construct behaviour of eccentrically braced structures with active links helsinki

8/11/2019 Construct Behaviour of Eccentrically Braced Structures With Active Links Helsinki

1/13

BEHAVIOUR OF ECCENTRICALLY BRACED STRUCTURES

HAVING ACTIVE LINKS CONNECTED OR NOT WITH R.C. SLAB

Paul IOAN and Serban DIMA

Technical University of Constructions Bucharest, Deart!ent of Steel Structures,

B"dul #acul Tei $%&, sector %, 'O "(%)*% Bucharest,

ABSTRACT

The resence in the lin+ one of t-o !aterials, a!on. -hich one is hetero.eneous, -ith very different

elasticity !odulus and -ith a different behaviour at cyclic !o!ents, leads to a oor co!utation

control of the behaviour of all these ones/ In the dissiative ones, in order to enable the develo!ent

of the lastic hin.es, -ith .reat rotations and hi.h ductility, secondary transverse bea!s are to be

rovided, their location bein. at the ends of the lin+s/ Alon. the lin+s0 len.th, the concrete -ill not be

connected by connectors to the steel bea!s, in order to enable only to the steel ele!ent 1lin+2 to

erfor! the lastic hin.es/ In order to avoid the alteration of steel lin+ rotations, -hich can occur at the

ends of the lin+ ele!ents, because of the resence of the reinforced concrete slab, secial 3oints -ill becreated, so that the slab one, above the lin+s and the rest of the slab to be disconnected/ 4o-ever, in

order to +ee the horiontal diahra.! effect for the -hole slab, do-els have been rovided bet-een

the t-o different ones of '/C/ slab/ The do-els are so sied that rotations could be develoed, but no

translations -ill be allo-ed/ Nu!erical testin. has been erfor!ed -ith short and lon. lin+s, t-o

hyotheses, -ith or -ithout '/C/ slabs bein. studied/ In both cases, is to be noted that the dissiative

ele!ent has not been ractically loaded, the loads actin. on the floor bein. trans!itted to the lin+0s

ends due to the e5istin. secondary bea!s/

KEYWORDS

Multi"storey steel structures, eccentrically braced fra!es, co!osite bea!s, co!osite lin+s, structureslocated in seis!ic areas, non"linear static analysis, non"linear dyna!ic analysis/

THE DESCRIPTION OF THE ANALYSED STRUCTURES

A !ulti"story steel structure -ith $* levels for a .eneral store, havin. the di!ension of the bays on the

t-o ortho.onal directions of 6,*! 5 7,*! and a live load on each floor of ),* +N8!%, -as analysed

1fi./ $2/ The buildin. has three sans of 6/*! and seven bays of 7/*!/ The level hei.ht 1&/*!2 is

constant alon. the -hole hei.ht of the buildin./ The construction has a dual solution, bein. !ade of

eccentrically braced fra!es and !o!ent resistin. fra!es on transverse direction, and concentrically

braced fra!es 19"shae2 and !o!ent resistin. fra!es on lon.itudinal direction 1fi./ $, c2/The colu!nshave a double T sy!!etrically section, -hich varies alon. their hei.ht 1resultin. three se.!ents2


2/13

havin. !a5i!u! ri.idity in the lane of transverse fra!es/ The bea!s have a double T section, bein.

ri.idly connected to the colu!ns/ T-o sections of bea!s have been chosen alon. the hei.ht of the

buildin., the bi..er rofiles bein. rovided at the first five storeys/ Secondary bea!s have been

rovided in the lon.itudinal direction, laced at the ends of the lin+s in the fra!e sans -ith bracin.

and at %/* ! bet-een a5es, in the sans -ithout bracin. 1fi./ $/a2/ The bracin.s have been !ade of

hot"rolled channels rofiles and have three stes of cross " section variation on the hei.ht of the

construction/

1 2 3 4 5 6 7 8

D

C

B

A

A B DC CA B D

a) b)

7 x 6m

8 8 8 8 8 8

e

lon.itudinal !ainbea!s

transverse

!ain bea!s

secondary bea!svertical bracin.

bea!s in M': bea!s " se.!ents

outside of the lin+

lin+

1 32 4 5 6 7 8 1 2 843 5 6 7

c)

Figure 1:Ten " story buildin.

