Example 2 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 ZD 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
| LO2 | DD3 |
|---|---|---|
SDS | 1.458 | 0.698 |
SD1 | 0.705 | 0.277 |
Ta = 0.2 SD1 / SDS | 0.096 | 0.483 |
Tb =SD1/SDS | 0.079 | 0.397 |
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 = 0.93337 s
Ty = 0.73874 s.
Lamda Account
X direction DD2
Tx=0.93337 > Tb=0.483
SAE (t) = SD1 / T = 0.705 / 0.755 = 0.93337
X direction DD3
Tx=0.93337> Tb=0.397
SAE (T) = 0,277 / 0.93337 = 0,297
Lamda = Sae (t) DD3 / Sae (t) DD = 0.297 / 0.397
Lamdax = 0.392 (visible in program = 0.3928)
Y direction DD2
Ty=0.73874>tb=0.483
SAE (t) = SD1 / T = 0.705 / 0.954 = 0.7384
Y direction DD3
Ty=0.73874>tb=0.397
SAE (t) = SD1 / T = 0.277 / 0.375 = 0.7384
Lamda = Sae (t) DD3 / Sae (t) DD2 = 0.397 / 0.954
Lamday = 0.393 (visible in program = 0.3928)
Relative floor shift upper limit control
The largest relative floor offset = 0.393 * 55.46 / 2800 (mm) = 0.0078 mm <0.008 provided
