Found 14 results

  1. There are issues which needs to be addressed: 1-Why there is much difference in punching shear results in SAFE and ETABS models considering same parameters in both models.(same modifier, same geometry,same assignment of shell behavior in both cases though SAFE does not have the option of thin shell all other the input is same),i have checked both the cases when the automatic rigid zone area over the column is on and the second case is when this option is off. 2- I have analyzed the both cases assuming the shell thick in ETABS and thick plate in SAFE behavior,in other case thin plate in ETABS and thick/thin PLATE both in SAFE,but results still vary. 3-Even when you export same slab in SAFE the punching shear results vary in both models .There is significant difference in unbalanced moment value in both models. 4-i am using licensed ETABS 16.2.0 and SAFE 16.0.0. 5-IN SAFE Made MODEL,what should be the concrete strength of stiff elements, it should be of column strength or it should be of slab strength, if you assign the same strength (concrete) as the column have then you will get reduced moments and if you assign the slab strength you will have more moments. i have read the csi knowledge , safe manual,thin/thick shell and plate behaviour and all other data related to these issues.
  2. Mat footing

    Hi, I was modeling a not so regular mat footing in SAFE software.The position of column was changed accordingly per grid but the main problem was when the design strips moment was checked along x direction,the following problem occured as shown in figure because previously the grid was maintained to the standard template.I went to Interactive data editing,but couldnt figure out the actual problem,Please help me how do I actually get this solved?Another problem was when I went to Design tool and changed punched shear overwrites for interior column different behavior or edge column behavior,I was not able to retrieve the same value as from the manual calculation.Another though on it was ,Is defining subgrade modulus of soil necessary ?what to do if only bearing stress is mentioned in the question.Please go through the attached figures herewith.Thankyou ,sep
  3. Punching of shear wall

    Dear all i have a wall 3.5m by 0.30 m supporting flat slab. 1. Since its definition is a wall then there is no need to check punching.right? 2. If i convert it in SAFE as a frame element column then there is need for punching. please advice
  4. How to check Punching Shear in a flat slab in SAP2000? Is there some direct command as in SAFE?
  5. Punching Shear In Safe

    Salam. I am reviewing a flat slab which i received as .fdb, punching shear for flat slab is displayed N/C. what could be the possible reason for? file is attached Slab @ +676 (Z=16').rar
  6. I am importing first floor slab from Etabs 9.2 to safe 8.0. the problem i am facing is that safe is showing punching shear ratio values of the shear wall on which the slab is resting. Usually when we design foundation safe take wall reactions as a beam with intermediate points and shows N/C as punching shear ratio. I am unable to understand what is happening when i import a roof slab. the image is attached the different set of values is due to manual meshing on etabs.
  7. Dears I argued with a senior Engineer about the punching shear check for shear wall; As far as I know : 1. The shear wall will attract high moments. 2. Also in the case of design itself, the controlling case from a combination that contains Earthquake will be the tension axial force not the compression (Please Verify or disagree!!!) 3. If I want to check punching for this shear wall I will take the moment at the Top of the shear wall (pier) which will be very high and I will take the axial force as the difference between the top of that wall and the bottom of the wall above so to achieve the axial force from that story only. 4. I found that I need to put shear reinforcement and some places it fails. 5. Now, the senior engineer told me no need for shear reinforcement in case of shear walls because of length of shear wall.!!!!!!! I said: Sir your case is right in Ultimate dead+Live combination not in case of earthquake because in this case there is high moments attracted by shear wall. He said : No tht moment in case of earthquake will not affect the slab , it will be taken by thear wall only !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! 6. Please help me in this subject. I am sure the shear wall in earthquake will suffer from high moments which in case cause punching need to be counted for . Regards
  8. Drop In Mat Foundation

    Dears seniors; I have an urgent issue I need your help all. The issue is that I want to make a MAT like in the picture please see the problem interpretation in the picture.
  9. I have an idea to discuss here related to Punching shear; that is In categorization of columns there are : 1. Interior ,where the distance from each face of a column to the slab edge is at least four times the slab thickness 2. Edge column, where one face of a column in direction of design strip is closer to the slab edge in the same direction by four times the slab thickness . 3. Corner column, where two adjacent faces of a column are closer to their associated slab edges by less than four times the slab thickness. But the issue that is SAFE doesn't consider these definitions so it may give safe results where it may be unsafe . Please discuss All Regards
  10. Dear Esteemed Fellows users of Safe program: Most international codes (including ACI, BS, ...) consider the impact of moments when calculating the punching shear stress in the Flat-Slabs. Referring to the attached picture, Is there any mistake in the sign of the considered moments in the punching result sheet and the correspondent moments signs appeared in the output results of the considered column. Remember that the main axes of the considered column are the default ones of Safe; axis 2 is parallel to the X axis and the axis 3 is parallel to the axis Y. The attached picture is a snapshot of the example BS 8110-97 RC-PN-001.FDB came with Safe-Verification-Design Examples. Your participation and feedback are deeply appreciated, thank you very much indeed.
  11. Aci Supplementary Documents

    Dear Madams/Sirs: I am looking for the following ACI two supplementary documents: ACI 352.1R-11 and ACI 421.2R-10. Best regards.
  12. What would be the assumed distribution of punching shear stress due to the transferred moment in flat slab in case of side and corner columns? Refer to the attached file in case of center column. Thank you very much indeed.
  13. I am designing a 2B+G+24 story building. I made the model in Etabs, and ran it, then exported the base reaction to safe for footing design. It has central core walls. When I ran safe (v8), the only version available with the office. It gave me a bearing pressure of about 14 ksf as opposed to allowable of 6 ksf, I increased the thickness from 4 ft to 9 ft gradually but pressure distribution remained same & value only deceased to around 11 ksf. Then I added foundation beams (tied up all columns provided them under all core walls) and assigned line support to them (Kv x width of beam). This run gave me a value of 5.6 ksf bearing pressure which is safe. But I have some questions. I calculated the total area required from total load of the building and its coming out almost equal to the building plot area available. For, punching requirement under single column I at least require a 5.5 ft deep raft thickness. 1. Can I model a raft like this with beams (12" x 72") under all columns (42" x 42") & (36x72") under core walls (24" thick); not inverted beams but beams with top flushed with raft top 3. when we define slab properties do I have to tick the " thick plate" option or not. What is the difference? 4. What is difference between slab types options? slab? footing? mat? 2. Do the slab elements between these beams will have a soil support also assigned to them? 3. Is this type of foundation safe for this high building? or do we have to go for piles or pile/raft interaction? Which would you recommend considering that top of raft is at -19 ft & ground water table is at -11 ft. 4. How to I assign wall supports in safe v8. By placing beams of above property on my raft slab & assigning a wall/line support to them (Kv x width of beam) or Assigning null property to beams and use safe v8 option in which it calculate support stiffness from its size. Kv is the vertical sub-grade modulus. 5. How do we detail thick rafts. Do we provide mid layer of steel. if so can somebody point a reference book or source on how to calculate it. Confused
  14. Safe Punching Shear Problem

    when ever I draw model on safe v.8. If punching shear ratio of raft foundation exceed. for example: If punching ratio of column on raft foundation 30" thick is 1.6, then I draw an other 10'x10' slab with same property in 30" thick raft with 33" on that particular column which have punching ratio 1.6. It wil come to 1.3 punching ratio.. then 36" and 39", after that punching ratio will come below 1. But when ever I remove 30" thick raft on that column then draw only 39" thick raft, i am facing same punching ratio problem. I did'nt understand what criteria SAFE is following..

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