a2 layout, b2 transverse fra!es, c2 lon.itudinal fra!es

The structure has been studied accordin. to $7 di!ensional and constructive alternatives, sho-n in

table $/

COMMENTS ON TESTING WAY OF THE STRUCTURE

The !odal analysis and the linear static calculation have been erfor!ed on the ho!o.enous satial

structure by !eans of SPAN calculation ro.ra! 1dra-n u by UTCB2, -hich includes the rovisions

of 'o!anian Nor! P$**";% re.ardin. the deter!ination of the static e


3/13

>?nCP *id

iii +++ , -here * @ %/* 1$2

The anchorin. of the colu!ns into the foundations has been erfor!ed by e!beddin. the! into the

reinforced concrete bulbs of the infrastructure, on the hei.ht of a level 1base!ent2/ In order to establish

the hei.ht of the colu!n anchorin. 1e!beddin.2, the additional loadin. co!bination -ith the

increased seis! has been used 1eP;/* *i -here * @ %/ 1%2

The above condition 1eB:2

-ith lon. lin+ 1##S, ##>2

In both alternatives 1A and B2, there has been studied the ho!o.enous structure -ith lin+s -ith s!aller

section 1S#S, ##S2, resectively e, ##>2 to the ones of the bea!s fro! the fra!e

sans -ithout bracin.s/ The follo-in. constructive solutions have been studied in order to analyse the

structures havin. reinforced concrete stabs 1table $2=

" 4o!o.enous lin+ the rest of the structure0s bea!s in co!osite solution, !aintainin. the

di!ensions of the steel bea!s/" 4o!o.enous lin+ the rest of the structure0s bea!s in co!osite solution, -ith decreasin. the

di!ensions of the steel bea!s, -ith M"sc @ Ms e


4/13

TAB#> $

ANA#FS>DCAS>S

N

Li!" Be#$%&eg$e!'&

u'&i(e ) *i!"

Be#$ i! MFR Fir&'

$(e

+eri(T1, & -T+e M#'e%ri#*Se/'i! M#'e%

ri#*Se/'i! M#'e%

ri#*Se/'i!

SLS

1

S0r'

T

M7/$e &*A4> &**A

Steel 4> 7**A4> *A

Steel 4> 7**A4> *A

$,$(

SLS

Steel

Concrete

4> 7**A4> *Ahr/c@ $*

Steel

Concrete

4> 7**A4> *Ahr/c@ $*

$,**

SLS

2

Steel

Concrete

4> **A4> &*A

hr/c@ $*

Steel

Concrete

4> **A4> &*A

hr/c@ $*

$,$*

SLS3

Steel

Concrete

4> &*A4> &**Ahr/c@ $*

Steel

Concrete

4> 7**A4> *Ahr/c@ $*

Steel

Concrete

4> 7**A4> *Ahr/c@ $*

$,**

SLS

4

Steel

Concrete

4> **A

4> &*Ahr/c@ $*

Steel

Concrete

4> **A

4> &*Ahr/c@ $*

$,$*

SLE

5

S0r'

T

M7/$e 7**A

4> *A

Steel 4>A 7**4>A *

Steel 4>A 7**4>A *

$,$7

SLE

6

Steel

Concrete

4> 7**A4> *Ahr/c@ $*

Steel

Concrete

4> 7**A4> *Ahr/c@ $*

*,;;

SLE

7

Steel

Concrete

4> 7**A4> *A

hr/c@ $*

Steel

Concrete

4> 7**A4> *A

hr/c@ $*

Steel

Concrete

4> 7**A4> *A

hr/c@ $*

*,;;

LLS

8

L!g

T

M*/)e >

Steel 4> **A

4> &*A

Steel 4> 7**A4> *A

Steel 4> 7**A4> *A

$,)

LLS

19

Steel

Concrete

4> 7**A4> *A

hr/c@ $%*

Steel

Concrete

4> 7**A4> *A

hr/c@ $%*

$,$)

LLS

11

Steel

Concrete

4> **A4> &*Ahr/c@ $*

Steel

Concrete

4> **A4> &*Ahr/c@ $*

$,%7

LLS

1

Steel

Concrete

4> **A

4> &*Ahr/c@ $%*

Steel

Concrete

4> 7**A

4> *A

hr/c@ $%*

Steel

Concrete

4> 7**A

4> *A

hr/c@ $%*

$,*;

LLS

12

Steel

Concrete

4>B **4>B &*hr/c@ $%*

Steel

Concrete

4> **A4> &*Ahr/c@ $%*

$,%$

LLE

13 L!g

T

M*/)e >

Steel 4> 7**A4> *A

Steel 4> 7**B4> *B

Steel 4> 7**A4> *A $,)%

LLE

14

Steel

Concrete

4> 7**B4> *Bhr/c@ $%*

Steel

Concrete

4> 7**A4> *Ahr/c@ $%*

$,$*

LLE

15

Steel

Concrete

4> 7**A4> *Ahr/c@ $*

Steel

Concrete

4> 7**B4> *Bhr/c@ $%*

Steel

Concrete

4> 7**A4> *Ahr/c@ $%*

$,*(


5/13

TAB#> $ 1cont/2

#e.end of the table

S#S short lin+ -ith section s!aller than the one of the ad3acent sans0 bea!s

S#> short lin+ -ith section e lon. lin+ -ith section e


6/13

T$ @ $/$* s

@ */*(rad

Figure 3 =

S#S

ho!o.enous short lin+ e


7/13

" the lastic hin.es aear u to * @%/, only in the dissiative ele!ents, in case of ho!o.enous

structuresG

" the !a5i!u! rotation of the short or lon. lin+s, for an a!lification factor * @%/, aears at floors

% and it is -ith *E s!aller that the allo-ed lastic rotation/

NON%LINEAR DYNAMIC CALCULATION TAKING INTO CONSIDERATION THE

HOMOGENOUS STRUCTURE.

