dcb 75

HERA Steel Design & Construction Bulletin Page 1 No. 75, August/September 2003

No. 75 The author(s) of each item or paper in this publication are noted at the beginning of the article.

August/September 2003 The material herein has been the subject of review by a number of people. The effort and input of these reviewers is greatly appreciated.

Introduction Welcome to the first Bulletin issue for the 2003/2004 year and to the 75th issue of the DCB. The first topic covers the design of portal frames with limited or no external restraint at the knees. Such applications are not common, however are readily covered by NZS 3404 [1]. This is followed by a brief elaboration on secondary beam/joist continuity for the assessment of floor vibration. The final and principal article is an update of the What's in the DCB summary last presented in DCB No. 69. This summary is now updated to Issue No. 75 - ie. up to mid-2003. The interactive access to the DCB via the HERA website will be updated to this new summary by the end of 2003.

Design of Portal Frames with Limited or No External Restraint at the Knees This article has been written by G Charles Clifton, HERA Structural Engineer.

Introduction and Scope Portal frames generally have good external restraint to the knees and apex. Such frames come within the mainstream design provisions of NZS 3404 [1] Clause 5.6. A wide range of restraint classifications for typical as-built details are given in HERA Report R4-92 [2], Restraint Classifications for Beam Member Moment Capacity Determination to NZS 3404. However, there are applications where the portal frames don't have the typical degree of external restraint at the knees. Two examples are shown in Figs. 75.1 and 75.2. The first case involves a

portal frame supporting a gable wall, but with no structural floor system at rafter level to provide lateral restraint. In this situation, there is no external twist restraint or lateral restraint for bending provided at the knees, however there is axial restraint, back through the gable wall, as the forces involved are low. The second case involves no external restraint at all to the knee - an example of which is shown in Fig. 75.2. The design of these two cases for member moment capacity, compression capacity and combined actions is now covered. Portal Frames With No External Twist Restraint But With External Axial Restraint Nature of the Axial Restraint Provided This is the example shown in Fig. 75.1. The axial restraint is provided to the knee in order that the portal frame column can be designed as pin ended between base and knee. It is provided by the gable wall framing system, through the use of a double stud (if needed). The axial restraint force,

*rN , is given from NZS 3404 Clause 6.7.2.1 as:

In This Issue

Page

Design of Portal Frames with Limited Restraint at the Knees

1

Secondary Beam/Joist Continuity Conditions for Assessment of Floor Vibration

6

What's in the DCB From Nos 1 to 75

7

References

21

17-19 Gladding Place P O Box 76-134 Manukau City, New Zealand Phone: +64-9-262 2885 Fax: +64-9-262 2856 Email: [email protected] Website: www.hera.org.nz


*rN = 0.025

*colN (75.1)

where:

*colN = design axial compression in the column.

Note that the restraint is provided through the external flange of the column at the knee and so is slightly off centre. It therefore relies on the twist restraint provided by the rafter to give effective axial restraint to the column cross section. This is a dependable assumption for all practical applications, provided that the stiffener arrangement is as shown in Fig. 75.1 (ie. with 2 horizontal stiffeners, not a single diagonal stiffener). The restraint force required to be resisted by the studs is low - for a column design compression of 20 kN, which is relatively high for a light framed

gable wall, 0.5 N*r = kN. The restraint force must be resisted by bending in the stud, between the stud top and bottom supports (see Fig. 75.1(b)). Often a double stud will be used for this. There must be direct connection between the portal frame knee and stud(s) to transfer this force.

There are no other points of effective external restraint to the rafter or knees of the portal frame. The portal frame must not be subject to inelastic demand due to earthquake, or to moment redistribution. Determining member moment capacity for the portal frame rafter In terms of the moment restraint classification at the knee, this is taken as partial restraint (P), in accordance with the second criterion from NZS 3404 Clause 5.4.2.2. (This was introduced in Amendment No. 1). This requires twist rotation to be effectively restrained and lateral deflection to be partially restrained. The latter condition is met by the axial restraint through the stud - this will not provide the same stiffness of restraint as the connection into a roof system would, however given that the studs are

designed to resist *rN .it will provide partial restraint. The key question is whether the former condition of effective twist restraint is met and what to do if it isn't. NZS 3404 Clause H5 gives a method for answering this question that is straight forward to apply. Details are as follows:

Fig. 75.1 Gable End Wall with Portal Frame Support


Fig. 75.2 Portal Frame Knee with No External Restraint

(1) Calculate Mob from NZS 3404 Equation H4.2

(for an equal flanged I-section: use Equation H4.1 for a general section). In applying that equation, all input properties are for the rafter. Le is calculated from Clause 5.6.3.1 for the PP condition at the knees, and L is the rafter length to column centrelines.

(2) Calculate bt from Clause H5.1.2

This involves calculating arz, which is the elastic stiffness of the end restraint against twist. For the portal frame in Fig. 75.1, arz is given by:

col

effcol,y,rz

3

L

I,E=a (75.2)

where: 3 relates to the pinned detail at the column base. If the column base is fixed for minor

axis bending, then replace 3 with 4. Iy,col,eff = 0.5 Iy,col (conservatively the inner half column section only is taken as providing the twist restraint to the rafter) Lcol = length of column segment (ie. in this case, the full column length) The rest of the input variables for b+ are for the rafter and have been determined during step (1).

(3) Calculate Mobr from Clause H5.1.1. (4) Calculate am (moment modification factor)

from Clause 5.6.1.1.1 (b). Equation 5.6.1.1 (2) can be used for any rafter bending moment distribution. This is determined for the full rafter length.

(5) Calculate Moa from Clause 5.6.4, ie:

m

oboa

MM = (75.3)


(6) Calculate as from Equation 5.6.1.1 (3) - for an equal flanged I-section. This also requires calculation of Msx,rafter.

(7) Calculate Mbx from Equation 5.6.1.1 (1), ie.:

Mbx = amasMsx (75.4)

Example As an example, consider a portal frame comprising a 250UB25 Grade 300 member. Column height (base to centreline of knee) = 2.8 m, rafter span = 6m. Calculate the member moment capacity for the rafter of this portal frame, for a given value of am = 1.6. That value is consistent with the bending moment distribution along the rafter shown in Fig. 75.1(a), in which most of the applied load comes from the central gable support. (1) Calculation of Mob

(The section properties for the 250UB25 are taken from [3] and not repeated herein.) Le = kt kl kr L = 1.02 x 1.4 x 1.0 x 6 = 8.57m kt = 1.02, from Table 5.6.3(1) of [1] kl = 1.4, from Table 5.6.3(2),

because the majority of load comes in from the gable support, which is laterally unrestrained onto the rafter

kr = 1.0, from Table 5.6.3(3) K = 0.43 from Equation H4.3 of [1] Mob = Mo

( ) ( ) kNm 21.2 K 1 L

GJEI 2

e

y =+=

(2) Calculate of bt

Nmm/radian 10 x 280.0 L

3EI 6

col

effcol,y,rz ==

Iy,col,eff = 0.5Iy,col = 1.28 x 10

6 mm4

bt = ( ) 75.1 K 1 5GJ /L2

ere =+

(3) Calculation of Mobr

( ) obtt

obobr M 12

M M

+

=

= 1.4Mob Mob In this case, the elastic buckling moment is not reduced by the support twist restraint conditions; hence:

Mobr = Mob = 21.2 kNm (4) m = 1.6 is given

(5) kNm 13.3 1.6

21.2

M M

m

oboa ===

(6) Calculate of s Msx = 92/0.9 = 102.2 kNm Moa = 13.3 kNm s = 0.12 (7) Mbx = m s Msx = 1.6 x 0.12 x 102.2

= 18.9 kNm For the rafter, f Mbx = 17.0 kNm. This example illustrates two important points relating to the portal frame application of Fig. 75.1, namely: The column does provide effective twist

restraint to the rafter, as is required for the P restraint classification

The laterally unrestrained nature of the gable support onto the top flange of the rafter decreases the member moment capacity, however that is unavoidable in this circumstance.

Determining member moment capacity for the portal frame column Just as the twist restraint to the rafter is provided by the (inside half of the) column, so the twist restraint to the column is provided by the inside half of the rafter. The process of determining what effect the stiffness of the elastic rafter has on the twist restraint at the knee for the column follows the same approach but with some changes. Details are as follows: (1) Calculate Mob from NZS 3404 Equation H4.2

In this case, all input properties are for the column

(2) Calculate bt from Clause H5.1.2

rafter

effrafter,y,rz

2

L

EI=a (75.5)


where: 2 relates to the rafter knee at the opposite end also having an applied moment Iy,rafter,eff = 0.5Iy,rafter Lrafter = length of rafter segment (ie. In

this case the full rafter length) (3) - (7) as for the rafter member moment

capacity determination, however using the column member section properties, dimensions and bending moment gradient.

