ISO/FDIS 16521

Design of concrete-filled steel tubular (CFST) hybrid structures

The proposed document provides the standards for the design, construction and inspection of concrete-filled steel tubular (CFST) hybrid structures. It is applicable to the static, seismic and fire design, construction and inspection of CFST hybrid structures to be used in high-rise buildings, largespan bridges, and other types of large-scale infrastructure in mountainous areas, earthquake-prone regions, corrosive environments and less-developed regions.

Conception de structures hybrides en tubes d'acier remplis de béton (CFST)

General Information

• Status: Not Published
• ICS: 91.080.99 - Other structures
• Technical Committee: ISO/TC 71 - Concrete, reinforced concrete and pre-stressed concrete
• Drafting Committee: ISO/TC 71 - Concrete, reinforced concrete and pre-stressed concrete
• Current Stage: 5020 - FDIS ballot initiated: 2 months. Proof sent to secretariat
• Start Date: 09-Jul-2024
• Completion Date: 09-Jul-2024

Standards Content (Sample)

FINAL DRAFT
International
Standard
ISO/TC 71
Design of concrete-filled steel
Secretariat: JISC
tubular (CFST) hybrid structures
Voting begins on:
2024-07-09
Voting terminates on:
2024-09-03
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
Reference number
FINAL DRAFT
International
Standard
ISO/TC 71
Design of concrete-filled steel
Secretariat: JISC
tubular (CFST) hybrid structures
Voting begins on:
Voting terminates on:
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
© ISO 2024
IN ADDITION TO THEIR EVALUATION AS
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
or ISO’s member body in the country of the requester.
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland Reference number
ii
Contents Page
Foreword .vii
Introduction .viii
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 5
5 Materials . 7
5.1 General .7
5.2 Concrete .8
5.2.1 Cement .8
5.2.2 Aggregates .8
5.2.3 Water .8
5.2.4 Admixtures.8
5.2.5 Additions .8
5.2.6 Concrete mixture specification .8
5.3 Steel tubes . .8
5.4 Steel reinforcement .9
5.4.1 Deformed reinforcement .9
5.4.2 Plain reinforcement .9
5.5 Other materials .9
5.5.1 Welding consumables .9
5.5.2 Fasteners .9
5.5.3 Protective paint systems .9
5.6 Storage of materials .9
6 Design and construction procedure . 9
7 General guides .11
7.1 Limitations .11
7.1.1 CFST members .11
7.1.2 Trussed concrete-filled steel tubular (CFST) hybrid structures . 12
7.1.3 Concrete-encased concrete-filled steel tubular (CFST) hybrid structures . 12
7.2 Limit states . 13
7.3 Ultimate limit state design format . .14
7.3.1 General .14
7.3.2 Factored load effects .14
7.3.3 Design resistances .14
7.4 Serviceability limit state design format . 15
8 Specific guides .15
8.1 Design working life . 15
8.2 Selections of materials, structural plans and detailing . 15
8.3 Seismic design requirements . 15
8.4 Selections of constructional methods and techniques . 15
9 Actions (loads). 16
9.1 General .16
9.2 Dead loads .16
9.3 Live loads .16
9.4 Snow loads .16
9.5 Wind forces .16
9.6 Earthquake forces .16
9.7 Thermal forces .17
9.8 Load partial factors and load combinations .17
10 Analysis . . 17

iii
10.1 General .17
10.1.1 Structural analysis purpose .17
10.1.2 Structural analysis methods.17
10.1.3 Structural analysis requirements .17
10.1.4 Loading cases .18
10.1.5 Construction stage analysis .18
10.2 Stress-strain relationships for materials .18
10.2.1 General .18
10.2.2 Concrete .19
10.2.3 Steel .
...

ISO/DIS FDIS 16521:2024(E)
ISO /TC 71/WG 2
Secretariat: JISC
Date: 2024-01-1606-24
Design of concrete-filled steel tubular (CFST) hybrid structures
FDIS stage
ISO/DISFDIS 16521:2024(Een)
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication
may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying,
or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO
at the address below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: + 41 22 749 01 11
EmailE-mail: [e-mail]
Website: www.iso.orgwww.iso.org
Published in Switzerland
ii © ISO 2024 – All rights reserved
ii
ISO/DISFDIS 16521:2024(Een)
Contents
Foreword . vii
Introduction . viii
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 3
4 Symbols . 8
5 Materials . 10
5.1 General. 10
5.2 Concrete . 10
5.2.1 Cement . 10
5.2.2 Aggregates . 10
5.2.3 Water . 10
5.2.4 Admixtures . 11
5.2.5 Additions . 11
5.2.6 Concrete mixture specification . 11
5.3 Steel tubes . 11
5.4 Steel reinforcement. 11
5.4.1 Deformed reinforcement . 11
5.4.2 Plain reinforcement . 12
5.5 Other materials . 12
5.5.1 Welding consumables . 12
5.5.2 Fasteners . 12
5.5.3 Protective paint systems . 12
5.6 Storage of materials . 12
6 Design and construction procedure . 12
7 General guides . 14
7.1 Limitations . 14
7.1.1 CFST members . 14
7.1.2 Trussed concrete-filled steel tubular (CFST) hybrid structures . 15
7.1.3 Concrete-encased concrete-filled steel tubular (CFST) hybrid structures . 15
7.2 Limit states . 16
7.3 Ultimate limit state design format . 17
7.3.1 General. 17
7.3.2 Factored load effects . 17
7.3.3 Design resistances . 17
7.4 Serviceability limit state design format . 18
8 Specific guides . 18
8.1 Design working life . 18
8.2 Selections of materials, structural plans and detailing . 18
8.3 Seismic design requirements . 18
8.4 Selections of constructional methods and techniques . 19
9 Actions (loads) . 19
9.1 General. 19
9.2 Dead loads . 19
iii
ISO/DISFDIS 16521:2024(Een)
9.3 Live loads . 19
9.4 Snow loads . 19
9.5 Wind forces . 19
9.6 Earthquake forces . 19
9.7 Thermal forces . 20
9.8 Load partial factors and load combinations . 20
10 Analysis . 20
10.1 General. 20
10.1.1 Structural analysis purpose . 20
10.1.2 Structural analysis methods . 20
10.1.3 Structural analysis requirements . 21
10.1.4 Loading cases . 21
10.1.5 Construction stage analysis . 21
10.2 Stress-strain relationships for materials . 22
10.2.1 General. 22
10.2.2 Concrete . 23
10.2.3 Steel. 29
10.3 Indices for the strength and stiffness of CFST hybrid structures . 31
10.3.1 CFST cross-section . 31
10.3.2 CFST hybrid structures . 33
11 Ultimate limit states of trussed concrete-filled steel tubular (CFST) hybrid structures . 34
11.1 General. 34
11.2 Resistances to compression and bending . 35
11.2.1 Axial compression . 35
11.2.2 Bending . 38
11.2.3 Combined compression and bending . 39
11.2.4 Resistances of CFST chords . 42
11.2.5 Resistances of webs . 50
11.3 Resistance to shear. 50
11.3.1 With horizontal webs . 50
11.3.2 With diagonal webs . 50
12 Ultimate limit states of concrete-encased concrete-filled steel tubular (CFST) hybrid
structures. 50
12.1 General. 50
12.2 Resistances of single-chord structures . 50
12.2.1 Axial compression . 50
12.2.2 Combined compression and bending . 51
12.2.3 Tension . 54
12.3 Resistances of four-chord structures . 55
12.3.1 Axial compression . 55
12.3.2 Combined compression and bending . 55
12.4 Resistances of six-chord structures .
...