The .ravitational !asses and loads fro! the secial co!bination shall be used/ The behaviour of the

structure under the dyna!ic action shall be follo-ed u, usin. site accelero.ra!s or

accelero.ra!s of the revious seis!/ A behaviour shall be considered roer if the lastic hin.es

aear usually in the dissiative ele!ents and ones, secially laced in the structure/ It is not

reco!!ended to rovide lastic hin.es on colu!ns and there shall not be acceted lastic hin.es

on the bea! se.!ents ad3acent to the lin+/ The lastic hin.es shall be acceted at the basis of the

colu!ns and at the to of the last level0s colu!n/ The values of the drift and the values of the lin+s

rotation shall be -ithin the li!its rovided by the nor!s .In case there are any variations fro!

these re


8/13

the non"linear static calculation shall be used for the non"linear dyna!ic calculation, as -ell, !eanin.

that there shall not be acceted any lastic hin.es in colu!ns, bea!s"se.!ents outside of lin+s and in

the dia.onals of the eccentrically braced fra!es/ The non"linear dyna!ic calculation also re.ards the

overall behaviour of the construction, in order that at least %E of the base shear force to be resisted by

the !o!ent resistin. fra!es/eff

r/c/

s s

r/c/

e

>bb =

>r/c@ Foun.Js !odulus for reinforced concrete

>s @ Foun.Js !odulus for steel

Figure 7=The e


9/13

Figure 19 :4o!o.enous lon. lin+ ho!o.enous bea!sG Northrid.e accelero.ra! " a @ */66./

Figure 11 :4o!o.enous lon. lin+ ho!o.enous bea!sG >l Centro accelero.ra! " a @ */)./

Figure 1 :4o!o.enous lon. lin+ ho!o.enous bea!sG Me5ico City accelero.ra! " a @ */$*./

Figure 12 :4o!o.enous lon. lin+ ho!o.enous bea!sG ?rancea 1a @ */%.2 Cheia 1 a@*/*6. 2


10/13

Figure 13 : 4o!o.enous lon. lin+ ho!o.enous bea!sG synthetic accelero.ra! 1acc/ ?rancea

sectru!2 a @ */%./

In case of usin. different accelero.ra!s for ho!o.enous structure -ith ##S, the follo-in.s resulted=" The ?rancea accelero.ra! leads to the .reatest lateral dislace!ents 1!a5@)$/* c!Lall@))/* c!2,

rotations of the lin+s 1@*/*)% radall@*/*% rad2 and shear base forces / As re.ards the !a5i!u!

value of the dissiate ener.y, its !a5i!u! value is roduced by the artificial accelero.ra! 1?rancea

$;(( sectru! " fi./ $&2

"The >l Centro $;&* 1fi./ $$2 and Me5ico City $;; 1fi./ $%2 accelero.ra!s roduce s!all lateral

dislace!ents and rotations of the lin+s of @$)/* c! resectively @*/**; rad/ The shear forces at

the basis of the structure and the !a5i!u! value of the dissiate ener.y are (*E resectively )E of

the ones roduced by ?rancea $;(( accelero.ra!/

"The Northrid.e $;;& 1fi./ $*2 accelero.ra! leads to .reater values of the lateral dislace!ent and

rotation of the lin+s of @$(/* c! resectively @*/*$& rad/ The shear force at the basis of the

structure is ;*E of the one roduced by ?rancea $;(( accelero.ra!, but the !a5i!u! value of the

dissiate ener.y is s!all, only &*E of the one corresondin. to ?rancea $;(( accelero.ra!/

It should be ointed out that, althou.h ?rancea $;(( accelero.ra! has a@*/%., it induces stresses and

defor!ations !uch .reater than the Northrid.e accelero.ra! -hich has a &/& ti!es .reater

acceleration 1 a @ */66.2/

Because of alyin. the accelero.ra!s, the structure re!ains defor!ed, -ith re!anent stresses in the

ones -ith reachin. of the elastic"lastic ran.e/ By alyin. a ne- accelero.ra!, after an esti!ated

ti!e of )* sec/ of free vibrations, the structure defor!ed by the revious accelero.ra! is forced to

oscillate around the defor!ed osition/ 1fi.$)2/

Usin. lin+s -ith reduced section, 1S#S, ##S2 it resulted a M8T ratio, -hich fra!es the lin+

