Architecture & Structural Engineering

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

image-20200609-103213.png

Earthquake parameters

image-20200610-114710.png

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

Active directions are marked with a red and blue line.

image-20200610-115106.png
image-20200610-115713.png
image-20200610-115354.png
image-20200610-115510.png

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)


image-20200610-120131.png

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