Considering the same example as used for the rafter, the value of bt decreases from 75 for the rafter to 7.5 for the column. However, this still generates Mobr = Mob, thus the rafter provides effective twist restraint to the column knee for the column segment. Portal Frames with No External Restraint to the Knees Determining member moment capacity for the portal frame rafter This is the situation shown in Fig. 75.2. In this case, the column must be designed and built as a fixed base cantilever column about the minor axis, although it may be pinned for major axis moment and axial loading. The length of rafter for design, Lb, can be taken as: Lb = Lclear + dbeam + 0.5dcol (75.6) where: Lclear = clear length from face of wall to inside

face of column db = depth of rafter dcol = depth of column The rafter point of restraint under the floor is taken as 1.0db in from the face of the wall, provided that the floor and wall system are integrally connected to the rafter. (This will typically be the case). The rafter segment can be conservatively considered to have partial (P) restraint classification at each end. The design for member moment capacity of that segment is to Clause 5.6, noting the following: (1) The structural system must be braced in the

direction out of the plane of the portal frame for these provisions to be applicable.

(2) The portal frame must not be subject to

inelastic demand due to earthquake, or moment redistribution.

(3) The moment modification factor should be

determined from NZS 3404 Equation 5.6.1.1(2).

(4) Given the restraints of (1) and (2), the load

can be considered applied at the segment ends, thus kl = 1.0 from Table 5.6.3(2).

Determining member moment capacity for the portal frame column This follows the same procedure as for the portal frame with the axial restraint at the knee. The key difference here is that the cantilever column must be designed for a notional horizontal load in the minor axis direction and the associated minor axis moments, as described below. Design of column for axial load, minor axis moment and combined actions The column must be designed for the in-plane moment and axial load that is generated by the portal frame action. Given its lack of external restraint at the knee, it must also be designed for:

(i) A notional horizontal force, *H , applied at

the intersection of the beam and column centrelines at the knee and acting about the column minor principal y-axis. This is shown in Fig. 75.2 and its magnitude is given by NZS 3404 [1] Clause 3.2.4.2.

(ii) A minor axis bending moment generated on

the cantilever column by H* and magnified by second-order effects, as required by [1].

How to account for the effects of (i) and (ii) is described in DCB No. 40, pp. 6-8. The column must be designed for combined

actions ( *y*x M and , M ,N

* ) in accordance with

NZS 3404 Clause 8.4.5. Because it is subject to

combined *xM and *yM , the effect of axial

compression N* must be considered. Sections which meet the alternative design provision criteria of Clause 8.1.5 will gain appreciable additional design capacity. Design of connection to column base This must be able to resist the minor axis moment

*yM . It may be pinned or fixed about the column

major axis.


Secondary Beam / Joist Continuity Conditions for Assessment of Floor Vibration This article has been written by G Charles Clifton, HERA Structural Engineer. Introduction and Scope HERA has produced a spreadsheet based computer program and users manual for assessment of floor systems for in-service floor vibration. These are contained in HERA Report R4-112 [4]. The design provisions are based on the principal North American provisions on this topic, namely the AISC Design Guide Series 11 [5] and ATC Design Guide 1 [6]. There are a number of input parameters for the vibration assessment of a region of floor that require careful designer consideration. One of these is the continuity condition applicable to the supporting beams or joists. The first part of this article briefly presents the requirements of the design procedures [5,6]. The second part specifies the changes that should be made to HERA Report R4-112 to ensure that these requirements are correctly implemented. Requirements from Design Procedure When designing for walking excitation from chapter 4 of [5] or chapter 2 of [6], the participating panel weight can be increased by up to 50% to allow for continuity when certain conditions are met. These conditions are: (i) the members must be continuous over their

supports and the adjacent span must be greater than 0.7 times the span under consideration, and

(ii) For secondary beams with simple shear

connections supported on one side of a primary beam and which lie on the same gridline as a secondary beam spanning onto the other side of the primary beam, continuity can be considered at that end of the secondary beam.

Continuity should not be considered for the following: (a) Flange mounted joists, such as Speedfloor

Joists. This is because the flexibility of the joist to primary beam connection is too large to develop continuity conditions.

(b) Secondary beams spanning onto a primary beam where there is no aligning incoming secondary beam on the other side of the primary beam.

(c) Primary beams or secondary beams

supported directly on columns Where the beams are supported on columns and the connection is rigid, then the stiffening effect of the column on reducing the midspan deflection and hence changing the frequency can be considered. Equations for different situations are given in section 3.4 of [5]. Where shear deflection is important, modifications to the calculated member second moment of area are required to calculate an appropriate frequency; see sections 3.5 and 3.6 of [5]. Changes to HERA Report R4-112 HERA Report R4-112 [4] is written for applications where: All secondary and primary beams are simply

supported Primary beams cannot take advantage of

continuity The guidance relating to the continuity condition is given on page 20 of [4]. For the continuity condition to apply, the secondary beam must align with an incoming secondary beam on (or very close to) the same gridline at the end under consideration. For Speedfloor joists, the continuity condition should always be set at zero. In Example 4: Speedfloor flooring system (Location 1) the continuity condition should be set to 0, not 2 as is currently stated. The effect on the design example final result is minimal, with the joist peak acceleration increasing from 0.07g to 0.10g and the combined floor acceleration increasing from 0.434g to 0.454g. In Example 5: Speedfloor flooring system (Location 2) the continuity condition should also be set to 0, not 1 as is currently stated. The effect is to increase the joist peak acceleration from 0.07g to 0.10g and the combined floor acceleration from 0.583g to 0.685g. In both cases the floor system remains satisfactory under the design check.


Whats Current in the DCBs from No. 1 to No. 75 This article has been written by G Charles Clifton, HERA Structural Engineer.

Introduction and Scope

This article presents an update on What's Current in the Bulletin Issues 1 to 75 - ie. through to mid 2003. This supersedes the previous article on this topic, published in DCB Issue No. 69. It will be placed on the HERA website for the interactive on-line service to access the DCBs by the end of 2003. The details presented herein are grouped under the same general topics as were the details in Issue Nos. 63 and 69. These topics are:

Contractual issues and quality Design examples, design queries and

design concepts Design for durability Design for earthquake Design for fatigue Design for fire and behaviour in fire Design for serviceability Design of specific types of structures Design of connections Design of structural hollow section members

and connections Design of members not listed elsewhere Design of non-ferrous metals Innovative and economical steel design Material properties and availability Publications Research results Steel Structures Standard, NZS 3404 Composite construction Miscellaneous items

Use of this format means that some items are referred to more than once, however it significantly increases the usability of the information presented.

Contractual Issues and Quality

Specifications

DCB No. 44 presents an overview of the HERA Specification for the Fabrication, Erection and Surface Treatment of Structural Steelwork, HERA Report R4-99 [7]. That specification was published in November 1998 and is still current. Inspection and quality An inspection regime for bolts in bolted connections is given in DCB No. 46, pp. 8-10. It covers snug tight and tensioned bolts.

A paper on quality control of metal spray coatings is overviewed and referenced from DCB No. 20, pp. 5. The role of the Territorial Authority in enforcing weld quality is addressed in DCB No. 40, pp.4-5. Ensuring that on-site quality control is achieved for intumescent paints is covered on pp. 6-7 of DCB No. 44. Ensuring that on-site quality control is achieved with welded shear studs, which was previously covered in that same issue, is now covered in DCB No. 74, pp. 1-5, which also introduces the new Stud Welding Standard, AS/NZS 1554.2 [8]. An inspection regime for the non-destructive examination of welds in a given project is presented in DCB No. 44, pp. 2-3. Design Examples, Design Queries and Design Concepts There are a large number of design examples and design queries presented in the 75 issues of the DCB to mid-2003. There are also design concepts given for a range of applications. Those which are still current are listed below, in chronological order, with the design examples listed first. Design examples cover the following: Design example 6.1, in DCB No. 6, pp. 1-2,

covers design for moment of a solid rectangular flat plate loaded about the x-axis

Design example 17.1, in DCB No. 17,

pp. 5-8 covers design of a single angle truss chord member to NZS 3404 [1]. The example, written for the 1992 edition of NZS 3404, is however still relevant. This example replaces the single angle design example in DCB No. 3, pp. 1-3 and amendment in DCB No. 3, pp. 3-4

Pages 2-5 of DCB No. 17 present the design

concepts and background to single angle member design

DCB No. 24, pp. 3-5, covers the design of a

monosymmetric beam comprising a Tee section with CHS bottom chord which is subject to wind uplift. DCB No. 69, pp. 2-5, covers further aspects of Tee section design

DCB No. 39, pp. 6-7, covers the design of a

horizontal cantilever canopy flat plate rib beam for major axis bending

DCB No. 40, pp. 6-8, covers the ultimate limit state design of a cantilever column


carrying a vertical axial load. The purpose behind this example is to illustrate application of NZS 3404 [1] for second-order effect determination and subsequent member design