-ithin the inter!ediary behaviour ran.e, -ith for!ation of lastic hin.es due to the co!bination of M

and T forces/ In this situation, !a3or e5ceedin. of the rotations at levels 6 have been noticed/ It

-ould still be -ron. to co!are the rotations of the lin+s resulted usin. a non"linear dyna!ic

calculation -ith the ones allo-ed by the nor!s, values resultin. in nor!s by correlatin. the rotations

-ith the drifts/ It should be ointed out that the nor!s rovide an elastic drift a!lified by a

coefficient, -hich varies around the sa!e value, re.ardless of the nor!/

In case the drifts are -ithin the li!its acceted by the nor!s, the rotations can be analysed accordin.

to the !a5i!u! rotation caacity of the lin+ in the elastic"lastic ran.e, -hich -as established durin.


11/13

e5eri!ents/ >lastic"lastic rotation caacity !eans the !a5i!u! rotation of a lin+, -ithout any local

stability loss/

Usin. the non"linear static calculation, for structures -ith co!osite bea!s -ith co!osite or

ho!o.enous lin+s, there resulted lastic hin.es -ithin the ele!ents desi.ned to -or+ in the elastic

ran.e, durin. the entire duration of the seis!, at values of the a!lification factor *@%/)/*/ Thisheno!enon did not occur in the non"linear dyna!ic calculation, -hich leads to the conclusion that, in

!any cases, the non"linear static calculation is !ore severe than the non"linear dyna!ic calculation/

CONCLUSIONS

The calculation of the !ulti"storey structures can be erfor!ed, in a first sta.e, ta+in. into account the

ho!o.enous bea!s throu.h all the stes of the calculation " then the ho!o.enous bea!s shall be

relaced -ith e


12/13

The lin+s can have the .eo!etrical characteristics of the section lo-er than the ones of the bea!s

fro! the ad3acent sans/ This is ossible be obtained by varyin. the -idth of the flan.es, u to

!a5i!u! )*&E of their di!ension, or by usin. s!aller rofiles/ This syste! .uides the for!ation

of lastic hin.es in the lin+s and not in the connections/

After a seis!, the structures, -hich have incursions in the elastic"lastic ran.e, re!ain -ith re!anentdefor!ations and stresses/ In the case of a ne- seis!, 1a rely or a seis! on non"consolidated

structures2, it finds another .eo!etry of the structure 1a defor!ed one2 and ones of the dissiative

ele!ents or dissiative ele!ents -ith re!anent stresses -hich are stron. effort concentrators/ :i./ $)/

sho-s the state of re!anent defor!ations 1rotations and dislace!ents2 and then the defor!ations

resulted fro! the alication of a ne- accelero.ra!/ These latest defor!ations -ere develoed -ith

re.ard to the defor!ed osition of the structure/ The second seis! should be considered as not havin.

an da!in. coefficient, because the non"structural ele!ents have been artially or totally destroyed by

the first seis! and the structure resents i!ortant stresses concentrators, -hich cannot be :N/SPON / &&6

Aribert /M/ 1$;;(2/ Modelisation ar ele!ents finis adote au5 outres et asse!bla.es de bQti!ents

!i5tes acier"beton/Proc. of the 8th Intern. Conf. Steel Struct.Ti!isoara 1'o!ania2

AISC";( 1$;;(2/ Seismic Provision for Structural Steel Buildings.

Bursi O/S/, Hra!ola H/, andonini '/, 1$;;(2/ Ruasi"static cyclic and seudo"dyna!ic co!osite

substructures -ith softenin. behaviour in SSS9!Na.oya 1aan2/

Code for aseis!ic desi.n of residential buildin.s, a.roootechnical and industrial structures 1P$**"

$;;%2/"omanian ministr# of Pu$lic %or&s and Teritor# Planning.Bucharest/ 1'o!ania2/

Dalban C/, Ioan P/, Di!a S/, Betea St/ Sanu St/ 1$;;2/ Proosals for I!rovin. the 'o!anian

Seis!ic Code/ Provisions concernin. !ulty"storey steel fra!es/IABSE Int. Conf. of Steel Struct. 'inal

"e(ort/ Budaest/

>urocode & >N? $;;& 1$;;%2/ Desi.n of co!osite Steel and Concrete Structures/ Part $/$ Heneral

rules for Buildin.s/Euro(ean Committee for Standardisation1$;;%2

>urocode 6 >N? $;;6 1$;;&2/ Desi.n rovisions for >arth


13/13

construct behaviour of eccentrically braced structures with active links helsinki

Documents