Over recent years SCI has experienced a steady increase in demand for its thermal modelling services of construction details in fire. The SCI uses finite element software to model the junction detail or element of construction which enables temperature profiles to be obtained for the constituent parts. From the temperature data obtained, the structural performance of the components can be determined at elevated temperatures. For steel components above 400°C the strength is determined using strength reduction factors from BS EN 1993-1-2, and a similar procedure can be applied to other structural materials.

The finite element models can include components of various different materials which need to be modelled accurately in the software. Thermal properties of the materials such as thermal conductivity [W/mK] and specific heat capacity [J/kgK] need to be specified. For many materials these properties vary with temperature. The variation with temperature in specific heat capacity and thermal conductivity of the steel is given in BS EN 1993-1-2. For other materials such as plasterboard, concrete and insulation these properties - and how they vary with temperature - are not so readily available.

Therefore, it is often necessary to calibrate finite element models against test data. This may typically be achieved using temperature data recorded during fire testing of an element of construction e.g. a wall or floor which includes the same materials in a similar arrangement to the construction detail being modelled.

Another aspect to consider is that not all components will be permanent in a fire situation. For this reason, SCI has developed a methodology of thermal modelling which allows specific components of the detail to be removed from the model at a specific time, the methodology then allows the analysis to continue from the point where the element was removed with a continuation of the temperature profiles.

The furnace or fire temperatures as defined in Eurocodes are generally applied in the finite element models, although of course these could be modified if there was a specific fire scenario that needed to be considered. The location of the furnace (i.e. heat source) relative to construction detail being examined needs careful consideration and skill by the modeller as this can be significant to the results. The SCI has carried out this type of thermal analysis for fire conditions for a range of construction details, including;

• Composite slab support details
• Hot-rolled steel edge beams
• Light steel fame walls and junctions
• Composite slabs
• Steel beams embedded in concrete
• Hot-rolled hollow section columns in modular frames

The results of these thermal models are generally used to determine the structural resistance at specific fire durations e.g. 60, 90 or 120 minutes. With the aim being to demonstrate that there is sufficient resistance (R) in the fire condition especially once the reduced design load has been considered at the accidental fire limit state. In some cases, the results can be used to evaluate the fire insulation (I) performance by review of surface temperatures on the unexposed side of an element.

For more information or if you are in need in SCI's services in this field please contact Andrew Way at SCI.

Junction detail of a composite slab supported by light steel wall

Edge beam exposed to fire from external side

Now available to purchase:
Design of Light Steel Sections to Eurocode 3 - ED005

Light gauge cold-formed steel members (generally referred to as light steel sections) are commonly used in a range of building types as secondary steelwork (e.g. purlins and cladding rails in industrial buildings) and as the primary load-bearing elements in light steel frames (e.g. in residential buildings). They may be used as individual structural members (e.g. floor joists) or as part of a structural frame.

In Eurocode 3 Design of steel structures, design rules for such members in the UK are given in several separate Parts, notably BS EN 1993-1-1, BS EN 1993-1-3 and BS EN 1993-1-5, each together its National Annex.

Previously a member only resource, this report is now available to purchase on the SCI Shop, and is prepared to aid designers in the application of the various rules in those documents, particularly in the applications in wall panels and floors.

Available as an electronic copy only.

To purchase a copy go the SCI Shop

Bridge Publications

The Steel Bridge Group has recently revised its guidance in relation to setting out bearings given in SCI P185, P382, P406 and P418. The revised guidance provides more clarity in terms of the permissible deviations for the purpose of setting out bearings and the responsibility of each construction party (designer, fabricator and contractor) to avoid their exceedance. An electronic copy of the updated publications is available to download from The SCI Shop or SCI Steelbiz and I H S.

Steel Bridge Group: Guidance notes on best practice in steel bridge construction sixth issue - P185/6
This is the 6th issue of the Guidance Notes produced by the Steel Bridge Group (SBG), a technical forum established to consider matters of high-priority interest to the steel bridge construction industry.

The 60 Notes contained in this publication offer guidance on best practice in steel bridge construction, explaining many construction processes and their influence on design and specification. Although aimed at bridge designers, many of the Notes offer general information that will be helpful to all designers of structural steelwork.

It complements the publication Steel Bridge Group: Model Project Specification (P382), which was written for use in conjunction with EN 1090-2.

