7/24/2019 Concrete Slenderness Limtiation

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Concrete Workshop

70

2nd order calculatio

2ndorder effects:

- Caused by structural deformations

- Important for walls, columns,

Eurocode

Criterion for 1stor 2

ndorder cal

According to the Eurocode, 2nd orderaccording to 5.8.2 (6)or 5.8.3.

EC 5.8.2 (6):

Second order effects may be ignoredgiven for isolated members in 5.8.3.1

EC 5.8.3.1-2:

As an alternative to 5.8.2 (6), seconcalled the slenderness criterion.

The slenderness ratio is defined as

= l0/ i (EC formula

where:

l0is the effective length

i is the radius of gyration of the uncra

The recommended value for lim follo

lim= 20ABC/ (E

where:

A = 1 / (1+0,2ef) (if ef is not known,

B = (if is not known, B = 1

C = 1,7 - rm(if rmis not known, C = 0,

efeffective creep ratio; see 5.8.4;

=Asfyd/ (Acfcd); mechanical reinforc

As is the total area of longitudinal rein

n = NEd/ (Acfcd); relative normal force

rm= M01/M02; moment ratio

M01,M02 are the first order end momen

culation

effects have to be taken into account in each direction, unle

if they are less than 10 % of the corresponding first order effand for structures in 5.8.3.3.

d order effects may be ignored if the slenderness is below

follows:

5.14)

ked concrete section

s from:

formula 5.13N)

A = 0,7 may be used)

,1 may be used)

may be used)

ment ratio;

orcement

ts, |M02| |M01|

s they may be ignored

cts. Simplified criteria are

certain value lim. This is