ultra shallow floor beams - macsteel service centres sa ... · pdf fileit is helpful to the...

USFBTM Design Guide

Ultra Shallow Floor Beams

Contents

01 Introduction

02 What is a USFB?

03 Floor Depths & Degree of

Symmetry

04 Span Range / Span-to-Depth

Ratio

05 Deflection & Pre-cambers

06 Services Through USFBs

07 Fire & Corrosion Protection

08 Design Software

09 How To Specify USFBs

10 Practical Details

11 Practical Detailscontinued

12 Macsteel Technical Support

contact us

13 USFB Design Enquiry Form

MASTEEL TRADING MACSTEEL Trading entered into an agreement with Europe’s leading supplier, inventor and patent holder of cellular

beams, ASDWestok (Pty) Ltd. The licence agreement allows Macsteel to manufacture and distribute cellular

beams throughout Africa and the Indian Ocean Islands. Macsteel Trading has recently acquired an additional licence to

manufacture and distribute Ultra Shallow Floor Beams.

Macsteel Trading has an extensive branch network in Southern Africa. It provides economies of scale and exceptional

service levels to the mild steel, special steel, pipes and fittings, fluid control, and value added markets.

Macsteel Trading is committed to the highest quality service and workmanship.

Cellular Beams

Cellular beams have proved to be one of the most significant developments in steel construction since their introduction

in 1987. They have been used in over 6000 projects in over twenty countries. Cellular beams can be used in a variety of

applications. Their primary use is as secondary floor beams to achieve long spans and service integration. They are used

as roof beams beyond the range of portal-frame construction, and are the perfect solution for curved roof applications,

combining weight savings with a low-cost manufacturing process. Cellular beams provide a very economical method of

producing tapered members, which have been used extensively in sports stadiums. They can also be used as gable

columns and wind-posts.

Ultra Shallow Floor Beams

The USFB (Ultra Shallow Floor Beam) is a new generation of beam, which massively extends the existing range of steel

options available for the flat slab market. USFBs can be shallower, making them ideal for projects in the Residential,

Health, and Education sectors in particular. This guide explains the principle of USFB design and suggests details for

typical applications. Macsteel Engineers are available to support the professional design teams in developing the

structural scheme, and to assist the fabricator in finalising the details for the USFB.

ULTRA SHALLOW FLOOR BEAM DESIGN GUIDE

01

INTRODUCTION

WHAT IS A USFBTM? USFB stands for ‘Ultra Shallow Floor Beam’. This is a new steel beam which considerably extends the existing

range of steel options available for the flat slab market. USFBs

are designed to meet the client’s required floor depth and are

manufactured in as little as 1mm increments. USFBs as shallow

as 160mm have been used in the UK.

The USFB is formed by welding two highly asymmetric

Cellular Tees along the web (Fig. 1). The deck or slab sits on

the wide bottom flange, producing a very shallow overall

construction zone.

USFB has numerous regularly spaced cells in

the web to permit the passage of reinforcement tie bars

(Fig. 2). The cells and/or elongated web openings can also

be used for the passage of services should this be required.

All standard floor construction systems can be combined

with the USFB to produce the minimum depth floor for a

given span. The biggest advantages are gained by integrating

the USFB into either pre-cast or metal deck construction.

WHAT IS A USFBTM?


02

Fig. 1 Two highly asymmetrical Cellular Tees are welded along the web

Fig. 2 Regularly spaced cells permit the passage of reinforcement tie bars

FLOOR DEPTHS There is no ‘standard’ USFB. The most important single

benefit to the Client and Engineer is that they can first decide

the precise required floor depth and then use the USFB

AutoMate software to design the optimum USFB to suit

that exact depth.

It is likely that the Client will have different depth

requirements in different areas of the building. The USFB

can easily cope with this, as it can be designed and

manufactured in as little as 1mm increments.

In the UK, USFBs as shallow as 160mm have been

designed. Such shallow members allow the use of most

widely available decking profiles, which sit within the

depth of the USFB.

FLOOR DEPTHS & DEGREE OF ASYMMETRY


03

Fig. 3 Minimum clearance for pre-cast units

Again, there is no ‘standard’ asymmetry. It has become

accepted practice in the industry to provide designs with

the bottom flange clearance a minimum of 75mm* from

the top flange for the pre-cast units, and 50mm for insitu

metal decks – see Fig. 3.