DCB No. 41, pp. 7-9, covers calculation of

the lifting capacity of a spreader beam. This is one of the more challenging applications of the beam member moment capacity (lateral buckling) provisions

DCB No. 51, pp. 16-22, presents two fully

worked beams to column MEP connection design examples. These utilise the material in HERA Report R4-100 [9] as well as performing all the additional checks required on the column section. They should be read in conjunction with DCB No. 52, pp. 13-16, which introduce an improved method of panel zone doubler plate reinforcing and apply it to the MEP design examples from DCB No. 51. See also DCB No. 57 for a detailed article on panel zone design and detailing that supersedes all previous articles on this topic, however that is going to be superseded by DCB No. 77, to be published January 2004

DCB No. 55, pp. 2-15, presents a very

detailed design example and commentary on the design of a cold-formed, thin-walled single angle truss chord member subject to combined compression and bending. The angle is formed from 3 mm thick cold bent plate and the design is to AS/NZS 4600 [10]

DCB No. 58, pp. 20-23, presents a detailed

design example on the semi-rigid Flange Bolted Joint (FBJ). DCB No. 62, pp. 16-18, presents errata to the FBJ procedure contained in DCB No. 58; these are minor. See also DCB No. 74, p.9, equations 74.1 and 74.2 for revised joint yield capacity for the FBJ.


design example for a brace/beam/column connection in a braced steel frame (EBF or CBF). This uses the design concepts presented in DCB No. 56, pp. 2-11. A short errata is presented in DCB No. 63, pp. 1-2

DCB No. 71, whole issue, presents the

second edition of the Slab Panel Method for the design of floor systems for dependable inelastic response in severe fires. A design example is given on pp. 12-14 and 28-29. How to overcome a potential problem with the use of the associated software is covered in DCB No. 73, p.24

DCB No. 72, pp. 14-15, presents an example of determining the site-specific corrosivity and then selecting a suitable coatings system in accordance with the current Corrosion Protection Standard [16].

DCB No. 73, pp. 3-11, presents a

comprehensive design example covering the design of nested RHS members for combined compression, moment and torsion, including determination of second-order effects

Design queries and concepts cover the following: DCB No. 1, pp. 2-3, addresses the question

as to whether local wind pressure coefficients from NZS 4203 [11] need to be applied to elements of cladding for design for serviceability limit state wind conditions

DCB No. 1, p. 3, covers how the torsion

constant and warping constant are calculated for a monosymmetric I-section with lipped compression flanges

DCB No. 4, p. 5, covers how the effective

section modulus of a half round steel section carrying water is calculated

DCB No. 5, p. 6, covers calculation of Zey for

an I-section which is symmetrical about the y-axis

DCB No. 7, p. 4-5, covers a restraint query.

However this and all other restraint queries up to DCB No. 34 have been superseded by HERA Report R4-92 [12]

DCB No. 16, pp. 3-4, covers the

determination of am factors for segments unrestrained at one end and subject to a load pattern not covered by NZS 3404 Table 5.6.2. The expression for am presented on page 4 of that issue has been incorporated into the program MemDes [13]

DCB No. 29, pp. 5-6, covers determination

of the design tension capacity of plain, round reinforcing bar members. The concepts presented therein are still applicable to reinforcement which is now produced to AS/NZS 4671 [14], although the minimum specified strengths have changed

DCB No. 49, pp. 1-4, presents advice on

member moment capacity determination for segments of portal frames. This supersedes advice given in articles on this topic in DCB Nos. 22 , 23 and 25


DCB No. 54, pp. 1-3, presents the convention on signs for member and applied actions (moment, shear, axial force) adopted, as of February 2000, for all subsequent HERA publications


background to the concepts involved in determining the shear stud design shear capacity for shear studs used in composite construction. This should be used to determine the shear stud capacity for applications that are not covered by NZS 3404 [1], but should be read in conjunction with section 4.2 of [17]. See [15] for the most recent guidance on design of shear studs in 55mm high trapezoidal steel decks

For shear studs used on beams supporting precast hollowcore concrete slabs, the guidance given in DCB No. 45, pp. 8-11, can be used, but only for hollowcore units of up to 250 mm deep. This whole topic is now covered in session 4.2 of [17], which should be read first by anyone wanting composite action from hollowcore slabs on steel beams. It provides the most up-to-date design criteria including making allowance for hollowcore units on steel beams to deliver acceptable behaviour under design severe earthquake attack

DCB No. 52, pp. 18-28, covers the lateral

restraint and load bearing capacity in the support regions of continuous beams

DCB No. 54, pp. 26-27, presents the concept of using rigging to restrain member buckling of long, isolated columns in compression

DCB No. 56, pp. 2-5, presents a method for proportioning design actions from the braces into the supporting members of brace/beam/column connections. This supersedes all the guidance in DCB No. 47, pp. 5-8

DCB No. 56, pp. 5-11, presents design concepts for brace/beam/column connections in braced steel frame seismic-resisting systems

DCB No. 56, pp.11-20, presents design concepts for moment-resisting column baseplate connections in seismic-resisting systems

DCB No. 58, pp. 1-20, presents design concepts for connections and systems using the semi-rigid Flange Bolted Joint (FBJ), followed by a design example. Refer also to

DCB No. 62, pp. 16-18, for revisions to the design procedure.

DCB No. 68, pp. 1-32, presents the design and detailing requirements for connections and systems using the semi-rigid Sliding Hinge Joint (SHJ), followed by a design example. This refers back to DCB No. 59, pp. 26-32, which covers the design concepts for the SHJ. Analytical studies on the SHJ are reported in DCB No. 70, pp 19-44

DCB No. 68, p. 33, covers determination of

the member compression capacity of a solid section to [1]

DCB No. 69, pp. 19-28, presents a

calculation method for plastic analysis DCB No. 69, pp. 2-5, presents how to

determine the effective section modulus of a Tee section

DCB No. 73, pp. 12-20, covers restraint

issues relating to the design of portal frame spine beams

DCB No. 73, pp. 21-23, elaborates on how

to read and use the output from the floor vibration program NZFl_Vib1 and associated users manual, HERA Report R4-112 [4]. Another issue with that program is covered on page 6 in this issue (No. 75).

Design for Durability A wide scope of design guidance for durability is covered, as noted below. This is presented in chronological order, covering those articles which are still current. DCB No. 20, pp. 1-2, presents general

guidance on selecting the appropriate environment for corrosion protection of external structural steelwork

DCB No. 20, pp. 2-5, covers allowance for

corrosion of unpainted beam top flanges in car parking buildings

DCB No 36, p. 6, covers galvanizing of

HSFG bolts DCB No. 41, pp. 1-5, presents an article on

single coat Inorganic Zinc Silicate paints

DCB No. 46, pp. 2-6, presents design long-term corrosion rates for steel piles, with follow-up material in DCB No. 62, pp. 6-8

DCB No. 46, pp. 5-7, presents design

corrosion rates for long-term exposure of


unprotected structural steel to exterior atmospheric conditions. The guidance in that article on allowance for microclimatic effects has been superseded by DCB No. 62, pp. 8-16. An example using this guidance is presented in DCB No. 72, pp. 14-15

DCB No, 46, p. 18, presents a short article

on the use of steel with no applied corrosion protection in benign interior environments

DCB No. 47, pp. 1-3, presents detailing

requirements for steel to concrete interfaces in exterior environments. This references back to DCB No. 46, as required

DCB No. 49, pp. 7-14, covers the durability

of car parking buildings, with follow-up material in DCB No. 56, p.25. This article is also in [17].

DCB No. 51, p. 8, overviews a coatings

guide for steel bridges DCB No. 51, pp. 12-14, provides guidance

on assessing the remaining structural capacity of corrosion-damaged steel beams, with an update in DCB No. 52, p. 4

DCB No. 52, pp. 5-7, introduces the

changes to the galvanizing standards and gives a list of galvanizing baths available in NZ, as of October, 1999

DCB No. 62, pp. 8-16, provides detailed

guidance on allowing for microclimatic effects such as unwashed surfaces

DCB No. 65, pp. 31-32, covers selection of

stainless steel for durability. This topic is greatly elaborated on in R4-111 [18]

DCB No. 72, pp. 10-14, covers use of the

2002 corrosion protection Standard [16]. Design for Earthquake

The principal source of design for earthquake is HERA Report R4-76 [19]. It was published in 1995 for application with the 1992 edition of NZS 3404. However, the changes required to use it in conjunction with NZS 3404: 1997 [1] are minor. Details of these changes are given in the useful set of notes entitled Tips on Seismic Design of Steel Structures [20], which are overviewed in DCB No. 56, p.28. These tips are also now included in each new copy of R4-76.

