Leaderboard

Salam, precast can be designed and cast in factory and moved to building location.

many engineers in pakistan use this practice when modeling a beam in etabs , that if beam is fail in shear and torsion than they just change the torsion modifier from 0.35 to 0.001 , and then redesign that beam , after designing that beam appear to be pass in shear and torsion , also showing zero r/f required for this particular beam. i want to know that is this the right way to model beam, does code provide such kind of solution ,or it has no meaning.

i am using SAFE 12.3.1 and i think its the latest version to draw a design strip select the layer A or B and then put the values of start and end of strip widths For example you want to draw strips of 1m width then click on draw design strips. Select layer A and put 0.5 in all 4 boxes of left start width, left end width, right start width and right end width. This 0.5m or 0.5ft is above and top of center line of design strip so the total width is 1m. Then just replicate this line to cover all your slab. Similary draw design strips for B layer. You can draw A layer parallel to X direction and B layer parallel to y direction each 1m width. If you click on "SHOW STRIP WIDTH" in view options dialogue box you can see the widths on screen Usually it doesnt matter you select column strip or middle stip because you are designing your for unit meter width. So you get reinforcement areas per m. If your strip width is more than 1m then you have to divide the resulting moments or reinforcement areas over that width to get moment per meter or reinforcement per meter.

The main difference between SAFE 8 and 12 is that SAFE 8: was analysis 2D plate behaviour only SAFE12: by default it takes full analysis rather than 2D plate I dont my self aware of the full analysis which SAFE 12 does but the answer to the question that why NON LINEAR UPLIFT analysis in SAFE 8 takes no time and why in 12 it takes hours. We faced this problem and asked CSI guyz! because personally i dont like the SAFE 8 interface but there were people saying that if you have to do the non linear analysis export it to SAFE 12 which i really dont like. SAFE 8 was doing only 2D plate analysis (so you dont have to put restraint in x and y) only vertical springs. But in SAFE 12 if you run the analysis and check the log you will find that there is instability error because of no restraint in x and y. in SAFE 12 the options to select non linear uplift analysis are also very complex. Its not clear to select NON LINEAR UPLIFT in individual load cases or to select the option CONVERT COMBO TO NON LINEAR COMBOS well dont select the first option to check UPLIFT in each load case (results will be very strange) rather convert all load combos to non linear for uplift (results will be fine) but remember here that if you are doing 3d analysis without restraining in x and y your simplest model could take upto 3 hrs to run bcz of instabilities. to compare the results with SAFE 8 and to save run time goto RUN>Advanced options> and select 2d plate analysis option so by selecting just option you convert safe 12 to 8. no need to use the older version of SAFE and also note that in SAFE 12: Tension is + and Compression is - SAFE 8: Tension is - and Compression is +

uplift non linear analysis is used so that we get zero tension soil! it can be done by iteration process by manually applying soil springs and removing tension springs...or more easily by program non linear uplift analysis option. there is a big conceptual difference between safe 8 and 12. i bet most of the guys are still confused to see the difference between 2 programs of same example.. pls continue this topic..im willing to go in details but step by step