CGI’s T2 MODEL REVIEW_CBD Puri (Boundary+Frame Model) R3 / 2017.06.09
1. Expected Yield Strength, Fye and Expected Tensile Strength, Fue value should be filled, Fye = 1.1*Fy and Fue = 1.1*Fue (According to FEMA 356 Table 5-3).
Example of Calculation:
Fy = 400 Fu = 500
Fye = 1.1*400 = 440 Fue = 1.1*500 = 550
2. Effective flange width for L Beam and T Beam should be in accordance with ACI 318- 11 section 13.2.4.
Fig. R13.2.4-Examples of the portion of slab to be included with the beam
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Example of Calculation for L Beam:
Width of Beam (bw) = 300 mm Depth of Beam (hw) = 550 mm Thickness of Slab (hf) = 120 mm
hb = hw – hf = 550 – 120 = 430 mm
4.hf = 4 x 120 = 480 mm
Min (hb or 4.hf) = 430 mm
Effective Flange (Ef) = bw + Min (hb or 4.hf)= 300 + 430 = 730 mm
Only Use one of L300x500 with Effective Flange Width 730, don’t make B300x500_L1, B300x500_L2, B300x500_L3, etc.
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Example of Calculation for T Beam:
Width of Beam (bw) = 300 mm Depth of Beam (hw) = 600 mm Thickness of Slab (hf) = 120 mm
2.hb = 2.(hw – hf) = 2.(600 – 120) = 2.(480) = 960 mm
8.hf = 8 x 120 = 960 mm
Min (2.hb or 8.hf) = 960 mm
Effective Flange (Ef) = bw + Min (2.hb or 8.hf)= 300 + 960 = 1260 mm
Only Use one of T300x600 with Effective Flange Width 1260, don’t make B300x600_T1, B300x600_T2, B300x600_T3, etc.
3. “For Boundary+Frame Model, you don’t need to calculate equivalent static force again. You only need 25% of response spectrum scale factor of full model (SW+Frame)”.
Equivalent lateral force (Equivalent static) is used only at the beginning of the calculation to find the scale factor for the dynamic force (response spectrum) in SW+Frame Model, and there is no need to include the eccentricity factor.
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4. Response Spectrum Scale Factor:
How do you get 1460 for sx and 1600 for sy? Is that number the result of “Scale Up”
25% of response spectrum scale factor of full model (SW+Frame) ? Please attach your calculation to get it!
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5. Modal Combination Method & Directional Combination Type:
A. Modal Combination Method should be checked,
a. Use QCQ, if the difference between Tx and Ty less than 15%
b. Use SRSS, if the difference between Tx and Ty more than 15%
B. Directional Combination Type, use SRSS.
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6. The eccentricity should be filled according to ASCE 7-10 section 12.9.5.
The eccentricity equal to eccentricity in the full model (SW+Frame).
7. Placement of Beams:
We see a lot of mistakes in laying rectangular beams, L beams and T Beams on your ETABS model. Beams Placement of Boundary+Frame model equal to Full model (SW+Frame). Please see beams placement we give on SW+Frame model review.
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8. Boundary Modeling:
The way you assign boundary on the model (Boundary+Frame Model) is not correct.
Number, position and length of boundary must be adjusted to the design result on
"Shear Wall+Frame Model".
NOTE:
Please correct your model as per the reviews we provide. For the next review please try not to make the same mistakes as previous reviews.
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