The items relating to design for earthquake covered in the DCB, and which are additional to

the material covered by [19, 20], are as follows (presented in reverse chronological order); DCB No. 74, pp. 5-24, introduces the

concept of the Floor Isolating System for Superior Earthquake Response and the first results from analyses on its performance and potential advantages over existing systems

Design of bolted hollow circular columns for

earthquake can be undertaken using the Circular Bolted Flange Annulus connection, which is presented in DCB Nos. 65, pp. 16-30, 66, pp. 12-16 and 67, pp. 1-16

Design of connections and systems using

the Flange Bolted Joint is covered in DCB No. 58, pp. 1-20, and DCB No. 62, pp.16-18

Design of connections and systems using

the Sliding Hinge Joint is covered in DCB No. 68, pp. 1-32

The use of the Reid Engineering Systems

Ltd Brace LOKTM as a load rated rod bracing system for CBFS is covered in DCB No. 64, pp. 2-3. The contact person at Reid is now Terry Seagrove, email: [email protected]

DCB No. 57, pp. 14-28, covers design and

detailing of panel zones in moment-resisting beam to column connections. That supersedes all earlier DCB articles on panel zone design and detailing, but is in turn to be superseded by DCB No. 77, January 2004

DCB No. 56, pp. 2-5, covers design

concepts for proportioning design actions from the braces into the supporting members of brace/beam/column connections

DCB No. 51, pp. 14-23, covers design of

MEP connections for seismic-resisting systems. See also DCB No. 57 and ultimately No. 77 for revised panel zone design criteria

DCB No. 50, pp. 20-26, covers general

concepts and derivation of design actions for connections in seismic-resisting systems. This includes specific guidance on design actions for column bases of MRFs, EBFs and CBFs, material which is not covered in R4-76 [14]

DCB No. 49, pp. 15-19 and DCB No. 50, pp. 5-7, cover issues relating to P-D response and design of steel seismic-resisting systems


DCB No. 47, pp. 20-21, presents details of a cost-effective X-braced, tension only CBF system with site welded strap braces

DCB No. 46, pp. 16-17, presents details of a cost-effective V-braced CBF system with site welded braces. This system has been used in several recent buildings

DCB No. 45, p. 16, covers derivation of Cs factors for CBF roof bracing systems

DCB No. 40, p. 3, contains a modification to apply to equations 18.5 and 18.6 of R4-76 [19] when calculating the column design seismic axial force in columns of tension braced CBF seismic-resisting systems

DCB No. 40, p. 4, presents the most recent empirical equations for preliminary determination of seismic-resisting system fundamental period of vibration

DCB No. 36, p. 6, presents an extreme upper limit on seismic design actions for connectors and connection components. These should be used where the system is such that the minimum design actions specified by NZS 3404 Clause 12.9.2 would be obviously excessive for the system

DCB No. 24, pp. 7-8, present the revised expressions for determining the post-buckling compression capacity of CBF braces that are given as Equations C12.2.3(1) and C12.2.3(2) in NZS 3404 [1]

DCB No. 19, pp. 6-7, covers design of single-brace concentrically braced framed systems. (These are not covered in R4-76 [19], but the provisions from that report are easily adapted for their use)

DCB No. 18, pp. 1-10, presents guidelines for assessing the seismic performance of pre-1975 moment-resisting steel framed buildings. These guidelines are currently being incorporated, in part, into a new document on this topic being prepared by a NZSEE Study Group for the BIA

DCB No. 8, pp. 1-6, DCB No. 9, pp. 1-4, and DCB No. 10, pp.1-3, present reports on the Great Hanshin (Kobe) Earthquake of January, 1995

Design for Fatigue The DCB to date has not provided direct guidance on design for fatigue, but instead has referenced good sources of design guidance. Details are as follows:

DCB No. 57, pp. 28-30, provides coverage of three sources of fatigue design guidance covering welded construction in general and welded hollow section joints in particular

DCB No. 32, p. 4, references a report

available from HERA on the fatigue testing of riveted bridge girders

Design for Fire and Behaviour in Fire Design for steel structures response in fire and information on steel structure behaviour in fire is one of the principal topics covered in the DCB and by the HERA Structural Division in general. The most current overview of fire engineering application to multi-storey steel framed buildings in New Zealand is given in [21], which was written in October 2002. HERA Report R4-105 [22] Notes Prepared for a Seminar on The Behaviour and Design of Multi-Storey Steel Framed Buildings for Severe Fires, Revised June 2001 covers Fire Engineering Design (FED) of multi-storey buildings and contains/supersedes much DCB material on FED of multi-storey buildings published prior to then. HERA Report R4-91 [23], Notes Prepared for a Seminar on Design of Steel Buildings for Fire Emergency Conditions, provides design and detailing guidance for low-rise buildings. Various DCB articles since [23] was published, in November 1996, have revised application of the procedures to keep them up to date with changes to key documents such as C/AS1:2001 [24], the Approved Document for Fire Safety. This contents listing covers the DCB articles on behaviour and design for fire that are still current. Because so much of the earlier published material on fire has been superseded by later articles or other documents, they are listed in approximate reverse chronological order: DCB No. 74, pp. 25-38, contains a report on

the modelling of four slab panel fire tests undertaken in 2002. The full details of this modelling work are published in HERA Report R4-118 [25].

DCB No. 72, pp. 2-10, gives an overview of

a large-scale fire test undertaken on a 7 storey reinforced concrete building and the implications for New Zealand

DCB No. 71, whole issue, presents the

detailed second edition of the design procedure for design of multi-storey steel framed buildings with unprotected secondary beams or joists for dependable inelastic response in severe fires. This supersedes the first edition, which was presented in DCB No. 66


DCB No. 70, pp. 1-19, presents key research results used to update the first edition of the method

DCB No. 70, pp. 44-45, presents details of a

simple parametric fire curve that can be used to model fully developed real fire conditions

DCB No. 70, pp. 45, presents a general

overview of the range of hot-rolled steel beam and column sections that will achieve a 15 min Fire Resistance Rating without passive fire protection

DCB No. 66, p. 16, gives an overview of a

useful paper on the heat straightening repair of damaged steelwork, which is relevant to fire design

DCB No. 65, pp. 4-13, gives a number of

design examples on the design of members for fully developed fires

DCB No. 58, pp. 25-30, in conjunction with a

Canadian paper described and referenced therein, covers the design of concrete filled steel hollow section columns for a specified fire resistance rating

DCB No. 54, pp. 3-26, presents a state-of-

the-art report, as of February 2000, on the performance and design of modern, multi-storey steel framed buildings in fully developed fires. However, as this is such a rapidly developing area, that article was getting out of date by February 2001. It was revised and updated for the seminars on Behaviour and Design of Multi-Storey Buildings for Severe Fires held in March 2001 and is now presented as session 4 of [22]. However, it does not reference the second edition of the Slab Panel Method, which was produced at the end of 2002

The collapsed wall condition concept, for

determining whether the steel columns supporting fire rated external wall elements of single-storey buildings are required to be passive fire protected, was first introduced in DCB No. 20, April 1996. It was then developed further in subsequent DCB articles and presented in detail in HERA Report R4-91 [23], in November 1996. Some errors in that report were noted and corrected through DCB No. 30, pp. 3-4 and more mention of the collapsed wall condition design concept made on page 6. The original condition was developed for a previous edition of the BIA Acceptable Solutions for Fire Safety and needed modification to be applied to the current

provisions C/AS1 [24]. Its application has been made easier by the radiation provisions of [24] now employing the same concept of a limiting width on the emitter as is incorporated into the collapsed wall condition concept. There have been two rounds of modifications made, namely in DCB No. 51, pp. 3-5 and DCB No. 52 pp. 2-3

Designers using the collapsed wall condition

concept should start with the advice given in DCB No. 52, pp. 2-3 under the article Extending Use of the Collapsed Wall Condition for Support of External Wall Panels. That article refers back, as required, to DCB No. 51 and to [23]. Pages 4 and 5 of DCB No. 51 give the method of application itself in terms of determining the emitter height and width

DCB No. 51, pp. 2-3, provides guidance on

modifying the S rating given by [24] to account for the thermal inertia of the bounding elements of the enclosure. This modification is very important, as the S ratings given in [24] are based on the most severe condition possible in buildings and require significant reduction for any building incorporating concrete floor slabs

DCB No. 51, pp. 5-6, provides guidance on

the fire resistance ratings for structural elements of steel framed car parking buildings

DCB No. 50, pp. 9-10, overviews a useful

paper on assessing the integrity of structural steelwork after exposure to fire. The other two FED articles in that issue have been superseded

DCB No. 48, pp. 3-13, presents results from

HERAs fire research programme on key aspects of the behaviour of a multi-storey steel framed building subject to fully developed natural fires

DCB No. 46, pp. 10-13, presents details on

eliminating the need for passive fire protection in multi-storey apartment and hotel buildings by using the shielding effects of the linings