This is an Electronic Document only.

Shop

Steel Bridge Group: Model project specification for the execution of steelwork in bridge structures (P382)
This publication provides a set of clauses to be used in bridge project specifications, that responds to the options and alternatives allowed in BS EN 1090-2, the execution standard for steelwork designed to Eurocode 3. The clauses are arranged under the headings in BS EN 1090-2 and for each clause a commentary is given, explaining the context of or background to the clause. The document has been prepared by the Steel Bridge Group and is intended to achieve the same quality and reliability as has been achieved with BS 5400-6. Revised, January 2012. (A separate document is available, in Word format, of the clauses alone, without commentary, to facilitate use in project documents.)

This is an Electronic Document only.

Shop

Determining design displacements for bridge movement bearings (P406)
Bridges are usually constrained against horizontal displacement by providing a fixed bearing at one support and movement bearings that permit linear displacement of their upper parts relative to their lower parts at other supports. Such displacements occur principally due to thermal expansion and contraction.

This publication provides guidance on the determination of design values of linear displacements for bridge movement bearings, for use in specifying the requirements for bearings designed and manufactured in accordance with EN 1337.

This is an Electronic Document only.

Shop

Steel Bridge Group: Completion of Appendix 18/1 (418)
This document provides guidance on the completion of an 'Appendix 18/1' document, to supplement the requirements of the Highways England and Network Rail client specifications for highway works and for railway steelwork.

This is an Electronic Document only.

Shop

The new Advisory Desk service emails sent this month included;

Advisory Desk Note - AD 413
Shear resistances of M12 Bolts

Advisory Desk Note - AD 415
Vertical tying of columns and column splices

If you are an SCI Sole Trader or Corporate Member and not receiving these emails alerts go to the SCI Information Portal and in your Profile click on notifications/alerts and select the notifications you require.

All the Advisory Desk Notes and Questions and Answers together with other technical resources are all available at all times on the SCI Information Portal.

For SCI Sole Trader and Corporate members, SCI offers support through our Advisory Desk Service. For questions asked which we feel are pertinent to the wider member audience we publish anonymously the questions and answers.

Where some questions relate to SCI Publications we publish the question and answers in Connect.

This month our published question is about;
Lap joints with single bolts

Question: Why does a single bolt in a lap joint need a hardened washer under both the bolt head and nut, according to
BS EN 1993-1-8 clause 3.6.1(10)?

Please see the answer to this Advisory Question/Answer - Ref No AD_QA_7158-21 and all Advisory questions on the SCI Information Portal.

The Advisory Desk Service is for SCI Corporate and Sole Trader Members advisory@steel-sci.com | +44 (0) 1344 636525

SCI Online Training Courses

Steel Frames and Disproportionate Collapse Rules

This online course is delivered in 3 sessions
Part 1 - 22 June 2021
Part 2 - 23 June 2021
Part 3 - 24 June 2021

Time: 10:00-12:00

This course provides a solid introduction into the design of steel framed buildings to avoid disproportionate collapse. The guidance provided is in accordance with the current Building Regulations, the Eurocodes and Approved Document A which all require that disproportionate collapse must be considered in the design of all buildings.

The course content includes an introduction to the concepts of disproportionate collapse, structural integrity and robustness, an explanation of all the regulatory and Eurocode 1 Part 1.7 requirements, strategies for compliance and workshops which enable delegates to apply some of the theory learnt during the course.

It is aimed at practicing engineers who need a general introduction or update on robustness and the issues which need to be considered when designing to avoid disproportionate collapse and comprises a set of lectures supplemented by a number of examples to ensure that basic ideas are understood.

Member Rate - £250.00
SCI Non-Member - £330.00

For more information and to book this course click here.

Next SCI Member webinar is;

Continuous Composite Beams
15 June 2021
Time: 12:30-13:30

Continuous composite beams offer greater resistance and increased serviceability performance, which may be of interest for long spans or heavily loaded floors. The steel tonnage is typically decreased in comparison with a simply supported beam. However, a more complex slab reinforcement detailing is required.

This webinar gives an introduction to the design of continuous composite beams in buildings according to Eurocode 4. Topics covered include different types of beam analysis, cross section design, member design and detailing.

Register here to view this webinar

For a list of webinars, on-line public courses visit the
SCI Information Portal

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