USFB AutoMate will design whatever degree of

asymmetry is input by the Engineer.

DEGREE OF ASYMMETRY

* Pre-cast (PC) units can have a minimum end bearing of 50mm (using the close bearing detail as specified by the PC unit manufacturers

SPAN RANGE The span range of the USFB extends beyond that previously

associated with this type of construction. The USFB is

totally bespoke. A top tee cut from any Universal Beam (UB)

or Universal Column (UC) can be married with any bottom

tee generally from a UC. In the UK spans of up to 12 metres

have been achieved.


04

George IV Bridge, Edinburgh (UK) – Eight floors of hotel & retail space with floor depths as shallow as 160mm

The USFB is designed to the Engineer’s and Client’s

specifications. Therefore, the span-to-depth ratio is not

fixed or even typical.

Once the Engineer inputs the layout, loading and the

exact depth or maximum depth required, USFB

Automate will design the optimum beam without those

parameters.

SPAN-TO-DEPTH RATIO

SPAN RANGE & SPAN-TO-DEPTH RATIO

DEFLECTION & PRE-CAMBERS As with traditional Cellular Beams, pre-cambers in the USFBs can be specified at no additional cost. The component

tees of the USFB can be easily set to the required pre-camber before they are welded together – see Fig. 4.


05

George IV Bridge, Edinburgh (UK) – Eight floors of hotel & retail space with floor depths as shallow as 160mm

DEFLECTION & PRE-CAMBERS

Fig 4 : USFB pre-camber set up in the assembly jig prior to rewelding. Cambers are free of charge

Phoenix Medical Centre, Newbury (UK) – 9.2m span USFBs, carrying pre-cast units and cambered 27mm

SERVICES THROUGH USFBs Whilst the cells in a USFB are predominantly used for rebar

to tie the slab together, there is an obvious ability to pass small

services and ducts within the depth of the steel beam.

This further reduces the overall depth of floor construction.

Web openings can be circular or elongated (see Fig. 5), which

considerably increases the size of ducts that can be

accommodated. Elongations may also be supplied to suit

irregular rebar layout requirements. These can be discussed

with Macsteel Engineers to establish optimum locations.


06

SERVICES THROUGH USFBs

Fig 5 : Elongated openings required for irregular layout of rebar

FIRE & CORROSION PROTECTION Fire protection to meet the required resistance

period should be provided to the bottom flange.

For normal internal conditions, it is accepted

good practice that sections to be encased in

concrete are left unpainted (except the soffit

and the edges of the bottom flange, as they

remain exposed) to maximize the bond between

steel and cast concrete.

Sections to be uncased and the edge conditions

should be considered in relation to the environ-

mental conditions pertaining to the project.


07

FIRE & CORROSION PROTECTION

Right: Watersmeeting Medical Centre, Bolton – USFBs ranging from 280mm to 325mm in depth. The bottom flange only was fire protected with on-site intumescent

DESIGN SOFTWARE All design programs are written and maintained by the Steel Construction Institute in the UK on behalf of ASD Westok.

The testing of the outputs from all the programs is now more rigorous than ever before and subject to far higher

standards of quality management than previously applied. The new suite of software includes:

Cellbeam Automate v7.0

An updated and improved version of Cellbeam featuring an Add-to-Table functionality, updated range of deck profiles

and many interface improvements including a new link to the CellVibe software.

USFB Automate v1.0

Ultra Shallow Floor Beams (USFBs) facilitate extremely shallow floor construction and can now be designed with ease

using this new software, featuring an Automate facility. By selecting the Automate option the user can obtain weight-

optimized USFB designs, based on minimum or fixed construction depth. Analysis are carried out at the construction

and normal stages, with slab options including composite metal decking, in-situ concrete and pre-cast (PC) units.

The interface, which is based on the Cellbeam model, also includes a direct link to the CellVibe software.