DCB No. 44, p. 7, mentions a publication

available from HERA on the fire engineering design of oil platforms and similar structures

DCB No. 28, pp. 2-3, provides a summary

of the scope and contents of HERA Report R4-91 [23]


DCB No. 27, pp. 1-8, provides interesting material on the link between the fire resistance ratings provided, the structural fire severity and the resulting performance in severe fire. That information, especially pp. 4-5, is still of background interest, although the design recommendations arising from it have been superseded

DCB No. 27, p. 8, provides an overview of

HERA Report R4-89 [26], Fire Protection Manuals, Section 7 (Passive Protection) and Section 8 (Active Protection)

DCB No. 15, p. 8, makes reference to HERA

Report R4-82 [27] Calculation of the Design Fire Resistance of Composite Concrete Slabs With Profiled Steel Sheeting Under Fire Emergency Conditions. An error in the equation for he on page 15 of [27] is noted and corrected in DCB No. 35, p.5

DCB No.12, pp. 6-8, covers the fire

resistance of composite beams with profiled steel decking, in particular addressing the issue as to whether the voids between top of steel and decking in a ribbed deck need filling with passive protection material when the beams are protected

DCB No.11, p. 6, covers fire stopping and

penetration seals for the construction industry

DCB No. 6, pp. 4-6, covers the accuracy of

the structural fire severity time equivalent equation, te = ef fb wf, used to develop the S rating provisions. Further brief background to the ventilation factor, wf, is given in DCB No. 8, pp. 7-8

Design for Serviceability Acoustic performance: DCB No. 57, pp. 2-14, presents guidance on

the acoustic performance of steel framed apartment buildings. However, in November 2003 that will be superseded by the Noise Control Handbook [28]

DCB No. 45, pp. 11-13, covers acoustic insulation provided by Dimond Hibond floor systems. That will be superseded by December 2003 by a Dimond publication

Deflections: DCB No. 49, pp. 4-7, together with DCB

No. 50, pp. 2-4, provide guidance on the stiffening effect of the cladding on portal frame deflections under lateral loading

Deflection of composite floor systems and the links between deflection and concrete placement are now covered in HERA Report R4-107-DD [29]. This was presented in conjunction with R4-112 [4] and R4-113 [17], at a composite construction seminar series in May 2002. A follow-up on this seminar series is given in DCB No. 67, pp. 16-21

The guidance given in DCB No. 37, pp. 9-10, on vertical deflection limits for crane runway girders, is superseded by the requirements of AS 1418 Part 18 [22]. This very important new standard is overviewed in DCB No. 61, pp. 6-9

Vibration of floor systems

The latest US/Canadian based design procedure for design of steel/concrete floor systems for satisfactory in-service floor vibration response is overviewed in DCB No. 56, pp. 25-27. The principal source of design guidance is HERA Report R4-112 [4], which comprises a program that operates this procedure, a comprehensive users manual and set of design examples. The program covers all floor system types supported on steel beams except precast concrete. Minor updates on R4-112 are published in DCB No. 73, pp. 22-23 and DCB No. 75 in p. 6. For floor systems involving Dimond Hibond supported on steel beams, the Hibond Design Wizard [31] covers the full preliminary and final design, including vibration assessment

Wind-Induced Serviceability Vibration

DCB No. 66, pp. 1-10, presents a procedure for the preliminary design assessment of multi-storey buildings for satisfactory in-service response to wind induced vibrations. When that procedure was written, the appropriate wind standard was in draft form. That draft has now been published as AS/NZS 1170.2 [32] and the procedure should be used in conjunction with the published standard. (All Clause references and technical details from DCB No. 66 are unaltered). An update on this topic is published in DCB No. 73, pp. 23-24

Design of Specific Types of Structures This section of the content listings covers articles relating to specific types of structures, typically covering a range of topics in relation to that type of structure. The listing is not exhaustive, especially in that it does not cover articles on components or other items that are applicable to more than one type of structure. Its principal purpose is to identify


articles that would not be referenced elsewhere within this contents overview Houses

DCB No. 52, pp. 9-10, covers guidelines for light-weight steel framed house construction

DCB No. 48, pp. 17-18, provides an

overview of a BHP publication on the use of steel in houses, which is available from HERA. The publication is written for Australian conditions, however much of it is directly relevant to New Zealand and all of it has at least some relevance. There are plans underway to produce a New Zealand version

Single-storey buildings DCB No. 50, pp. 2-4, covers the stiffening

effect of cladding on portal frame buildings DCB No. 52, pp. 2-3, covers design of

external walls for fire resistance DCB No. 40, pp. 1-3, covers design of

haunches, tapered universal beam sections in portal frame rafters

DCB No. 21, pp. 5-6, covers the minimum

required pitch for profiled metal roofing and references an excellent publication for profiled metal roofing design and installation

Multi-storey buildings DCB No. 49, pp. 20-24, presents general

concepts in selecting structural form and detailing for maximum cost-effectiveness in multi-storey steel framed buildings

DCB No. 50, pp. 20-26, presents connection

design and detailing issues in selecting structural form and detailing for maximum cost-effectiveness in multi-storey steel framed buildings

DCB No. 52, pp. 22-25, covers optimising

the cost of multi-storey steel framed buildings in New Zealand

DCB No. 49, pp. 7-14, covers durability of

multi-storey car parking buildings. This topic is also covered in section 3.3 of [17] with matters arising presented in DCB No. 67, pp. 16-21

Pallet racking systems There have been various articles on pallet racking systems in the DCB, however the following two

issues present the current guidance and supersede earlier articles; DCB No. 31, pp. 1-10, covers general issues

and design of selective pallet racks DCB No. 53, pp. 6-12, covers design of

drive-in pallet racks Bridges HERA has not published much guidance relating to bridges in the DCBs, nor in our Structural Division activities. The priority given to bridges may be raised from mid-2004 following a review of the potential of this market sector being undertaken in the 2003/2004 year. Meanwhile, the following is available: DCB No. 46, pp. 2-6, presents design long-

term corrosion rates for steel piles, with follow-up material in DCB No. 62, pp. 6-8

DCB No. 47, pp. 1-3, presents detailing

requirements for steel to concrete interfaces in exterior environments. This references back to DCB No. 46, as required

DCB No. 51, pp. 6-9, gives an overview of

three international publications, available from HERA, that contain material of relevance to bridge designers. In each case, even though the publications are not specifically written for New Zealand application, they will be of benefit in bridge design and coatings selection. Their applicability to New Zealand is outlined in each case. The three publications cover:

concepts and design charges for

composite steel road bridges (Australian)

coatings guide for new steel bridges (Australian)

coatings system performance - review of actual performance of different systems (UK)

DCB No. 51, pp. 12-13 and No. 52, p. 4

gives an article on assessing the structural capacity of corrosion damaged steel bridge beams and a brief design example

Design of Connections Background This section incorporates the summary guidance presented in DCB No. 53 and DCB No. 63, with new material that is presented in Issue Nos. 64-68. It uses the same sub-headings as those used in the Issue No. 53 article.


Introduction The principal publication for design and detailing of connections is the Structural Steelwork Connections Guide, HERA Report R4-100 [9]. This is being replaced in November 2003 with an expanded second edition. The DCB No. 50 article that covers supplementary issues associated with [9] will be revised for the second edition of R4-100 and presented in DCB No. 77 There is also a considerable amount of connection design and detailing information presented in previous DCB issues that is complementary to the guidance presented in [9]. Some of that information was prepared in response to connection issues arising during the preparation of Report R4-100, other topics have been covered independently and subsequently. The information is spread through many DCB issues. The purpose of this article is to briefly present the location and scope of this information to assist designers in making full use of it. The guidance is presented under a series of headings starting with general issues and then moving on to each connection type. Prior to starting this article, a quick reminder to readers of the connection types covered in HERA Report R4-100 [9]. These are:

Web side plate (Designation: WP) Flexible end plate (Designation: FE) Beam to column welded moment

(Designation: WM) Beam to column moment-resisting bolted

end plate (Designations: MEP and STP) Beam to beam moment-resisting bolted

endplate splice with flush endplates (Designation: MEPS)

Bolted welded beam splice (Designation: BWBS)

Bolted compression splice in columns subject to combined actions including axial compression (Designation: BCS)

Bolted tension splice in columns subject to combined actions including axial tension (Designation: BTS)

Pinned column baseplate, column carrying compression and shear (Designation: BP-P).

