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

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Earthquake parameters

Open

Calculation of Ta and Tb values

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