CellVibe v1.0

In 2007 the SCI (UK) produced publication P354 ‘Design of Floors for Vibration: A New Approach’. A feature of this

publication was the ‘simplified method’ for the evaluation of the dynamic response of regular grid floors. The new

CellVibe software utilizes the P354 simplified method to provide an easy-to-use and rapid evaluation of the dynamic

response of floors. Suitable for up to 6x6 bay rectilinear grid arrangements, CellVibe includes provision for metal deck,

in-situ concrete and PC unit slabs. CellVibe also allows data to be imported from Cellbeam and USFB software.


08

DESIGN SOFTWARE

Please note that the design

software is available free of

charge. Please contact us to

request a copy

HOW TO SPECIFY USFBs It is helpful to the tendering steelwork contractor / fabricator, and ultimately to the steel detailers, if USFBs are noted in

a consistent manner. Several approaches are possible, but the notation and the detailed tabular specification given below

are the most commonly used.

USFB Notation: Example:

USFB depth: 250mm

Top tee: 203 x 203 x 52 kg/m UC

Bottom tee: 305 x 305 x 97 kg/m UC

USFB 250 x 203/305 x 74.5 kg/m

a : 250mm overall depth of USFB

b : 203mm nominal top tee flange width

c : 305mm nominal bottom tee width

d : 74.5 kg/m USFB mass

Tabular Specification:

Cell Data Mark

Section

Reference Material

Mass

(kg/m) Steel Grade

Tee Depths*

(mm) Diam (mm) Pitch (mm)

USFB 1 250x203/305x74.5 Top: 203x203x52

Bot: 305x305x97 74.5

S355

S355

100

150 75 150

* It is very common that the tees are asymmetric in depth as well as flange width

Tee depths can be specified to Macsteel by the Engineer from the outset should they be relevant, e.g. for

particular services to run through. The USFB AutoMate software can print out beam elevations showing the

cell arrangement, infilled cells, tee depths, etc.


09

HOW TO SPECIFY USFBs

a b c d

PRACTICAL DETAILS There is a wealth of available data on best practice details

for very shallow combined steel/concrete floor construction.

These details can also be used for USFBs.

The options shown below are therefore merely indications

only of typical construction details that may be adopted for

USFBs. The Consulting Engineer should satisfy himself that

they meet the requirements for the codes applicable to a

particular project.


10

PRACTICAL DETAILS

Compatible Floor Systems

All standard floor construction systems can be combined

with USFB to produce the minimum depth floor for a

given span.

• Pre-cast hollow core units

• Pre-cast solid planks

• Metal deck (re-entrant, trapezoidal or deep deck)

• Timber joints

The greatest advantages are likely to be gained by integrating

the USFB into either pre-cast or metal deck construction. The

Consulting Engineer should satisfy himself that any floor

system adopted is suitable for the intended purpose.

In order to provide a suitable bearing for the floor system

on the bottom flange, the following minimum outstand for

the lower flange is recommended in line with existing good

practice and proprietary slab manufacturers guidance.


11

PRACTICAL DETAILS Continued

• Pre-cast hollow core and pre-cast plank = 75mm*

bearing

• Metal deck = 50mm bearing

• Timber joints = 50mm bearing

(NB: Please consult manufactures for specifications)

Edge cantilevers are easily and efficiently achieved by

passing rebar through the cells in the USFB. For

external conditions suitable cold bridging details

should be used.

* PC Units can have a minimum end bearing of 50mm (using the close bearing detail as specified by the PC unit manufacturers)

OFFICE BASED DESIGN SERVICE Macsteel Trading has an office based design service to provide free advice and design assistance. To help optimize the

design of specific projects and assist engineers to gain familiarity and expertise in cellular beam and ultra shallow floor

beam (USFB) design, Macsteel Trading engineers will attend project design meetings.

TECHNICAL SEMINARS In house technical seminars can be arranged to promote the efficient design of cellular beams and USFBs, and

proficiency with the associated software. Design courses are also held on an annual basis to provide a step by step

approach to designing cellular beam and USFBs using our software.