DCB No. 61, pp. 3-6, presents an amendment to the FE connection provisions of R4-100 [9] This summary covers only design and detailing information complementary to and additional to that presented in Report R4-100. Connections: general issues DCB No. 50, pp. 20-25, covers the following general issues:

General principles of design for connections not subject to potential inelastic demand

General principles of design for connections which are subject to potential inelastic demand

Design actions on connections at the bases of MRF, EBF and CBF seismic-resisting system columns

DCB No. 57, pp. 14-28, covers the design and detailing of panel zones in moment-resisting beam to column connections and supersedes all previous guidance on that topic. It covers rigid and semi-rigid connections to I-section and to hollow section columns. There will be three minor revisions to this procedure made in DCB No. 77, based on advanced FEA of moment-resisting connections undertaken as part of the development work towards the new edition of R4-100. Still current parts of DCB No. 57 will also be presented so that the full guidance is in the new issue. DCB No. 56, pp. 29-32, covers determination of the tension capacity of bolt/plate combinations, for any combination of bolts and plate. Flexible end plate connections Required width of supporting column flange

(or web) is covered in DCB No. 50, p. 12 Welded moment connections Design of tension/compression column

stiffeners is covered on pp. 12-14 of DCB No. 50

Design of the web panel zone, including

doubler plate reinforcement, is covered on pp. 14-28 of DCB No. 57, especially p. 25

Moment end plate connections Design of tension/compression column

stiffeners is covered on pp. 12-14 of DCB No. 50

Column flange requirements (width, tension

capacity) are covered on pp. 15-16 of DCB No. 50. Design of the web panel zone, including doubler plate reinforcement, is covered on pp. 14-18 of DCB No. 57, especially pp. 25-27

MEP connections in category 1 or 2 seismic-

resisting systems are covered on pp. 15-16 of DCB No. 51 (this extends the coverage of [5] to these two categories; R4-100 covers category 3 and non-seismic connections) Note that the panel zone design is now covered by DCB No. 57, pp. 14-28. (The


second edition of R4-100 will introduce a revised MEP connection with thinner, stiffened endplates and covering all categories of seismic demand)

Two design examples are presented on

pp. 16-22 of DCB No. 51 and updated on pp. 15-16 of DCB No. 52 and pp. 22-27 of DCB No. 57, in relation to the panel zones

Beam bolted welded splices R4-100 covers splices between the same

beam size; extending this to splices between beams of different weights within the same designation is covered on pp. 17-18 of DCB No. 50

Column splices R4-100 covers splices between the same

column size; extending this to splices between columns of different weights within the same designation is covered on pp. 18-19 of DCB No. 50

Extending this further to splices between

columns of different designations is covered on pp. 19-20 of DCB No. 50

Semi-rigid joints DCB No. 58, pp. 1-24, presents the design

and detailing provisions for the Flange Bolted Joint (FBJ). There is a minor revision in DCB No. 62, pp. 16-18 and an extension to the original scope of application in DCB No. 64, pp. 3-24

DCB No. 64, pp. 24-33, covers finite

element analysis work undertaken to October 2001 on the Sliding Hinge Joint (SHJ). The full design and detailing procedure for the SHJ is presented in DCB No. 68, pp. 1-32. DCB No. 70, pp. 19-44, presents details of the numerical integration time history analyses and finite element analyses undertaken on systems and joints

Three dimensional views of both joint types

are given in DCB No. 65, pp. 13-15 Following a number of recent requests for a

design procedure for moment-resisting connections into concrete filled CHS columns, the concepts for this have been developed and are available on fax if requested. They will be written up in DCB No. 66.

Brace/beam/column gusset plate connections Design guidance for proportioning the

design actions from the braces into the supporting members of brace / beam / column connections is given in DCB No. 56, pp. 2-5. This design guidance allows the analysis to proceed on the basis that the centrelines of all members intersect, then the joint to be reconfigured to achieve an economical layout without violating this assumption. This article supersedes previous advice on this topic in DCB No. 47

Design concepts for brace / beam / column

connections in a braced steel frame seismic-resisting system are given in DCB No. 56, pp. 5-11

A fully worked connection design

using these concepts is given in DCB No. 61, pp. 9-21, with a minor errata in DCB No. 63, pp. 1-2

Design of a gusset plate is given on pp. 4-5

of DCB No. 47. This is the only part of the article on beam / brace / column gusset connections given on pp. 3-8 of that issue that is still current; the rest is superseded by DCB No. 56, pp. 5-11

Column base connections Design actions on connections at the bases

of seismic-resisting system columns are covered in DCB No. 50, pp. 22-25. That guidance extends the coverage of R4-76 [19] into the column base area for moment-resisting and for braced framed systems

General design guidance on connections at

the bases of seismic-resisting system columns is given in DCB No. 50, pp. 25-26

For moment-resisting column baseplate

connections in seismic-resisting systems, comprehensive design and detailing concepts are given in DCB No. 56, pp. 11-20. This article either references or incorporates the relevant details from DCB No. 50, pp. 22-26, mentioned above

Design of connections for fire endurance Connections that will undergo inelastic rotation during severe fire attack must be suitably designed and detailed to deliver this. The connections in R4-100 [9] have been designed and detailed to achieve this, and the same will apply to the next edition of R4-100.


The semi-rigid connections (FBJ and SHJ) will also achieve this. DCB No. 58, pp. 28-30, presents

recommendations on connection design and detailing for fire endurance between beams and concrete-filled SHS column members

Circular bolted flange annulus connections A design and detailing procedure for externally bolted flange joints between CHS columns of around 650 mm diameter or larger has been developed. The flange plate does not run into the interior of the column, thus leaving this space free for access or for concrete filling. The guidance is contained in three DCB Issues, namely: DCB No. 65, pp. 16-30, presents the design

procedure. It is applicable to splice joints and to joints at the column base on a concrete support. It is applicable to splice joints in associated structural system columns and those that form part of a seismic-resisting system

DCB No. 66, pp. 12-16, presents a worked

design example of a splice joint in a 2 metre diameter column

DCB No. 67, pp. 1-15 presents results of the

finite element analysis verification study Design of unstiffened bolted flange CHS joints, where the flange plate is continuous over the interior of the column, is covered in DCB No. 63, pp. 3-4 and also for a different method in DCB No. 46, pp. 17-18, with an update on pp. 2-3 of DCB No. 61 Miscellaneous connection topics Use of AISI 4140 steel rods as hold-down

bolts is covered on pp. 5-6 of DCB No. 39. Tightening of these bolts is covered on pp. 19-20 of DCB No. 56

Obtaining high strength structural bolts, nuts

and washers in sizes above M36 is covered in DCB No. 52, pp. 3-4, which references back to DCB No. 51, p. 14. This also gives guidance on sizing of nuts when these must be custom made

Suitable bolt tightening equipment for fully

tensioning MSFG bolts larger than M24 (for which an impact wrench is not practical) is covered on p. 24 of DCB No. 56

Details of the Riedbar Brace LOK Load

rated turnbuckled system are given on pp. 2-3 of DCB No. 64

An interesting example of applying lateral thinking in baseplate design is given on pp. 1-2 of DCB No. 14

Design of Structural Hollow Section Members and Connections The DCBs cover a range of topics in regard to SHS members and connections. These are as follows; Design concepts for moment-resisting

connections into concrete filled CHS columns are available by fax on request. They will be written up in DCB No. 76

DCB No. 65, pp. 16-30, presents a design

procedure for circular bolted flange annulus connections

DCB No. 63, pp. 3-4, DCB No. 61, pp. 2-3,

DCB No. 46, pp.17-18, cover design of bolted circular flange joints in tubular structures

DCB No. 58, pp. 25-30, covers design of

SHS columns for fire endurance DCB No. 38, pp. 1-2, reviews two

publications, available from HERA, that provide detailed design guidance on a range of SHS connection types

DCB No. 39, pp. 3-4, reviews the design

guidance, available from HERA, on the DuraGal range of members

Refer also to HERA Report R4-104 [34] for

much information on research and design of tubular members, structures and connections

Design of Members Not Listed Elsewhere This section covers articles on design of members that are not listed elsewhere herein. Beams and columns DCB No. 53, pp. 1-6 and pp. A1-A20,

presents a design procedure for openings in beam webs. An errata is presented in DCB No. 69, pp. 1-2

DCB No. 54, pp. 26, 27 covers rigging restraint for long, isolated columns in compression

DCB No. 52, p. 9, briefly mentions precambering of hot rolled beams, but this topic is now much more comprehensively covered in R4-107-DD [29]


DCB No. 52, pp. 11-13, covers lateral restraint and load bearing capacity in the support regions of continuous beams

DCB No. 64, pp. 38-39, covers restraint of

load-bearing stiffeners in simply supported I-section beams

Preliminary design guidance of beams and columns is covered in the following: For floor systems incorporating Hi-bond

decking, use the excellent preliminary design option from the Hibond Design Wizard [31]

DCB No. 37, pp. 7-9, preliminary design of

composite members using published charts DCB No. 33, pp. 4-5, covers rapid

assessment of fMsx, preliminary sizing of portal frame members, preliminary design of simply supported composite floor beams. (These are presented in earlier DCBs referenced from this issue, especially DCB No. 2, pp. 1-2. The preliminary design guidance for connections presented on pp. 5-7 of DCB No. 33 is superseded by R4 100 [9])

