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  1. Assalamualaikum SE Pakistan in this pca seismic guide detailing it says that the rebar hook shall be bends towards to the center of column but i always see the bend is towards to the outer of column, which one is right? and why? all the best
    1 point
  2. Hooks bent inwards provide confinement and increase ductility. Thanks.
    1 point
  3. Solutions; 1. Why dont you import the cad drawing (as shown in image) into SAFE and draw footings with proper orientation? 2. Like you got reactions under so many combinations from ETABS for each column, in the same way, you could select all columns and export to EXCEL the local forces at and then filter for zero location and proceed with manual design. 3. Get global reactions (like you did already) but one group at a time. By one group i mean all the columns on one radial grid line. All columns on that grid will have same orientation and angle right. Export to EXCEL, transform forces in XY to that angle. New rotated forces will be; Fx' = Fx Cos theta + Fy Sin theta Fy' = -Fx Sin theta + Fy Cos theta there you go, you now have the new rotated forces. Repeat it for each radial line and then design footings manually.
    1 point
  4. (1). Structure Aspect Ratios The Horizontal/plan aspect ratio (Length to Width ratio) of the side block is 160/18=8.8 While its vertical/slenderness ratio (height to width ratio) is 60/18=3.33 I didn't come across any code limitations regarding these ratios But an indian research paper "Effect of Aspect Ratio & Plan Configurations on Seismic Performance of Multistoreyed Regular R.C.C. Buildings: An Evaluation by Static Analysis" concludes that, (a) The buildings with Horizontal Aspect Ratios 4 or less than 4, the seismic performance is reasonable. Above this, the worse effects of excessive forces, storey drift and displacement values may be obtained. Hence they should be discarded due to their unsatisfactory, weaker and unreasonable performances on the bases of above seismic parameters, which can cause detrimental and disastrous effects or otherwise be treated with the enough earthquake resistant elements. (b) The buildings with Vertical Aspect Ratios less than 4, the seismic performance is reasonable. Above this, the worse effects of excessive overturning, storey drift and displacement, period of vibration, etc. values may cause detrimental and disastrous effects to the buildings. Hence slender building configuration, as far as possible, should not be chosen, or otherwise be provided with the adequate earthquake resistant solutions. (2). Flexible Tower on Rigid podium UBC-97 Section 1629.8.3 item 4 says "Structures having a flexible upper portion supported on a rigid lower portion where both portions of the structure considered separately can be classified as being regular, the average story stiffness of the lower portion is at least 10 times the average story stiffness of the upper portion and the period of the entire structure is not greater than 1.1 times the period of the upper portion considered as a separate structure fixed at the base." And UBC-97 Section 1630.4.2 Item 2 says 2. The following two-stage static analysis procedures may be used for structures conforming to Section 1629.8.3, Item 4. 2.1 The flexible upper portion shall be designed as a separate structure, supported laterally by the rigid lower portion, using the appropriate values of R and ρ. 2.2 The rigid lower portion shall be designed as a separate structure using the appropriate values of R and rho. The reactions from the upper portion shall be those determined from the analysis of the upper portion amplified by the ratio of the (R/ρ ) of the upper portion over (R/ρ ) of the lower portion.
    1 point
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