CONTACT US

Design, Technical Assistance and Quotations

PAOLO TRINCHERO National Steel Product Director

Cnr Simon Bekker and Crompton Roads, Germiston South PO Box 7729, Johannesburg, 2000, South Africa

Tel: (011) 871 4600 Fax: (011) 871 4667

Email: [email protected] / [email protected]

TEBOGO RAALEKA Structural Engineer


Tel: (011) 871 4600 Fax: (011) 871 4667

Email: [email protected]

Fabrication and Quotations

GEORGE NIEUWOUDT Manager: Production / Value Added Services


Tel: (011) 871 4660 Fax: (011) 871 4654

Email: [email protected]


12

TECHNICAL SUPPORT

USFB Design Enquiry Form CONTACT DETAILS Company : Name : Address : Email : Tel : Fax : PROJECT DETAILS Project Title : Beam Ref :

LAYOUT Span : m NOTES / ADDITIONAL INFORMATION Distance to adjacent beam LHS : m

Distance to adjacent beam LHS : m

INSITU CONCRETE Slab : mm Top Mesh :

Deck Type : Thickness : Grade : MPa Weight : (tick) Normal : Lightweight :

PC UNITS Thickness : mm Mass : kN/m2 Structural Topping Thickness: mm Mass : kN/m2

LAODING Live (unfactored) : kN/m2

Partitions (unfactored) : kN/m2 Services & Finishes (unfactored) : kN/m2 Other (unfactored) : kN/m2

LIMITS EITHER Maximum Depth D 1 : mm OR Maximum Depth D 2 : mm * Bearing Dimension X : mm Minimum Natural Frequency : Hz ** Live Load Deflection : mm

13

TM

Note: Exclude self-weight of deck & slab

Leave blank if no limit



* Unless otherwise

instructed we will assume min.

75mm Precast, or min. 50mm Insitu

** DEFLECTION DUE TO DEAD LOAD SHOULD NOT

BE A CRITICAL FACTOR, AS USFBs CAN BE PRE-

CAMBERED AT NO EXTRA COST PHOTOCOPY THIS FORM & FAX YOUR ENQUIRY TO US: FAX (011) 871 4666

D1 D2

X

THIS FORM IS PROVIDED AS A TEMPLATE PLEASE PHOTOCOPY & FAX BACK

CELLULAR BEAM - PAST PROJECTS

AWARDS AND COMMENDATIONS 2007 : SAISC SPECIAL COMMENDATION

2008 : SAISC OVERALL WINNER – MAPONYA MALL

2009 : SAISC ARCHITECTURAL STRUCTURES – GOTTLIEB GROUP

CONTACT US

MACSTEEL TRADING (PTY) LTD

Cnr Simon Bekker and Crompton Roads, Germiston South

PO Box 7729, Johannesburg, 2000, South Africa Tel: (011) 871 4600 Fax: (011) 871 4667

Email: [email protected] / [email protected]

A Africa Trade Centre Alberton City Shopping Centre AMH Centurion Motor Dealership Anchor Steel Arcelor Mitsui Building Durban B BB Auto - Polokwane Motor Dealership Bidvest Siemens Bliss Chemicals Wadeville BMW Lyndhurst Motor Dealership C,D,E Cape Town High Court Citroen Centurion Motor Dealership East Rand Nissan F,G,H General Motors Gottlieb Offices & Distribution Centre Greenstone Hill Office Park Heineken Sedibeng Breweries Factory Hospital Privado de Maputo Honda Motor Dealership

I,J,K Impala Platinum Toll Offloading & Sampling Facility Imperial Select - Atlas Road Jumbo Cosmo Cash & Carry Kia Motors - Northcliff King David Linksfield Sports Pavilion Kisumu Airport Kenya Klerksdorp Fresh Produce Market Kwanobuhle Shopping Centre L,M,N Liberty Building Cape Town Macsteel Trading Rustenburg Factory Maponya Mall Soweto Mariental Steel Namibia Mauritius Commercial Bank MTN Head Office O,P,Q Oostenburg Waste Facility PE Coldstore Uitenhage Pick 'n Pay Centurion Lifestyle Centre Pick 'n Pay Maponya Mall Pietermaritzburg Taxi Rank

Polokwane International Airport Terminal Building Project Vital Cape Town R,S,T,U Renault Northcliff Motor Dealership Safcor Siemens Distribution Centre Sinaba Multipurpose Stadium Spinning Mill Mauritius Spirit Word Ministries - Stilfontein Tongaat Sports Facility Toyota SA Motors Mezzanine Ulundi Transport Facility V,W,X,Y,Z Vilanculos Airport Maputo

Website: www.macsteel.co.za/cellbeam

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