Crane runway girders and rails DCB No. 61, pp. 6-9, overviews the design

of crane runway girders and monorail beams to the provisions of the new standard, AS 1418 Part 18 [30]

DCB No. 47, pp. 18-20, covers crane rails:

materials and attachment systems Cold-formed steel members DCB No. 46, pp. 16-18, introduces the

Cold-formed Steel Structures Standard, AS/NZS 4600 [10], and accompanying design guidance

DCB No. 55, pp. 2-15, presents a detailed,

fully worked design example with commentary for a cold-formed member subject to combined actions

DCB No. 39, pp. 1-3, covers material grades

for cold-formed SHS members Design of Non-Ferrous Metals The DCBs are written principally for structural steel application, so the coverage of non-ferrous metal design is limited to the following:

DCB No. 16, p. 5, overviews an excellent book available from HERA on design for aluminium alloy structures

Reference [35] is a good summary paper,

written in October 2002, on design of stainless steel members. It cross-references to the comprehensive seminar notes on stainless steel material properties, selection and design presented in R4-111 [18] and to the design standard, AS/NZS 4673 [36]

An overview of [36] is given in DCB No. 65,

pp. 31-32 Innovative and Economical Steel Design The following articles on innovative steel applications and economics/costing of steelwork are covered: DCB No. 30, pp. 1-3, presents an article on

the rational way of costing steelwork. The concepts are still current, but the detailed costing provisions are now contained in HERA Report R4-96 [37]

DCB No. 44, pp. 7-8, presents an overview

of the Structural Steelwork Estimating Guide [37]. This is the principal source of estimating guidance for all cost items relating to structural steelwork

DCB No. 52, pp. 22-25, optimising the cost

of multi-storey steel buildings in New Zealand, presents summary guidance on choice of deck, floor beams, gravity columns and seismic-resisting systems for car parking buildings, apartment / hotel buildings and office buildings

DCB No. 64, pp. 37-38, raises three issues

that can cause significant unnecessary fabrication costs. These relate to weld details and to the late changing of member sizes

DCB No. 65, pp. 2-3, covers a new deep

deck profile which has been manufactured in New Zealand since mid-2002. More details on it are given in [38]

DCB No. 72, p. 15 and DCB No. 73, pp. 1-2,

present a case study on a column splice cost comparison

A series of innovative structural steel articles have been published, covering the following: DCB No. 45, pp 13-15, steel structure

supporting a new second storey of classrooms built over existing buildings


DCB No. 46, pp. 16-17, cost-effective V-braced CBF seismic-resisting system with site welded braces. This system has recently been used in a 17 storey building in Wellington

DCB No. 47, pp. 20-21, cost-effective

X-braced, tension only, CBF seismic-resisting system with site welded strap braces

DCB No. 54, pp. 28-30, low-rise car parking

providing increased carpark capacity DCB No. 61, pp. 21-22, 14 storey apartment

building with timber floors (currently the tallest residential building in the world with no concrete in the structure or floors)

Material Properties and Availability Articles on material properties and availability of components are as follows: DCB No. 39, pp. 1-3, covers the grades of

steel plate, flat, sections and SHS commonly available. That article supersedes earlier articles on the same topic, except where these are referenced from that issue

HSFG bolt, nut and washer availability in

sizes above M36 is covered in DCB No. 51, p.14, with further guidance on nut availability in DCB No. 52, pp. 3-4

Details on the Lindapter range of fasteners

is given in DCB No. 38, p.4 and 43, pp. 5-6 Use of AISI 4140 steel rods for hold-down

bolts is covered in DCB No. 39, pp. 5-6 and DCB No. 56, pp. 19-20

DCB No. 8, pp. 4-6, covers availability and

use of the Torque Control (TC) high strength structural bolt

DCB No. 5, p. 2, covers the designation of

steels of UK origin Shear stud availability is covered seperately, under Composite Construction: Welded shear stud design, supply and installation on page 20-21 herein. Publications There are a number of articles on publications/conferences in the DCBs. Details are as follows (the publications are not listed in the references unless they are referenced from elsewhere in this article):

DCB No. 36, pp. 4-5, covers the Composite Floor Preliminary Design Charts

DCB No. 38, pp. 1-4, covers the following:

- Design of Structural Steel Hollow Section Connections, First Edition

- Hollow Structural Section Connections and Trusses

- Design of Semi-Continuous Braced Frames

- Semi-Rigid Connections in Steel Frames

- Seismic Behaviour of Steel Plate Shear Walls

- Various Winstone Wallboards publications covering fire and noise control

- Two publications giving properties of members to overseas design standards

DCB No. 39, pp. 3-5, covers the following:

- Range of DuraGal publications - Building Design Using Cold Formed

Steel Sections: Construction Detailing and Practice

DCB No. 51, pp. 6-9, overviews three useful

publications for bridge design and coatings selection

DCB No. 58, pp. 31-32, covers the status of

the HERA Structural Steelwork Design Guides Vol. 2, as of October 2000

DCB No. 62, pp. 18-19, covers the SCI

publication Appraisal of Existing Building Steelwork

DCB No. 63, pp. 16-17, covers an SCI

publication on the use of steel sheet piles as permanent walls, thereby maximising the use of steel in basements

DCB No. 72, pp. 16, presents a brief

overview of a publication that presents design wind speeds for the Asia-Pacific region. The information is presented in a format compatible with AS/NZS 1170.2 [32]

DCB No. 72, p. 16, presents an overview of

the new AS/NZS 1170.3 [39] which covers design actions from snow and ice

DCB No. 72, pp. 16-17, presents an

overview of the most recent corrigenda to the AISC Design of Structural Connections - 4th Edition.


Research Results Results from HERAs research projects and other structural steel research projects are presented throughout the DCB. Articles presenting research results have already been listed in relation to the topic or topics they cover. Steel Structures Standard, NZS 3404 The following articles relate to NZS 3404:1997 [1], or were written for the 1992 edition and are still current. They are presented in chronological order: DCB No. 16, pp. 3-4, covers am factors for

segments unrestrained at one end and not covered by Table 5.6.2 of [1]

DCB No. 17, pp. 2-8, covers single angle

design DCB No. 29, pp. 4-5, provides the

background to Equations C12.2.3 of [1] DCB No. 34, pp. 1-7, presents an article on

design to NZS 3404:1997 made simple. This topic is covered in more detail in a comprehensive set of seminar notes [31] and an excellent SESOC publication [32]

DCB No. 36, pp. 1-3, presents follow up

questions and answers from the mid-1997 seminar series on NZS 3404

DCB No. 37, p.9, summarises a reference

paper to the NZS 3404 provisions for SHS members. This paper is included in [26], which provides much more comprehensive coverage

DCB No. 43, p. 5, gives a change to the

significant axial force provisions that has been introduced in Amendment No. 1

DCB No. 45, pp. 7-8, presents more

changes introduced via. Amendment No. 1 DCB No. 48, pp. 1-2, presents a partial twist

restraint scenario not covered in the 1997 edition of [1] and which is introduced via. Amendment. No. 1

DCB No. 51, pp. 9-12, gives the background

to two significant changes introduced via. Amendment. No. 1. These relate to bearing at a pin and lateral restraint of inelastically responding members

DCB No. 55, pp. 16-18, gives the background to the revised web slenderness limits introduced via. Amendment. No. 1 for

rectangular and square hollow section members

DCB No. 64, pp. 38-39, covers the restraint of the ends of load bearing stiffeners in simply supported I-section beams

DCB No. 75, pp. 1-5, covers the application

of NZS 3404 to portal frames with limited or no external restraint at the knees.

Composite Construction The listing of DCB articles on composite construction is presented in two groups; first are those relating to composite systems and members, and second are those relating to the design supply and installation of shear studs. Much of the material on composite design and construction has been incorporated into or replaced by the material contained in R4-107-DD [29], R4-112 [4] and R4-113 [17]. Those publications should be referred to as the principal sources of guidance on this topic. The DCB articles that are still current as stand-alone advice on a particular topic are given below. In all instances, they also form part of R4-113 or are referenced from there. Composite members and structures

DCB No. 67, pp. 16-21, covers matters arising from the May 2002 composite seminar series. This should be read in conjunction with [4, 17, 29]

DCB No. 53, most of issue, covers design for openings in the webs of composite beams. An errata is presented on pp. 1-2 of DCB No. 69

DCB No. 35, pp. 4-5, overviews the COBENZ 97 spreadsheet program for composite beam design

DCB No. 29, p. 7, gives a reference for the design capacity of Hilti shear connectors

Welded shear stud design, supply and installation

DCB No. 55, pp. 18-28, covers the concepts involved in determining the design shear capacity of shear studs. Use when the application is outside the scope of NZS 3404, except for

DCB No. 45, pp. 8-11, covers the design shear capacity of shear studs with precast hollowcore slab units. However, those provisions should only be used for HCUs of up to 250 mm thick and in accordance with the restrictions of [17]


DCB No. 74, pp. 1-5, covers the welding and testing of shear studs in accordance with the new Joint Stud Welding Standard, AS/NZS 1554.2 [8]. That standard and the DCB guidance covers all levels of stud welding machine technology, including wet weather capable machines

Miscellaneous Items This article on whats in the DCB from Issue No. 1 to Issue No. 68 ends with a listing of miscellaneous items that are still current but have escaped mention earlier. They are presented in chronological order.

