Example 3 for Lamda Coefficient used in Story Drift Determination
The relative floor displacement report of the structure, whose earthquake parameters are given as the local ground class ZE and in the screenshot below, will be checked manually and then compared with the program report.
Typical plan view of the building
Earthquake parameters
Calculation of Ta and Tb values
| DD2 | DD3 |
|---|---|---|
SDS | 1.191 | 0.849 |
SD1 | 0.926 | 0.473 |
Ta = 0.2 SD1 / SDS | 0.155 | 0.111 |
Tb =SD1/SDS | 0.778 | 0.557 |
Modal participation multipliers of + - 5% eccentricity loadings read from the dynamic analysis report
Active directions are marked with a red and blue line.
Modal E1
Modal E2
Modal E3
Modal E4
Selected periods:
Tx=0.94939 sn
Ty = 0.76614 sn
Lamda Account
X direction DD2
Tx =0.94939 > TB=0.778 -> Sae(t) = SD1/T = 0.926/0.94939=0.981
X direction DD3
Tx=0.94939 > Tb=0.557 -> Sae(t) = 0.473/0.94939= 0.498
Lamdax = 0.498 / 0.981 = 0.51 (visible in program = 0.5113)
Y direction DD2
Ty = 0.76614 <Tb = 0.778
SAE (t) = 1.191 SDS =
Y direction DD3
Ty=0. 0.76614 > Tb=0.557
SAE (t) = SD1 / T = 0.473 / 0. 0.76614 = 0.64
lamday = 0.64 / 1.191 = 0.518 (visible in the program = 0.519)
Relative floor shift upper limit control
0.508 * 72.71 / 2800 (mm) = 0.013> 0.008 not provided
0.518 * 55.63 / 2800 (mm) = 0.013> 0.008 not provided
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