DCB No. 1, pp. 1-2, introduces the HERA Limit State Design Guides Volume 1 [12]

DCB No. 21, p. 5, gives details of Gib Fireboard, which was introduced at that time (May 1996)

DCB No. 23, pp. 5-7, covers results from the experimental testing of large-scale, beam to column joints, undertaken to verify the design model presented in R4-76 [19] (and also in DCB No. 11, pp. 2-6)

DCB No. 28, p. 5, references a US paper giving the design capacity of bolted moment-resisting endplate connections with multiple bolt rows at the beam tension flange. An alternative to the use of that paper is to determine the capacity from first principles, using the SCI Publication No. 207/95 as is covered in DCB No. 56, pp. 29-32

DCB No. 31, p. 10, gives a short article on the difference between nominal and characteristic yield stress and the significance of each in design

DCB No. 32, pp. 4-5, covers calculating the bending moment in a pin

DCB No. 36, pp. 5-6, overviews an interesting paper on the design of slender, monotubular steel arches

DCB No. 44, p. 7, gives a very brief report

on the 1998 Second World Conference on Steel in Construction

DCB No. 46, p. 1 and p. 18, mentions some of the structural steel topics covered by the 1998 Australasian Structural Engineering Conference

DCB No. 63, pp. 15-16, gives an overview of design aids for structural steelwork published by or obtainable from the Australian Institute of Steel Construction

Finally, to end on a more whimsical note and show that the DCB is not (quite) all work and no play, DCB No. 70, pp. 46-47, presents an Engineer's view of Santa Claus (which concludes he can't exist). DCB No. 71, pp. 2-3, presents the rebuttal (which concludes that he can).

References 1. NZS 3404: 1997, plus Amendment No. 1:

2001, Steel Structures Standard; Standards New Zealand, Wellington, New Zealand.

2. Clifton, GC; Restraint Classifications for

Beam Member Moment Capacity Determination to NZS 3404: 1997; HERA, Manukau City, 1997, HERA Report R4-92.

3. Design Capacity Tables for Structural Steel,

Third Edition, Volume 1: Open Sections; Australian Institute of Steel Construction, Sydney, Australia, 2000.

4. Khwaounjoo, YR; Report and Users Manual

for NZF1_Vib 1 Program (Program for the Analysis of Floor Vibration); HERA, Manukau City, New Zealand, 2002, HERA Report R4-112.

5. Murray, TM et. al.; Floor Vibration due to

Human Activity; American Institute of Steel Construction, 1997, Steel Design Guide Series 11.

6. Allen, DE et. al.; Minimising Floor Vibration;

Applied Technology Council, Redwood City, USA, 1999, ATC Design Guide; 1.

7. Clifton, GC; HERA Specification for the

Fabrication, Erection and Surface Treatment of Structural Steelwork; HERA, Manukau City, 1998, HERA Report R4-99.

8. AS/NZS 1554.2:2003, Structural Steel

Welding Part 2: Steel Welding (Steel Studs to Steel); Standards New Zealand, Wellington.

9. Hyland C; Structural Steelwork Connections

Guide Incorporating Amendment No. 1; HERA, Manukau City, New Zealand, 1999/2001, HERA Report R4-100.

10. AS/NZS 4600:1996, Cold-Formed Steel

Structures; Standards New Zealand, Wellington.

11. NZS 4203:1992, General Structural Design

and Design Loadings for Buildings; Standards New Zealand, Wellington, New Zealand.


12. Clifton, GC; Structural Steelwork Limit State Design Guides Volume 1; HERA, Manukau City, 1994, HERA Report R4-80.

13. Bird, GD; MemDes V2 Program for

Member Design to NZS 3404, Version 2; BHP New Zealand Steel, Auckland, 2001.

14. AS/NZS 4671: 2001, Steel Reinforcing

Materials; Standards New Zealand, Wellington.

15. Zaki, RJ et. al.; "Shear Stud Capacity in

Profiled Steel Decks", Report Done as Part of ME Study Requirements at the School of Engineering, Civil Resource Engineering, University of Auckland, September, 2003.

16. AS/NZS 2312:2002, Guide to the Protection

of Structural Steel Against Atmospheric Corrosion by the Use of Protective Coatings; Standards New Zealand, Wellington.

17. Clifton, GC (Editor); Notes Prepared for a

Seminar on Composite Steel Design and Construction; HERA Manukau City, New Zealand, 2002, HERA Report R4-113.

18. Clifton, GC (Editor); Notes Prepared for the

Designing Stainless Steel Structures Seminar; HERA, Manukau City, 2002, HERA Report R4-111.

19. Feeney MJ and Clifton G C; Seismic Design

Procedures for Steel Structures; HERA, Manukau City, 1995, HERA Report R4-76 ; to be read with Clifton, GC; Tips on Seismic Design of Steel Structures; Notes from Presentations to Structural Groups mid-2000; HERA, Manukau City, 2000.

20. Clifton, GC; Tips on Seismic Design of Steel

Structures; Notes from Presentations to Structural Groups mid-2000; HERA Manukau City, 2000.

21. Clifton, GC and Feeney, MH; Fire

Engineering Application to Multi-Storey Steel Structures; The Inaugural New Zealand Metals Industry Conference, Rotorua, 2002, Paper No. 14; HERA, Manukau City, 2002.

22. Clifton, GC and Robinson, J; Notes

Prepared for a Seminar on The Behaviour and Design of Multi-Storey Steel Framed Buildings for Severe Fires, Revised June 2001; HERA Manukau City, 2001, HERA Report R4-105.

23. Clifton, GC and Forrest, E; Notes Prepared

for a Seminar on Design of Steel Buildings for Fire Emergency Conditions; HERA, Manukau City, 1996, HERA Report R4-91.

24. C/AS1: 2001, Approved Document for NZBC

Fire Safety Clauses C1, C2, C3, C4; Building Industry Authority, Wellington.

25. Mago, N and Clifton, GC; Stage 2

Development of the Slab Panel Design Method; HERA, Manukau City, 2003, HERA Report R4-118.

26. Barber, DJ; HERA Fire Protection Manuals

Sections 7 and 8, Passive / Active Fire Protection of Steel; HERA, Manukau City, 1996, HERA Report, R4-89.

27. Barber, DJ; Calculation of the Fire

Resistance of Composite Concrete Slabs With Profiled Steel Sheet Under Fire Emergency Conditions; HERA, Manukau City, 1994, HERA Report R4-82.

28. Noise Control Handbook; HERA/SCI-NZ,

Manukau City, 2003. 29. Clifton, GC; Draft for Comment: Control of

Deflection and Placement of Concrete in Composite Floor Systems; HERA, Manukau City, 2002, HERA Report R4-107-DD.

30. AS 1418.18; 2001, Cranes (Including Hoists

and Winches) Part 18: Crane Runways and Monorails; Standards Australia, Sydney, Australia.

31. Bird, GD and Klemick, MP; HiBond Design

Wizard for Composite Design of the Hi-Bond Flooring System, Version 1.2; Dimond, Auckland, 2003.

32. AS/NZS 1170.2:2002, Structural Design

Actions Part 2: Wind Actions; Standards New Zealand, Wellington.

33. Mago, N; Verification of Revised MEP

Procedure, FEA Study; HERA, Manukau City, 2003, HERA Report R4-120.

34. Hancock, GJ. et.al.; Notes Prepared for the

Tubular Structures Seminar; HERA, Manukau City, 2001, HERA Report R4-104.

35. Clifton, GC; Design of Cold-Formed

Stainless Steel Structures; The Inaugural New Zealand Metals Industry Conference, Rotorua, 2002, Paper No. 30; HERA, Manukau City, 2002.

36. AS/NZS 4673:2001, Cold-Formed Stainless

Steel Structures; Standards New Zealand, Wellington.


37. Hyland, C; Structural Steelwork Estimating Guide; HERA, Manukau City, 1998, HERA Report R4-96.

38. Stickland, S; Corus Deep Composite Floor Deck; The Inaugural New Zealand Metals Industry Conference, Rotorua, 2002, Paper No. 16; HERA, Manukau City, 2002.

39. AS/NZS 1170.3:2003, Structural Design

Actions Part 3: Snow and Ice Actions; Standards New Zealand, Wellington.

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